Directivity Pattern of Line Arrays

array elements

4

steering angle (degrees)

35.2

plot points

15

Highly directional acoustic and electromagnetic antennae are often built from linear arrays of omnidirectional transmitting (or receiving) elements. This Demonstration plots the directivity pattern of an unshaded line array of

n

omnidirectional elements, steered to the angle

ϕ

with respect to the array axis. The patterns have cylindrical symmetry about the array axis. The array elements are plotted as white dots to show their number and orientation. An even number of elements results in a null along the axial direction of the array. An odd number of elements results in an endfire sidelobe, which, for many applications, is undesirable. The directivity pattern can be regarded as a transmission or reception sensitivity pattern.