Design considerations for broadbanding phased array elements

Component bandwidths in excess of one to two octaves are required by current technology, and similar demands apply with respect to antennas. This article is concerned with approaches which make it possible to obtain two-octave bandwidth antennas. The low-frequency problem is examined, taking into account its significance in a phased array. Attention is given to a linear array of elements with spacing d and height H, an array element with dimensions d x H, a ridge-loaded horn, a stripline notch array, isolated element gain vs electrical dimension, a dual polarized array, stripline element gains relative to reference standard, and aspects of array coverage. It is shown that array elements can be designed to cover at least two octaves in bandwidth with good efficiency. This is achieved by selecting array elements which have basically good broadband characteristics, and by using a design optimization approach.