T-Shape Resonator-Fed Duplex Antenna with Enhanced Bandwidth

A T-shape resonator-fed duplex antenna with enhanced bandwidth is proposed. A square stacked patch is introduced to achieve a dual-band antenna. The stacked patch is fed by the T-shape resonators which are consists of three 1/4 wavelength short-circuited lines in every operation band. The dual-band antenna is regarded as the last-order resonator and coupled by the filter network of two channels through a gap and a slot. Compared with the traditional stand-alone patch antenna, the proposed duplex antenna shows wider bandwidth, more stable gain in radiation band. The working principle and design process are described in this paper. Finally, a duplex filter antenna operating at S band is fabricated and measured. The isolation between the transmission channel (uplink) 2.27- $\mathbf{2.51GHz (FBW=\ 10\%)}$ and receiving channel (downlink) 2.83- $\mathbf{3.03GHz(FBW=6.9\%)}$ is over 33dB. The measured results show a good agreement with simulation results.