The purpose of this article is to present a theoretical method for analyzing an E‐plane gap‐coupled rectangular microstrip array antenna which consists of one center‐fed patch and several parasitic elements by use of the transmission‐line model and the equivalent circuit parameters for the capacitive gap between microstrip patch and the open end of the patch. Antenna characteristics such as radiation pattern and return loss are computed theoretically and compared with experimental results for illustrating the usefulness of this method.