An Integrated Approach to RF Antenna-Filter Co-Design

In this letter, a co-designed antenna-filter is presented. The antenna-filter is composed of a microstrip patch antenna and a hairpin filter, both of which share the same ground plane to reduce the size. Instead of using the traditional 50-Omega interfaces, the impedance between the filter and antenna is optimized to improve the performance. The simulated and measured results have demonstrated that co-designed antenna-filter has a better bandwidth (4.7%, 4.064.26 GHz) and a larger gain (4.3 dBi) than the traditional version with 50-Omega interfaces impedance.