G.P. Junker

Input impedance of dielectric resonator antennas excited by a coaxial probe

A formulation based upon the method of moments (MoM) is presented for the computation of input impedance of dielectric resonator antennas. The class of antennas modeled by this method consists of axially symmetric dielectric resonators fed by thin wire elements. The formulation is general in that the feed structure may be interior or exterior to the dielectric resonator. To demonstrate the utility of this technique, parametric studies are performed on a cylindrical dielectric resonator antenna (CDRA) operating at frequencies that excite the important HEM/sub 11/ resonator antenna mode. The integrity of this technique is established both experimentally and numerically. >

Bandwidth enhancement for split cylindrical dielectric resonator antennas

A numerical study of split cylindrical dielectric resonator antennas on a conducting ground plane excited by a coaxial probe is presented. The numerical solution is based on the method of moments for a body of revolution coupled to a wire. We consider in this study bandwidth enhancement for dielectric resonators excited in the HEM11 and HEM12 modes for the split dielectric cylinder. A wideband performance of about 35% has been achieved for the antenna and experimental measurements have verified this finding.

Input impedance of aperture-coupled dielectric resonator antennas

Dielectric resonator antennas (DRA?s) 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 comnute the antenna inmt 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.

Bandwidth Enhancement for Split Cylindrical Dielectric Resonator Antennas

A numerical study of split cylindrical dielectric resonator antennas on a conducting ground plane excited by a coaxial probe is presented. The numerical solution is based on the method of moments for a body of revolution coupled to a wire. We consider in this study bandwidth enhancement for dielectric resonators excited in the HEM 11 and HEM 12 modes for the split dielectric cylinder. A wideband performance of about 35% has been achieved for the antenna and experimental measurements have verified this finding.

Effect of fabrication imperfections for ground-plane-backed dielectric-resonator antennas

The effect of imperfections in terms of surface roughness which could lead to the introduction of air gaps between the dielectric resonator (DR) and the contacting conducting surfaces is investigated. Results of studies which illustrate the effect of air gaps upon the input impedance and resonant frequency of cylindrical dielectric resonator antennas (CDRAs) operating in the TM01 and HEM11 modes are presented.

A novel delta gap source model for center fed cylindrical dipoles

A novel delta gap source model is presented which improves the convergence of the numerical solution of the electric field integral equation (EFIE) using thin wire theory. This delta source model yields a stable solution for the current at the source location, both computed and measured current distributions and input admittances for cylindrical monopole antennas are presented. >

Multiport network description and radiation characteristics of coupled dielectric resonator antennas

An efficient procedure is presented to investigate the mutual coupling effects and radiation characteristics of dielectric resonator (DR) antennas operating in an array environment. The procedure is based on the method of moments (MoM) as applied to a system of surface integral equations (SIEs) for the coupling of a dielectric body of revolution (BOR) to a nonBOR geometry. The antenna array elements are situated on a ground plane and fed by coaxial probes. Multiport network impedance parameters computed by this method show good agreement with those obtained by measurement. Computed driving point impedances are given for arrays exhibiting optimum pattern performance in terms of low cross polarization and good pattern symmetry.

Input impedance of an aperture coupled dielectric resonator antenna

The input impedance of a cylindrical dielectric resonator antenna excited by an aperture slot is computed. The technique used is based upon the surface integral equation formulation for bodies of revolution coupled to arbitrary objects. The method of moments (MoM), together with an efficient matrix solution algorithm, is used to obtain the equivalent magnetic current on the slot. The antenna impedance is then obtained from this equivalent magnetic current. The results of this numerical procedure, when compared to those obtained from a competing technique, show excellent agreement. Results of a parametric study on a dielectric resonator antenna are presented.<<ETX>>

Mutual coupling effects and radiation characteristics of a linear array of dielectric resonator elements fed by coaxial probes

Theoretical port impedances and radiation patterns of a linear array of dielectric resonator antenna elements are numerically computed. The technique used is based upon the surface integral equation formulation for bodies of revolution (BORs) coupled to non-BOR geometries. The method of moments (MoM) is used to obtain the equivalent surface electric and magnetic currents from which the port impedances and radiated fields are determined.

MoM solution of wire radiators coupled to dielectric bodies of revolution

A formulation based on the method of moments (MoM) is presented for active and parasitic wire radiators in the presence of dielectric bodies of revolution (DBOR/Wire). The formulation is general in that the wire radiators may be interior or exterior to the dielectric body of revolution (DBOR). This work is in essence an extension of techniques presented for the MoM solution of wire radiators in the presence of conducting bodies of revolution. The utility of the MoM has been expanded in the sense that the antenna engineer now has at his disposal a design tool which may accurately predict the input impedance of DBOR/Wire radiators. The validity of this technique is established by analyzing a dielectric resonator antenna and comparing the results of the DBOR/Wire formulation with those obtained by other techniques.<<ETX>>