Circular formed dual-band dual-polarized patch antenna and a method for designing compact combined feed networks

Firstly, a novel method of designing compact combined feed networks is introduced here to convert 4-port Dual-band Dual-polarized Patch Antenna (DDPA) into 2-port DDPA. It is shown that by using this method excitation of unwanted modes is blocked and good return losses for operation bands of the obtained 2-port DDPA are achieved. The calculations of method are based on transmission line model. Secondly, a 4-port aperture coupled DDPA is presented in new circular form; GSM and DCS bands are chosen as operation bands. Then, the introduced method in the first section is used to the 4-port DDPA presented in the second section and a compact 2-port DDPA suitable for application in GSM/DCS systems is obtained. Details of the design and the experimental results are presented.