Finite ground plane effects on the radiation pattern of small microstrip arrays

The radiation characteristics of microstrip antennas consisting of two patch elements on small size substrates are studied by means of an approximate solution technique. Special attention is paid to the shielding effect due to finite ground plane diffraction. Experimental and theoretical results show that the back radiation is influenced by the sidelobe level and can further be reduced when the antenna is boxed. For a correct radiation pattern computation these diffraction effects need to be included in the design of small array as well as in that of single element antennas.