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Linear Array Pattern Synthesis The fields radiated from a linear array are a superposition (sum) of the fields radiated by each element in the presence of the other elements. Each element has an excitation parameter, which is current for a dipole, voltage for a slot | Phased Array Antennas. Robert C. Hansen Copyright 1998 by John Wiley Sons Inc. ISBNs 0-471-53076-X Hardback 0-471-22421-9 Electronic CHAPTER THREE Linear Array Pattern Synthesis INTRODUCTION Linear arrays of radiating antenna elements have been developed over many decades. This chapter brings together the important developments that provide a detailed understanding of array design and synthesis. Included are the design of narrow-beam low-sidelobe arrays shaped beam arrays arrays designed by constrained optimization and aperiodic arrays. Many older data have been recalculated using the excellent available computing power as well as appropriate new supplementary data. Pattern Formulations The fields radiated from a linear array are a superposition sum of the fields radiated by each element in the presence of the other elements. Each element has an excitation parameter which is current for a dipole voltage for a slot and mode voltage for a multiple-mode element. This chapter is concerned primarily with the forced excitation problem where the drive of each element is individually adjusted so that the excitation is as desired. This adjustment of the drive accommodates the mutual coupling among feeds which changes the element input impedance admittance . A more common situation is that of free excitation the feed network is designed to produce the desired excitations but as the scan angle or frequency changes the element scan impedance change will result in a change of excitation. These matters are discussed more fully in Chapter 7. The excitation of each element will be complex with amplitude and phase. This discrete distribution is often called an aperture distribution where the array is the aperture. The far-field radiation pattern is the discrete Fourier transform of the array excitation. The pattern is sometimes called the space factor. A commonly used array notation is appropriate for this chapter the angle from broadside is 9 the element spacing is J and