Electronically scanned microwave arrays employing synchronous ferrite phaseshifters

A new microwave scanning array is described which permits a precision in pointing and pattern shape heretofore unattainable in systems using ferrite phase shifters. The core of this new array is a synchronous reciprocal ferrite device which operates via a synchronously rotating magnetic field, similar to the classical alternator. This provides a continuously increasing phase shift which is linear in time to the same degree that the angular velocity of the magnetic field is constant. The latter is precisely controlled through quadrature currents in identical quadrature coils. The rate of phaseshift change is governed by the frequency of the coil currents. A uniform progressive phase shift is achieved in the array by using frequency multiples in the coils of successive phase shifters. These frequencies are precisely related through master crystals and frequency dividers. All the non-linearity difficulties of conventional ferrite phase shifters are avoided, thus eliminating costly and complex computer compensation. The scan range is adjusted by selection of the percent dead time and interelement spacing. Two-dimensional scanning is possible using a combination of frequency scan in one plane and synchronous ferrite scan in the other.