An Ultra-wideband Log Spiral Antenna with Back Cavity

Abstract

For ultra-wideband direction finding applications, this paper presents a dual arm conical logarithmic spiral antenna design. The antenna is fed by gradient printed balun. In order to optimize the standing wave, beam width and circular polarization axis ratio, the back cavity design is adopted, and the absorbing materials are loaded on the inner wall of the cavity. Through comprehensive optimization, more than 10 times the frequency bandwidth is obtained. The rotary arm can be printed on the thin medium substrate by radium engraving plating process, and the measured results also verify the design very well.