Analysis of natural waves of planar lines

Planar structures have become increasingly important for modern microwave technology in connection with their employment as waveguides and circuit elements. However, the implementation of passive and active components requires the determination of the line characteristics and the discontinuity properties by means of suitably simple computational procedures. Such procedures are vital as basis for computer-aided design methods, which are needed for an economical manufacture of planar circuits. The present investigation is concerned with the development of simple procedures for the calculation of planar circuit characteristics. Exact methods are employed to verify the validity of simple approximate procedures. In this connection, the natural waves of planar waveguides are determined accurately and by means of an approximate approach. Attention is given to an analysis of some discontinuities, and the design of band-pass filters in finline technology and transitions between various finlines.