Bandwidth‐reconfigurable filtering microstrip patch antenna using contactless varactor‐loading scheme

Abstract

A bandwidth (BW)‐reconfigurable filtering microstrip patch (MP) antenna is investigated in this paper. Two pairs of slots with different lengths are etched on the patch to not only bring two radiation nulls for good filtering performance but also generate additional high resonant mode for extending the operating BW of the antenna. A contactless varactor‐loaded microstrip line embedded in the middle layer of the two stacked substrates of the MP antenna is constructed as a tuning structure so that the MP mode and the lower radiation null can be adjusted simultaneously. As a result, the fractional BW (FBW) of the filtering antenna can be reconfigured with a BW agility of 55.3% while the high selectivity is maintained. For demonstration, a prototype is implemented and tested. The simulated and measured results with good agreement are presented.