Design of Dielectric Resonator Antenna on Microwave Substrate

Abstract

In this thesis, designs of dielectric resonator antennas on microwave substrate are investigated. Both discrete and substrate-integrated DRAs are covered, which are operated in microwave and millimeter-wave bands, respectively. There are three major parts in this thesis.

For the first part, dualfunction cylindrical dielectric resonator (DR) as a DR antenna (DRA) and a load of a broadband phase delay line is investigated for the first time. The DRA is located on the microstrip line and used to load the phase delay line to match the impedance and shift the phase for broadening the bandwidth. At the same time, the delay line is used to feed the DRA. By using the 90° and 180° phase delay lines, the circularly-polarized (CP) and differential DRAs can be realized. Compared with the hybrid coupler-embedded antennas, the phase-delay-line DRA is much more compact and simpler for not requiring any external 50-Ω load. For demonstration, the wideband CP and differential cylindrical DRAs with embedded DR-loaded phase delay lines have been designed at 2.4-GHz WLAN frequency.

In the second part, a compact substrate-integrated two-port dual-frequency antenna is presented. It consists of a patch-loaded slot antenna and a substrate-integrated dielectric resonator antenna (DRA) for microwave and near millimeter-wave applications, respectively. The former is a hollow patch-loaded slot antenna, whereas the latter is a DRA fabricated in the hollow region of the loading patch by using air and metalized vias. Beneath the antenna substrate is a second substrate on which the feed networks of the two antennas are printed. For demonstration, a two-port dual-frequency antenna working in 24-GHz ISM band and 5.2-GHz WLAN band has been designed. Since the slots of the two antennas are perpendicular to each other, the isolation between the two antennas is very good; it is 40 dB and 35 dB in the lower and upper bands, respectively.

In the last part, substrate-integrated linearly and circularly polarized (LP/CP) planar DRA arrays are investigated for 60-GHz millimeter-wave applications. Air holes and metalized vias are used again to isolate the DR from the substrate. In both LP and CP designs, single element is first studied with ANSYS HFSS to simulate its reflection coefficient, radiation pattern and antenna gain. Next, in-phase and sequential-rotation feeding networks are designed for the LP and CP arrays respectively. The arrays are finally formed by using the element and the feeding network that have been designed. To generate CP radiation, a loaded patch with a pair of 45° inclined slice is deployed based on the LP design. It is noted that the DRA works in its HEM11δ mode in both the dual-frequency and array designs. Both the LP and CP arrays can fully cover the 60-GHz unlicensed band with satisfactory performance.

Date of Award	8 Sept 2016
Original language	English
Awarding Institution	City University of Hong Kong
Supervisor	Kwok Wa LEUNG (Supervisor)