Methods of Measuring Inaccessible Arbitrary Linear Microwave Two-Ports

摘要

New methods were developed which make possible the measurement of the complete network description of inaccessible, arbitrary, linear microwave two-ports located in highly frequency sensitive environments and under the constraint of very low permissible power levels. Here 'arbitrary' implies that the unknown two-port, r, may be nonreciprocal or reciprocal, active or passive, and symmetric or asymmetric; 'inaccessible' is meant to describe two-port r as being located between two other unknown, perhaps arbitrary, two-ports, x and y, which are of no interest in themselves. The constraint that two-ports x and y cannot be measured independently of each other is also imposed. An example of an inaccessible two-port might be an obstacle located in the uniform waveguide region of a transmission cavity where, for some reason, the two coupling structures cannot be measured while the cavity is any way physically disassembled. While the measurement methods and the associated network problems are stressed, the circuitry developed for actually carrying out such measurements and the results of experiments intended to demonstrate the capability of this system are also given. To meet the various demands of the problem as a whole, several subsidiary and essentially independent problems, each of interest in itself, had to be solved.