“Sparseness” in broadband array antennas

Broadband phased arrays are being used in a wide number of imaging application in radio astronomy and radar. To improve the cost effectiveness, the system must meet the minimum performance requirements with the fewest number of elements. Since the array geometry affects many aspects of the overall performance such as directivity, sidelobes, and mutual coupling, the geometry design and optimization of the array can vary significantly depending on the required application. In this paper the main aspects broadband antenna array geometry design are outlined with different design and optimization techniques of broadband antenna array are divided into three main categories. The paper also outlines the main tradeoffs involved with each category with design examples.