A Reconfigurable Dual-Band Dual-Circularly Polarized Antenna for Vehicle Global Navigation Satellite System Application

A simple and novel reconfigurable dual-band dual-circularly polarized (CP) cavity backed high-gain antenna for vehicle global navigation satellite system (GNSS) is first reported in this paper. This design consists of a simple planar printed monopole with four branches, four pin-diodes and a modified cavity. Four pin-diodes are used to control the length of these four branches. By asymmetrically changing the states of these four diodes, this antenna can resonate both right-hand circular polarization (RHCP) wave and left-hand circular polarization (LHCP) wave at two bands. An elliptical cavity with a metal step is adopted to realize unidirectional radiation. To verify the concept, one prototype is fabricated and measured. The measured impedance bandwidths (|S11| < -10 dB) are 22.69% (1.055-1.325 GHz) and 5.68% (1.54-1.63 GHz), and the 3-dB axial ratio (AR) bandwidths are 7.4% (1.211-1.304 GHz) and 3.91% (1.554-1.616 GHz) with only 1.261 center frequency-ratio (CFR). The proposed antenna has advantages of simple structure, reconfigurability, higher gain, and smaller CFR.