Rectangular Dielectric Resonator Antennas Fed by Dielectric Image Guide
Author: Asem S. Al-Zoubi
Publisher:
Published: 2008
Total Pages: 298
ISBN-13:
DOWNLOAD EBOOKAbstract: A linear array of rectangular dielectric resonator antenna (DRA) is studied. The array is excited by a dielectric image guide. The advantages of using the dielectric image guide (DIG) are the low losses at high frequencies, and wideband performance. Two different methods of coupling between the dielectric resonator elements and the image guide are investigated. The first method of coupling is to couple the image guide to narrow apertures (slots) that are in turn exciting the dielectric resonator elements. Two problems are found in this design. First, this design causes high return losses around the slot resonances. This problem is resolved by adding a reflection cancelling slot near each main slot. The second problem is the high back radiation. This problem is resolved also by using a conducting reflector on the DIG feeding side of the antenna. The second method of excitation is the proximity coupling method between the dielectric resonator antennas and the DIG. Coupling analysis and design of single element and two different arrays are performed. It is found that this design achieve low back radiation, but high cross polarization. The cross polarization is reduced by suppressing some high order modes that are excited in the DRA elements. This suppression of these modes is performed by wrapping the middle of each DRA by a conducting strip. The coupling between the DRA and the DIG is controlled by the separation distance between them. A Dolph-Chebyshev amplitude distribution is used to control the sidelobe level of the far field radiation patterns. A prototype was build for each design from a 7-element array. The measured and computed results are in good agreement. Two 15-elemet arrays are studied numerically and show that to improve the antenna efficiency, and a reasonable number of elements must be used to couple most of the input power to the radiating elements.