[Show abstract][Hide abstract] ABSTRACT: In this paper, new dense dielectric (DD) patch array antenna prototype operating at 28 GHz for the future fifth generation (5G) short-range wireless communications applications is presented. This array antenna is proposed and designed with a standard printed circuit board (PCB) process to be suitable for integration with radio-frequency/microwave circuitry. The proposed structure employs four circular shaped DD patch radiator antenna elements fed by a 1-to-4 Wilkinson power divider surrounded by an electromagnetic bandgap (EBG) structure. The DD patch shows better radiation and total efficiencies compared with the metallic patch radiator. For further gain improvement, a dielectric layer of a superstrate is applied above the array antenna. The calculated impedance bandwidth of proposed array antenna ranges from 27.1 GHz to 29.5 GHz for reflection coefficient (S11) less than -10dB. The proposed design exhibits good stable radiation patterns over the whole frequency band of interest with a total realized gain more than 16 dBi. Due to the remarkable performance of the proposed array, it can be considered as a good candidate for 5G communication applications.
16th international symposium on antenna technology and applied electromagnetics (ANTEM 2014), Victoria, BC, Canada; 07/2014
[Show abstract][Hide abstract] ABSTRACT: In this paper, the design of a millimeter-wave array antenna prepared to work on the 56-64.2 GHz (13.6%) frequency band is presented. The introduced antenna array is designed for low-loss, high-gain and low cross-polarization levels. The proposed antenna exhibits a high gain of 8 dBi and good linear polarization across the desired frequency range. Simulated results confirm that this antenna is a good candidate for short-range wireless communications applications at millimeter-wave frequencies.
IEEE International Symposium on Antennas and Propagation (AP-S) and USNC-URSI Radio Science Meeting, Memphis, Tennessee, USA; 07/2014
[Show abstract][Hide abstract] ABSTRACT: A hybrid compact isolator with a cross section of 17$,times,$11 mm$^2$ is proposed to reduce the electromagnetic coupling between two vertically polarized Tx/Rx microstrip antennas, both operating at 9.4 GHz. This isolator is built by embedding a piece of artificial material between two metallic walls. The obtained results using this hybrid isolator demonstrate that the coupling between the two antennas is significantly reduced across at least 55% of the matching band. To substantiate the proposed configuration, a prototype is fabricated and tested, and the corresponding measured results are presented. Furthermore, the discrepancies between the simulations and measurements are interpreted with the aid of the electromagnetic (EM) simulator.
[Show abstract][Hide abstract] ABSTRACT: In this paper, a new dense dielectric (DD) patch array antenna prototype operating at 28 GHz for future fifth generation (5G) cellular networks is presented. This array antenna is proposed and designed with a standard printed circuit board process to be suitable for integration with radio frequency/microwave circuitry. The proposed structure employs four circular-shaped DD patch radiator antenna elements fed by a 1-to-4 Wilkinson power divider. To improve the array radiation characteristics, a ground structure based on a compact uniplanar electromagnetic bandgap unit cell has been used. The DD patch shows better radiation and total efficiencies compared with the metallic patch radiator. For further gain improvement, a dielectric layer of a superstrate is applied above the array antenna. The measured impedance bandwidth of the proposed array antenna ranges from 27 to beyond 32 GHz for a reflection coefficient (S11) of less than −10 dB. The proposed design exhibits stable radiation patterns over the whole frequency band of interest, with a total realized gain more than 16 dBi. Due to the remarkable performance of the proposed array, it can be considered as a good candidate for 5G communication applications.
[Show abstract][Hide abstract] ABSTRACT: We present the potential use of reinforced continuous carbon fiber composite (RCCFC) material to build reconfigurable transmitter/receiver communication systems. The frequency agile characteristic is obtained by the rotation of the antennas on the ground plane which is made of anisotropic RCCFC material. The current distribution on the RCCFC composite ground plane can be controlled by exciting the desirable modes and eliminating the unwanted ones. Probe-fed rectangular microstrip-patch antennas are fabricated and the reconfigurable characteristics are investigated both numerically and experimentally.
IEEE Transactions on Antennas and Propagation 01/2014; 62(2):1002-1006. · 2.33 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Miniaturized low-profile monopole antennas loaded by metamaterial (MTM) structures are presented. The antenna is loaded by zeroth-order resonator (ZOR) and complimentary split-ring resonator (CSSR) units, resonating over three frequency bands so that they can be tuned by changing the geometrical parameters of the MTM structures. Surface current distribution and equivalent circuit models are provided to describe the principle of operation. The experimental results are presented to validate the numerical results. Showing the monopole-shape radiation pattern characteristics at all resonant frequencies, the proposed MTM antennas are suitable for vehicular wireless applications.
IEEE Transactions on Antennas and Propagation 01/2014; 62(2):555-562. · 2.33 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this paper, a new experimental system for through wall gap detection and concealed vacancies behind wall is introduced. The Ultra Wide Band (UWB) system is based on the principles of Synthetic Aperture Radar (SAR) and Ground-Penetrating Radar (GPR) for through wall imaging to detect hidden gaps and/or hiding persons behind walls. The system uses a very short pulse generated by the vector network analyzer (VNA) to illuminate the wall under investigation through an UWB antenna probe. The detection process is achieved using time domain measurements of the probe reflection coefficient S11. Some numerical analyses have been carried out for verifying the principle of operation. The experimental results show a great ability not only for the gap detection between walls but also for estimation of the gap width with a very good accuracy (6.25% in the worst case) for different types of walls.
[Show abstract][Hide abstract] ABSTRACT: A method of improving the radiation characteristics of the patch antenna arrays using two different electromagnetic bandgap (EBG) structures is presented. The proposed antenna arrays are designed for low-loss, high-gain and low sidelobe levels (SLL) at far field applications. It is composed of a coaxial probe driven square patch operating at 4 GHz. Two mushroom EBG layers are introduced around the patch array. One is a mushroom while the other is using a planar EBG. By using these EBG structures, both gain and sidelobe levels are improved. All simulation results are demonstrated.
[Show abstract][Hide abstract] ABSTRACT: A method of improving the radiation characteristics of the slotted oversize patch antennas using electromagnetic bandgap (EBG) rows is presented. The proposed antenna is designed for low loss, high gain and low cross-polarization at far field applications. It is composed of a coaxial probe driven oversize slotted patch, backed by a metallic ground plane. Two mushroom EBG rows are introduced around the slotted patch antenna. By using these EBG layers, both gain and sidelobe levels (SLL) are improved. The realized gain is increased by almost 2 dB while the SLL is reduced by 3 dB in E-plane and 9 dB in H-plane.
Radio Science Conference (NRSC), 2013 30th National; 04/2013
[Show abstract][Hide abstract] ABSTRACT: The authors present reconfigurable antennas based on anisotropic reinforced continuous carbon fibre composite (RCCFC) material. By the rotation of the anisotropic RCCFC ground plane, the current distribution can be changed to select a desirable mode of resonance and suppress unwanted modes. Hence, the RCCFC ground plane behaves as a mode filter in the proposed reconfigurable antennas. Several types of probe-fed reconfigurable microstrip-patch antennas are presented, including the RCCFC conductivity characteristics, the principle of reconfigurable operation and the simulated and measured performance. The outstanding mechanical strength of RCCFC materials along with the promising radiation characteristics of these reconfigurable antennas make them good candidates for radio cognitive and military applications.
[Show abstract][Hide abstract] ABSTRACT: Design, fabrication and testing of millimeter-wave (MMW) dielectric resonator antenna (DRA) surrounded by electromagnetic band-gap (EBG) structure are presented. For this purpose, MMW mushroom-like, circular patch EBG (CP-EBG) cell is designed and fabricated. The propagation characteristics of the proposed CP-EBG structure are measured using the asymmetric microstrip line method. A cylindrical DRA incorporating the developed CP-EBG structure is then designed and its performance is evaluated with and without the CP-EBG around the 60 GHz bandwidth. Measurements show a significant improvement in the antenna radiation characteristics when it is surrounded by CP-EBG structure. A gain increase of up to 3.2 dBi is obtained while preserving the gain flatness over the suggested bandwidth ( ± 0.7 dB). An additional backlobe suppression of up to 6.5 dBi is achieved. Moreover, radiation toward substrate edges is significantly reduced.
IEEE Transactions on Antennas and Propagation 01/2013; 61(8):4354-4357. · 2.33 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A low-cost and highly efficient printed Yagi antenna structure with high radiation efficiency is presented. The proposed prototype consists of two stacked planar layers. The first layer electromagnetically couples energy to the printed Yagi array parasitic elements located on the second layer. A reduced-size 60-GHz prototype (1.0687 × 0.8015 cm2) is designed to operate over the Industrial, Scientific, and Medical (ISM) band. The measured impedance bandwidth is more than 5 GHz with a gain of 10 dB measured at 60 GHz. With these features, this antenna achieves a low profile that makes it suitable for millimeter-wave monolithic microwave integrated circuits (MMICs) packaging as well as for short-range wireless communications and imaging applications.
[Show abstract][Hide abstract] ABSTRACT: In this paper, an ultra-wideband (UWB) antenna array for through-wall microwave imaging (TWMI) system is introduced. The detection system consists of 4-element balanced antipodal Vivaldi antenna array (BAVA) fed by 1-to-4 UWB modified Wilkinson power divider. The antenna element, array, and feed network are optimized, fabricated and tested. The main working principle of the detection system is based on time domain reflectometry (TDR). Wherein, very short pulse generated by the vector network analyzer (VNA) is used to illuminate the wall under investigation through the array system. The experimental work of scanning a 20 × 20 cm area of two wall separated by 15 cm air gap with the purpose of detecting 4 cm (diameter) metallic ball concealed in a gap between the walls shows a good accuracy. In order to enhance the resolution of the received image, a special filtering process has been developed and implemented.
Wireless Technology and Applications (ISWTA), 2013 IEEE Symposium on; 01/2013
[Show abstract][Hide abstract] ABSTRACT: This paper proposes a compact and inexpensive two-layer ultra-wideband (UWB) butterfly-shaped microstrip 4×4 Butler matrix beam-forming network. Measured and simulated results of the proposed matrix configuration confirm UWB performances for transmission magnitudes and phases with good return losses and isolation characteristics. To demonstrate the functionality of the designed Butler matrix, four identical tapered slot antenna (TSA) elements are connected to four output ports of the Butler matrix and the radiation pattern characteristics are simulated, presented and discussed.
Ultra-Wideband (ICUWB), 2013 IEEE International Conference on; 01/2013
[Show abstract][Hide abstract] ABSTRACT: In this letter, the numerical and experimental investigation of triangular-shaped
microstrip power divider is designed for C-band applications using defected ground
structure (DGS). Numerical simulations are carried out using different computer-aided
design tools based on different numerical techniques, ie, Ansoft HFSS and CST Microwave
Studio. Good agreement is found between the calculated results using both HFSS and CST.
A parametric study is carried out to address the effect of DGS parameters on the ...
[Show abstract][Hide abstract] ABSTRACT: In this letter, the effect of moving the feed on the operation bandwidth of a broadband reflectarray is investigated through simulation and measurement. A new broadband cell element with optimized dimensions to achieve linear phase shift is proposed in this investigation. A square reflectarray of 40×40 cm2 comprising this particular unit cell was designed and fabricated to demonstrate wideband operation at X-Ku band. The effect of feed movement on the operating band was studied by exciting the reflectarray with a plane wave and monitoring the near field on the line passing through the assumed feed locations over a wide frequency band. Considering three different feed positions, the reflectarray was simulated, and good agreement between simulated and measured results was observed. It is shown that changing the feed location leads to a considerable shift in operating frequency window of the reflectarray and also its maximum gain, which gives rise to the possibility of changing the operating band without redesigning the reflectarray by only moving the feed. Moreover, a remarkable value of 36% of 1.5 dB gain-bandwidth was measured, which is higher compared to previously reported designs in the literature.