Design and analysis of an optimized cavity-backed zigzag Archimedean spiral antenna

This paper presents a two-arm, zigzagged Archimedean spiral antenna with an optimized cavity. A multilayer dielectric absorber has been introduced in the cavity to facilitate unidirectional operation of the antenna. In order to incorporate the frequency-dependent complex permittivity data of the absorbing materials inserted in the cavity, precise microwave instrumentation has been used to determine these parameters experimentally. Based on this data, a genetic algorithm optimization procedure has been applied to derive the most favourable geometry of the absorbing cavity. Our results show that a design thus optimized significantly improves key performance parameters, maximizes the co-polarized gain and minimizes the cross-polarized gain of the antenna across its operational bandwidth.