Radiation from Dielectric Leaky-Wave Antennas with Circular and Rectangular Apertures

The dielectric leaky-wave antenna considered here consists of multiple dielectric layers above a ground plane, with a simple source such as a dipole inside the layers. The layers act as a guiding structure for the radiating leaky wave field, which propagates radially outward from the dipole source. Such an antenna may produce either a broadside beam or a scanned conical beam, depending on the chosen scan angle. For the practical case of a finite-size aperture, the radiation pattern is determined by integration of the tangential fields over the aperture. For narrow-beam structures the leaky-wave field on the aperture may extend to large distances, and hence it is important to have an efficient calculation of the radiation pattern for such cases. It is shown here how to efficiently calculate the radiation pattern for a dielectric leaky-wave antenna having a finite-size aperture that is either circular or rectangular in shape. The derived formulas apply for a dipole source inside any type of dielectric layer structure, and thus include the usual case of a microstrip antenna element on a single layer, as well as the more specific leaky-wave antenna structure considered here.