MBA versus phased array for electronic beamsteering

Antennas for space, air and ground applications require a single aperture to produce one or more pencil beams capable of being steered at electronic speed. Phased arrays and multiple beam antennas (MBA) with an array feed are candidates for these applications. In the phased array, beam steering is accomplished by changing the steering phases between the array elements; in the MBA, beam steering is achieved by selecting an appropriate subarray in the array feed and then weighting those subarray elements using amplitude and phase control units. The decision as to which antenna type is best suited for a particular application depends on parameters such as frequency, gain, scan range, etc. Also, the array feed complexity of an MBA depends on the antenna type and its f/D, while the phased array´s complexity depends on the region over which grating lobes are not allowed. The paper defines the conditions under which one antenna type is better than the other.