Miniaturized circularly polarized patch antenna using coupled shorting strip and capacitive probe feed

This paper proposes a single-feed miniaturized circularly polarized (CP) patch antenna aimed to cover Chinese BeiDou navigation satellite system (BDS) B3 band (1268.52 +/- 10.23 MHz). Four unbalanced circular patches as perturbation elements are loaded onto corners of a square patch radiator to ensure CP property. To simultaneously realize miniature size and adequate CP bandwidth, each circular patch is coupled to an L-shaped shorting strip consisting of a horizontal arc-shaped strip connected to the ground plane through a vertical shorting pin. In addition, a capacitive probe feed fulfilled by embedding an annular gap is used to compensate large probe inductance due to thick substrate, and therefore good impedance matching can be obtained. The antenna occupies an overall size of lambda(0)/8 x lambda(0)/8 x lambda(0)/13.6, where lambda(0) denotes the free space wavelength at 1268 MHz. Experimental results show that it achieves a 10-dB return loss impedance bandwidth of 75 MHz (1237-1312 MHz) and a 3-dB axial ratio (AR) bandwidth of 31 MHz (1253-1284 MHz). The measured 3-dB AR beamwidth and CP gain are above 170 and 4.0 dBic, respectively, across the entire BDS B3 band. (C) 2018 Elsevier GmbH. All rights reserved.