Investigation of the Equivalent Circuit Parameters and Design of a Dual Polarised Dual Frequency Aperture Coupled Microstrip Antenna

This communication presents a simplified approach to the design of a single feed dual polarised, dual frequency (1.9 and 2.4 GHz) aperture coupled microstrip antenna. Using simulation and practical investigation, the coupling between the microstrip feed line and aperture, along with the coupling between the aperture and patch, is investigated and modelled using equivalent transformers. The results obtained are used to reduce the number of interdependent design parameters, thereby allowing initial approximate values to be determined more directly with only fine tuning subsequently required to obtain good matching at both frequencies. Excellent agreement is obtained for the simulation and practical results of the return loss and the gain of the antenna.