Linearly polarized radial-line slot-array antennas with improved return-loss performance

The standard linearly polarized radial-line slot-array (RLSA) antenna exhib its poor return loss as seen by its coaxial feed. This paper describes tech niques that improve the poor return-loss performance of this antenna, by us ing two interchangeable methods: i) reflection-canceling slots on the front and back surface of the antenna, and ii) beam squinting. A series of 550 m m diameter linearly polarized Ku-band prototype antennas were constructed t o experimentally investigate the efficiency of each of these methods. In or der to cut experimental costs, initial radiation-pattern modeling was perfo rmed theoretically, and then prototypes were developed using inexpensive al uminum foil. Measurements of the developed prototypes indicated that both t he reflection-canceling and beam-squinting methods provided a substantial i mprovement in return loss over the desired frequency band.