Utilizing Symmetry of Planar Ultra-Wideband Antennas for Size Reduction and Enhanced Performance

TL;DR

This paper introduces a generalized feeding technique for symmetrical ultra-wideband antennas, enabling size reduction and improved impedance matching while maintaining or enhancing performance.

Contribution

It proposes a universal method to miniaturize symmetrical antennas using a common feeding approach, supported by characteristic mode analysis.

Findings

Wider bandwidths achieved with halved structures

Improved impedance matching over full-size antennas

Enhanced understanding of radiation mechanisms through modal analysis

Abstract

With the increasingly new ultra wide-band applications, antenna researchers face huge challenges in designing novel operational geometries. Mono-pole and quasi-mono-pole antennas are seen to be the most compact and easily incorporate able solution for portable devices taking the advantages of printed circuit board (PCB) techniques. Most antennas of such type have symmetrical structures. It is possible to attain wider operating bandwidths by meeting symmetry conditions while chopping the antenna into halves for a compact structure. However, there is no generalized way of applying such a technique. The presented paper addresses this issue by proposing a common feeding technique that can be applied to any antenna which is miniaturized using its symmetrical structure. The proposed technique enables feeding the halved structure to achieve wider and better impedance matching than the reported full-size antennas. The theory of characteristic modes is applied to quasi-mono-pole structures to get an insight of the antennas mechanism. The radiation patterns are also correlated with modal current distributions to understand the radiation characteristics of the modified structure. Lastly, the method is implemented on some example antennas to illustrate its potential.