New Printed Filtering Antenna with Selectivity Enhancement

In this paper, a new printed filtering antenna with selectivity enhancement is presented. Based on the co-design approach, the printed meander-line antenna and a quarter-wavelength resonator are used and integrated to be the filtering antenna. Here, an antenna performs not only a radiator but also the last resonator of the bandpass filter. A new structure of the quarter-wavelength resonator is also proposed, which can provide a shunt resonator with high capacitance and introduce two extra transmission zeros for selectivity enhancement. According to the filter specifications, a design procedure is depicted in detail. One example of a 2.45 GHz two-pole filtering antenna is described based on the second-order Chebyshev bandpass filter with 0.1 dB equal-ripple response. Furthermore, the proposed structure supply good filter skirt selectivity. The measured results, including the return loss and antenna gain versus frequency, have good agreement with the designed one.