A dual-polarized Ku-band microstrip antenna array: a compact feeding network and a refinement strategy using microwave holographic imaging

Future SAR imaging of terrestrial snow cover may require a 15m-spaceborne, dual- polarized Ku-band microstrip antenna array. The entire array consists of sixty 16x16-element subarrays, each mounted on a deployable panel. At the operating frequency of 13.4GHz, the radiation pattern is desired to have a reasonable envelop in the narrow beam direction (xz-plane), with the broad beam in yz-plane steerable up to plusmn6deg. To prevent the grating lobe when scanning the beam using T/R modules, the spacing between two rows of the 16x16 subarray (two 1x16 arrays) can not exceed 0.85lambda₀. By considering the dual-polarization requirement, the design of each 1x16 array is quite challenging since there is not enough space in the y-direction to accommodate the feeding network with conventional corporate feeding structure. In this paper, a novel compact feeding network based on a single-layered substrate is applied to design and fabricate the 1x16 array. In particular, a refinement strategy of the feeding network is proposed by constructing the measured aperture field of the array using microwave holographic imaging technique (Ramat-Samii, 1985 and 1987).