Switchable cylindrical dielectric resonator antenna

A switchable cylindrical dielectric resonator antenna operating in four different radiation modes is reported. Two linear polarised, one circular polarised, and a nonradiating mode are implemented. The experimental results of the resonant frequency, boresight axial ratio, gain, unloaded Q-factor, impedance bandwidth and radiation efficiency are presented for the operating modes and compared with the theoretical values     

Leaky-mode cylindrical dielectric resonator antenna

A cylindrical dielectric resonator (CDR) antenna, operating in leaky TM-modes, is presented. The antenna is composed of the CDR, short-circuited by parallel rectangular conducting plates. The radiation pattern depends on the size and shape of conducting plates. This technique provides an opportunity to change the radiation pattern without affecting antenna resonant frequency. Numerical examples based on the integral equation method are presented to show advantages of this design     

Circular polarised cylindrical dielectric resonator antenna

A circular polarised cylindrical dielectric resonator antenna excited using a simple microstrip feed line is reported. The experimental results of the resonant frequency, radiation pattern, boresight axial ratio, gain, unloaded Q-factor, impedance bandwidth and radiation efficiency are presented     

Two-dimensional cylindrical dielectric resonator antenna array

A square 2×2 subarray and infinite phased array of aperture-coupled cylindrical dielectric resonator antennas is investigated experimentally. The return loss, radiation pattern, and antenna gain are studied and compared with those of the single element antenna, and the waveguide simulator is used to measure the return loss of the element in an infinite array environment     

FDTD analysis of probe-fed cylindrical dielectric resonator antenna

The finite-difference time-domain (FDTD) method is employed to analyze a probe-fed cylindrical dielectric resonator antenna. Numerical results for the input impedance and radiation patterns of the dielectric resonator (DR) antenna operating in HEM_11δ mode are presented and compare favorably with measurements. The effects of various parameters on the characteristics of the DR antenna are studied. Fabrication imperfection effects and the cross-polarization characteristics of this type of DR antenna are also investigated for the first time     

Small eletric monopole mode dielectric resonator antenna

A novel dielectric resonator (DR) antenna is reported. The lowest order mode of the proposed antenna radiates like an electric monopole. The dimensions of the antenna are much smaller than a previously reported structure radiating in a similar mode, e.g. for an antenna fabricated out of ε_r=20 material, the diameter and height of the DR are ~0.08 λ₀ each     

New direct coupling configuration between TE/sub 01 delta / dielectric resonator modes

A new geometric configuration is presented to carry out negative coupling between dielectric resonators (DRs) acting in their dipolar TE/sub 01 delta / mode. These DRs are coupled in a direct manner so that transmission lines, metallic screws or irises as usually used become unnecessary.<>     

X-band TM/sub 01/-TE/sub 11/ mode converter with short length for high power

A mode converter for X-band located between a generator and an antenna to convert TM/sub 01/ to TE/sub 11/ mode with high efficiency for a high power transmitting system is presented. The proposed mode converter has extended radius and excessive curvature with symmetric structure in order to convert between two modes efficiently with short length. The measured and simulated results of the return loss, mode patterns and efficiency of the proposed mode converter with 200 mm length are provided.     

Broadband cylindrical dielectric resonator antenna excited by modified microstrip line

The impedance bandwidth of a high permittivity cylindrical dielectric resonator antenna excited by a microstrip line was significantly improved by modifying the feed geometry. The 10 dB return loss bandwidth is enhanced from 12 to 26% without much affecting the gain and other radiation properties of the antenna. Good agreement has been observed between the predicted and measured results.     

Ultra wideband monopole/dielectric resonator antenna

A hybrid antenna is presented, consisting of an annular dielectric resonator antenna combined with a quarter-wave monopole to simultaneously act as a radiator and a loading element, producing an ultra wideband response. A prototype antenna is designed and a 3:1 bandwidth is demonstrated.     

Two port analysis of dielectric resonator antennas excited in TE01 mode

Results of a numerical and experimental study of the transmission and input reflection coefficients of a two element array of half-split cylindrical dielectric resonator (CDR) antennas are presented. The antenna elements are situated on a ground plane and fed by a coaxial probe. A procedure based on the method of moments (MoM) for the coupling of a body of revolution (BOR) to a non-BOR geometry together with classical microwave network theory is implemented. Some of the numerical results are verified experimentally     

FDTD analysis of probe-fed cylindrical dielectric resonator antennaoperating in fundamental broadside mode

An analysis of a cylindrical dielectric resonator antenna operating at the fundamental broadside mode using the finite-difference time-domain (FDTD) method is presented. Good agreement between theoretical and experimental results on the input impedance of the DR antenna is obtained. The effects of the probe length, feed position and the dielectric constant on the input impedance are presented     

1D dielectric electromagnetic band gap (EBG) resonator antenna design

This article presents a new methodology allowing to design a planar electromagnetic band-pap antenna (choice of theebg material, sizing, feeding). This kind of antenna has already been presented.ebg antennas are very thin (compared with parabolic reflectors) high gain antennas. This article makes easier the realization ofebg antennas whatever the operating frequency, the gain, or still the bandwidth. A study about the sensitivity of the material properties on the performances is also presented. Finaly two exemples using this design method are described.     

Precision measurement of coupling between microstrip and TE01 mode dielectric resonator

The coupling between a microstrip transmission line and a dielectric resonator with a relative dielectric constant of 80 has been measured as a function of the distance between the resonator and the microstrip. Precision measurement involves the TRL de-embedding procedure, and data fitting to a fractional linear transformation on a complex plane. A comparison is made of covered and uncovered resonators, demonstrating the influence of radiation     

Scattering of the TE/sub 01/ and TM/sub 01/ Modes on Transverse Discontinuities in a Rod Dielectric Waveguide-Application to the Dielectric Resonators

Our purpose is to determine the resonance frequency together with the radiation quality factor of dielectric resonators. To do that, the reflection and the scattering properties of the TE/sub 01/ and TM/sub 01/ modes, incident on an abruptly ended dielectric rod, are analyzed. After the building of the complete mode spectrum on each side of the discontinuity, the continuity relations in the discontinuity plane associated with the orthogonality properties lead to a coupled integral equation system. That one is solved by means of an iterative procedure, providing all the characteristics of the discontinuity (reflection or coupling coefficients, radiation losses). Then, these solutions are used to determine the resonant frequency and the radiation quality factor of cylindrical resonators which are considered as waveguide lengths between two interacting discontinuities.     

Compressed-width leaky EH/sub 1/ mode PBG antenna

The recently developed electric-magnetic-electric (EME) microstrip is successfully used to design a compact leaky-mode antenna with fan beam radiation patterns. The EME microstrip consists of composite metals paralleling the electric and magnetic surfaces, where the magnetic surface is made of an array of coupled inductors. The frequency scanning behavior, experimentally and theoretically confirmed by matrix-pencil analyses, indicates that the line width can be reduced by 20%, compared to that of the conventional microstrip with the identical radiation angle of the first higher order (EH/sub 1/) mode at the same frequency.     

Experimental investigation on new steerable dielectric resonator antenna

A new steerable-dielectric resonator antenna is described. It consists of a movable annulus of heterogeneous dielectric sections surrounding a cylindrical core of another dielectric. The antenna far-field radiation was found to be manipulated by changing the angular position of this ring. This antenna demonstrates resonance at ~1.2 GHz with a fractional bandwidth of 28.3% (Sn₁₁< - 10 dB), confirming an HFSS simulation of the same structure.     

Reflectarray element based on strip-loaded dielectric resonator antenna

A new low-loss reflectarray element based on a dielectric resonator antenna (DRA) loaded with a metallic strip etched on the top of the DRA is presented. The strip behaves as a parasitic element, and by adjusting its length, the desired reflected phase is achieved. A set of DRA samples were fabricated and measured in C-band. A low loss (less than 0.9 dB) is demonstrated when the phase is varied. It is also shown that the loss is much higher (up to 5 dB) when the strip is directly printed on a dielectric substrate with the same characteristics.     

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     

Use of parasitic strip to produce circular polarisation andincreased bandwidth for cylindrical dielectric resonator antenna

An experimental investigation is undertaken to determine the effect on the bandwidth and polarisation of a cylindrical dielectric resonator antenna when a parasitic strip is attached to its surface. Particular configurations are found that increase the bandwidth and produce circular polarisation