Toward Improved Control of Medium Wave Directional Arrays

Relatively few types of variable power division circuits have been used in medium wave directional antenna feed systems, most of which suffer phase variation as the power division is adjusted. This paper discusses a class of circuits which can be used to implement a phase invariant adjustable power divider. Also discussed are variable phase shifters which have limited effect on power distribution. These features can simplify the original tuning and possible periodic maintenance. A computer analysis of the probable performance of such devices is presented. The associated problem of system analysis is discussed, particularly the inclusion of the effects of the antenna element coupling. To this end a lumped passive element model for a generalized linear reciprocal N port is presented.