Jaimon Yohannan

MICROSTRIPLINE FED CYLINDRICAL DIELECTRIC RESONATOR ANTENNA WITH A COPLANAR PARASITIC STRIP

The paper discusses the experimental analysis on a cylindrical dielectric resonator antenna (DRA) with a parasitic conducting strip, loaded coplanar with the 50Ω microstripline feed. The antenna offers an impedance bandwidth as high as 17.33% at a centre frequency of 2.77 GHz, as a result of the enhanced coupling produced by the coplanar strip. The return loss, impedance, polarization and radiation characteristics of the antenna are studied. The radiation patterns are broad and the low cross-polarisation levels confirm that the antenna is linearly polarised over the entire impedance bandwidth.

A Wideband Conical Beam Cylindrical Dielectric Resonator Antenna

The letter proposes a novel cylindrical dielectric resonator antenna (DRA) geometry with low radiation Q-value facilitating wide band operation with conical radiation patterns. The DRA is fed by a microstrip transmission line with a vertical strip that is attached to the DRA surface. At optimum dimensions and position of the vertical strip on the horizontal microstrip, the DRA exhibits an impedance bandwidth (

A Novel Technique for Localizing the Scatterer in Inverse Profiling of Two Dimensional Circularly Symmetric Dielectric Scatterers Using Degree of Symmetry and Neural Networks

\vert {\rm S}_{11}\vert < - 10

Microstripline fed circular sector dielectric resonator antenna

dB) of

Detection of dielectric contrast of breast tissues using confocal microwave technique

{\sim}35\hbox{\%}

Dielectric ring resonator band pass filter for 2.4 GHz WLAN frequencies

at the centre frequency of 3 GHz. Measured radiation patterns are conical in shape and are stable with moderate gain across the matching band.

Microwave ceramic resonator antenna for communication applications

A novel technique for localizing the scatterer in microwave imaging of two-dimensional circularly symmetric dielectric scatterers using degree of symmetry and neural networks is presented. The degree of symmetry for a transmitter position is computed as a function of the difference between the first half and the spatially reflected second half of the measured scattered field vector. A Probabilistic Neural Network (PNN) classifier is trained with the degree of symmetry vectors for the different object configurations. It classifies the degree of symmetry vector of the unknown circularly symmetric scatterer presented to it into one of the classes that indicate the radius and location of the centre of the scatterer. Thus the scatterer is localized in the imaging domain. This not only reduces the degrees of freedom in the inversion for the unknown object, thereby aiding the global convergence of the solution, but also results in a reduction in computation time. The technique has been tested on synthetic data and the results are promising.

Synthesis of Dielectric Resonators for Microwave Filter Designing.

A microstripline fed circular sector dielectric resonator antenna is investigated. A 180/spl deg/ sector of a cylindrical DR on a ground plane has been used for the study. The proposed configuration offers an increase in bandwidth (24%) with broadside radiation pattern. In addition, the configuration offers simple feed structure, compact size and thus easy integration with handheld communication equipment.

Microstripline fed cylindrical sector dielectric resonator antenna

Confocal microwave technology is explored as a screening tool to detect regions of dielectric contrast of breast tissues. When exposed to microwaves, malignant breast tissues exhibit electrical properties that are significantly different from that of healthy breast tissues. In vitro studies of normal and cancerous breast tissues are performed using a prototype of confocal microwave imaging. Experimentally obtained time domain results are substantiated by finite difference time domain analysis and good agreement is reported. Distance to the region of dielectric contrast is computed accurately using these results.

Coaxial fed hexagonal dielectric resonator antenna

A Microwave band pass filter employing dielectric ceramic ring resonator is designed, fabricated and tested. Band pass filter characteristics are studied by measuring the return loss and transmission characteristics of the microstrip line fed dielectric ring resonator. S-parameters, electric field and magnetic field distributions are computed using FEM method and compared with measured results. The measured values agree with predicted values obtained using FEM. Centered at 2404 MHz the fabricated dielectric ring resonator filter shows a measured 3-dB band width of 20.6 MHz.