Compact Designs of Quasi-isotropic and Unidirectional Dielectric Resonator Antennas for Wireless Communications

For a wireless communication system, the antenna is a very important part because it directly affects the signal transmission and reception. Recently, the dielectric resonator (DR) antenna (DRA) has been studied extensively due to a number of advantages including its low loss, small size, low cost, and ease of excitation.The complementary antenna is an important topic. It consists of electric and magnetic currents from which useful and interesting radiation patterns can be obtained. A number of complementary antennas have been realized using the slot and dipole antennas, but all of them are bulky in the structure and/or complicated in the feed. In this project, a novel DRA design concept that involves both electric and magnetic currents is proposed for the first time. The electric and magnetic currents are obtained from the small ground plane and the DR resonant mode, respectively. This new kind of DRA, named as complementary DRA, is very compact in size with a very simple feed. In this project, the complementary DRA will be used to design quasi-isotropic and unidirectional antennas (quasi-isotropic antennas are considered because it is very difficult, if not impossible, to obtain a truly isotropic antenna).The quasi-isotropic antenna is useful in some applications such as radio-frequency identification (RFID) systems because it has good coverage of signal at different angles. For DRAs, however, only broadside and omnidirectional radiation modes have been investigated and no quasi-isotropic radiation pattern has been generated thus far. In this project, compact quasi-isotropic antennas are designed using complementary DRAs. Wideband versions will also be provided for wideband wireless systems.Two kinds of unidirectional antennas will be designed using complementary DRAs, namely the lateral and boresight unidirectional DRAs. The design technique of the former will be applied to the dualfunction glass-swan DRA which simultaneously serves as an indoor decoration and the antenna of a wireless router. For the boresight case, the design technique will be used to suppress backward radiation of a broadside-mode DRA. This is very useful especially when a small ground plane is needed for a compact design. Wideband designs will also be provided for both kinds of unidirectional DRAs. In addition, circularly polarized boresight unidirectional DRAs will be covered for different needs.For each antenna, simulations will be done using ANSYS HFSS and verified with measurements. Also, a guideline will be given to facilitate the design.