Broadband quad‐polarisation reconfigurable antenna

A new broadband quad-polarisation reconfigurable antenna is proposed. The reconfigurable antenna consists of a +45° polarised dipole and a -45° polarised dipole. Each dipole is excited by a broadband balun. A reconfigurable feeding network is employed to feed the ±45° polarised dipoles. When the ±45° polarised dipoles are separately fed, ±45° linear polarisations are obtained. As the ±45° polarised dipoles are simultaneously fed with a +90° or -90° phase difference, left-handed circular polarisation (CP) or right-handed CP is asserted. It is shown by simulation and experiment that the quad-polarisation reconfigurable antenna achieves an overlapped impedance bandwidth of 37% (0.69-1.0 GHz) for return loss >15 dB and an overlapped bandwidth of 36% (0.66-0.95 GHz) for axial ratio <;3 dB.