A Four-Arm Circularly Polarized High-Ga n High-Tilt Beam Curl Antenna for Beam Steering Applications

A novel circularly polarized (CP) beam-steering four-arm curl antenna with four feed points is presented. The antenna provides steerable high-gain high-tilt right-handed CP (RHCP) beams for satellite communications. The antenna operates over a test frequency band of 1500-1670 MHz and covers the entire Li band. The four arms are arranged symmetrically with respect to the center of the antenna, and each arm is fed by a coaxial line. When one of the four feed points is excited and the remaining feed points are either open-circuited or terminated to 50 Omega impedance, the antenna generates an RHCP tilted beam of 49 degrees in the elevation plane. At a test frequency of 1575 MHz, the antenna provides a gain of 8.12 dBic. The antenna can switch the tilted beam in the four different space quadrants in the azimuth plane by exciting one feed point at a time. It is found that over the test hand, the antenna provides a total efficiency of more than 89% and a gain of greater than 8 dBic.