Gain enhancement of dielectric resonator loaded waveguide antennas with dielectric overlays

The gain characteristics of a dielectric resonator loaded coaxial fed circular waveguide antenna (DRLWA) with overlaying parasitic discs have been investigated experimentally. Results indicate that, when properly spaced, the overlays can enhance the gain by more than 6 dB.<>     

Perforated dielectric resonator antennas

A dielectric resonator antenna (DRA) is formed by perforating a dielectric substrate with a lattice of holes. The performance of several perforated DRA prototypes is compared to a conventional DRA and the results demonstrate better gain and cross-polarisation levels. This technique of fabricating DRAs using perforations is intended for array applications, eliminating the need to position and bond individual elements.     

Dual-polarized dielectric resonator antennas

Two high input-isolation dual-polarized dielectric resonator (DR) antennas are presented in this communication. First, a slot-coupled feed technique with two narrow slots forming a "T" configuration is employed to design a dual-polarized DR antenna. Input isolation exceeding 35 dB has been obtained in the band for this design. Secondly, a hybrid feed mechanism with a coplanar waveguide (CPW) feed and a slot feed is used to achieve a dual-polarized DR antenna. A vertical strip is added at the center strip of the CPW feed to improve the coupling to the DR antenna. Also, input isolation exceeding 35 dB has been obtained in the band. Good cross-polarization levels less than -20 dB in the broadside direction are attained. The measured far-field radiation patterns are stable in the passband and the measured gains are around 5.5 dBi for the two feed ports of both cases.     

Coplanar waveguide feed for microstrip patch antennas

A coplanar waveguide (CPW) loop is shown to be an effective low VSWR feed for microstrip antennas. The low VSWR transition between the CPW and the antenna is obtained without the use of a matching circuit, and it is relatively insensitive to the position of the antenna and the feed.<>     

介质谐振器天线研究进展

综述了介质谐振器天线技术三十多年来的主要研究进展.归纳了宽带/超宽带、圆/双极化、高阶模/高增益、毫米波设计及介质谐振器天线阵等方面的技术进展,也介绍了介质谐振器天线的特点与分析方法等.     

Broadband stacked dielectric resonator antennas

The input impedance of stacked cylindrical dielectric resonator antennas is investigated experimentally. The dielectric resonators are made of different materials. The bandwidth of 25% has been observed for a standing wave ratio better than 2.<>     

可调介质谐振天线的研究进展

可调介质谐振天线是无线通信领域的研究热点,本文对近年来可调介质谐振天线的研究热点和研究现状进行了介绍,并对可调介质谐振天线已有的研究方法进行了总结和分析,概述了加载寄生导电片、加载寄生槽(缝隙)、采用液体介质、增加空气带隙、使用特殊介质材料、使用开关(转换)器件这几种可调技术,最后分析了各种可调技术的优缺点。     

Wideband simple cylindrical dielectric resonator antennas

Bandwidths of the coaxial fed and aperture coupled cylindrical dielectric resonator antennas (DRAs) with broadside radiation patterns are enhanced by exciting the HEM/sub 11/spl Delta// (1相似文献   

Input impedance of aperture-coupled dielectric resonator antennas

Dielectric resonator antennas (DRAs) excited by a narrow-slot aperture in a conducting ground plane are analyzed using a numerical technique based upon a surface-integral equation formulation for bodies of revolution (BORs) coupled to non-BOR geometries. An efficient matrix-solution algorithm, together with a simple microstrip transmission-line model or a delta-source model are used to compute the antenna input impedance. Input impedances obtained with this technique show favorable agreement to those obtained via another numerical technique, as well as to those obtained by measurement     

Excitation of dielectric resonator antennas by a waveguide probe: modeling technique and wide-band design

Analysis of a dielectric resonator antenna (DRA) fed by a waveguide probe is presented. The probe is excited by the dominant mode of a waveguide and extends into the DRA through an aperture in the waveguide wall. The DRA has, in general, an arbitrary shape and resides on an infinite ground plane, which coincides with the exterior of the waveguide broad wall. A simple and efficient analysis procedure is implemented where the problem is divided into two parts. In the upper part, the input impedance of the DRA excited by a coaxial probe is obtained with respect to the feeding position on the ground plane independent of the waveguide part. Then the input impedance is transformed to the waveguide part as a concentrated load at the end of the probe connected to the waveguide wall. The effect of the wall thickness is taken into account by modeling the section of the probe passing through the waveguide wall as a coaxial cable transmission line supporting the transverse electromagnetic mode. Thus the DRA input impedance is transferred from the ground plane reference to the waveguide inner wall reference. Results obtained using the method of moments are compared with those obtained using the finite-difference time-domain method and exhibit very good agreement. The procedure is used to achieve a bandwidth of 50% for a stacked DRA excited by a waveguide probe.     

Mutual impedance of hemispherical dielectric resonator antennas

The mutual coupling between two hemispherical dielectric resonator antennas is studied analytically. The radiation fields of the antennas are derived rigorously from a Green's function. The mutual impedance is then determined from a reaction formula. Comparison between theory and experiment is presented     

Array of circular-polarised cross dielectric resonator antennas

A compact array of circular polarised cross-shaped dielectric resonator antennas (XDRAs) is presented. The array consists of 2×2 XDRAs elicited by microstrip-fed slot apertures in the X-band. By using sequential rotation to feed the XDRAs, the circular polarisation bandwidth is significantly increased from 5% for the individual XDRA to 16% in the array. The array also achieves a wide impedance bandwidth: a 10 dB return loss was maintained over a 25% bandwidth     

Conical dielectric resonator antennas for wide-band applications

Wideband dielectric resonator antennas are designed by shaping the dielectric materials. New dielectric resonator antennas of conical shape are experimentally examined and some results are verified numerically. Four different cone shapes are considered. The excitation is considered to be a coaxial probe displaced from the cone axis. Two configurations show wideband performance. The split cone achieved about 50% impedance bandwidth. The radiation patterns are computed within the band to examine the effect of the different modes excited on the radiation patterns     

Two-path cutoff waveguide dielectric resonator filters

The authors propose an evanescent-mode wave-guide filter consisting of two parallel cutoff waveguide paths with dielectric resonators. They introduce an accurate design method incorporating both the full-wave analytical method and the impedance inverter method. The specified overall characteristic is then synthesized with the help of a computer-aided design method. Measurements on several kinds of filters modeled at X-band show excellent agreement with the designed characteristics     

Wideband flipped staired pyramid dielectric resonator antennas

A wideband aperture coupled flipped staired pyramid shaped DRA is presented. An impedance bandwidth of 62% (S/sub 11/<-10 dB) is measured. The proposed DRA has a stable broadside radiation pattern across the matching band, with an average gain of 6.5 dBi. Simulation results obtained from Fidelity give good agreement with measured results.     

Design and analysis of multisegment dielectric resonator antennas

The multisegment dielectric resonator antenna (SDRA) has previously been developed to significantly enhance the coupling to a microstrip line. The MSDRA greatly facilitates the integration with a printed feed distribution network for use in a large array environment. The thickness and permittivity of the dielectric insert of the MSDRA can be adjusted to match the element impedance to that of the feed line. A detailed study of the effects of varying the dielectric insert parameters was carried out and useful guidelines are presented for the design of MSDRAs     

Broadband dielectric resonator antennas excited by L-shaped probe

Dielectric resonator antennas (DRAs) designed for broadband applications and excited by L-shaped probe are presented. The L-probe is housed under an air-filled groove between the DRA and the ground plane. A 32% matching bandwidth (S/sub 11/<-10 dB) is achieved with broadside radiation patterns. The new structure is constructed from the same dielectric materials. Thus, it is mechanically better than other wideband DRAs that consist of more than one dielectric material such as the stacked DRA. Some results are verified experimentally. The performance of this DRA and those fed by traditional probes and slots are investigated numerically. In addition, comparisons between L-probe excited DRAs and L-probe excited microstrip patch antennas are discussed.     

Conformal strip excitation of dielectric resonator antenna

A new excitation scheme that employs a conducting conformal strip is proposed for dielectric resonator antenna (DRA) excitation. The new excitation scheme is successfully demonstrated by using a hemispherical DRA whose exact Green function is found using the mode-matching method. The moment method is used to solve the unknown strip current from which the input impedance is obtained. Novel recurrence formulas were obtained so that the impedance integrals are evaluated analytically. This solves the singularity problem of the Green function and substantially reduces the computation time. An experiment was carried out to verify the theory. The co- and cross-polarized field patterns are also shown. In addition, an experimental technique which deals with the problem of an air gap between the DRA and the ground plane is presented     

Investigation of low profile, conformable, dielectric resonator antennas

An experimental investigation studied a cylindrical dielectric resonator antenna placed in a conducting well. Both the resonant frequency and input impedance increased as the wells became smaller, but the radiation patterns remained essentially unchanged. Resonators with smaller height-to-diameter ratios showed these effects to a lesser degree.     

Numerical analysis of dielectric resonator antennas excited in quasi-TE modes

A numerical analysis of a half-split cylindrical dielectric resonator (CDR) antenna on a conducting ground plane excited by a coaxial probe is presented. A procedure based on the method of moments (MoM) for the coupling of a body of revolution (BOR) to a non-BOR geometry is implemented. The antenna is operating in the TE/sub 01/ and HEM/sub 12/ modes. This antenna configuration has potential uses where high power handling capabilities and wide operating bandwidth are required.<>