 
Summary: 1
Causality and Waveguide Circuit Theory
Dylan F. Williams, Senior Member, IEEE, and Bradley K. Alpert, Member, IEEE
National Institute of Standards and Technology, 325 Broadway, Boulder, CO 80303
Ph: [+1] (303)4973138 Fax: [+1] (303)4973122 Email: dylan@boulder.nist.gov
Abstract We develop a new causal power
normalized waveguide equivalentcircuit theory that,
unlike its predecessors, results in network
parameters usable in both the frequency and time
domains in a broad class of waveguides. Enforcing
simultaneity of the voltages, currents, and fields and
a power normalization fixes all of the parameters of
the new theory within a single normalization factor,
including both the magnitude and phase of the
characteristic impedance of the waveguide.
INTRODUCTION
We develop a causal powernormalized waveguide
equivalentcircuit theory. The theory determines
voltages, currents, and network parameters suitable for
use in both frequency and timedomain circuit
