Identifying unambiguous frequency pattern for target localisation using frequency diverse array

The beampattern of a conventional frequency diverse array (FDA) with linear frequency pattern (i.e. the centre frequency of each antenna element is linearly increasing) is coupled in range and angle. FDA with random frequency pattern can decouple the range and angle with high probability only when the number of elements is sufficiently large. The ambiguity of frequency patterns that are random permutations of a linear FDA is examined. An eigenvector-based criterion to identify possible ambiguity in target localisation using such arrays is proposed. Numerous results are presented to verify the effectiveness of the proposed ambiguity identification criterion.