Ka band umbrella reflectors for CubeSats: Revisiting optimal feed location and gain loss

Developing compact deployable umbrella reflector antennas for CubeSats potentially enables several advanced applications requiring high antenna gain. The size and weight constraints imposed by the CubeSat standard makes a smaller number of gores attractive for CubeSat applications. This work revisits the determination of the optimum feed location and gain loss with an emphasis on a smaller number of gores. We review the underlying assumptions of previous approaches that analyzed umbrella reflectors with a large number of gores. Furthermore, this work provides a comparison with results through parametric tuning of feed position using Physical Optics (PO)-based diffraction analysis. Our results pinpoint the cases in which the previous approximations may not hold, necessitating parametric tuning of feed position for optimal gain. We also discuss the effects of feed taper on the RMS error and the optimal placement of the feed.