Characteristics of Spiral Antennas in the Estimation of Direction-of-Arrival

Multi-arm spiral antennas are widely employed in the applications of radar direction-finding system. In practical applications, they can be integrated with external structures such as radomes and RF lens. The external structures alter the antennas´ natures of frequency-independency and may impact their performance in predicting the direction of an incident plane wave. This paper evaluates their performance based on an analytic analysis via ray tracing techniques and validated by physical optics (PO). Two external structures including radomes and RF lens are examined. Characteristic analysis is performed and discussed in the numerical examples