A Twinaxial Feed for Cavity-Backed Spiral Antennas

Abstract

Wideband planar antennas with balanced feeds, such as spiral antennas, often require wideband microstrip exponential tapers with intricate printed circuit board interconnects at right angles. A twinaxial feed scheme is proposed for a cavity-backed spiral antenna, which eliminates this need. The overall assembly features an input VSWR of below 2.8:1 across the band of 630 MHz to 2.87 GHz, which is comparable to that of the antenna simulated in isolation with a differential port feed.