A patch array designed for an aircraft to satellite communication link is described by Sanford (35) and is shown in Fig. 17. Eight patches are mounted together with the phase shifting and feeding circuitry to scan the beam in the elevation direction. Designed for operation at 1.5 GHz, the array, including radome, is 3.6 mm thick. Element phasing was optimized for maximum multipath rejection at low scan angles and to account for the curvature of the mounting surface. Each element was pointed in a different direction and has an inherent phase error relative to the center elements. A digital computer was used to determine how the design parameters actually affect the performance of the array. The spacing of the array elements must be greater than 0.32A (in free space) because the physical size of the radiating element on teflon fiberglass requires thin space. The spacing required to prevent
|
|
where D is the separation distance between the patch element, A is the wavelength in free space, and в is the maximum beam steering angle. For a 50° maximum steering angle, D must be less than 0.57A.