Multiple feed transmit-array antennas with reduced focal distance

The performances of a single- and a quadruple-feed transmit-array are compared in X-band. The study has been carried out using an in-house CAD tool based on analytical formulas, and ideal focal source and unit-cells in order to provide generic results. We show that a quadruple-feed configuration leads to a reduction of the focal length by about a factor two, with similar performance in terms of gain and aperture efficiency. In the case of quadruple-feed transmit-array, the 3-dB gain bandwidth is improved as compared to the single-feed case from 40% to 65%.