THREE-DIMENSIONAL FOURIER-TRANSFORM DEVICE

Abstract

Signals from antenna elements (14) of a rectangular array (12) are translated in frequency by mixers (16) fed from a chirped local oscillator (19). The resultant signals are fed to the first of two groups (20 and 36) of two-dimensional delay lines connected in series at right angles to each other. The two-dimensional delay lines are dispersive, having a linear relationship of delay to frequency, and the sweep rate of the local oscillator (19) is such that the signals caused by a given frequency component at the mixer input ports are completely compressed in time when they reach the output ports (46) of the delay lines of the second group (36). As a consequence, the device performs a three-dimensional Fourier transformation from time and two spatial dimensions to temporal frequency and two dimensions of spatial frequency. When fed by a two-dimensional antenna array, the output of the device can readily be interpreted as indicating the direction of the source and the frequency at which it is radiating.

Source: Google Patents

35 USC §181 Secrecy Order

Inventor

• 1JOHN T. APOSTOLOS

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