Multiport Power Combining Patch Antenna With Stable Reflection Coefficient and Radiation Pattern in Six Polarization States

A new kind of multiport power-combining patch antenna in multiple polarization states is proposed in this paper. The proposed antenna consists of a ground, a stacked patch, and a driven patch fed by four centrally symmetric ports. Based on the S-parameter analysis of the multiport antenna, six polarization states (0°, 90°, 45° linear polarization, and left-handed and right-handed circular polarization) with stable reflection coefficients and radiation pattern can be realized by controlling the input phases of four ports. In this way, it is not necessary to use extra feeding network to realize the multiple polarization states. Moreover, in addition to radiating electromagnetic energy just like conventional antennas, the proposed multiport antenna can also realize on-antenna power combining without the need of power combiner. As a result, the losses and size caused by extra power combiner and feeding network can be avoided. For verification, the four-port patch antennas in different polarization states are designed and compared. Moreover, a four-port antenna integrated with four power amplifiers is fabricated and measured. The results show that both on-antenna power-combining and multiple polarization states can be realized without the need of power combiner and polarization feeding network.