Circular Patch Filtering Antenna Design Based on Hairpin Bandpass Filter

A circular patch filtering antenna (CPFA) is presented based on the Chebyshev hairpin bandpass filter (CHBF) synthesis. The circular patch radiator connected to the last stage of the hairpin resonator using tap technique that can extract the radiation quality of the patch while the feedline connected to the first stage of the resonator using coupling technique that result in the same value between the radiation quality of the patch and the external quality of the filter. The CPFA was designed and simulated to be operated at operating frequency 4.45 GHz with 2.6% fractional bandwidth. The CPFA has also been fabricated and measured. The measurement shows a good agreement with the simulation results.