A Transmission Line Method to Compute the Far-Field Radiation of Arbitrary Hertzian Dipoles in a Multilayer Structure Embedded With PEC Strip Interfaces

A transmission line (TL) method was proposed to compute the far-field radiation of Hertzian dipoles in a multilayer dielectric structure previously. This method is generalized here to deal with a structure embedded with perfectly electric conducting (PEC) strip interfaces. The problem is solved by analyzing an equivalent network, where each PEC strip interface is mapped into a four-port network, and each dielectric layer is mapped into two two-port networks for transverse electric (TE) and transverse magnetic (TM) modes. The S matrix of a four-port network is obtained analytically by applying the asymptotic boundary conditions. As an application, the PEC strip interfaces are used to reduce the cross polarization or rotate the polarization of a dielectric resonator antenna (DRA). In addition, the TL method is valid for a structure with any type of homogeneous and reciprocal layers whose S matrices are known. It is also able to solve two kinds of problems which cannot be done by a full-wave analysis equipped with a periodic boundary condition. Furthermore, the investigation of the system matrix singularity helps us to avoid the cavity mode in designing a radiating structure.