Modelling of probe‐fed cylindrical dielectric resonator antennas

Probe‐fed cylindrical dielectric resonator antennas (CDRAs), with dielectric constant ϵ_r=37 and supported by an infinite ground plane, are simulated using the finite element method. From this, closed form expressions are obtained for the resonant frequency, directivity, and unloaded Q‐factor, applicable to a wide range of antenna dimensions. The effects of (a) the finite circular ground plane, (b) the air gap between the CDRA and the ground plane, (c) the air gap between the CDRA and the feed probe, and (d) the length of the probe on these parameters are studied for a particular CDRA and appropriate correction factors are derived. The simulated results are compared with those obtained experimentally for various ground planes, probe lengths, and probe spacings. The closed form expressions provide good agreement with the experiments in resonant frequency, unloaded Q‐factor, and impedance bandwidth, but less accurate prediction in antenna directivity for the specified range of parameters. ©1999 John Wiley & Sons, Inc. Int J RF and Microwave CAE 9: 2–13, 1999     

Method for accurate measurement of complex permittivity of tissueequivalent liquids

A microwave method for determining the electrical properties of lossy liquids is presented. The method is optimised for measuring the complex permittivity of human tissue equivalent liquids typically used together with human head phantoms in SAR (specific absorption rate) measurements. The method presented has a considerably better performance than conventional methods     

Nonstandard methods in many-valued logics

 Since MV-algebras include, in an essential way, infinitisimals it was felt that a systematic study of relationships of nonstandard methods and MV-algebras was needed. In this paper we try to introduce some basic frameworks to study MV-algebras from a nonstandard point of view. Also one can see that for a complete study of MV-algebras many external objects need to be treated differently.     

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-element endfire dielectric resonator antenna array

The radiation from a two-element endfire dielectric resonator antenna array has been experimentally investigated and compared with theoretical formulations. The measured gain of the array is 4.6, which is 35% higher than the gain of a single element DRA. The measured impedance bandwidth is 11.4%, which is 0.7% lower than the bandwidth of the single element DRA. Good agreement has been observed between the predicted and measured results     

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