Resonance conditions for a substrate-superstrate printed antenna geometry which allow for large antenna gain are presented. Asymptotic formulas for gain, beamwidth, and bandwidth are given, and the bandwidth limitation of the method is discussed. The method is extended to produce narrow patterns about the horizon, and directive patterns at two different angles.

Gain enhancement methods for printed circuit antennas

In this communication a high directive electromagnetic bandgap (EBG) antenna operating in wide frequency band for both return loss (RL) and directivity is examined. In this EBG antenna an aperture coupled microstrip antenna (ACMA) is used as a feeding source and a frequency selective surface (FSS) is used as a superstrate layer. Suitable use of the superstrate layer, microstrip patch and coupling aperture simultaneously, leads to produce separate resonance frequencies and therefore the wide frequency band for RL. Also, high directivity is achieved only by using the superstrate layer that has been made by the FSS layer with square loop elements. At first, a wideband ACMA is designed to operate in x-band. In this step appropriate design of coupling aperture is of a great importance. Secondly, after the design of optimum superstrate layer by the FSS structure, it is added to the ACMA in order to increase both bandwidth and directivity.

Wideband High Directive Aperture Coupled Microstrip Antenna Design by Using a FSS Superstrate Layer

We introduce a new technique for designing wideband polarization converters based on miniaturized-element frequency selective surfaces (MEFSSs). The proposed structure is a two-dimensionally anisotropic periodic structure composed of arrays of subwavelength capacitive patches and inductive wire grids separated by thin dielectric substrates. The structure is designed to behave differently for field components of the two orthogonal polarizations and transmits a circularly polarized wave once illuminated by a linearly polarized plane wave. Using equivalent circuit models for MEFSSs, a synthesis procedure is developed that can be used to design the polarization converter from its required bandwidth and center frequency of operation. Using this procedure, a prototype of the proposed polarization converter operating within the X-band is designed, fabricated, and experimentally characterized using a free-space measurement system. The measurement results confirm the theoretical predictions and the design procedure of the structure and demonstrate that the proposed MEFSS-based polarization converter operates in a wide field of view of $\pm45^{\circ}$ with a fractional bandwidth of 40%.

Wideband Linear-to-Circular Polarization Converters Based on Miniaturized-Element Frequency Selective Surfaces

A new class of circularly polarized (CP) Fabry-Perot cavity antennas is introduced that maintain the simplicity of a linearly polarized primary feed and a single cavity structure. The proposed antennas employ a double-sided partially reflective surface (PRS), which allows independent control of the magnitude and phase responses for the reflection and transmission coefficients. In conjunction with an anisotropic high-impedance surface (HIS) ground plane, this arrangement allows for the first time a single cavity antenna to produce a specified gain in CP from a linearly polarized primary source. A design procedure for this class of antennas is introduced. The method exploits a simple ray optics model to calculate the magnitude and phase of the electric field in the cavity upon plane wave excitation. Based on this model, analytical expressions are derived, which enforce the resonance condition for both polarizations at a predetermined PRS reflectivity (and hence predetermined antenna gain) together with a 90 ° differential phase between them. The validity of the concept is confirmed by means of an example entailing an antenna with gain of approximately 21 dB at 15 GHz. Full-wave simulation results and experimental testing on a fabricated prototype are presented and agree well with the theoretical predictions.

/pdf/design-method-for-circularly-polarized-fabry-perot-cavity-8i9cozq5li.pdf

Design Method for Circularly Polarized Fabry–Perot Cavity Antennas

This paper presents a wideband circularly polarized millimeter-wave (mmw) antenna design. We introduce a novel 3-D-printed polarizer, which consists of several air and dielectric slabs to transform the polarization of the antenna radiation from linear to circular. The proposed polarizer is placed above a radiating aperture operating at the center frequency of 60 GHz. An electric field, ${E}$ , radiated from the aperture generates two components of electric fields, ${E} _{\mathrm {x}}$ and ${E} _{\mathrm {y}}$ . After passing through the polarizer, both ${E} _{\mathrm {x}}$ and ${E} _{\mathrm {y}}$ fields can be degenerated with an orthogonal phase difference which results in having a wide axial ratio bandwidth. The phase difference between ${E} _{\mathrm {x}}$ and ${E} _{\mathrm {y}}$ is determined by the incident angle $\phi $ , of the polarization of the electric field to the polarizer as well as the thickness, ${h}$ , of the dielectric slabs. With the help of the thickness of the polarizer, the directivity of the radiation pattern is increased so as to devote high-gain and wideband characteristics to the antenna. To verify our concept, an intensive parametric study and an experiment were carried out. Three antenna sources, including dipole, patch, and aperture antennas, were investigated with the proposed 3-D-printed polarizer. All measured results agree with the theoretical analysis. The proposed antenna with the polarizer achieves a wide impedance bandwidth of 50% from 45 to 75 GHz for the reflection coefficient less than or equal −10 dB, and yields an overlapped axial ratio bandwidth of 30% from 49 to 67 GHz for the axial ratio ≤ 3 dB. The maximum gain of the antenna reaches to 15 dBic. The proposed methodology of this design can apply to applications related to mmw wireless communication systems. The ultimate goal of this paper is to develop a wideband, high-gain, and low-cost antenna for the mmw frequency band.

A Wideband Millimeter-Wave Circularly Polarized Antenna With 3-D Printed Polarizer

A compact multiband antenna system using a dielectric resonator antenna (DRA) is presented in this paper. Designed to be integrated in a tablet, it is not only heavily miniaturized (λ0/15×λ0/38×λ0/94 at 800 MHz), but also able to cover three frequency bands for different wireless applications (DVB-H, WiFi and WiMAX). Since a reconfigurable radiation pattern can result in an improved quality and reliability of wireless links, two DRAs have been integrated to implement this feature on the three frequency bands. These improvements are demonstrated by the presentation of the correlation coefficient and the effective diversity gain, both measured in a reverberation chamber. The experimental measurements are in very good agreement with the simulated ones. Good overall performances are obtained, and the requirements of all three applications are perfectly met. Moreover, the antenna operative frequencies are independent of the ground plane dimensions, making this system a very good candidate for all kinds of mobile devices.

Compact and Multiband Dielectric Resonator Antenna With Pattern Diversity for Multistandard Mobile Handheld Devices

This letter describes a comprehensive approach to design circularly polarized electromagnetic band-gap(EBG) antennas. Some solutions have already been proposed to that end, but they require the design to be started from scratch. With the proposed method, the circular polarization will be obtained through the use of a meander-line polarizer (MLP) located above an existing linearly polarized EBG antenna. Thanks to a global approach, a 20-dBi circularly polarized antenna, boasting an axial ratio (AR) lower than 1 dB over the 29.530 GHz frequency band, has been conceived, realized, and successfully measured.

Global Design of an EBG Antenna and Meander-Line Polarizer for Circular Polarization

A switched beam antenna with broadside beam based on a novel design of Butler feeding network is presented. This novel design requires only 90° hybrid couplers in the Butler matrix part with the aim of producing a broadside beam. A three-beam prototype has been fabricated. Measurements indicate that the broadside beam is primordial to avoid a shadowing area in this direction.

Switched-beam antenna based on novel design of Butler Matrices with broadside beam

This letter presents a novel design of compact dielectric resonator antenna (DRA) that is dedicated to ultrawideband applications such as digital video broadcasting-handheld (DVB-H). The dimensions of the radiation element are lambda0/7 times lambda0/13 times lambda0/28 at 466 MHz. A miniaturization technique has been used in order to reduce the antenna size, and a parametric analysis of the antenna is performed. The measured results agree well with the simulated ones. The proposed antenna offers a bandwidth of 70% around 700 MHz for -8 dB impedance matching bandwidth definition and covers the Ultra High Frequency (UHF) IV, V and Global System for Mobile communications (GSM) bands.

Ultrawideband Dielectric Resonator Antenna for DVB-H and GSM Applications

The purpose of this letter is to offer new performance characteristics to base station antennas. The proposed antenna is developed for the European project BROADWAN framework. We propose a new switched beam antenna array based on the 5 times 8 novel Butler matrix topology which provides a cosecant squared elevation pattern. In this letter, the implementation of the beamforming network and the cosecant squared feed lines at 42 GHz are detailed and a comparison between simulated and experimental results is presented.

Majed Koubeissi

Papers

Compact and Multiband Dielectric Resonator Antenna With Pattern Diversity for Multistandard Mobile Handheld Devices

Global Design of an EBG Antenna and Meander-Line Polarizer for Circular Polarization

Switched-beam antenna based on novel design of Butler Matrices with broadside beam

Ultrawideband Dielectric Resonator Antenna for DVB-H and GSM Applications

Design of a Cosecant-Squared Pattern Antenna Fed by a New Butler Matrix Topology for Base Station at 42 GHz