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Chapter 5 251

5.5 BEAM STEERING TECHNIQUES

5.5.1 Introduction

We are accustomed to using our vision, voice, and hearing as primary tools to perceive the
world around us. With the development of civilization and increasingly complex,
interdependent global population, we need to “see as much of the world as possible” and “talk
and listen to it” as quickly as possible. Radars make our vision more sensitive, sophisticated
and farther reaching, while communication systems extended our ability to “talk and
listen.” However, that might not be enough; we must be active and “gaze” around continuously
looking for friendly or threatening objects, the sources of “good and bad news.” Meanwhile and
by definition, our “eyes and ears” in radar and communication systems are a broad variety of
antennas, and they must have the ability to search our surrounding world by emitting and
receiving information. Reviewing the plot in Figure 5.4.10, we can see that changing the
relative phase shift between adjacent array elements is an effective way of altering
or steering the direction of the main beam or beams. Most importantly, during such surrounding
space observation, an antenna stays motionless removing the restrictions on antenna size and
mass. Two such monster-sized array antennas with electronic beam steering are shown in Figure
23
5.5.1 .

Figure 5.5.1 Arrays for Early Warning Radars (left) and for SPY radar (right)

5.5.2 Linear Array Beam Steering

The challenge is that the array patterns in Figure 5.4.10 are mostly bidirectional. As a result,
the power radiated by the array is divided equally between two beams thereby hurting the array
directivity. As we have demonstrated before (Section 5.4.3 of this chapter) one of these beams

23 Public Domain Image, source: http://worldalliance.postalboard.com/t295p285-full-wa-national-news-
network and http://pena-abad.blogspot.com/2012/07/spy-radar-arrays-arrive-in-adelaide.html