Design of a dual polarized rectangular patch antenna using DGS

This paper presents a high port isolation dual frequency orthogonally polarized rectangular patch antenna integrated with defected ground structure (DGS). A spiral-shaped DGS-integrated microstrip line enhances the port isolation of the antenna, while feeding the 2.45 GHz port, port-1 to the antenna and filtering out 3.0 GHz receiving signal from port-2. Similarly a rectangular shaped DGS-integrated microstrip line enhances the port isolation of the antenna, while feeding the 3.0 GHz port, port-2 and filtering out the 2.45 GHz signal from port-1. The microstrip line at two different ports integrated with DGS restricts the highorder harmonics signals coming from transmitter or receiver. The patch is excited through microstrip feed line of 75Ω line impedance. DGS-integrated microstrip line offers image impedance of 150Ω and it is controlled by DGS geometry. An experiment of investigating isolation between the ports has been performed by employing with and without DGS. Measurements show an improvement of more than 25dB in the port isolation when DGS integrated microstrip antenna.