A Ku/Ka-dual band reflectarray to emulate a cylindrical reflector for titan cloud precipitation radar and altimeter

Abstract

A Ku/Ka dual-band reflectarray * has been developed as a demonstration model for the next generation of Titan Cloud Precipitation Radar and Altimeter (TCPRA). The reflectarray developed is a substitute of a parabolic cylindrical reflector and it is offset-fed by two linear arrays. The antenna has a 50-cm-square aperture and uses two 2-mil thick membranes for both bands enabling transformation into a future larger deployable structure. To show the scanning capability in the cross-track plane, the antenna utilizes the phased array feeds with one for broadside beam and the other for 20 o tilted beam along the focal line. Measurement results performed in the indoor anechoic chamber at Texas A&M University will be presented in this paper.Introduction -In the past several years, a microstrip reflectarray using inflatable structures and thin membranes [1-3] has been investigated to demonstrate a future deployable antenna technology. In this paper, a reflectarray antenna is studied to support light-weight, dual frequency, and wide-swath scanning antenna proposed in [4,5], for the next generation of spaceborne precipitation radar. As a demonstration model, a 50-cmsquare reflectarray with dual frequency capability has been developed with two linear feed arrays. The reflectarray fabricated is dual-linear polarized with both vertical and horizontal polarizations. At each frequency band, the feed array system has two sets of feed arrays designed with one having main beam direction at 0 o and the other at 20 o to show scanning capability in the cross-track plane. Each feed array has 32 X 2 patch elements. The challenges in the feed array design are to achieve -25 dB sidelobe and -30 dB cross polarization level requirements. Measurements are performed in the indoor anechoic chamber at Texas A&M University. Because the range at Texas A&M University is not long enough to support a true far-field measurement, the results shown here should be used as a reference to more accurate experiments in the near future.