Systematic Study of Feed Line and Ground Plane Modifications for Design of Miniaturized Wideband Antennas

In this paper, the analysis of feed line and ground plane modifications and their effect on the structure footprint is carried out in the context of ultra-wideband (UWB) antenna design. Two particular types of modifications are considered, a multi-section stepped-impedance feed line, and a multi-section slit below the feed. Contribution of these modifications to achievable miniaturization rate is investigated, both with respect to the type and the geometrical complexity (number of sections). The results obtained for two reference UWB monopoles indicate that both types of modifications permit significant reduction of the antenna size without degrading its electrical and field properties. At the same time feed line modifications are more advantageous (56% versus 43% of average miniaturization rate). Increasing the number of sections leads to further improvements (at the cost of making the design process more challenging) just as combining both types of alterations. The results are consistent for both reference antenna structures.