Abstract: The elements of a spatially aperiodic phased array antenna have an unequally spaced circular distribution, that is effective to decorrelate angular and linear separations among elements of the array. For any radial direction passing through an element of the array, the vector distance from any point along that radial direction to any two elements of the array is unequal and uniformly distributed in phase, modulo 2.pi.. Angular separation between successively adjacent antenna elements varies in accordance with an Nth root of two, wherein N is the number of antenna elements in the array. To locate each element, a first element is placed at any arbitrary location along the circumference of the array. The angular spacing .alpha..sub.1 of a second element relative to the first element is defined such that .alpha..sub.1 =2.pi.*(2.sup.1/N -1). The angular spacing .alpha..sub.j of each additional element relative to the first element is defined by .alpha..sub.j =.alpha..sub.j-1 *2.sup.1/N, where j varies from 2 to N.

Abstract: An aperture transformation sidelobe canceller includes a plurality of auxiliary feed elements disposed in the vicinity of, but critically offset from, a main feed horn. The signal paths for the auxiliary feed horns are coupled through a low loss cascade RF variable direction coupler network to be combined with the RF signal path for the main antenna feed. The combined signal path is coupled to a performance monitoring processor which, in turn, adjusts the coupling action of each variable directional coupler to achieve the necessary weighting and combining of the auxiliary feed signal paths. The critically offset auxiliary feed elements provide the capability of achieving very broadband and deep nulls from the simple variable directional coupler network. The null availability makes it possible to null the entirety of the main elements sidelobe region, including backlobe and even the first sidelobe region of the antenna pattern, as the offset auxiliary feed horns provide substantial coverage in this region.

Abstract: An adaptive array signal processing system employs a correlation discriminant operator or signal recognizer. The operation of the signal recognizer is dependent upon noise decorrelation rather than noise filtering, so that an unbiased, although sometimes noisy, measurement of desired signal power can be effected on an instantaneous basis. In the signal recognizer, an input signal, as derived from the summation of a plurality of weighted signal receiver outputs, e.g. antenna voltages, and containing both information and noise, is combined with an a priori reference signal through a time delay multiplication process. The combined or output signal of the signal recognizer contains an information component that is effectively correlated with the information component in the input and a noise component that is effectively uncorrelated with any other signal in the system.

Abstract: A low offset field effect transistor correlator circuit where one signal is applied to a balanced input through capacitors to the drain and source electrodes of a field effect transistor and having a second signal applied to the gate of the transistor. Low pass filters are connected to the source and drain, and the correlated input signals appear across resistors connecting the outputs of the filters.

Abstract: A system having a pair of input signals, one of which is modulated and transformed into a pair of signals phased 180.degree. apart. These signals are acted on by a FET correlator where the second input signal controls the FET gate. Correlator output is amplified and a blocking capacitor removes DC offset, a synchronous switch operated at the modulated frequency converts the remaining AC to DC which is amplified to the output.

Abstract: A low offset AC correlator avoids DC offset and low frequency noise by frequency operating the correlation signal so that low noise, low level AC amplification can be substituted for DC amplification. Subsequently, the high level AC signal is demodulated to a DC level.