Experimental Characterization of Multiconductor Transmission Lines in Inhomogeneous Media Using Frequency and Time Domain Techniques

Abstract

The problem o f m u l t i c o n d u c t o r t r a n s m i s s i o n l i n e c h a r a c t e r i z a t i o n has b een a t o p i c o f i n t e r e s t f o r many y e a r s . P r e v i o u s work1 ' 2 p r o v i d e s meth ods o f t im e domain c h a r a c t e r i z a t i o n f o r m u l t i c o n d u c t o r t r a n s m i s s i o n l i n e s in homogeneous media w here a l l t h e p r o p a g a t i o n modes have t h e same v e l o c i t y . In g e n e r a l , f o r a m u l t i ­ c o n d u c t o r l i n e (N c o n d u c t o r s p l u s a ground r e f e r e n c e ) in c r o s s s e c t i o n a l l y in homogeneous m e d i a , t h e r e w i l l be N p r o p a g a t i o n modes e a c h h a v i n g a d i f f e r e n t v e l o c i t y . A know ledge o f t h e modal v e l o c i t i e s and t h e modal am­ p l i t u d e s i s needed in o r d e r t o o b t a i n t h e p e r u n i t l e n g t h i n d u c t a n c e and c a p a c i t a n c e m a t r i c e s from t h e c h a r a c t e r i s t i c impedance m a t r i x 3 . The p r o p a g a t i o n modes f o r m u l t i c o n d u c t o r t r a n s m i s s i o n l i n e s w i t h i n ­ homogeneous d i e l e c t r i c s a r e d i s c u s s e d i n r e f e r e n c e 4 .