Abstract: A low profile slot antenna is provided which includes first and second oppositely disposed metallic plates with a dielectric layer disposed therebetween. An array of horizontal and vertical radiating elements are formed in the first metallic plate. An array of horizontal coupling slots and an array of vertical coupling slots are formed in the second metallic plate. The antenna further includes a planar feed network electrically coupled to the coupling slots. The feed network is connected to a conductive waveguide tube located at the central portion of the antenna. Orthogonal probes couple the waveguide tube to a transceiver. Accordingly, the slot antenna may operate to transmit and receive linearly polarized energy. The antenna may further include a polarization converter for converting between linear and circular polarization so as to allow for antenna operation with single or dual circular polarization energy.