Analysis of radiation characteristics of a probe fed rectangular cavity-backed slot antenna with finite-size ground plane

Slot antennas cut on the conductor have been extensively and continuously investigated both on the flat plate and curved surface. The research on the rectangular slotted-waveguide antenna has been widely conducted because it is very useful to model as the array element of a very large aperture antenna. When the ends of the waveguide are shorted by the conductor, it becomes the cavity. Therefore, the effect at the shorted ends must be taken into account. This paper presents the analysis of the linear electric probe excited rectangular cavity-backed slot antenna with finite-size ground plane. The feeding structure is simple, free from conduction and dielectric loss, high power handling and suitable for slot array applications. The integral equations for the rectangular cavity-backed slot antenna fed by a probe inside the cavity are established with the infinite ground plane, assumed outside the cavity. The method of moments with the aid of dyadic Green's function plays a vital tool in solving those equations. However, for small aperture antennas or small cavity sizes the effect at the edge must be included. The uniform geometrical theory of diffraction is a powerful method to determine the diffracted field due to the edge effect of the finite-size ground plane. The radiation pattern of the probe fed rectangular cavity-backed slot antenna with finite ground plane is compared with that from the infinite ground plane assumption. The diffraction amplitude for various distances between the slot and the edge of the ground plane is also illustrated.