Influence of pilot signal on directivity of self-phased arrays under conditions of multipath propagation

This paper presents an investigation of a pilot signal influence on directivity of self-phased array under conditions of multipath propagation (either reflections or jamming signals), A suggestion is made that an average reduction in directivity owing to the cutting off (or "dropping out") of some channels of the array be used as a criterion of this influence, It has been shown that an essential reduction in directivity is possible in the case of weak pilot signal or large (close to unity) reflection coefficient. If the level of direct pilot signal is higher than the cutoff threshold, the average reduction in directivity does not exceed 3 dB, although substantially greater reduction (presence of "ejections") can be observed in certain specific cases. A reduction in directivity due to reflections can be removed by means of enhancing the sensitivity of the pilot signal channel. The method suggested in this paper can also be used in order to estimate influence of several reflections on self-phased array directivity.