Trade-Off Between Maximum Broadside Directivity and Scan Range of Small Phased Arrays

The primary performance parameters for a phased array are scan range and gain. They depend on both the array factor and the element pattern, with an increasingly directive element increasing the array directivity but decreasing the scan range. This trade-off is discussed in terms of the element spacing and the element directivity using a simple element pattern model. Many array results are from the classical model of separating the element and array factors but are not applicable to practical small arrays because the embedded element patterns can be different from each other. In terms of wideband design, there is an optimum element spacing for a linear array, for maximum scan range, maximum broadside gain, and array size (number of elements).