WIDE-BAND MATCHING OF WAVE-GUIDE DISCONTINUITIES BY FDTD METHODS

Finite Difference-Time Domain (FDTD) methods offer, in principle, prom ise of great flexibility for application to waveguide discontinuities of any kind. The problem of appropriate termination in the guide envir onment has recently been addressed. Main remaining disadvantages are t he volume of computation involved and lack of analytical insight. More over equivalent circuits are prerequisites to effective CAD and synthe sis. With a view to remedying these shortcomings, we discuss the extra ction from the FDTD analysis of equivalent circuits. Two significant e xamples are considered: the inductive post and the 90 degrees H-plane corner, including a modified form of the same. The circuits thus obtai ned are subsequently employed in the CAD problem of matching over the full waveguide band the modified corner by means of two inductive scre ws. Theoretical and experimental results are in excellent agreement yi elding a reflection less than or equal to-12 dB over the band 36-40 GH z and showing the effectiveness of the approach.