High-Performance Circularly-Polarized Patch Subarrays for Dual-Band Direct-to-Earth Communications in Future Mars Rover Missions

The recent success of the Mars Science Laboratory has garnered worldwide interest in further exploration of Mars. In this paper, we discuss our latest developments in circularlypolarized patch subarrays to be integrated into a larger 30 dB gain array. This larger array will facilitate a dual-band Directto- Earth (DTE) link with the Deep Space Network at X-band. The frequency ratio between both bands is rather small with a value of 1.17, and current dual-band or wideband CP patch elements are not easily suited for X-band frequencies, antenna array requirements, or the harsh environments in space. Our array elements are single-feed and single-layer, easing fabrication requirements. Each element achieves circular polarization through an optimized CP Half E-shaped patch design. More importantly, the subarray achieves the desired directivity, axial ratio, and impedance matching performance with a compact design, allowing straightforward integration into the larger array for future Mars Rovers. Our measurements of the 4 4 subarray prototype demonstrate the desired performance for creating an X-band DTE link.