A Half-Moon Antenna

Abstract

This work presents a half-moon antenna (HMA), which is composed of two semi-circular top and bottom conducting plates joined by a rectangular conducting plate. The HMA has a wide radiation beam. Radiation in the y-z plane (in the E plane) is hemispherical with a half-power beam width (HPBW) of more than 200/spl deg/. Radiation in the x-y plane (in the H plane) forms a sector beam with an HPBW of more than 100/spl deg/. To reduce the backward radiation and improve the gain, chokes are added to the HMA. An increase in the gain of approximately 1 dB is obtained. In order to obtain a tilted beam, the radius of the bottom plate is reduced. The maximum beam direction of the tilted beam /spl theta//sub max/ is not sensitive to frequency. Within a frequency range of 11 to 14 GHz (24%), /spl theta//sub max/=167/spl deg//spl plusmn/2/spl deg/. The gain is found to be G=9.5/spl plusmn/0.5 dBi within this same frequency range.