Timed Arrays

3ARRAYS OF POINT SOURCES

Arranging the elements in an aperture is the critical first step in the array design process. Point sources replace real antenna elements in order to determine the element spacing, lattice, aperture shape, and number of elements that meet array performance requirements. Some concepts are easier to explain in terms of a transmit antenna and other times as a receive antenna, so the presentation in this book switches between the two. The type of element, polarization, mutual coupling feed network, and so on are important and will be addressed in subsequent chapters.

3.1 POINT SOURCES

An isotropic point source is a single point in space that radiates equally in all directions. The amplitude and phase of the electromagnetic field radiated by an isotropic point source are constant at a set instant in time and distance from the source. The mathematical representation of the point source in rectangular coordinates is

(3.1)

This point source is at but can be moved to (x′, y′, z′) by modifying (3.1) to

(3.2)

The field propagating away from the point source changes according to

(3.3)

while a field propagating toward the point source changes according to ...