Modeling of planar radial-guide antennas

The paper describes an efficient approach to the electromagnetic modeling of planar antennas, which use a radial waveguide or cavity as feeding network. The considered antennas include a radial line slot array antenna, in which a radial guide feeds an array of slots arranged in circular rings or spirals and a radial line planar antenna, in which a radial guide using coupling probes feeds an array of circular rings of microstrip patches or curl wires. The presented approach considers the investigated structures as circuits cascaded in a radial direction. Using suitable electromagnetic field analysis methods interaction between slots or coupling probes is taken into account. Based on the developed models, computer programs are developed for determining equivalent circuit parameters of the feed network and the radiation patterns of the investigated radial line planar antennas. The developed models and associated computer programs should be of considerable interest to the designers of radial line antennas aiming at applications such as terrestrial and satellite communications and radar.