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Antenna design is a mature field of research; it is therefore rare that a new approach arises in view of the traditional methods. In the past antennas had simple form based on Euclidean geometry. Fractal antennas do not follow this design. Their complex structure is built up through replication of a base shape. The purpose of this research is to explore fractal element antennas, through simulation and design experimentation. This research revealed unexpected results, which provided additional insight into these unique structures. Results of MoM and FDTD simulation methods as well as measurements of physical models of the circuit- and field-antenna parameters are presented and discussed. Measurements well confirmed simulation.

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... A fractal is a geometric object which is usually folded/meandered shape in all magnification ratio that can be subdivided into parts which are the approximation to the whole geometry [4,5]. Fractals are known as infinitely complex because of its similarity at all levels of magnification [6]. ...

... Fractal geometry has many applications in life and opens new research directions in many fields such as biology, economics, art, etc. [4,7]. The fractal antenna is usually compact and operates at multiple frequencies, where some important characteristics of fractal geometries can be applied to as self-similarity, to operate the multi-band antenna, self-filling of the fractal to design the small antennas, mass and boundary fractals to design an antenna array [4,5,8]. ...

... At each side of the square patch, remove a rectangle with an area of it (L 1 × D 1 ). The dimensions of each side L 1 and D 1 are scaled by the ratio L 1 = L/A, and D 1 = L/B, where 1/A and 1/B are called the scaling factors, corresponding to 1/δ in (5). In general, for generic Minkowski island fractal geometry, the values of A, B are equal, A = B = 3. ...

This study presents an antenna design that operates at the three bands of the Global Positioning System (GPS) receiver. The optimised Minkowski island fractal structure combined with the central window is used to design the radiation surface to reduce the size and adjust the resonance frequencies of the antenna. The antenna was designed, and simulated by HFSS computer code, and was fabricated on microwave laminate FR4‐epoxy by fast laser prototyping. The resulting fractal antenna has been operating at three GPS‐bands: fL2 = 1.227, fL5 = 1.176, and fL1 = 1.575 GHz, with return loss S11 < −15 dB, bandwidths BW > 21.5 MHz, for VSWR < 2, at 50‐Ω input impedance, the power gains ∼2.4, 2.85, and 4.2 dBi, and axial ratio of right‐handed circular polarisation 1.5, 03, and 06 dB at fL5, fL2, and fL1, respectively. The simulated and experimental results agree favourable.

... Low-frequency and wide vibration AZs are expected to obtain a better vibration reduction effectiveness in general. More recently, the waves scattered by fractal configurations (Sierpinski carpet and Sierpinski gasket) have been noted by many researchers [18][19][20][21][22][23][24]. However, the fractal periodic mediums were primarily studied in respect to photonic materials [18][19][20], while research on phononic crystals and periodic elastic mediums has also been carried out [21][22][23][24]. ...

... More recently, the waves scattered by fractal configurations (Sierpinski carpet and Sierpinski gasket) have been noted by many researchers [18][19][20][21][22][23][24]. However, the fractal periodic mediums were primarily studied in respect to photonic materials [18][19][20], while research on phononic crystals and periodic elastic mediums has also been carried out [21][22][23][24]. Fractal structures can be applied to tune the light beaming, which can be used for an optical communication system [18][19][20]. ...

... However, the fractal periodic mediums were primarily studied in respect to photonic materials [18][19][20], while research on phononic crystals and periodic elastic mediums has also been carried out [21][22][23][24]. Fractal structures can be applied to tune the light beaming, which can be used for an optical communication system [18][19][20]. Analogously, the sound waves and elastic waves can be also scattered by fractal structures in the forms of Sierpinski carpet and gasket [21][22][23][24]. ...

This work investigated the dispersion curves of phononic crystals with quasi-Sierpinski carpet unit cells via improved plane wave expansion method. The position vector derivative method was applied to generate Sierpinski and quasi-Sierpinski carpet unit cells. Wave dispersion mechanisms of fractal phononic crystals were investigated by calculating the vibration modes of unit cells. The results show that (quasi-)fractal phononic crystals are benefit for obtaining multiple and wider band gaps, especially for the second stage case. For quasi-Sierpinski carpet unit cells, the multiple band gap feature becomes much more obvious due to the increase of the filling fraction. Numerical analysis of a finite quasi-fractal phononic crystal indicated the potential application of phononic crystals with quasi-Sierpinski carpet unit cells.

... More recently, the wave propagation dispersed by fractal or quasi-fractal structures have been explored by many researchers. These fractal or quasifractal structures exist primarily in Sierpinski gasket [23][24][25][26][27] or Sierpinski carpet [27][28][29][30][31] form. In a study on the Sierpinski gasket, Krzysztofik [23] presented a modified Sierpinski fractal monopole antenna and found that fractal technology allows design of smaller, high-performance multiband antennas. ...

... These fractal or quasifractal structures exist primarily in Sierpinski gasket [23][24][25][26][27] or Sierpinski carpet [27][28][29][30][31] form. In a study on the Sierpinski gasket, Krzysztofik [23] presented a modified Sierpinski fractal monopole antenna and found that fractal technology allows design of smaller, high-performance multiband antennas. Castiñeira-Ibáñez et al. [24,25] developed an optimized Sierpinski fractal technique that enables the creation of a wide band gap in an acoustic case. ...

... Research to date on periodic structures has two points remained to be proven. Firstly, the unit cell or the structure considered to be the Sierpinski carpet has been mainly studied with respect to photonic materials [23,26,27,29,30] while research on Sierpinski-carpet phononic crystals or periodic structures has been fairly rare [28,31]; the properties of elastic wave propagation in periodic structures with a traditional Sierpinski-carpet form were neglected. The dispersion curves of periodic structures due to different stages have not studied comprehensively, either. ...

In this study, the dispersion relationships and characteristics of directional periodic structure waveguides with Sierpinski carpet unit cells were investigated. Finite element method was used to analyze the Sierpinski-carpet periodic structures with square Pb cylinders inserted in the rubber background. The dispersion curves of unit cells with different stages were investigated first, then group velocities of periodic structures at given frequencies were calculated and used to analyze the directional waveguide characteristics in the Sierpinski-carpet periodic structures. The dynamic responses of finite periodic structures were investigated to observe the directional features, and the results were used to support the fact that Sierpinski carpet unit cells with different stages can control the propagation behavior of elastic waves in specific ways; the dispersion curves grew compressed as the stage increased. Multiple band characteristics were observed in the case of the second-stage fractal configuration. The directional propagation characteristics in Sierpinski carpet periodic structures can be utilized to further extend the range of vibration reduction zones. The results of this study have significant potential in terms of the application of Sierpinski-carpet periodic structures for vibration isolation.

... Therefore in the last years there is a strong interest in fractal-shaped antennas usage in telecommunication devices. Their characteristics largely correspond to those challenges -multiband usage and relatively small sizes [1][2][3][4][5][6][7][8][9]. ...

... Many authors attempt to adjust the boundaries of the frequency bands using a modification of known fractal structures [1][2][3][4][5][6][7]. In [1] is proposed multiband fractal-like antennas based on triangle monopole antenna with trapezoidal slot or slots for achieving operation in several frequency bands. ...

... In [1] is proposed multiband fractal-like antennas based on triangle monopole antenna with trapezoidal slot or slots for achieving operation in several frequency bands. In [2] are investigated similar structures and the antenna based on Sierpinski fractal in which only the bottom triangle of the fractal is developed to the next iteration. Similar fractal structures are discussed also in [3][4][5]. ...

In this paper modified Sierpinski gasket fractal antenna is proposed. It is based on combination of first, second and third Sierpinski fractal iterations. The modified antenna features small size and relatively high gain. The performance (return losses and radiation pattern) of this antenna is investigated and compared to a simple monopole and deterministic Sierpinski gasket. The antenna is fine-tuned to accommodate the full frequency range Wi-Fi 2.4 GHz and 5 GHz bands.

... However, they present also some disadvantages, where the most limiting are: a narrow bandwidth (for patches); low efficiency and gain; radiation from feed and junction and low power handling capacity. Among the fractal shapes used for antennas: the von Koch curve, the Minkowski curve, the fractal tree, the Sierpinski (gasket and carpet) fractals and the Cantor set are the most usual [8]. ...

... The Sierpinski gasket is created by subtracting a central inverted triangle from a main triangle shape (Figure 2; n = 0). In each iteration the middle triangle(s) are removed from the antenna, preserving three (first iteration) or nine (second iteration) equally sized triangles, which are one-half or one-forth the height of the original triangle (zero iteration) [8]. From (1), it can be observed that the height of each sub-gasket will determine the resonant frequencies of the antenna. ...

This paper presents new communication solutions to smart grids in the home area network
based on the existent wireless facilities. Different types of wireless systems: cellular networks and
WLAN are analyzed. The large number of available frequency bands, for these systems, point to a fractal
multiband antenna solution. A Sierpinski gasket antenna has been designed for cellular systems
(GSM 900, DCS 1800 and UMTS) and a Minkowski island to both cellular networks and WLAN
communications. The system was thereafter implemented and tested using SMS messages to support
communications between the EV and the infrastructure. This can be used to accomplish V2G energy
exchange, thus allowing efficient energy management on the smart grid.

... These reasons bring new challenges to antenna design and in the resent years there is a strong interest in fractal-shaped antennas usage in wireless communications. Their characteristics largely correspond to those challengesmultiband usage and relatively small sizes [1][2][3][4][5]. ...

... These multiband fractal-like antennas operate in several frequency bands and the dimensions of slots allow adjustment of the edges of the bands. In [2] are analyzed similar structures and the antennas designed as Sierpinski fractal in which only the bottom triangle of the fractal is modified by development to the next iteration. In some papers [5] are presented modified Sierpinski fractal antenna with non-equilateral and non identical triangles. ...

In this paper the dielectric substrate width influence on frequency properties of the modified Sierpinski gasket monopole antenna are investigated. Return loss and radiation pattern of antennas with different width of substrate was simulated and analyzed. Increase of the dielectric substrate width lead to decrease of the frequencies bands but also narrow them.

... We also refer to the recent survey papers [20,21] for an extensive study of the literature and state of the art summary of fractal antenna research. The reader may also consider exploring the articles [19,20,22,23] for more detailed analysis, various types and applications of fractal antennas available in the literature. ...

Fractals are geometric shapes and patterns that can describe the roughness (or irregularity) present in almost every object in nature. Many fractals may repeat their geometry at smaller or larger scales. This paper is the second (and last) part of a series of two papers dedicated to an eclectic survey of fractals describing the infinite complexity and amazing beauty of fractals from historical, theoretical, mathematical, aesthetical and technological aspects, including their diverse applications in various fields. In this article, our focus is on engineering, industrial, commercial and futuristic applications of fractals, whereas in the first part, we discussed the basics of fractals, mathematical description, fractal dimension and artistic applications. Among many different applications of fractals, fractal landscape generation (fractal landscapes that can simulate and describe natural terrains and landscapes more precisely by mathematical models of fractal geometry), fractal antennas (fractal-shaped antennas that are designed and used in devices which operate on multiple and wider frequency bands) and fractal image compression (a fractal-based lossy compression method for digital and natural images which uses inherent self-similarity present in an image) are the most creative, engineering-driven, industry-oriented, commercial and emerging applications. We consider each of these applications in detail along with some innovative and future ready applications.

... With the advancement of wireless communication technology, multiband antenna has played a very crucial role in the wireless personal area network [1][2][3][4][5][6][7][8][9]. Mobile devices, such as hand-held computers and smart phones, are widely using wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) [10][11][12][13][14]. e WLAN/WiMAX module, used to avail of these environments, is capable of operating at multiple frequency bands. ...

This paper proposes a novel multiband antenna using circle and triangle fractals for wireless application. By cutting a triangle slot in the circular monopole, a novel fractal method of the circular nested triangle structure is presented. The above structure is iterated four times, which forms the proposed fractal antenna. The antenna adopts the microstrip feeding method. In order to improve out band rejection and expand bandwidth, a ring resonator is designed on the back of the dielectric plate. The designed antenna covers 1.8 GHz–2.9 GHz applied to Bluetooth, TD-SCDMA, WCDMA, CDMA2000, and LTE33-41, 3.4 GHz–4.6 GHz applied to LTE 42/43 and WiMAX, and 5 GHz–5.6 GHz applied to WLAN. The substrate is FR4 with a dielectric constant of 4.4 and a loss tangent of 0.02. The size of the fabricated antenna is 87.5 × 61 × 1.6 mm. The measured pick gain achieves 2.98 dBi, 2.58 dBi, and 3.34 dBi at 2.6 GHz, 3.8 GHz, and 5.3 GHz, respectively. The measurement and simulation results are in good agreement, which verifies the rationality of the design.

... This leads to the requirement of a large space for antennas for different communications. In order to mitigate this difficulty, multiband antennas can be designed and only one antenna can be made to work at several frequency bands as indicated in figure 1 [2]. The multi-band behavior design of the antenna can be achieved by incorporating fractal structures in microstrip antennas. ...

... A comparison of the parameters and characteristics of the proposed antenna with other similar fractal monopole antennas recently reported in the literature is given in Table 4 to highlights the improvement and novelty of the antenna structure. It can be seen that the proposed fractal antenna has two main advantages compared to antennas in References [34][35][36][37][38][39][40]. The primary advantage of the proposed antenna structure is that it exhibits a wide bandwidth with a relatively small size F I G U R E 1 4 Simulated and measured normalized radiation patterns of the proposed antenna at 2.44, 2.535, 3.45 and 5.5 GHz because two techniques (described in Section 2.1) were applied to broaden the bandwidth. ...

A novel flexible polymer/fabric fractal monopole antenna with a wideband performance is presented. A thin sheet of highly conductive fabric and a natural rubber‐based composite have been used for conductive and non‐conductive parts of the antenna, which allow keeping the antenna as flexible and thin as possible. The proposed antenna has been simulated, prototyped and tested. Results show that the antenna has a simulated impedance bandwidth of 3.8 GHz (2.2–6.0 GHz) and a measured impedance bandwidth of 3.7 GHz (2.3–6.0 GHz) to cover the most commonly used standards in wireless communication systems. The radiation efficiency of the antenna reaches over 93% throughout the operating frequency band with satisfactory radiation patterns and gain.

... The printed UWB monopole antenna consists of a monopole patch and a partial ground plane. Various geometries (rectangular, circular, elliptical, triangular, hexagonal, etc.) of the monopole patch have been implemented to achieve UWB behavior [3][4][5][6][7][8]. The most commonly used definition for the UWB antennas is the bandwidth ratio (high frequency to low frequency ratio) [9], [10] and typically, these antennas can achieve an impedance bandwidth ratio up to 4:1. ...

A novel reconfigurable antenna covering an 11.5:1 bandwidth is designed and fabricated for cognitive radio applications. The proposed novel antenna has two independent paths to cover 430 MHz to 5 GHz frequency range. The first path is directly connected to an ultra-wide-band antenna, which covers 1–5 GHz operation frequency range. The second path, for the frequency range between 430 MHz and 1 GHz, goes through a dc-controlled varactor based matching network. The switching functionality between wideband (1 to 5 GHz) and reconfigurable region (430 MHz to 1 GHz) is realized by two discrete switches. The designed antenna has a simple structure and compact size of 60 mm × 100 mm. The proposed novel antenna has great potential for use in cognitive radio systems.

... This is one of the most popular fractal structure used for multiband performance and can be constructed from a triangle. The self-similar current distribution on these antennas is expected to cause their multi-band characteristics [6] . ...

... Fractal is a natural phenomenon or a set of mathematical structures often have folded on any magnification ratio, it can be split into sections, each small part of it looks like the overall but with a smaller rate. Some characteristics and importance of fractals [4], [14] are as: infinite detail, optionally small scales; usually identified by simple recursive processes (IFS); too unusual to be described in traditional Euclidean geometric language; have some sort of self-similarity structure in the different magnification ratio; have fractal dimension. ...

The design of fractal antenna covering two-bands of WLAN-MIMO system is presented. To achieve compact size and dual frequency operation the Minkowski fractal island were
used. The design and numerical simulations were done by means of HFSS software. The antenna operates at 2.443 and 5.261 GHz WLAN-bands. The overall dimension of the antenna is 23×23 mm2. Antenna was fabricated on microwave laminate FR4- epoxy. The numerical and experimental results agree favorable

... Fractal is a natural phenomenon or a set of mathematical structures often have folded on any magnification ratio, it can be split into sections, each small part of it looks like the overall but with a smaller rate. Some characteristics and importance of fractal [7]: • have detail at arbitrarily small scales; • are usually defined by simple recursive processes; • are too irregular to be described in traditional geometric language; • have some sort of selfsimilarity; • have fractal dimension. ...

This paper presents the design of a compact size Sierpinski carpet fractal antenna, operating in C-band with two resonant frequencies of TV satellite system, namely (3.625-4.2) GHz, and (5.85-6,425) GHz. Antenna is designed on FR4 microwave laminate, with return loss S11<-18 dB. Bandwidth of antenna is BW> 80 MHz, for VSWR<2, at 50 ohm input impedance. To achieve compact size, despite of fractal structure advantage authors used the probe feed and shorting pins on antenna aperture. The design optimization was supported by means of HFSS computer code. Simulated as well as experimental result agree favorable.

... These antennas many times use designs where part of it is active for one band, and another part is active for other band [3]. Microstrip patch antenna is a promising choice for the future technology because of its advantages like light weight and low profile [4][5][6]. Fractal geometry deals with self-similar shapes that remain unchanged under different scales [7]. Combine fractal geometry with electromagnetic theory have led to access of new shapes in antenna designs [8]. ...

Fractal shapes has unusual properties. These unique features will affect antenna parameters when designed in fractal shapes. Two fractal shapes combined together to generate new fractal shape dipole antenna. Seirpinski and modified Koch fractal shapes allow this antenna to operate at too far apart frequencies lies in X and K band. Fractal dimension of modified Koch is found to be 1.08 which led the antenna to be electrically small. This is explaining the resonant points at higher frequencies. Uniting X and K band in single antenna will make the possibility of combining the applications of these two bands in one device. Good results have been obtained from calculating antenna parameters.

... Now a day communication systems uses multiband antennas to overcome its developing requirements. Wireless local area network (WLAN) and (WiMAX) have been vastly applied in mobile devices particularly in smart phones [1,2]. The quick developments of wireless communication system have made antenna designs to focus on multiband and small simple structures that can be easy to fabricate. ...

Bandwidth of the operating frequency of an antenna is an important parameter in antenna design. It is strongly related to the performance of data rate. Hence to get more data rates for mobile applications, much higher bandwidths are needed. Frequency bands lies above 6 GHz, characterized by more continuous frequency range than bands below 6 GHz. This gives more chance to meet these requirements. To this end Pentagon fractal antenna is proposed here. It has multiband behavior and very good gain and directivity with excellent efficiency which make it very suitable for above 6 GHz applications.

... These antennas many times use designs where part of it is active for one band, and another part is active for other band [3]. Microstrip patch antenna is a promising choice for the future technology because of its advantages like light weight and low profile [4][5][6]. Fractal geometry deals with self-similar shapes that remain unchanged under different scales [7]. Combine fractal geometry with electromagnetic theory have led to access of new shapes in antenna designs [8]. ...

Fractal shapes has unusual properties. These unique features will affect antenna parameters when designed in fractal shapes. Two fractal shapes combined together to generate new fractal shape dipole antenna. Seirpinski and modified Koch fractal shapes allow this antenna to operate at too far apart frequencies lies in X and K band. Fractal dimension of modified Koch is found to be 1.08 which led the antenna to be electrically small. This is explaining the resonant points at higher frequencies. Uniting X and K band in single antenna will make the possibility of combining the applications of these two bands in one device. Good results have been obtained from calculating antenna parameters.

... In that study, Sierpinski and Koch monopole antennas were initiated, and these fractal antennas have multiband performance over different frequency bands as shown in Figure 8. Such performance Emerging Microwave Technologies in Industrial, Agricultural, Medical and Food Processing is based on the repetitive nature of the fractal structures, bends and corners [12][13][14][15], and some more fractal antennas such as modified Sierpinski monopole, modified half-Sierpinski gasket and Mod-P Sierpinski fractal antennas were introduced for multiband applications in [16][17][18]. Fractal Array Antennas and Applications http://dx.doi.org/10.5772/intechopen. 74729 19 Like Sierpinski fractal gasket antennas, Sierpinski fractal carpet structures have also been used in the designing of antenna elements [19]. ...

... Now a day communication systems uses multiband antennas to overcome its developing requirements. Wireless local area network (WLAN) and (WiMAX) have been vastly applied in mobile devices particularly in smart phones [1,2]. The quick developments of wireless communication system have made antenna designs to focus on multiband and small simple structures that can be easy to fabricate. ...

Bandwidth of the operating frequency of an antenna is an important parameter in antenna design. It is strongly related to the performance of data rate. Hence to get more data rates for mobile applications, much higher bandwidths are needed. Frequency bands lies above 6 GHz, characterized by more continuous frequency range than bands below 6 GHz. This gives more chance to meet these requirements. To this end Pentagon fractal antenna is proposed here. It has multiband behavior and very good gain and directivity with excellent efficiency which make it very suitable for above 6 GHz applications.

... This is one of the most popular fractal structure used for multiband performance and can be constructed from a triangle. The self-similar current distribution on these antennas is expected to cause their multi-band characteristics [6] . ...

A modified Sierpinski Gasket fractal antenna for multiband application is proposed in this paper. The modified ground plane and the microstrip feed are used to obtain the wider bandwidth at the resonance frequency. The antenna is designed and printed on two layers FR-4 substrate (ϵr=4.4 and h=1.6 mm) to cover the UMTS and 2.4/5.2 WLAN. The radiation pattern of the proposed antenna is similar to an omnidirectional. The proposed antenna has maximum gain of 1.88, 1.6, 4.31 dB at 2, 2.4, 5.2 GHz, respectively The properties of the antenna such as return losses, radiation pattern, input resistance and gain are determined via numerical CST Microwave Studio 2010 software.

... The geometry of fractal antenna in the form of a Sierpinski gasket is completely determined by four parameters: the height h of the triangle, the countersink angle α, the number of iterations I, and by the scaling factor (δ = h i /h i + 1 , where h i is the height of triangle). As it was described in Ref. [20], the Sierpinski monopole behaves like the antenna of logarithmic-periodic geometry [16,19,29] ( Figure 8c), with the each next resonant frequencies separated by the distant relative but reversed to self-similarity scale factor δ = 2. The antenna has similar parameters for the next resonant frequency, with a moderate bandwidth BW = 21% [15À17, 28,29,48]. ...

... The need to satisfy these important requirements has given rise to a strong research activity that led to the development of a large class of antennas. In this context, of particular interest are the wideband [33][34][35][36][37][38], the multiband [39][40][41][42][43][44][45][46][47][48], and the UWB printed monopole antennas, simple [49][50][51][52][53][54][55][56][57] and with notched bands to avoid interference with other radio communication systems [58][59][60][61][62][63][64][65][66][67][68] or those suitable for supporting the circular polarization [33,[69][70][71]. A large class of geometries (rectangular, circular, elliptical, triangular, hexagonal, annular, etc.) has been proposed in order to improve the impedance matching of said antennas with the feeding line, generally consisting of a microstrip line, simple or tapered [40-42, 51-57, 62, 69, 72, 73], or based on a coplanar waveguide (CPW) having a single or multiple transition [34,35,39,60,71,74]. ...

A comprehensive review concerning the geometry, the manufacturing technologies, the materials, and the numerical techniques, adopted for the analysis and design of wideband and ultrawideband (UWB) antennas for wireless applications, is presented. Planar, printed, dielectric, and wearable antennas, achievable on laminate (rigid and flexible), and textile dielectric substrates are taken into account. The performances of small, low-profile, and dielectric resonator antennas are illustrated paying particular attention to the application areas concerning portable devices (mobile phones, tablets, glasses, laptops, wearable computers, etc.) and radio base stations. This information provides a guidance to the selection of the different antenna geometries in terms of bandwidth, gain, field polarization, time-domain response, dimensions, and materials useful for their realization and integration in modern communication systems.

... Wojciech et al. presented modifications on traditional Sierpinski gasket by controlling the space factor between the first two resonances and achieved significant size reduction. Their proposed antenna features several controlling parameters which makes it very flexible in terms of band allocation and fine-tuning [13]. Kritikos et al. [14] described a detailed insight into the advances in fractal electromagnetics and multiband behavior of fractal shaped structures when used as antenna radiators. ...

A planar modified Sierpinski–Meander hybrid fractal antenna suitable for future wireless communication networks capable of exhibiting heptaband behavior has been presented in this paper. Proposed radiating structure is obtained by combining a modified Sierpinski gasket and Meander like antenna (for lower frequency) to obtain a hybrid structure exhibiting multiband behavior. Difficulty of designing a complex fractal structure has been eased by using scripting method (*.vbs) in HFSS obtained from IFS and MATLAB. Proposed antenna has partial-defected L-shaped ground structure which helps to obtain higher values of Gain. It has dimensions of 54 × 46 × 1.6 mm3 and resonates at 2.4, 4.437, 5.38, 7.01, 7.60, 8.41 and 9.09 GHz which covers useful applications like Bluetooth, WLAN, Wi-Fi, ISM, RFID, 4G/LTE, radiolocation and mobile/fixed satellite service. Prototype of the proposed structure is fabricated on FR4 substrate and tested. Measured results are analyzed and compared which are in good agreement with the simulated ones.

... This deviation is observed for standard as well as perturbed Sierpinski gaskets. Estimated formulas were given for standard and perturbed Sierpinski gaskets, to locate the operational frequencies [11,[14][15][16]. The formula developed in [14] is applicable for perturbed structures, but this also provides a compromised value for the first band. ...

A neural network (NN) based analysis model is developed for locating the operating frequencies of generalized Sierpinski fractal antenna. The developed model can locate the operating frequencies of standard as well as perturbed antennas. The performance of the neural model is validated with simulations as well as with results reported in literature.

... Otherwise ground plane equal to the length and width of substrate has been utilized for the analysis of initial antenna design. The degree of similarity between the resonant frequency bands of the Sierpinski gasket triangle is notified by referring the scaling factor S f [25]. ...

Immense understanding of antenna designers illustrate that a general microstrip antenna demonstrate low efficiency. Various techniques have been adopted to improve the performance characteristics of microstrip antenna. This paper deals with the optimization of Sierpinski fractal antenna structure by utilizing the particle swarm optimization (PSO) and curve fitting method. The required data for optimization and fitting the curve has been obtained by varying different design parameters of the proposed antenna. Electromagnetic solver Ansoft HFSS 13.0 is used for generating the parametric data. The MATLAB curve fitting tool is referred for developing the equations which exhibits the relations between the parameters of proposed antenna design. Particle swarm optimization technique is then applied to find the optimum values of the design parameters for the bandwidth enhancement of proposed antenna. Curve fitting based optimized design represents the remarkable improvement in the bandwidth of conventional microstrip line fed Sierpinski fractal antenna for broadband applications.

... However, the typical antennas are usually large in size due to the operating wavelength, so they are difficult to meet the requirements of modern antennas. There are several techniques used to decrease the size of antenna, such as incorporating a shorting pin in a microstrip patch [1], using short circuit [2], and cutting slots in radiating patch [3,4], by partially filled high permittivity substrate [5] or by Fractal microstrip patch configuration [6]. Besides, transmission line metamaterial (TL-MM) [7] is one of the methods that provides a conceptual way for implementing small resonant antenna [8][9][10][11][12][13][14][15]. ...

A compact
2
×
2
metamaterial-MIMO antenna for WLAN applications is presented in this paper. The MIMO antenna is designed by placing side by side two single metamaterial antennas which are constructed based on the modified composite right/left-handed (CRLH) model. By adding another left-handed inductor, the total left-handed inductor of the modified CRLH model is increased remarkably in comparison with that of conventional CRLH model. As a result, the proposed metamaterial antenna achieves 60% size reduction in comparison with the unloaded antenna. The MIMO antenna is electrically small (30 mm × 44 mm) with an edge-to-edge separation between two antennas of
0.06
λ
0
at 2.4 GHz. In order to reduce the mutual coupling of the antenna, a defected ground structure (DGS) is inserted to suppress the effect of surface current between elements of the proposed antenna. The final design of the MIMO antenna satisfies the return loss requirement of less than −10 dB in a bandwidth ranging from 2.38 GHz to 2.5 GHz, which entirely covers WLAN frequency band allocated from 2.4 GHz to 2.48 GHz. The antenna also shows a high isolation coefficient which is less than −35 dB over the operating frequency band. A good agreement between simulation and measurement is shown in this context.

... The more convoluted and longer surface currents result in lowering the antenna resonant frequency for a given overall extension of resonator. Therefore, given a desired resonance frequency, the physical size of the whole structure can be reduced [6]. Antenna Model and Dimensions: Figure 1 shows the fractal aperture antenna with multiple number of slots in a systematic manner. ...

Introduction In the study of antennas, fractal antenna theory is a relatively new area. However, fractal antennas and its superset fractal electrodynamics is a hotbed of research activity. In the research journals, we see reports of active research covering such diverse areas of fractal electrodynamics as the study of scattering from fractal surfaces i.e. a signature of the surface is imprinted within the scattered field to the study of the radiation from lightening. A fractal is a rough or fragmented geometric shape that can be subdivided in parts, each of which is (at least approximately) a reduced-size copy of the whole. Fractals are generally self-similar and independent of scale [1-2]. There are many mathematical structures that are fractals; e.g. Sierpinski's gasket, Cantor's comb, von Koch's snowflake, the Mandelbrot set, the Lorenz attractor, et al. Fractals also describe many real-world objects, such as clouds, mountains, turbulence, and coastlines that do not correspond to simple geometric shapes [3]. Fractal antenna theory is built, as is the case with conventional antenna theory, on classic electromagnetic theory. Fractal antenna theory uses a modern (fractal) geometry that is a natural extension of Euclidian geometry. The effects of electromagnetic waves on fractal bodies have been intensively studied in recent years. Different from Euclidean geometries, fractal geometries have two common properties, space-filling and self-similarity. Self similar objects look roughly the same at any scale [4-5]. Thus, in an antenna with fractal shape, similar surface current distributions are obtained for different frequencies. The space filling property, when applied to an antenna element, leads to an increase of the electrical length. The more convoluted and longer surface currents result in lowering the antenna resonant frequency for a given overall extension of resonator. Therefore, given a desired resonance frequency, the physical size of the whole structure can be reduced [6]. Antenna Model and Dimensions: Figure 1 shows the fractal aperture antenna with multiple number of slots in a systematic manner. The current model is designed and simulated using commercial EM Simulator HFSS. HFSS can link field data between multiple HFSS models to capture the entire behaviour of the Antenna system from transmitter to receiver. The applications of HFSS are Antenna systems, advanced package co-design for single and multi-chip integration, On-chip passives and High-speed packages and interconnect. The dimensions of the antenna includes 56.7X42.9X1.6 mm. Feed location along Y-axis at 14.3 mm and feed length of 11.9 mm with coaxial inner radius of 1.19 mm and outer radius of 4 mm. Figure 1. Fractal Antenna Model Results and Analysis:

... Koch fractal geometry exhibits well-known features that have been used to construct miniaturized monopole and loop antennas [23][24][25]. By applying the Koch fractal shape to the antennas, the overall electrical length of the antennas increases and the resonance frequency becomes lower than that of conventional monopole, loop, and patch-type antenna. ...

Different fractal antennas based on aperture
coupled feeding technique are studied, analysed and
compared for size reduction, low profile, and good
omini‐dirctional pattern suitable for RFID applications.
The results are used as a guideline to propose modified
fractal shapes patch antennas having lower size
reduction parameters. All the designed antennas are
based on zero ‐ order square patch antenna where
different fractal geometries are introduced to
miniaturize the size of antenna for 5.8 GHz band. A
maximum reduction in patch antenna size of 59.80 % is
achieved when using modified Minkowski pre‐fractal
patch antenna.

The work presented in this thesis concerns the study and design of frequency reconfigurable antennas for wireless application systems. After introducing the printed antennas, including the characteristics of this type, feeding techniques, and the description of the fractal antennas, UWB antennas and multiband antennas. A state of the art on reconfigurable antennas and the different types of reconfiguration that exist were discussed. The first part of the practical implementation is focused on the fabrication of new three fractal antennas have to operate at the frequency band allocated by the Federal Communications Commission (FCC) for Ultra-Wideband (UWB) applications. The second part of this thesis, several prototypes of reconfigurable antennas allowing various functions (a switch between multiband mode) were simulated and realized. The approaches more original considered have been implemented with real switches (PIN diode). The experimental results agree with those obtained by simulation and validate a reconfigurable operation mode necessary for multimode communication systems.

In mathematical definition, a fractal is a self-similar subset of Euclidean space whose fractal dimension strictly exceeds its topological dimension which in turn involves a recursive generating methodology that results in contours with infinitely intricate fine structures. Fractal geometry has been used to model complex natural objects such as clouds coastlines, etc., that has space-filling properties. In the past years, several groups of scientists around the globe tried to implement the structure of fractal geometry for applications in the field of electromagnetism, which led to the development of new innovative antenna configurations called “fractal antennas” which is primarily focused in fractal antenna elements, and fractal antenna arrays. It has been demonstrated that by exploiting the recursive nature of fractals, several marvellous kinds of properties can be observed in antennas and arrays. The primary focus of this article is to provide a compressed overview of the developments in fractal-shaped antennas as well as arrays over the last few decades where the most prominent contributions mostly from IEEE journals have been highlighted. The open intention of this review work is to show an encouraging path to antenna researchers for its advancement using fractal geometries.

Current advances in the electrical conductivity levels of conducting polymers (CP) and remarkable improvements in their stability are making these materials very striking potential alternatives to copper in planar antennas. This is mainly so in applications where light weight, inexpensive and conformal antennas are a consideration. There have been isolated efforts in the past towards using conducting polymer as material for antenna and transmission line design. This chapter attempts to give a methodical investigation of key factors that are significant for understanding of these materials, their design and simulation as basis material for building microwave antennas. The proposed conducting polymer-based antenna offers great mechanical flexibility and robustness which indicates its promising potential for possible seamless integration in flexible electronics.

The word “Meta” is taken from Greek whose meaning is “beyond”. “Metamaterials” have the exotic properties beyond the naturally occurring materials. According to Wikipedia, metamaterial is defined as “a material which gains its properties from its structure rather than directly from its composition”.

Material selection is an important step prior to the actual fabrication of any electronic device. Owing to the availability of large set of materials, it is important to select the best possible material in order to enhance the performance of a device. Material selection approaches provide an easy way to recognize the trade-offs between conflicting materials properties and also to select the optimal material for better device performance. In addition to this, these approaches also help us to provide ranking to the alternatives from best to worst. Therefore, these approaches provide a platform to select and prioritize the possible materials and also provide support to perform rigorous evaluation of the possible alternatives. This chapter describes material selection methodologies in detail and explains the steps to be taken for each methodology to find out the most promising material for a given device.

Now a day, due to their several key advantages over the conventional wire and metallic antennas, Microstrip antennas have been used for many applications, such as Direct Broadcasting Satellite (DBS) systems, mobile communications, Global Positioning System (GPS) and various radar systems.
Their advantages include low profile, lightweight, low cost, ease of fabrication and integration with RF devices etc.

In this paper, the design of fractal antenna operating at two frequencies0, 1.228 and 1.5745 GHz, of the GPS satellite system is presented. To achieve compact size and dual frequency operation the Minkowski fractal island and shorting pin on radiating element were used. The design and numerical simulations were done by means of HFSS software. Antenna was fabricated on microwave laminate FR4-epoxy. The numerical and experimental results agree favorable.

This paper presents a multiband antenna based on modified sierpenski fractal structure along with metamaterials for wireless applications. Multi bands are obtained at 2.1 GHz, 5.73 GHz, 7.6 GHz and 8.4 GHz with return losses -21.49 dB,-36.36 dB,-45dB, and -23.46 dBrespectively. The dimension of the substrate used for this antenna is 52 x 60 x 1.6 mm³ and dielectric constant is 4.4 with tanδ of 0.002. The peak gain of 6.6 dB, return loss of -45 dB and VSWR of 1 are obtained at 7.6 GHz. Metamaterial unit cells are loaded on ground to improve the antenna parameters. This is a simple and compact design and has multiband features suitable for WIMAX, WLAN, C-band and X-band applications. This design is simulated by using HFSS 14.

In this paper, the design of fractal antenna operating at two frequencies 0, 1.228 and 1.5745 GHz, of the GPS satellite system is presented. To achieve compact size and dual frequency operation the Minkowski fractal island and shorting pin on radiating element were used. The design and numerical simulations were done by means of HFSS software. Antenna was fabricated on microwave laminate FR4-epoxy. The numerical and experimental results agree favorable.

This paper presents the design of a compact size Sierpinski carpet fractal antenna, operating in C-band with two resonant frequencies of TV satellite system, namely (3.625 – 4.2) GHz, and (5.85 – 6,425) GHz. Antenna is designed on FR4 microwave laminate, with return loss S11 80 MHz, for VSWR<2, at 50 ohm input impedance. To achieve compact size, despite of fractal structure advantage authors used the probe feed and shorting pins on antenna aperture. The design optimization was supported by means of HFSS computer code. Simulated as well as experimental result agree favorable.

A new design etching localized electromagnetic band-gap (EBG) structure on the power plane was proposed to mitigate simultaneous switching noise (SSN) in this paper, of which the unit cell is presented based on Sierpinski space-filling curve for the advantage in miniaturizing. The proposed 6-cells localized board shows good performance whose -40dB noise suppression bandwidth is broaden from 177MHz to 20GHz which is almost covering the whole noise band in UWB applications. Meanwhile, the signal integrity of localized design with single-ended signals is analyzed with eye diagram, proving the new design could also maintain fair signal transmission quality.

In this paper a loop antenna is designed at 2 GHz and its performances is compared with fractal loop antennas. It has been seen that as the order of iteration of the loop antenna increases so does the values of gain, standing wave ratio and reflection coefficient. Standing wave ratio reaches the coveted value of 1 and reflection ratio reaches -10dB which are required for proper matching. It is also found that the fractal loop antenna exhibits improved impedance and Standing Wave Ratio (SWR) performances in a reduced physical area as compared to non-fractal Euclidean geometries. Therefore it is very suitable for direction finding in Radars applications.

High performance structure technology, miniaturization and multi-band methods of internal antenna were investigated. The main research orientations and application characteristics of internal antenna in recent years were summarized. The key technology in the design of high performance internal antennas of mobile terminals such as antenna structured method, combinatorial method, bandwidth enhancement, and loaded method were investigated and analyzed. Meanwhile, based on the practices of actual internal antenna production, we discussed the difficulties in miniaturized, multiband and high performance internal antennas and provided some effective solutions. The research indicated that the advanced manufacturing technology has promoted the implementation of the 2-3 bands internal antenna, however, the implementation of three or more bands should mainly depend on the combinatorial method. Predictably, the new technology of internal antenna is coming to the fore which will promote wider application of mobile terminals and meet the future demand for development of seamless, ubiquitous mobile radio communication network.

This paper presents a unique design for dual band textile antenna. The proposed antenna is well suited for useful ISM band applications. This dual band antenna design is based on a method that uses the principle of self-replication in fractal-like geometries for generating multiband operations. However we have used the first iteration for getting dual band operation. The obtained operating frequencies are 2.45 GHz and 5.8 GHz which covers WLAN, PAN as well as cordless phone bands. The proposed monopole type antenna is built on a flannel cloth substrate with ground plane that is partially present at the back of this substrate. By varying the size of slot present in the monopole we can change the second resonant frequency as per requirement. The antenna is fed through a microstrip feed line. Simulation results show that proposed textile antenna is well suited for ISM band applications. For the first iteration, antenna prototype is fabricated with conductive metalized nylon fabric (Zell) and results are measured on antenna analyzer. The obtained results are in good agreement with the simulation results. This antenna is well suited for medical applications where there is requirement to continuously monitor biometric data for proper health care. Other applications of textile antenna include defense, firefighting and recreation areas.

A novel dual-broadband dielectric resonator antenna (DRA) is presented. The proposed antenna has realised both dual-band and wideband features by applying the modified Sierpinski structure to the antenna design of the proposed DRA. The measured impedance bandwidths for │S11│ < −10 dB are 2.25–2.6 GHz (14.46%) and 3.1–4.1 GHz (27.78%), which can cover the wireless local area network (WLAN, 2.4–2.484 GHz) and the worldwide interoperability for microwave access (WiMAX, 3.4–3.69 GHz) bands. Meanwhile, stable radiation patterns and gains of about 5 and 3.8 dBi at 2.4 and 3.5 GHz, respectively, have been observed.

This paper deals with modified sierpinski fractal wideband antenna design. As research in the field of antenna design has already established, therefore it is exceptional that a novel approach is used over conventional antenna design methods to optimize the existing sierpinski fractal antenna. The implemented antenna exhibits the broadband behaviour in the frequency bands of 12.2 GHz to 13.4 GHz and 21 GHz to 30 GHz in which it follows S11 ≤ -10 dB all through the frequency bands. The measured peak gains within the specified frequency bands vary from 8 dB to 22 dB. This high gain is achieved by employing the modifications to the initial sierpinski geometry. The experimental and measured results of the modified coaxial probe fed sierpinski fractal antenna are also presented. Experimental results are also validated.

The multiband behavior of the fractal Sierpinski antenna is described. Due to its mainly triangular shape, the antenna is compared to the well-known single-band bow-tie antenna. Both experimental and numerical results show that the self-similarity properties of the fractal shape are translated into its electromagnetic behavior. A deeper physical insight on such a behavior is achieved by means of the computed current densities over the antenna surface, which also display some similarity properties through the bands. Peer reviewed

The use of fractal geometry in designing antenna has been a recent topic of interest. It have already proved that fractal shaped have their own unique characteristics that improved antenna achievement. This paper presents about one of familiar geometry in fractal antenna, Sierpenski gasket monopole antenna is proposed for a multiband application. Two different dimension of the antenna has been designed and investigated. The design achieves a good multiband throughout the frequency range from 1 to 10 GHz for both designed

A scheme for modifying the spacing between the bands of the
Sierpinski antenna is introduced. Experimental results of two novel
designs of fractal antennas suggest that the fractal structure can be
perturbed to enable the log-period to be changed while still maintaining
the multiband behaviour of the antenna

The traditional Sierpinski gasket monopole antenna is well known for its multiband behavior, but it cannot be printed on the circuit board of a portable wireless device due to the limited space availability. In this paper a modified Sierpinski gasket monopole antenna is presented that possesses a small physical size, high efficiency and the ability to allocate both the 2.4 and 5.2 GHz Industrial Scientific and Medical bands without the need of a matching network. The modified element respects the multiband behavior of the gasket since the input impedance characteristics of the upper bands maintain their symmetry. Several modification techniques are proposed making the monopole very flexible in terms of band allocation and fine-tuning. The dimensions of the ground plane are also proven to play a significant role on the operational bandwidth of the antenna system.

The contributions of this book represent only a small sample of the work of the many researcher electromagneticians who have had the pleasure of being associated with Professor Papas, either as students or as colleagues. Many of us continue to work in the many and diverse areas that modem electro magnetism encompasses. There is, however, a common thread that was derived from our association with Professor Papas that has greatly influenced our thinking and technical style of expression. Professor Papas, from his studies at Harvard, brought with him to Pasadena a very fundamental and classical point of view that was instilled in all those who were associated with him. He saw research problems as a combination offundamental physical and mathematical principles and the electromagnetic "reality. " He searched and demanded clarity and often, in the rather involved and engaging discussions which took place in his office, he demanded that the "baby picture" be clearly drawn on the blackboard. This requirement, certainly for some of us who were working in widely varied subjects ranging from relativistic plasmas to almost periodic media, has forced us to reexamine the fundamentals. The clear and lucid marriage of fundamental concepts to applications has been the trademark of Professor Papas's intellectual tradition, and has greatly in fluenced the thinking of all of those who have associated with him.

The design of multiband and small antennas has been a challenging problem in the field of electromagnetics engineering for decades. Basically, the problem is that the overall size of the antenna is directly linked to the wavelength such that both a multiwavelength operation and a size reduction become difficult. Although several approaches have been widely proposed in the literature, all of them have been based on particular solutions for specific applications. Recently, the introduction of the fractal technology and some of its first practical applications has opened a wide-scope of new chances in the development of multifrequency and small antennas.

Antennas and antenna arrays are essentially narrowband devices. Their characteristic size determines their operating wavelength. Fractal structures, having no characteristic size and a multiscale self-similar shape, are suggested for the design of multifrequency antennas and arrays. The multiband properties of some fractal arrays and array factors are presented here. Experimental results on multiband fractal antennas are described as well. Fractal antennas are shown to display a multiband behavior from both the return-loss and radiation pattern points of view.

A top-loading technique for monopole antennas which permits us to obtain a multiband performance from a wide set of antenna geometries is presented. Dual-band and a triple-band monopole antenna designs are described in detail, featuring both similar input impedances and radiation pattern across the different bands. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 434–437, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20162

The combination of fractal geometry with electromagnetic theory opens an interesting window for research to find new antenna designs and applications. Fractal technology applications can be divided into six main groups: (1) multifrequency antenna elements, frequency-selective surfaces, and arrays; (2) electrically small antennas; (3) high-directivity radiating elements; (4) low-sidelobe arrays; (5) undersampled arrays; and (6) fast computational methods. This article reviews most of the work done in the fractal technology field covering the last six fields.

A dual-band monopole antenna that permits tailoring the shape of the radiation patterns to provide bidirectional coverage is presented. The antenna provides an optimum input return loss and could be used in those applications where a bidirectional pattern is required. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 445–448, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10490

The space-filling fractal geometry of the Hilbert curve is examined in terms of its effectiveness in lowering resonant frequency. It is demonstrated that the complex geometry associated with the space-filling Hilbert fractal curve is inherently ineffective in lowering resonant frequency compared to other less complex geometries of the same size and total wire length. The effectiveness of the geometry in lowering resonant frequency is a direct function of the current vector alignment established by the wire layout.

In this paper a fractal antenna, namely the modified Sierpinski gasket monopole is presented that possesses a small physical size, high efficiency and the ability to allocate both the 2.4 and 5.2 GHz ISM-bands. The modified element respects the multiband behavior of the gasket since the input impedance characteristics of the upper bands maintain their symmetry. Several modification techniques are proposed making the monopole very flexible in terms of band allocation and fine-tuning. Results of MoM & FDTD -methods of simulations of the circuit- and the field-antenna parameters are presented and discussed

It has been previously demonstrated that the self-similar fractal gap structure of the Sierpinski gasket can be perturbed to modify the periodic behavior of the antenna's multiple operating bands. Here, the central gap structure of the previously described modified Parany Gasket is perturbed, resulting in a similar allocation of operating bands and periodic multiband behavior.

"...a blend of erudition (fascinating and sometimes obscure historical minutiae abound), popularization (mathematical rigor is relegated to appendices) and exposition (the reader need have little knowledge of the fields involved) ...and the illustrations include many superb examples of computer graphics that are works of art in their own right." Nature

The development of safety guides for human exposure to radiofrequency fields (RFF) must be based principally upon the results of animal experiments since, with the exception of obvious heating effects, there is a paucity of quantitative data relating to the action of these fields on mankind. In using the results of animal experiments, one must be careful to distinguish the difference between exposure fields and the fields in the tissues that produce the biological action. This difference, which varies markedly with frequency, body size, and exposure conditions, must be accounted for in the use of animal data for predicting safe human exposure levels over a broad frequency range. Based on a critical evaluation of the world literature on the subject, it is the consensus of the ANSI Subcommittee C95.4 (charged with developing voluntary safety standards for human exposure to RFF) that fields in the tissues should be restricted to levels that would limit average specific absorption rate (SAR) of the energy to less then 0.4 W/Kg. This led to recommended exposure fielde equivalent to 100 mW/cm<sup>2</sup>, for frequencies (f) 0.3 MHz to 3 MHz; 900/f<sup>2</sup> mW/cm<sup>2</sup>, 3 MHz to 30 MHz; 1 mW/cm<sup>2</sup>, 30 MHz to 300 MHz; f/300 mW/cm<sup>2</sup>, 300 MHz to 1500 MHz; 5 mW/cm<sup>2</sup>, 1.5 GHz to 100 GHz.

The novel configuration of a shorted fractal Sierpinski gasket
antenna is proposed. The new configuration is similar to the inverted L
antenna and the shorted loop monopole. Using only half the Sierpinski
gasket structure, the symmetrical side is folded over to be parallel to
the ground plane. While the 50Ω feed remains at the apex, a
shorting pin is placed at the far end of the gasket. A planar
configuration of this design is also demonstrated

A new top-loaded reduced-sized dual-band (1.9 GHz and 3.5 GHz)
monopole antenna for wireless communications is presented. The antenna
provides better than -15 dB input return loss and keeps the same
radiation pattern over both bands. In addition, a low-profile
performance is achieved

A novel configuration of the Sierpinski triangular gasket antenna is proposed. A quasi-log-periodic performance was achieved for the operating bands of GSM, DECT and WLAN by using a new band spacing control technique. This design enhances the input matching performance to well over -10 dB with a 50 /spl Omega/ feed.

Experimental and computed results show a multiband behaviour over
five bands for the new fractal Sierpinski antenna. Such a behaviour is
based on the self-similarity properties of the antenna's fractal shape,
which might open an alternative way for designing new multiband and
frequency independent antennas

Recent efforts by several researchers around the world to combine fractal geometry with electromagnetic theory have led to a plethora of new and innovative antenna designs. In this report, we provide a comprehensive overview of recent developments in the rapidly growing field of fractal antenna engineering. Fractal antenna engineering research has been primarily focused in two areas: the first deals with the analysis and design of fractal antenna elements, and the second concerns the application of fractal concepts to the design of antenna arrays. Fractals have no characteristic size, and are generally composed of many copies of themselves at different scales. These unique properties of fractals have been exploited in order to develop a new class of antenna-element designs that are multi-band and/or compact in size. On the other hand, fractal arrays are a subset of thinned arrays, and have been shown to possess several highly desirable properties, including multi-band performance, low sidelobe levels, and the ability to develop rapid beamforming algorithms based on the recursive nature of fractals. Fractal elements and arrays are also ideal candidates for use in reconfigurable systems. Finally, we provide a brief summary of recent work in the related area of fractal frequency-selective surfaces.

This paper describes novel configurations of shorted fractal Sierpinski gasket antenna. The antenna uses half the structure of a conventional Sierpinski gasket antenna and is folded over to be parallel to the ground plane, to form an element similar to that of the inverted L antenna. A quasi log periodic resonance behavior is obtained with a shorting pin placed at the far end of the antenna. Several configurations are shown and a design using two shorting pins which improves the bandwidth at the fundamental band is also demonstrated.

In personal communications, the electromagnetic interaction
between handset-mounted antennas and the nearby biological tissue is a
key consideration. This paper presents a thorough investigation of this
antenna-tissue interaction using the finite-difference time-domain
(FDTD) electromagnetic simulation approach with detailed models of
real-life antennas on a transceiver handset. The monopole, side-mounted
planar inverted F, top-mounted bent inverted F, and back-mounted planar
inverted F antennas are selected as representative examples of external
and internal configurations. Detailed models of the human head and hand
are implemented to investigate the effects of the tissue location and
physical model on the antenna performance. Experimental results are
provided which support the computationally obtained conclusions. The
specific absorption rate (SAR) in the tissue is examined for several
different antenna/handset configurations. It is found that for a
head-handset separation of 2 cm, the SAR in the head has a peak value
between 0.9 and 3.8 mW/g and an average value between 0.06 and 0.10 mW/g
for 1 W of power delivered to the antenna. Additionally, the head and
hand absorb between 48 and 68% of the power delivered to the antenna

Systematization of the terminal antennas of mobile communication systemsComparative study of different handset-terminals

- J Jedrzejczak

J. Jedrzejczak, "Systematization of the terminal antennas of mobile communication systems—Comparative study of different handset-terminals," M.Sc. thesis, Wrocław Univ. Technol., Wrocław, Poland, 2005.

Fractal-shaped antennas and their application to GSM/900/ 1800 presented at the AP2000 Millennium Conf

- C Puente

C. Puente, "Fractal-shaped antennas and their application to GSM/900/ 1800," presented at the AP2000 Millennium Conf. Antennas Propagat., Davos, Switzerland, Apr. 9–14, 2000.

Fractal monopole antenna for Dual-ISM-Bands applications presented at the 36th Eur EuMCA dual-band bidirectional multilevel monopole antenna

- W J Krzysztofik
- U K Manchester
- Sep

W. J. Krzysztofik, "Fractal monopole antenna for Dual-ISM-Bands applications," presented at the 36th Eur. Microwave Conf. Proc., EuMC-2006, Manchester, U.K., Sep. 10–15, 2006. [20] J. Soler, C. Puente, and A. Puero, "A dual-band bidirectional multilevel monopole antenna," Microw. Opt. Technol. Lett., vol. 34, no. 6, pp. 445–448, Sep. 2002.

Mod-P Sierpinski fractal multiband antenna

- J Soler
- J Romeu
- C Puente

J. Soler, J. Romeu, and C. Puente, " Mod-P Sierpinski fractal multiband antenna, " presented at the AP2000 Millennium Conf. Antennas Prop-agat., Davos, Switzerland, Apr. 9–14, 2000.

The challenge of miniaturization of the handset antennas of mobile communication systems

- W J Krzysztofik
- J Jedrzejczak

W. J. Krzysztofik and J. Jedrzejczak, " The challenge of miniaturization of the handset antennas of mobile communication systems, " in Proc. Nat. Conf. Radio Commun., Radio Broadcast. Television, Kraków, Poland, Jun. 15–17, 2005, pp. 221–224.

Fractal monopole antenna for Dual-ISM-Bands applications A dual-band bidirectional multilevel monopole antenna

- W J Krzysztofik
- U K J Soler
- C Puente
- A Puero

W. J. Krzysztofik, " Fractal monopole antenna for Dual-ISM-Bands applications, " presented at the 36th Eur. Microwave Conf. Proc., EuMC-
2006, Manchester, U.K., Sep. 10–15, 2006.
[20] J. Soler, C. Puente, and A. Puero, " A dual-band bidirectional multilevel
monopole antenna, " Microw. Opt. Technol. Lett., vol. 34, no. 6, pp.
445–448, Sep. 2002.

IEEE Standard for Safety Levels with Respect of Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz

- Std

A dual-band bidirectional multilevel monopole antenna

- J Soler
- C Puente
- A Puero

Sanchez-Hernez Multiband Integrated Antennas for 4G Terminals

- W J Krzysztofik