Basit Ali Zeb

A Fabry-Perot cavity antenna (FPCA) with extremely wide 3-dB gain bandwidth is presented. Its superstructure consists of a single all-dielectric slab formed from concentric rings with transverse dielectric contrast. The bandwidth enhancement is realized by optimizing permittivity values of the concentric rings using particle swarm optimization. The designed FPCA has a peak gain of 17.6 dB and operates from 10.7 to 22.4 GHz, which is 70% of gain bandwidth.

The authors utilise a one‐dimensional (1D) stack of three identical unprinted dielectric slabs as a superstructure to design a novel yet simple tri‐band electromagnetic bandgap resonator antenna (ERA). The design, inspired from classical single‐band 1D ERAs, is conceived by creating two resonant defects in the superstructure configuration to make it suitable for tri‐band and high gain operation. A prototype, fabricated using FR4 material, is tested with a waveguide‐fed slot antenna at 10.3, 11.9 and 13.7 GHz with a frequency ratio of 1.33:1.16:1. The slot feeds the cavity simultaneously in the three frequency bands and provides good impedance matching in each frequency band. Peak measured gains of 14.3, 13.4 and 16.1 dBi and radiation efficiencies of 83, 85 and 85% are achieved in the lower, middle and higher frequency bands, respectively.

A quarter‐wavelength‐thick unprinted dielectric slab is placed above a slot antenna to achieve high gain with a large bandwidth. By optimally truncating the high‐permittivity superstrate to a small area of 2.25λ ₀ ² , 8–10 dB enhancement in the directivity of the slot is achieved over a 3 dB directivity bandwidth of 16–18%. A prototype antenna was fabricated and tested at 11.5 GHz. Its measured peak gain is 16.95 dBi and the 3 dB gain bandwidth is 16.25%. The proposed antenna is simple and, more importantly, has a lower profile with a total height of 0.593 λ ₀ .

Two identical unprinted dielectric slabs are placed above a dual‐polarised (DP) stacked‐patch feed antenna to transform its less‐directive radiation into almost equal and high‐gain DP beams in two frequency bands. The dual‐band operation is achieved by engineering the reflection characteristics of a classical all‐dielectric superstructure such that cavity resonance condition is satisfied in two frequency bands. A prototype of this dual‐polarised electromagnetic band gap resonator antenna with a frequency ratio of 1.245 has been fabricated and measured peak gains of 17 and 16.6 dBi at 10.6 and 13.15 GHz, respectively, and cross‐polarisation levels of less than –18 dB, have been achieved. The proposed antenna has a simple configuration and is easy to manufacture, making it a good candidate for DP point‐to‐point wireless links.

A novel technique to design a phase-correcting structure (PCS) for an electromagnetic band gap (EBG) resonator antenna (ERA) is presented. The aperture field of a classical ERA has a significantly nonuniform phase distribution, which adversely affects its radiation characteristics. An all-dielectric PCS was designed to transform such a phase distribution to a nearly uniform phase distribution. A prototype designed using proposed technique was fabricated and tested to verify proposed methodology and to validate predicted results. A very good agreement between the predicted and the measured results is noted. Significant increase in antenna performance has been achieved due to this phase correction, including 9-dB improvement in antenna directivity (from 12.3 dBi to 21.6 dBi), lower side lobes, higher gain, and better aperture efficiency. The phase-corrected antenna has a 3-dB directivity bandwidth of 8%.

Since the pioneering work of Von Trentini in 1956, significant improvements in the performance of electromagnetic band gap resonator antennas (ERA) have been made. The focus of this paper is on the computational models and computational efficiency related to the enhancement of 3-dB directivity bandwidth of such antennas. We explore to what extent the two unit-cell numerical electromagnetic models, Superstructure Model and Defect-Cavity Model, can be efficiently used to reduce the computation burden of the design process to achieve the best antenna bandwidth. It was found that they are very useful for antennas with medium or large superstructure areas but for smaller antennas that have much wider bandwidths numerical analysis of the whole antenna is required to achieve the best directivity bandwidth.

A dual-band circularly polarized (CP) electromagnatic band-gap (EBG) resonator antenna (ERA) is presented. The antenna employs an all-dielectric superstructure, which consists of two identical unprinted dielectric slabs, and a dual-band corner-truncated patch feed. A prototype antenna is fabricated and tested using a superstructure made out of 3.175-mm-thick Rogers TMM10 material. Measured peak gains are 16.1 dBic [left-hand circular polarization (LHCP)] and 16.2 dBic [right-hand circular polarization (RHCP)], measured radiation efficiencies are 93% and 91%, and the boresight axial ratios are 1.9 and 1.5 dB at 9.65 and 11.75 GHz, respectively. This dual-band antenna is easy to fabricate, making it suitable for high-gain low-cost CP applications.

Wideband electromagnetic band gap resonator antennas that can provide gains from 15 dBi in extremely small physical areas are proposed. It is shown that strongly truncated circular superstructures and ground planes with identical areas can be used to significantly improve the aperture efficiency of these antennas. An example antenna design with a maximum aperture efficiency of 121% is described. The antenna has a half power directivity bandwidth of 35% at a peak directivity of 15.6 dBi. It is made out of unprinted all-dielectric superstructure and has a single antenna.

A novel method is presented to design single-feed high-gain EBG resonator antennas (ERAs) with significantly wider bandwidths. Dielectric contrast is introduced to 1-D EBG superstructures composed of unprinted dielectric slabs, and the thicknesses of each of these slabs is optimized to achieve a wideband defect mode in a unit-cell model. Next, antennas are designed and their superstructure areas are truncated to increase the antenna bandwidth and aperture efficiency while decreasing antenna footprint. We demonstrate that a small superstructure area increases the 3-dB bandwidth of ERAs significantly. A prototype ERA designed with a single feed and superstructure area as small as 1.5 λ ₀ ×1.5 λ ₀ has a measured 3-dB directivity bandwidth of 22% at a peak gain of 18.2 dBi. This prototype antenna was made out of three slabs of different dielectric constants, two of them touching each other. This prototype demonstrates more than 85% reduction in the ERA footprint alongside a drastic improvement in bandwidth over the 3%-4% measured bandwidth of the classical single-feed ERAs with unprinted slabs.

Resonant cavity antennas (RCA) are superstrate based antennas which are capable of enhancing the directivity of simple sources such as dipoles and patches. These antennas have recently received significant research interest from antenna community owing to their simple design, planar nature and highly directive characteristics but narrowband nature. One of the main research goals associated with RCAs is to enhance their half power directivity bandwidth. In this paper, a very simple RCA design is proposed which improves the half power directivity bandwidth almost 74% more than that exhibited by the conventional RCAs. The proposed antenna has a peak directivity of 20dBi with less than ±0.5dB variation over most of the operating bandwidth. The improved bandwidth of the antenna along with stable directivity, consistent beam quality and sufficiently suppressed sidelobe levels make it highly suitable for wireless point-to-point communication links.