Parameter Extraction of Asymmetric Reciprocal Transmission Lines (ARTLs) From Scattering Parameters With Transmission-Line-Based Analyses of Differential Antennas

Abstract

Conventional transmission line (TL) models are ineffective for analyzing asymmetric reciprocal TL (ARTL) structures due to their inherent asymmetry. Recently, the bi-characteristic-impedance TL (BCITL) model was proposed to generalize the conventional TL model for ARTL structures and has proven to be effective for the design and analysis of asymmetric structures. This paper comprehensively derives a novel method for the direct extraction of ARTL parameters (characteristic impedances and a complex propagation constant) from scattering parameters using the BCITL model. Notably, the proposed method yields results equivalent to those previously established for metamaterial characterization, highlighting the universality of ARTL parameter extraction in arbitrary ARTL analysis. For illustration purposes, we use the proposed extraction method to analyze symmetric and asymmetric two-port differential microstrip patch antennas through sequential and simultaneous differential excitations. The results show the correctness of the proposed method and highlight the advantages of ARTL parameters over scattering parameters in terms of sensitivity and ability to reveal the useful physical characteristics of the ARTL structures.

Keywords

• Asymmetric reciprocal transmission line
• circuit miniaturization
• differential antenna
• material characterization
• parameter extraction