Study On The Low-profile, Circularly Polarized Archimedean Spiral Antenna

With the rapid development of the electric science technology, the design of thelow-profile, wide-band antennas has been an urgent problem. This paper discusses thelow-profile, wide-band, circularly polarized Archimedean spiral antennas which are used inUHF and S bands in detail.Based on the theoretic analysis, a study is made on low-profile, wide-band andcircularly polarized antenna, the author’s major contributions are as follows.1. The design of the single-arm spiral antenna unit. The antenna which is proposed in thispaper has a simple feed structure——the coaxial line. With a metal disc loaded, it has alow VSWR and a low profile. And what’s more, a absorbed resistance is loaded in theend of the spiral line, which makes that the antenna has a good circularly polarizedperformance.2. The design of the two-arm spiral antenna unit. A two-arm Archimedean spiral antenna,which can achieve different radiation patterns by changing the phase of two armselectric current, is proposed in this paper. The two-arm spiral antenna has the sameperformance with the single-arm spiral antenna.3. The design of2x2spiral array. The antenna array has a1to4microstrip power divider.The two adjoining units has a90°phase difference because of the unit rotation.4. The design of19-unit phased array. The phased array can achieve the beam scaning bychanging the feeding phase of unit, and has a high gain performance in the lowelevation.