Reconfigurable multi-polarization and multi-band circular patch antennas implemented by large amount of diode switches

A reconfigurable multi-polarization and multi-band circular patch antenna is proposed. This antenna is coaxial-fed at center with 18 PIN diodes placed across a circular ring slot on the patch. By different diode on-off states, four frequency bands can be produced. Due to the circular symmetry, in theory the polarization can rotate at a 20° interval with the same antenna characteristics. A prototype operating in GSM900, LTE1500, GSM1800 and IEEE802.11b/g bands is designed and fabricated. The measured results shows that the 10-dB bandwidths of the four bands are almost covered.