Accurate design of Ka-band flat scanning antennas for mobile satellite terminals

Because of its good efficiency and relatively low cost slotted waveguide technology is a promising candidate for the fabrication of electronically scanning antennas for advanced communication services. Such antennas can typically be used for mobile satellite terminals. For practical implementation of the beam steering, however, the problem of grating lobes must be solved. In this paper, Elliott design method [1,3] has been extended to large slotted waveguide scanning arrays. Dielectric filling has been employed to reduce the distance between radiating elements. The synthesis of the scanning planar array is based on a rigorous FDTD characterization of the isolated slot in terms of an equivalent shunt admittance. The computed results are shown to be in good agreement with other methods. As an example, a 30° ÷ 50° scanning array with 32 × 20 slots has been designed showing 30dB minimum gain over 500 MHz bandwidth at 30 GHz; a pointing error less than 0.5° is obtained with 3-bit phase shifters.