| dc.description.abstract | Beam steerable antennas are required for use in a range of emerging applications, including satellite internet, and 5G mobile access at millimeter wave (mmWave) frequencies. Liquid metal, as a new material, attracts an increasing attention due to its advantages of low insertion loss, low harmonic distortion, and large tuning ranges. Unlike conventional beam steerable antennas, there is relatively little work has been done on the topic of antennas reconfigured using liquid metal with beam steering capability. In this thesis, the research focuses on the development of patch antennas as well as arrays, achieving beam steering capability based on liquid metal. The proposed antennas reported in this thesis have low cost, wide scan angle, and low scan loss. Firstly, a theoretical calculation of the transmission behavior limit for the multi-layer reconfigurable transmit-array unit cell is proposed, which could guide the future similar designs. The theoretical calculations have been validated through computer simulation. This is the first study to be applicable to transmit-array unit cells in which the conducting resonators, on the different layers, are shaped differently. Based on the above theoretical study, we further design a reconfigurable transmit-array unit cell using liquid metal. It has low profile with only three conducting layers. The proposed prototype was fabricated and measured within an open-ended waveguide. It is the first time that a reconfigurable transmit-array unit cell, employing liquid metal, provides a large phase shifting range together with low insertion loss. Then beam steerable microstrip patch antennas are also presented. The proposed antennas utilize two beam switching techniques in concert, including parasitic steering technique and switchable ground plane. The proposed antennas have low scan loss across the large scan angle range. The proposed antennas were fabricated and measured. The measured results agree well with the simulated results and validate the effectiveness of the proposed antennas. More importantly, the switchable ground plane as a novel beam switching approach is firstly proposed in this work. Finally, an improved microstrip patch antenna was reported. The improvement enables continuous beam steering. To this end we designed a liquid metal channel and fabricated it using a 3D printer. With this improved channel, the updated patch antenna can achieve a continuous beam steering. This is the first microstrip patch antenna having the capability of continuous beam steering in the elevation plane. This thesis proposes novel antenna solutions based on liquid metal with beam steering capability. The designed antennas with essential characteristics, including low cost, wide scan angle, low scan loss, and high efficiency, could be used in future wireless communications. | en_US |
