Multilayer Pentagon Ring Dual-band Microstrip Antenna for GPS Aided GEO Augmented Navigation Receivers

A compact, dual-band, multilayer, circularly polarized pentagon ring microstrip antenna is proposed for GPS aided GEO augmented navigation (GAGAN) receivers operating in L band with center frequencies 1176.45MHz (L5) and 1575.42MHz (L1). The antenna has two pentagon rings patch antenna in two different layers connected together with six shorting pins. The pentagon ring antenna is evolved from equilateral triangle in order to maintain compactness. On adjusting the length of truncated sides of pentagon antenna and exciting the lower patch by a coax-feed, circular polarization is produced in both the frequencies. The multilayer structure aids in producing high gain of the antenna. The size of proposed antenna is reduced by 54 % when compared to conventional patch antenna. The simulated 10dB impedance bandwidth is 20MHz for both the L5 and L1 bands. The peak gains are 2.52dB and 3.35dB at L5 and L1 respectively. The antenna is left hand circularly polarized (LH CP) with axial ratio of 2.3dB at L5 and 0.71dB at L1.