A dual-polarized slot-ring antenna with independent tuning

Tunable resonant antennas are useful for wireless communications because a single antenna can cover several different frequency bands while rejecting noise and interference at frequencies outside of the selected band. Dual-polarized antennas extend the flexibility of a system even further. Slot-ring antennas are capable of both tuning and dual-polarized operation, but no tunable dual-polarized antennas have been demonstrated to the authors´ knowledge. Square dual-polarized slot-ring antenna in which both polarizations can be tuned independently from 4.4 GHz down to 1.92 GHz with capacitive loading. Measured results are presented using ceramic chip capacitors, but varactor diodes will be used in future designs.