Generic Spectral Immittance Approach for Fast Design of Multilayered Bilateral Structures Including Anisotropic Media

In this letter, the spectral domain immittance-based approach is generalized for a fast and efficient design of bilateral microwave structures with multilayered anisotropic layers. This technique is based on the derivation of dyadic Green's functions by introducing, for the first time, a new conjoint admittance parameter. An original configuration based on three-line bilateral couplers is computed and validated using neural network models. Furthermore, numerical examples are presented and close agreement is obtained between simulated results and published data. The CPU time is also investigated

I. Introduction

The recent advances in microwave integrated circuits (MICs) and microwave monolithic integrated circuits (MMICs) have generated growing interest in multilayered planar circuits built on anisotropic substrates [1]–[3]. While the existing theories are limited to bilateral structures with a limited number of layers [4], the proposed generic approach can be easily generalized to any form of bilateral coupling between transmission lines. Furthermore, and for the first time, an original extension of the immittance approach technique [5] is presented to derive the dyadic admittance Green's functions for a fast and efficient design of microwave structures with lossy biaxial anisotropic substrates. A new conjoint admittance parameter is introduced such as the resulting admittance matrix is not diagonal. Such recursive form can significantly speedup the CPU time compared to other techniques [6], [7]. It was demonstrated through examples of passive structures including original configurations based on three line bilateral couplers. Computed data were validated using neural network models.