Maximum limits of efficiency for low-loss reciprocal adapters

Since the efficiency η
αl
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 η
αl
for low-loss reciprocal adapters. Maximum limits of error are given in terms of the magnitude of the load reflection coefficient for one estimate η
α0
, 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 η
α0
and η
α
, the maximum efficiency of the adapter.