Broadband dual-polarized slot loop antennas with high isolation orthogonal modes operation

A dual-polarized slot loop antenna fed by microstrip line is proposed. The dual-polarized slot loop antenna with dual radiating modes including microstrip line- and slotline-mode are excited by a wideband microstrip/slotline transition and a capacitively coupled “T” configuration stub, respectively, which are employed to enhance the impedance bandwidth. The planar design makes the antenna easy to integrate with RF circuitry on the same board. The slot loop antenna occupies an area of 12 × 18 mm2. From the measured data, the 25-dB port-to-port isolation of the antenna can be achieved. Also, the 10-dB return-loss impedance bandwidths of 32% and 67%, respectively, are obtained. Improved cross polarization level in both E-and H-plane patterns between the two polarizations about 20dB.