OVERSTEERING OF END-FIRE ARRAYS WITH FREQUENCY-INVARIANT BEAM PATTERNS

摘要

In this paper we propose and assess a technique to tune thetrade-off between the directivity and the robustness of afrequency-invariant beam pattern, without the need to modifythe designed FIR filters. Starting from a filter-and-sumbeamformer over a superdirective array, synthesized by astochastic and analytic method, which possesses themaximum directivity that the array may achieve and takinginto account the probability density functions of thetransducers’ characteristics, we introduce a post-synthesisoptimization that allows to choose a given systemperformance, after the investigation of a wide space ofrealistic possibilities. The a posteriori performance tuningwill be referred to as oversteering and is effective only forend-fire array. By comparing the results of the proposedtechnique with those of the optimum synthesis, it is possibleto evaluate the proposed method effectiveness in producingfrequency-invariant beam patterns with an end-fire lookingdirection and a number of interesting trade-offs betweendirectivity and robustness.