An analysis of the performance of multi-aerial Adcock direction-finding systems

This paper presents a theoretical discussion of the performance of crossed fixed-aerial Adcock direction-finder systems employing more than two aerial pairs. Comparison is made with the conventional four-aerial Adcock system, with regard to both spacing error and sensitivity. Improvements are obtained by increasing the total number of aerials over the four of the conventional Adcock system, so that, for a given accuracy, a gain may be achieved either in frequency coverage or sensitivity, or in both together. It is also shown that an increase in the number of aerials above eight is of little practical advantage, since the spacing for small errors approaches the absolute limit of 1.22¿. A modified system, in which two aerials are connected in parallel to replace each of the single vertical aerials, is also discussed. This system has a performance nearly as good as the fully symmetrical eight-aerial system, and when used in conjunction with a twin-channel receiver it is expected to give the better performance. Finally it is shown that a star connection of the aerials provides a correct sense signal, only when the aerial spacing is less than 0.76¿.