OMNIDIRECTIONAL MILLIMETER-WAVELENGTH ANTENNAS BASED ON SEGMENTAL DIELECTRIC RESONATORS WHICH SUPPORT WHISPERING GALLERY MODES

Subject and Purpose. The subject of investigation is a new class of resonant-type transmit antennas intended for operation at millimeter wavelengths. The model under consideration is based on the idea of diffractional re-emission of waves into the azimuthal direction by local inhomo-geneities of the basically cylindrical structure. The purpose of the work is to justify the possibility of using such an effect for creating antennas with a circular radiation pattern, and to suggest an appropriate design. Methods and Methodology. The research program included both experimental work and application of advanced computer simulation techniques. The modern methods employed have allowed studying electromagnetic field distributions both in internal domains of the dielectric resonators and in the far-field zones of the resonator-based antennas. Results. Design solutions have been proposed for resonant-type, omnidirectional transmit antennas to operate in the millimeter waveband. The characteristic parameters are sizes of their radiating elements, specifically the segmental members equidistantly disposed along the azimuthal direction on the cylindrical surfaces of dielectric disks. The radiational characteristics of such antennas, with segments of either localized or extended dimension (compared with the operating wavelength) have been investigated. Electric field intensity distributions in the far-field region and the respective gain factors of the antennas have been studied. Conclusions. The antennas based on segmental dielectric resonators have been shown to form multi-lobe radiation patterns covering the angular sector of 0–360 along the azimuth. By placing the local segments at the resonant field’s antinodes (of the operating mode) it is possible to achieve relatively high values of the gain, reaching 15.5 dB at the lobe maxima