The scanning performance of wide-angular scanning linear arrays is primarily degraded by the limited angular profile of the employed elements' patterns. This paper introduces an innovative strategy for compensating this degradation by using subarrays. Our design uses a uniform linear array with half-wavelength spaced elements, supplemented by subarrays that are symmetrically placed at its edges. The employed subarrays have controlled patterns, favoring some directions for effective scan-loss compensation (SLC) and suppressing other directions for lowering the sidelobes level (SLL). Two types of feeding configurations, making use of fixed power dividers in combination with 1-bit phase switch, are used for producing the desired patterns. The complete array design and physical validation, starting from the elements, continuing with the subarrays and ending with the system integration are also discussed in detail. The integration of the subarrays yields notable performance improvements at large scanning angles when compared with uniform linear arrays. The peak and first SLL of -14.1 dB, and the SLC of 2 dB are obtained when the array with CUP antennas as elements is scanned to the maximum scan angle direction.@en

A novel approach is proposed for compensating the scan loss in wide-angular scanning array antennas due to the pattern falloff of physical radiators. The method is based on replacing elements in (linear) arrays with sub arrays with enhanced radiation intensity at large angles. This strategy is best applicable in the case of sparse arrays that intrinsically provide the space for accommodating sub arrays. An optimised linear sub array, with 5 dB radiation intensity enhancement at 60° is designed. This sub array is then incorporated in linear array antennas with (approximately) 50% thinning factors. An up to 1.2 dB improvement of the maximum directivity at 60° beam scanning is obtained. The obtained results allow conjecturing that a similar strategy, when applied to planar arrays, will lead to an even more significant scan-loss reduction, this yielding a substantial performance enhancement for wide-angular scanning radar array antennas.

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A full-scale concept demonstrator for the scan loss mitigation via integrating subarrays in sparse, linear arrays is presented for the first time. The array uses technologically attractive cavity-backed, U-slot, patch antennas. An effective computational philosophy is proposed, validated and applied for a full electromagnetic characterisation of the resulting very large, non-uniform array. The computational results highlight impressive improvements when compared to the performance of sparse arrays comprising elementary radiators, exclusively. These results provide compelling arguments for the superiority of a physical concept demonstrator designed along these lines.

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