A NEW ANALYTICAL METHOD FOR STUDYING HIGHER ORDER MODES OF A TWO-WIRE TRANSMISSION LINE

Regarding the increasing application of trahertz (THz) technology, the interest in using two-wire waveguides is getting more and more popular due to their favorable propagation properties. Therefore, a more accurate analysis of these structures is very important. In this paper, a simple analysis of the guided waves in a two-wire waveguide based on Bipolar Coordinate System (BCS) has been investigated. The structure under study is two infinite, perfect electric conductor (PEC) cylinders in z direction, whose axes are positioned at a distance d from each other. The solution of TE and TM modes is sought by the aid of electromagnetic formulation, and an analytical expression is proposed for electromagnetic fields and cutoff wavenumbers, which have not been present in any of the previous studies. In this study, for the first time a BCS is used to formulate two-wire waveguide problem, and the validity range of the answer is discussed. The values of the cutoff wavenumbers are calculated for the first few modes of TE and TM, using both the proposed method and Finite Difference Method (FDM). The precise correspondence of the obtained values with the proposed method with those of FDM, along with the high speed and simplicity in implementation, introduces the present method as an appropriate candidate for analyzing transmission lines using parallel cylinders.