Compact Dual-Band Proximity-Fed Circularly Polarized Patch Antenna for BDS Applications

This paper presents a compact dual-band proximity-fed circularly polarized (CP) patch antenna for BeiDou Navigation Satellite System (BDS) operation at B1 (1,561 MHz) and B3 (1,268 MHz) bands. The antenna aperture is minimized down to 26.6 mm (lambda/9 at the B3 band) in diameter and 12 mm (lambda/20 at the B3 band) in thickness using high permittivity dielectric substrate and meandered slots. The antenna design features that the resonant frequency in the higher band could be tuned independently by adjusting the branch length and breadth without affecting the lower band. To achieve right-handed CP (RHCP) radiation property, quadrature phase feeding is employed together with a broadband 0 degrees-90 degrees hybrid utilizing a small surface mount LTCC hybrid coupler chip. Experimental results show that the RHCP gain maintains larger than 1.5 dBic and the axial ratio (AR) stays below 3 dB within the B1 and B3 bands. This antenna design is a promising candidate for small BDS arrays as well as other dual-band BDS applications.