Planar Arrays on Lattices and Their FFT Steering, a Primer
NAVAL RESEARCH LAB WASHINGTON DC ADVANCED RADAR SYSTEMS BRANCH
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This is a primer for practicing design engineers on two topics. The first is the theory of the simplest planar receive arrays, those positioning identical antenna elements on a point lattice and using terminated guard elements at the array periphery. The second is multi-beam phase-shift steering of such arrays using generalized Cooley-Tukey FFT structures. Array theory here largely avoids electromagnetics and instead uses classic LTI-system arguments from signals and systems. The FFT realization of the general multidimensional DFT for beam steering is developed using nested sublattice chains. The needed lattice basics are covered in detail, and the usual coset decompositions are avoided in favor of a simpler geometric approach based on tiling the element-position and beamspace direction cosine planes. Example array architectures use the hexagonal lattice equilateral triangular grid with the classic optimal zero-aliasing spacing.
- Active and Passive Radar Detection and Equipment
- Target Direction, Range and Position Finding