A new class of medium-size high-efficiency reflector antennas

The new class of reflector antennas that is described in this communication yields a higher directive gain than obtained with conventional reflector antennas of the same area. An antenna of this new design consists of a reflecting surface, a peripheral rim, and a feed system in the reflector center. It is analyzed as a combination of two radiating sources whose radiation maxima and mutual phase relations can be simply adjusted for highest directive gain in the axis normal to the reflector. The marked directive gain increase is explained on the basis that there is a virtual extension of the radiating aperture beyond the physical dimensions of the reflector. The two antenna models that are described develop directive gains of almost 3 dB above those of conventional reflector antennas of equal size and comparable pattern characteristics. Optimized for a given frequency, the new design covers a pattern bandwidth of approximately 4:1.