Dual Circularly Polarized Broadband Microstrip Antenna Array for Space Re-Entry Vehicle Applications in S Band

This paper presents the design details of an integrated 4x4 element dual feed dual circularly polarized microstrip antenna array in the S-band. The dual circular polarization is achieved by the use of quadrature hybrids. Power division for the dual input array is achieved through two 1x16 equal split equal phase corporate feed networks. The quadrature hybrids and corporate feeds for the proposed array are designed in multilayer printed circuit boards (PCB) in stripline configuration. This antenna can be used to transmit or receive both right-handed circularly polarized (RHCP) waves or left-handed circularly polarized (LHCP) waves simultaneously or one at a time by terminating the other port with 50Ω resistance. The proposed antenna has 700MHz of 10 dB impedance bandwidth (27%), 400MHz of 3dB axial ratio bandwidth and 300MHz of 3dB gain bandwidth centred at 2.5GHz with a peak gain of 15.5dB in both polarizations. It has a 3dB beam width of 26˚ and cross-polarization levels below 20dB in both the polarizations. Design and simulation of patch array, quadrature hybrids and 1x16 corporate feeds in multilayer configuration, PCB stack-ups, fabrication, integration and testing processes are discussed in detail. The effect of thermal protection system (TPS) of the re-entry vehicle on antenna performance parameters was studied and presented