In this study, a novel filtering patch antenna (FPA) based on quarter-wavelength or /4-resonator filtering topology is presented, and its frequency response is efficiently synthesised to achieve the prescribed higher-order frequency selectivity. As the resonant patch radiator is capacitively fed by two inductively coupled /4 resonators, three transmission poles are created in the operating band to demonstrate the third-order bandpass filtering property. In design, two adjacent /4 resonators are coupled via a shorting pin as the K inverter, while one of them is coupled with the resonant patch via coupled line as the J inverter. As their equivalent parameters are numerically de-embedded, the overall equivalent filtering network of this proposed FPA is constituted and synthesised with the Chebyshev-function filtering response. Next, the relationship between the realisable fractional bandwidth and in-band return loss is thoroughly investigated for a patch radiator with its constant unloaded quality factor. Finally, a prototype FPA at 4.0GHz is designed, fabricated, and measured. The measured and simulated results are found in good agreement with each other, demonstrating a few attractive features of the proposed FPA, inclusive of wide operating bandwidth, sharp filtering selectivity, and flat radiation gain, as benefited by the three in-band poles.