Maximum limits of efficiency for low-loss reciprocal adapters

Since the efficiency ηαl of an adapter for connecting two different transmission lines is a function of the reflection coefficient of the adapter termination, it will be different for each new use of the adapter. This paper suggests two estimates of ηαl for low-loss reciprocal adapters. Maximum limits of error are given in terms of the magnitude of the load reflection coefficient for one estimate ηα0, which is the efficiency of the adapter when terminated in a matched load. Similar error limits are given for the second, more precise estimate, which requires accurate knowledge of both ηα0 and ηα, the maximum efficiency of the adapter.