A study of effect of element pointing error on power density in near field of reflector arrays

This paper addresses the issue of acceptable power density levels in arrays of small antennas to be used for uplink transmission functions at NASA/JPL's deep space network (DSN). This problem is of interest due to safety considerations as well as interference with receivers on nearby flying objects such as helicopters or other systems. Specifically, array element pointing errors can produce hot spots due to coherent combining of the radiation from individual elements in the near and mid field regions of the antenna arrays which may be larger than is expected and could become unacceptable. Therefore care must be taken that such situations do not occur. In this paper the interference problem is formulated and limits are obtained to prevent the peak addition of signals which could be 6 dB higher than that achieved by individual elements. Ample plots and example are provided to clarify the concept and provide guidelines for pointing error specifications