M. Cuhaci

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.

A Ka-Band Dielectric Resonator Antenna Reflectarray

A reflectarray that uses a Dielectric Resonator Antenna (DRA) as the radiating element has been developed at Ka-Band. A variable length DRA provides the required phase shift at each cell on the reflectarray surface. Experimental results for this configuration show a similar performance to reflectarrays based on microstrip patch antennas.

A modal expansion method of analysis and measurement on aperture-coupled microstrip antenna

The coupling of a feedline to a rectangular patch through an aperture in the ground plane separating them is described using modal field analysis. The cavity model is used to describe the patch, the feedline is represented by a dynamic planar waveguide model, and the coupling is via a magnetic current in the aperture. Both theoretical and experimental results for the antenna performance are presented and design curves are generated. Very good agreement between theory and experiment was obtained. Results and design curves were obtained for antennas at 5 and 10 GHz, respectively. >

Development of a dual band circularly polarized microstrip reflectarray

The development of a dual-band circularly polarized microstrip reflectarray in Ka-band is presented. This reflectarray is composed of a set of cross dipole cell elements for each band that are etched in an interlaced lattice configuration. Two reflectarrays based on single and double layer configurations are introduced. Adjusting the length of orthogonal dipoles of the same cell element to maintain 90° relative phase shift between their re-radiated fields, will result in a reflectarray that converts an E-field that is linearly polarized along the bisector of the orthogonal dipoles into a circularly polarized field. Measurement results demonstrated 36% radiation efficiency and axial ratio better than 2.0 dB for 3% bandwidth for both bands and for both configurations.

EHF aperture-coupled microstrip antenna development

Aperture-coupled microstrip antennas have been developed for operation in the millimeter wave region. A combination of patch dimensions and aperture size determines the antennas resonating frequency. The measured return loss indicated an achievable bandwidth of 1.2% for a VSWR of less than 2:1. The measured radiation patterns at 45 GHz display the expected characteristics of microstrip patch antennas. Measurement of several antennas confirms the repeatability of the results.

Application of Fabry-Perot resonator for sidelobe suppression of antenna elements and arrays

A novel multilayer Frequency Selective Surface (FSS) is proposed for the suppression of far side lobes of radiating elements. Based on the affinity of the proposed structure with a Fabry-Perot resonator, a method is developed for its analysis and design. A double layer filter is designed, fabricated, and used in conjunction with several radiating elements that suppressed side lobes in the angular range of 40° - 50° by 15dB.

Development of a dual band circularly-polarized cassegrain microstrip reflectarray

A design procedure and experimental results are presented for a high-gain dual-band, circularly-polarized (CP) reflectarray antenna with a Cassegrain feed, operating at Ku/Ka-band (Tx=30 GHz, Rx=20 GHz). The performance of this Cassegrain reflectarray antenna is compared with other CP reflectarray antennas designed by the authors of this paper. A transmit gain of 38 dBic and a received gain of 36 dBic with axial ratio of less than 2 dB for both bands was measured for this antenna.

Application of waveguide technology for the characterization of photoconductivity of poly(9-vinylcarbozole) for millimeter-wave applications

3OHC60-PVK as a photoconductive polymer is proposed for millimeter wave applications. The fabrication process for this photoconductive polymer is presented along with a waveguide setup for measuring its photoconductivity. The photoconductivity of the polymer sample is measured at different optical excitations and compared with metal and silicon. Measurement results demonstrate a high photoconductivity in this polymer sample, even higher than that of high-resistivity silicon illuminated under similar optical power.

Dielectric resonator antenna technology for wireless applications

This paper features some of the recent advances in dielectric resonator antenna technology at the Communications Research Centre, Ottawa, Canada. Several novel elements are presented offering significant enhancements to parameters such as impedance bandwidth, circular polarization bandwidth, gain, or coupling to feed structures. A variety of linear and planar arrays are also presented to illustrate the performance of these elements in an array environment. Dielectric resonator antenna technology offers a promising alternative to conventional antennas for wireless communication applications.

Development of a dual band circularly-polarized offset feed microstrip reflectarray

The design procedure and experimental results are presented for a high-gain, dual-band, circularly-polarized (CP) reflectarray antenna with an offset feed, operating at the Ku/Ka-band (Tx=30 GHz, Rx=20 GHz). The performance of this offset reflectarray antenna is compared with other CP reflectarray antennas designed by the authors of this paper. A transmit band gain of 38 dBic and a receive band gain of 36 dBic both with an axial ratio of less than 3 dB were measured for this antenna.