Polarization-Reconfigurable Antenna Using Combination of Circular Polarized Modes

This paper presents a novel polarization-reconfigurable antenna based on the combination of circularly polarized (CP) modes, which is capable of changing its polarization states among arbitrary linear polarizations (LPs), left-handed circular polarization (LHCP) and right-handed circular polarization (RHCP). A truncated square patch with two isolated aperture-coupling feeds is used as radiation element operating at 2.45 GHz, which can operate in two orthogonal CP modes with low crosstalk. By exciting one of the two feeding microstrip lines, LHCP or RHCP mode can be independently generated. Meanwhile, by simultaneously exciting the two feeding microstrip lines with identical amplitudes but with different initial phases, LP mode with polarization plane oriented in any desired azimuth direction can be obtained. The simulated and measured peak gain of the proposed antenna remains at about 6.8 dBi at 2.45 GHz and the impedance matching bandwidth ranging from 2.25 to 2.60 GHz is fully overlapped for all the polarization states. Experimental results show a good performance of the proposed antenna.