Aperiodic array consisting of subarrays for use in small mobile Earth stations

A simple yet practical method of designing an aperiodic array consisting of subarrays is shown. By properly controlling the excitation phase of each subarray, the designed aperiodic array has the capability to track a geostationary satellite within some limited angles. Starting with an initial position of the subarrays, their optimum positions in terms of the side lobe performance can be obtained by a newly developed algorithm which uses the steepest descent method together with an appropriately defined cost function. An example of an aperiodic array consisting of 16 subarrays in the 14 GHz band is shown. It can track a geostationary satellite at the maximum of 2° off its mechanical boresight (the direction perpendicular to the surface of the array). Although it is nearly square with the maximum dimension of only 47λ (wavelength), its calculated side lobe patterns satisfy most of the requirements specified in the International Telecommunication Union (ITU) recommendations, which must be met by all earth stations with antennas of larger than 50λ in diameter.