Analysis of an antenna structure which yields equalE- andH-plane patterns is presented in this paper. The structure consists of an excited slot with two symmetrically disposed and parasitically excited monopoles. The equalisation of theE- andH-plane patterns depends upon the coupling between the slot and the monopoles, which is a function of monopole height and separation from the slot. An evaluation of coupling between monople and slot is done, and an optimum configuration is obtained. The analytical results obtained as shown to be in close agreement with the experimental ones obtained by other researchers.