Topological modifications for performance improvement and size reduction of wideband antenna structures

Abstract

Compact antennas belong to the key components of modern communication systems. Their miniaturization is often achieved by introducing appropriate topological changes such as simple ground plane slots or tapered feeds. More sophisticated modifications are rarely considered in the literature because they normally lead to significant increase of the number of tunable parameters, which makes the antenna design process more challenging. On the other hand, complex topological changes are questionable as their effects on radiator performance and/or size reduction are difficult to be verified in practice. In particular, parameter sweeping commonly used for dimension adjustment is incapable of their appropriate handling. In this work, the effect of feed line and ground plane modifications on performance and size reduction of a wideband antenna is investigated. Considered geometrical changes include a ground plane slot and a stepped-impedance feed line (both with gradually increasing number of sections). The modified structures have been optimized for minimum in-band reflection and minimum size using a robust gradient-based algorithm. The obtained results demonstrate that complex topological modifications may be useful for achieving both good performance and small size when handled comprehensively.