Miniature Triband Shared Aperture Circular Polarized Patch Antenna for High Temperature Air Born GNSS Application

This paper brings out the design aspects of miniature triband shared aperture circular polarized patch antenna for high temperature long endurance airborne Global Satellite Navigation System (GNSS) application. GPS L1(1.59GHz), L5(1.176GHz) and IRNSS S(2.49GHz) bands are designed on three separate patch layers in which L5 band patch is at bottom, L1 is at middle and S band is on topmost layers. Only bottom most layer has ground plane and rest of the two layers are ground free. Substrate materials are selected for three layers to offer best efficiency in compact size. Two orthogonal degenerate modes are excited at each layer at each band to get circular polarization using chopping of diagonally opposite edges. Single coaxial connector soldered at top most patch layer to excite three resonances. Antenna kept in cavity of stainless steel housing and covered with fused silica radome to handle high temperatures. The full antenna with radome is simulated in CST microwave studio. The bandwidth of circular polarized antenna was 24MHz, 59MHz and 40MHz in three frequencies. Antenna configured with <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.26 \lambda_{0}$</tex> size of lowest frequency. It is designed and proposed for airborne GNSS services with compliance of thermal and structural requirements.