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An approach to the analysis of microstrip antennas on cylindrical bodies is presented. The printed radiator is replaced by as assumed surface current distribution, and the fields are solved taking into account the presence of the dielectric layer and the metallic cylinder. Calculation takes place in the Fourier domain. The far field, calculated asymptotically from this solution, is used to get the radiation patterns of the wraparound antenna for any dielectric and the half-wavelength patch for epsilon_{r} = 1 .

Content uploaded by Joseph Ashkenazy

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All content in this area was uploaded by Joseph Ashkenazy on Aug 07, 2014

Content may be subject to copyright.

... The tangential H-field on the patch metal can be given using the mode of the cavity model described in previous subsection. If the metal is taken into account as infinite thin, a relation between the surface current and the internal field of the cavity is found [25], [27]. ...

... and ∅ are Fourier transformed current of the -direction and ∅−direction, respectively. The details in regard to the elements of M−matrix can be seen by Ashkenazy et al. [27]. ...

The Federal Communications Commission (FCC) has adopted a new rule, on April 23, 2020, making 1200 Megahertz of frequency spectrum in wireless fidelity (Wi−Fi) 6 GHz frequency band (5.925−7.125) GHz for the unlicensed user. Based on the announcement, a cylindrical shaped antenna resonated at 6.5 GHz frequency is proposed for Wi−Fi applications in the routers through this work. A material named FR4−Epoxy having dielectric constant 4.4 and loss tangent 0.02 is used in substrate layer that builds up the antenna compact enough. The antenna with a dimension of length 60 mm and radius 3.55 mm at all is manifested in a tiny cylindrical shape and consequently, can be a compatible candidate for implementation in wireless routers conveniently. The behaviour of radiation characteristics of cylindrical shaped antenna is analyzed. Circular polarization of radiation surrounding the antenna, a very significant characteristic of an antenna to be applied for Wi−Fi applications, is realized by the proposed antenna. The value of gain, wide bandwidth cohering across the frequency band, minimum value of reflection coefficient and voltage standing wave ratio, high radiation efficiency, and all the other better performances pledge that the antenna is apposite to the Wi−Fi applications.

... The surface current distribution (Figure 7) of the low-profile antenna at three distinct frequencies was analyzed to characterize the patch's key properties. Numerous reported articles have considering various facts like the dielectric layer [42], and key parameter analysis like the radiation pattern, Q factor [43], green function for the wave equation [44], etc. Though limitations in each approach exist, nevertheless, we preferred the green function method since the microstrip patch is thin (z = z ), and the characteristics of the impedance are known. ...

A low-profile high-directivity, and double-negative (DNG) metamaterial-loaded antenna with a slotted patch is proposed for the 5G application. The radiated slotted arm as a V shape has been extended to provide a low-profile feature with a two-isometric view square patch structure, which accelerates the electromagnetic (EM) resonance. Besides, the tapered patch with two vertically split parabolic horns and the unit cell metamaterial expedite achieve more directive radiation. Two adjacent splits with meta units enhance the surface current to modify the actual electric current, which is induced by a substrate-isolated EM field. As a result, the slotted antenna shows a 7.14 dBi realized gain with 80% radiation efficiency, which is quite significant. The operation bandwidth is 4.27–4.40 GHz, and characteristic impedance approximately remains the same (50 Ω) to give a VSWR (voltage Standing wave ratio) of less than 2, which is ideal for the expected application field. The overall size of the antenna is 60 × 40 × 1.52 mm. Hence, it has potential for future 5G applications, like Internet of Things (IoT), healthcare systems, smart homes, etc.

... Such antenna has been the subject of mostly theoretical investigations among researchers. Calculation of the resonant frequencies was done by Krowne [2], while Wu [3] and Ashkenazy [4] calculated the radiation pattern. Luk [5] was presented a theoretical investigation of a thin, cylindrical-rectangular microstrip patch antenna which includes resonant frequencies, radiation patterns, input impedance and Q factors. ...

This article presents design of circularly polarized antenna in planar and curved form with crossed elliptical slots at a diagonal in radiator and ground. The planar antenna offers axial ratio bandwidth (ARBW) of 40.3 MHz, impedance bandwidth (IBW) of 193 MHz, gain of 8.9 dBi and beamwidth in elevation and azimuth plane as 99.41° and 112.92°. The curved antenna offers ARBW of 48 MHz, IBW of 212 MHz, gain of 8.73 dBi with beamwidth in elevation and azimuth plane as 96.4° and 88.84° respectively. The main advantage of proposed design is it offers nearly similar radiation performance in planar and curved form.

This paper presents a new cavity model surrogate-based optimization for electrically thick probe-fed circularly polarized rectangular microstrip antennas. The proposed methodology feeds back input impedance and far-field information from full-wave electromagnetic solvers in order to calibrate known sources of inaccuracy within the cavity model. Said calibration is achieved by solving a constrained non-linear least squares problem. The calibrated cavity model is used to generate a new antenna geometry that will be subjected to the same calibration process until convergence is achieved. The amount of iterations needed to achieve convergence for several configurations is less than or equal to three, this indicates that the cavity model surrogate-based optimization can be used as an efficient design technique. In addition, the optimization process correctly anticipated that unequal fringing field lengths for the resonant modes are required to calibrate the cavity model, demonstrating that great physical insight is gained throughout the optimization process. For the validation of the proposed design procedure, eight electrically thick antennas were designed and optimized, of which three were manufactured and tested. Good agreement between simulated and experimental results were observed, validating the applicability of the proposed strategy.

A wideband conformal microstrip patch antenna suitable for airborne applications is proposed. Dumbbell shaped slots located symmetrically at suitable fraction of wavelength distance from the centre of the patch and a partially cut ground plane is utilized to enhance the operating bandwidth of the patch antenna as compared to the standard conventional patch. Fractional impedance bandwidth (S11<-10dB) of about 86% with operating range 1.14 GHz to 2.87 GHz for the proposed planar and 81% bandwidth within frequency range 1.16 GHz to 2.74 GHz for the cylindrical antenna configuration (covering S and L bands) is obtained. The antenna shows satisfactory gain in both E and H planes within the operating frequency range. The radius of curvature has been taken electrically small (1.25λ) to clearly illustrate the effect of curvature on the performance characteristics of the antenna.

This paper deals with a general network model for predicting the input impedance of a coplanar-waveguide-fed notch antenna operating over the first two (anti-)resonant modes. The model parameters (radiation conductance, open-end capacitance, short-end inductance, CPW-to-slot transition characteristics) are theoretically derived using the spectral domain approach. Various antenna sets, including several substrates (FR4, Rogers AD6006/DiCLAD880) and width-to-height ratios, are considered for validation. The proposed model showed positive correlation with full-wave simulations.

Resonant frequencies f_{r} of a cylindrical-rectangular microstrip antenna are theoretically calculated. Comparison is made to f_{r} for a planar rectangular patch antenna, including the simplest planar patch modes having no field variation normal to the patch surface. The validity of using planar antenna patches to characterize microstrip antennas is examined.

The fundamental solution for printed circuit antennas on cylindrical substrates is presented in this paper. Exact expressions are obtained for the electromagnetic field both inside the substrate as well as the surrounding free space produced by an arbitrarily oriented printed circuit dipole. Asymptotic results are derived for a cylindrical thin substrate whose diameter is large compared to wavelength.

Arrays of dipoles around spires or other vertical supports are useful for the broadcasting of ultra-high-frequency waves. To the author's knowledge no sound method of computing the radiation patterns which takes into account the effect of the support has previously been presented. The three arrangements of dipoles around a vertical cylinder which are of interest are (1) an array of vertical dipoles, (2) an array of horizontal dipoles whose axes lie on the circumference of a circle, and (3) an array of horizontal dipoles whose axes point radially outward. There are several phase relationships for the currents which are of practical interest for each of these arrays. The necessary number of dipoles in various types of arrays to obtain a horizontal radiation pattern approaching a circle within any specified tolerance are shown by curves. The interference phenomena caused by a plane wave passing a vertical cylinder are discussed and shown graphically. Several radiation patterns for one dipole near a cylinder are discussed. A detailed study of a 4-element horizontal dipole array surrounding a cylinder whose diameter is 1.27 wavelengths, or whose periphery approximates that of the Chrysler Building spire at the assigned television frequency, has been made. Both horizontal and vertical patterns for three different phase relationships of the dipole currents have been calculated. Formulas for the radiation patterns for arrays of all three types having various numbers of elements and fed in several different ways are tabulated.

An approach to the analysis of microstrip antennas which is applicable also to relatively thick substrates using the relevant Green's function is presented. The Green's function is derived and closed form expressions for various antenna characteristics which explicitly take into account the presence of the dielectric material are obtained in terms of the electric surface current density. For rectangular microstrip elements near resonance the current distribution is approximated using lossless transmission line analysis, thus enabling the complete evaluation of the characteristics of the element near resonance. The results obtained in this approach for the radiation resistance, surface wave resistance, radiation pattern, directivity, and bandwidth are presented in a detailed set of graphs for a representative set of parameters.

The radiation pattern of microstrip wraparound antennas was obtained here using a theory based on dyadic Green's functions for concentric-cylindrical layered media. The dielectric layer that is usually neglected as a first-order approximation was considered here. An asymptotic expression for the dyadic Green's function that takes into account only the space wave is first obtained. Radiation patterns for various radii, permittivities, and thicknesses of the dielectric layer of a microstrip wraparound antenna were obtained using as a source a uniform annular magnetic current obtained by means of a cavity model with conducting magnetic walls. The calculated values of the percent pattern coverage decreases as the thickness and the permittivity of the dielectric layer increase. The influence of the dielectric layer is more pronounced for radiation direction near that of the axis of the cylindrical surface. It is also shown that the radiation patterns at a frequency of 2.0 GHz are not much dependent on the diameter of the antenna for values from 3 to 120 in.

A survey of microstrip antenna elements is presented, with emphasis on theoretical and practical design techniques. Available substrate materials are reviewed along with the relation between dielectric constant tolerance and resonant frequency of microstrip patches. Several theoretical analysis techniques are summarized, including transmission-line and modal-expansion (cavity) techniques as well as numerical methods such as the method of moments and finite-element techniques. Practical procedures are given for both standard rectangular and circular patches, as well as variations on those designs including circularly polarized microstrip patches. The quality, bandwidth, and efficiency factors of typical patch designs are discussed. Microstrip dipole and conformal antennas are summarized. Finally, critical needs for further research and development for this antenna are identified.

A new class of antennas using microstrips to form the feed networks and radiators is presented in this communication. These antennas have four distinct advantages: 1) cost, 2) performance, 3) ease of installation, and 4) the low profile conformal design. The application of these antennas is limited to small bandwidths. Phased arrays using these techniques are also discussed.

Microstrip antenna technology Cylindrical-rectangular microstrip antenna

- K R Carver
- J W C M Mink
- Kroxrne

K. R. Carver and J. W. Mink, " Microstrip antenna technology, " IEEE Trans. Anfennas Propagat., vol. AP-29, pp. 2-24, 1981. C. M. Kroxrne, " Cylindrical-rectangular microstrip antenna, " IEEE Trans. Antennas Propagat., vol. AP-31, pp. 194-199, 1983.