L-shaped strip-fed patch array based on mutual coupling

A novel E-plane patch array with a reduced number of the active elements is developed by making use of strong mutual coupling between passive and active elements. Although only half the number of elements is excited in the proposed array, it can provide similar gain to an ideal conventional array in which all elements are excited; meanwhile the cost and loss are greatly reduced. The operating principle is proved from the points of impedance matrix and electric field distribution. Simulations and measurements show that even when the active element spacing is as large as 1.55 lambda(0) (where lambda(0) is the free-space wavelength at the centre frequency), the proposed array can still present a gain approximately equal to that of an ideal conventional array with a half-element spacing (0.775 lambda(0)).