A Method of Introducing Coupling Null by Shorting Pins for Stacked Microstrip Patch Antenna Array

In this communication, a method is proposed to generate coupling null by introducing shorting pins into a stacked microstrip patch antenna (S-MPA) array, named shorted S-MPA (SS-MPA). The currents on different regions of the driven patch, with approximately equal amplitude but out of phase, are formed, due to the shorting pins, which makes the electric field component Ex canceled, introducing a new dip near the lower resonant frequency. The new dip works with the inherent dip produced by the radiation cancellation between two patches near the higher resonant frequency. High isolation is achieved over the wide impedance bandwidth of the SS-MPA array. Expected results are obtained from the fabricated two-element SS-MPA array. Moreover, the proposed scheme is employed to a three-element array successfully.