Wideband Circularly Polarized Antenna And Low-Cost Phase-Shifters Using Partially Transmitting Surface

This paper presents a design for a circularly polarized (CP) antenna and a low-cost phase shifting mechanism using a partially transmitting surface (PTS). Both the return loss (S11) and the axial ratio (AR) bandwidth enhancement is achieved by using a partially transmitting surface (PTS) type of superstrate, placed above a crossed-Bowtie shaped antenna with cloverleaf arms. Designs for achieving a continuous phase variation, ranging from either (i) 10° to 70° (ii) or 10° to 43° are presented, the former with a wider phase range of 60° but a relatively narrow impedance matching bandwidth, as compared with the latter design whose phase range is 33°, but the impedance bandwidth is wider. The realized return loss (S11) bandwidth of the antenna is 38.5%, and its 3dB axial ratio (AR) bandwidth is 41.5 %. Furthermore, the gain of the antenna is enhanced in the band of 4.2 to 6.2 GHz via the use of the PTS superstrate