A Switchable 256 Elements Ka band Circularly polarized Phased Array Using 45 Degree Linearly Polarized Element

This paper presents a scalable 256-elelment (16 x 16) Ka-band switchable circularly polarized phased array. The proposed phased array antenna can generate LHCP and RHCP, which can be selected by setting the phased shifters in the beamformer chips with 6-bit phase control in SiGe BiCMOS. This phased array uses 64 silicon quad-core receive chips with 4 channels to feed 2x2 quad antennas. Those silicon core-chip chips are assembled on a 12-layer printed circuit board (PCB) together with a Wilkinson divider network and SIW cavity backed patch antennas. The low-cost design uses Taconic TSM-DS3 based multilayer printed circuit board (MPCB), and surface mount technology (SMT). The phased-array can scan to ± 60° in all planes with low sidelobes, a 3-dB beamwidth of 12.6° and 21.2 dBi gain at broadside in 8 x 8 array. The 3-dB axial ratio (AR) in the mainlobe region is lower than 4.8 dB when scanning. It is scalable without grating lobes to allow economical construction of larger phased arrays. The compact size makes it suitable for a low-cost Ka-band SATCOM terminal.