Design of broadband vector-sum phase shifters and a phased array demonstrator

Abstract

Phased array antenna systems provide significant advantages and are used in modern radar and wireless communication systems. Phase shifters are one of the key components in electronically steered phased array antennas. Designs have been explored to increase the bandwidth of vector-sum phase shifter (VSPS) with low Root-Mean-Square (RMS) phase and amplitude error using commercial-off-the-shelf components on printed circuit board (PCB). In addition, other S-parameters like return losses, gain variation over frequency were also analyzed and improved. In this thesis, a wideband VHF VSPS has been designed for a bandwidth ratio of up to 20:1 with desirable RMS phase error for a 3-bit phase shifter. Broadband L-band VSPS is then also designed to cover the entire L-band and also improve on the S-parameters. Lastly, a 4-element phased array demonstrator using the L-band VSPS has been built and has successfully demonstrated beam steering capability at 1.8 GHz.