Circularly polarised integrated filtering antenna with polarisation reconfigurability. Issue 15 (13th October 2017) - Lu, Yunlong
Abstract : A new design of circularly polarised integrated filtering antennas with reconfigurable polarisation is proposed in this study. Two phase‐reconfigurable coupled λ /2‐resonator pairs have been used to feed the antenna and generate the second‐order filtering response and the circular polarisation (CP) simultaneously. By switching the PIN diodes inserted in the feeding network, a phase difference of +90° or −90° can be realised at the outputs of the feeding network. This renders the antenna's capability of switching its polarisation from right‐hand CP (RHCP) to left‐hand CP (LHCP) or vice versa. The use of the coupled‐resonator pairs significantly improves the frequency selectivity and out‐of‐band rejection of the CP antenna. To the best of the authors' knowledge, this is the first report of a multifunctional antenna which has integrated filtering performance, CP, and polarisation reconfigurability. To verify the design concept, a reconfigurable CP antenna operating at 2.45 GHz is implemented. The simulated and measured results agree well with each other and show that the antenna has an impedance bandwidth of 4.5%, an average in‐band gain of 6.0 dBic (LHCP)/6.1 dBic (RHCP), out‐of‐band rejections of >10.8 dB, and 3 dB axial ratio bandwidth of 9.4%/10.5%.