Four-arm sinuous antenna for direction finding system

This paper proposes a feeding method for four-arm sinuous antenna, which is realized by using microstrip printed board welded on metal pyramid. It is an effective way to solve the problem of input impedance transformation and broadband balun. Then a four-arm sinuous antennas working at 0.4GHz to 2GHz is given, the measured results of VSWR and radiation pattern show that the feed form is reliable and effective, and the antenna has excellent performance in the operating bandwidth.