Polarization reconfigurable loop antenna for satellite communications

This paper presents a polarization reconfigurable printed loop antenna which could alter its polarization states electronically to right-hand circular polarization (RHCP), left-hand circular polarization (LHCP) or linear polarization (LP). By inserting four PIN diodes into the symmetric gaps of a dual-loop planar antenna, the proposed antenna can switch its polarization status by controlling the on-off state of PIN diodes electronically. Meanwhile, a coplanar stripline (CPS) has been employed as an impedance transformer for this antenna. It is shown that the antenna can achieve a 5.4% 3-dB AR bandwidth with a wider impedance bandwidth of 12.5% for both RHCP and LHCP and a 7.1% impedance bandwidth for LP. The proposed antenna has a uni-directional radiation pattern with a peak gain of 9.8 dBi under all polarization status. The presented antenna can achieve polarization reconfigurability and a high gain, while having a low profile and low cost. It is promising for applications in satellite communications and terrestrial wireless communication systems.