Compact low-profile UWB antenna with characteristic mode analysis for UHF TV white space devices

摘要

A compact ultra-high frequency (UHF) ultra-wideband (UWB) antenna for Television TV white space (TVWS) applications is presented in this study. The proposed radiating body is transformed from a rectangular plate following physical essence revealed by characteristic mode analysis. Modal current distributions and their contributions to the total radiation are further analysed after printing the radiating body onto a thin substrate. It is proved that the structure achieves efficient radiation over a wide range of frequencies by exciting multiple modes. In addition, effects of significant parameters on the antenna performance are discussed, and according to which the geometry is optimised. A prototype is fabricated and measured to verify its ultra-wide impedance bandwidth and monopole-like radiation pattern. Realised gain and radiation efficiency over the UHF TV spectrum are also measured. The bandwidth efficiency product against antenna electrical size are analysed and compared with theoretical limit and products of existing designs.