Ashkan Abolfathi

Bio: Ashkan Abolfathi is an academic researcher from Semnan University. The author has contributed to research in topics: Antenna efficiency & Antenna (radio). The author has an hindex of 2, co-authored 4 publications receiving 11 citations.

An X-Band Substrate Integrated Waveguide Fed Patch Array Antenna: Overcoming low efficiency, narrow impedance bandwidth, and cross-polarization radiation challenges

Abstract: In this article, the efficient development of a new class of multilayer microstrip patch antenna (MPA) fed by a substrate integrated waveguide (SIW) for X-band applications is presented. It consists of performing the feed network in the SIW and the radiating structure in the microstrip technology. The proposed structure demonstrates that the best alternative to a costly, heavy, and bulky rectangular waveguide feeder is an SIW, which provides miniaturization, performance enhancements, cost reductions, and ease of integration with MPAs. The proposed patch array is composed of three stacked layers from top to bottom, including two SIW layers as a feeding network and one layer as the antenna layer. To verify the concept of the proposed antenna, a prototype of a 2 × 2 SIW patch array with a 39 × 41 mm2 physical aperture was fabricated and measured with an impedance bandwidth of 9.18% for $\left|{{S}_{11}}\right|{ and a radiation efficiency above 78% in the whole operating frequency bandwidth. The maximum measured gain of the proposed array at 10 GHz is 11.1 dB, which is equivalent to 57.7% of the aperture efficiency. The proposed array can be easily developed to be used in larger arrays, and it is a good candidate for generating a symmetrical unidirectional pattern with a low cross-polarization level.

Dual Beam Leaky Wave Antenna Using Dumbbell-Shaped Slots based on Substrate Integrated Waveguide

Abstract: A dual beam leaky wave antenna (LWA) array is designed and investigated in this paper, which using the substrate integrated waveguide (SIW) technology based on TE20 mode at X-band. The dumbbell-shaped slots are etched out on the both sides of SIW. Using these types of slots has increased the bandwidth of the antenna, so that the proposed antenna bandwidth is between 9.4-14 GHz. Another advantages of this structure are the good gain, proper directivity, and radiation efficiency, so that at 12 GHz the antenna peak gain reaches to 12.6 dB. The beam scanning range changes from 5° to 78° in the first and fourth quadrants. The scanning range of this antenna is ~ about 73° degrees in each quadrant that makes it proper for radar applications. This antenna is analyzed and simulated by the CST Microwave Studio software.

SIW Corporate-Feed Network for Circular Polarization Slot Array Antenna

Abstract: In this paper, multilayer feeding network for linear slot array antenna is studied. A substrate integrated waveguide (SIW) corporate-feed network for linear slot array antenna based on three layers is presented. This design has eight right-handed circularly polarized radiation elements, one power divider with SMA connector to SIW adapter structure and six SIW power divider by coupling slot method. The feed network and antenna structures has been designed at X-band frequency. The SMA to SIW power divider and SIW power divider by coupling slot has in-phase and out-of-phase feature, respectively. The proposed feeding method takes the advantages of miniaturization of structure compared with the corporate-feed network by T-junctions. Also, proposed network for feeding radiation elements, eliminated undesirable surface current of the coaxial connector transition, which reduction of these currents causes lower side-lobe level at the antenna radiation pattern. Dimensions of manufacture array structure are 132.8 * 23 * 2.4 mm3 and the substrate is Rogers RO4003c. This antenna has the capability to expand the number of elements and feed network for achieving higher gain. Due to the unidirectional radiation pattern, this antenna useful for monopulse radar and automotive radar applications.

An X-Band Substrate Integrated Waveguide Fed Patch Array Antenna: Overcoming low efficiency, narrow impedance bandwidth, and cross-polarization radiation challenges

Abstract: In this article, the efficient development of a new class of multilayer microstrip patch antenna (MPA) fed by a substrate integrated waveguide (SIW) for X-band applications is presented. It consists of performing the feed network in the SIW and the radiating structure in the microstrip technology. The proposed structure demonstrates that the best alternative to a costly, heavy, and bulky rectangular waveguide feeder is an SIW, which provides miniaturization, performance enhancements, cost reductions, and ease of integration with MPAs. The proposed patch array is composed of three stacked layers from top to bottom, including two SIW layers as a feeding network and one layer as the antenna layer. To verify the concept of the proposed antenna, a prototype of a 2 × 2 SIW patch array with a 39 × 41 mm2 physical aperture was fabricated and measured with an impedance bandwidth of 9.18% for $\left|{{S}_{11}}\right|{ and a radiation efficiency above 78% in the whole operating frequency bandwidth. The maximum measured gain of the proposed array at 10 GHz is 11.1 dB, which is equivalent to 57.7% of the aperture efficiency. The proposed array can be easily developed to be used in larger arrays, and it is a good candidate for generating a symmetrical unidirectional pattern with a low cross-polarization level.

Liquid Crystal-Based Wideband Reconfigurable Leaky Wave X-Band Antenna

Abstract: In this paper, a pattern and frequency reconfigurable leaky wave X-band antenna based on liquid crystal is designed. The frequency sweep characteristics of traditional leaky wave antennas are replaced by electrical properties of liquid crystal materials. Through the liquid crystal tuning, the main lobe pattern is deflected by 25 degrees at a frequency shift of 1GHz, where the liquid crystal tuning is saturated at 20V bias voltage. The relative frequency reconfigurable bandwidth is 19%, the relative pattern reconfigurable bandwidth is 9.3% and the maximum gain is 10dBi. Moreover, the pattern and frequency response are well preserved during the tuning.

Monopulse Antenna Array Based on Three-Modes With Orthogonal Radiation Beams

Abstract: A compact multi-layer substrate integrated waveguide (SIW) monopulse antenna array operating at X-band is proposed. The structure consists of four stacked layers, including one layer for the radiating 4 × 4 rectangular microstrip antenna elements and two SIW layers for the comparator network. The sum and difference modes provide orthogonal radiation patterns in the azimuth and elevation planes. The two SIW layers of the comparator network feature a compact multi-feed design while maintaining high isolation between the antenna ports. To validate the proposed antenna concept, silmulations and measuremets are carried out. The obtained resuts show good performnces, a -10-dB impedance bandwidth of 13.45 % (9.35-10.7 GHz) for the sum and difference ports, better than 30 dB isolation between the antenna ports, the difference radiation patterns better than -38 dB null-depth. The comparison between the simulated and measuremed results shows a good agreement.