Ceramic rod array scanned with ferrite phase shifters

Steering a radiation beam originating from a stationary antenna rapidly and at will is one of the most attractive problems in the field of antenna engineering. This paper describes some aspects of the authors´ efforts to develop an efficient and reliable electronic scanning antenna system. The prototype of the antenna consists of a linear array, a power distributor, an electronic phase-shift feed scheme, and its driver. The array consists of ceramic rod antennas, which are fed separately from the ends of parallel waveguides lined up in the H-plane. The power distributor is composed of directional couplers and magic tees, and is used for beam forming. The electronic phase-shift feed scheme is provided by inserting a ferrite phase shifter into each of the above-mentioned waveguides. The waveguides are of equal length and are connected in parallel to the microwave source (transmitter, receiver, or both) through the power distributor. The driver generates a number of sawtooth wave currents, which have different repetition frequencies derived from the design equation, and excite the corresponding ferrite phase shifters. Thus a uniform progressive phase shift, which varies in a sawtooth waveform with time, is achieved along the array and the radiation beam is scanned with higher efficiency. The design and engineering of the antenna are discussed, with special attention to performance reliability and reproducibility.