Gain enhancement of a dual feed microstrip array antenna using parasitic elements

In this paper, an in-phase/anti-phase dual feed microstrip array antenna with parasitic elements is proposed to improve the antenna´s gain and it is experimentally evaluated. The proposed antenna provides various kinds of functionality such as direction-of-arrival estimation, beam steering and polarization switching with a simple structure. Better than 2-dB gain enhancement is expected by using the parasitic elements. The separation and height of the parasitic elements are also discussed. The separation of 0.8λ0 with height of 0.5λ0 provides the highest gain for both the in-phase and anti-phase feeds.