Antenna Designer´s Notebook-similarities in the design equations for rectangular and circular patches

The transcendental equations, which arise in the cavity-model of patch analyses, are reexamined. It is shown that when the radiation quality factor is not too small, useful approximations to the ensuing design equations may be obtained in a format common to both types of patch. To achieve this, it is assumed that natural loss-tangent effects in the substrate may be neglected. An emphasis is placed on the role of the cavity-wall conductance/susceptance ratio. It is important that a value for this parameter be selected with care in cases requiring a wideband frequency response