Polarization agile slot-ring array antenna using Magic-T circuit

Herein, a novel polarization agile slot-ring array antenna is presented. The proposed slot-ring array antenna is composed of three parts as follows: (I) four slot-ring antennas, (II) a Magic-T circuit and (III) two phase shifters. Since the output ports of the Magic-T can be switched by the phase differences, the slot-ring array antenna can radiate and switch four polarizations, the ±45-deg. linear polarizations (LPs), right- and left-hand circular polarizations (RHCP, LHCP). There are no longer needed any switching devices, that is, the slot-ring array antenna is a very simple and compact configuration. Therefore, it is very promising in wide areas of wireless application, such as communications systems and various kinds of RF sensors. In this paper, the basic behavior of the 7.5 GHz slot-ring array antenna is investigated by simulation.