Radar and ARPA Manual

142

RADAR AND ARPA MANUAL

Figure 3.19 The double pentagonal array

3.4.3.1

Principle

of

operation (Figure

3.21)

Paraxial rays, impinging on the outer spherical surface,

are refracted by different amounts at each shell interface

so that they are focused at a point on the opposite surface

of the sphere. Here the energy is reflected by a metal

band in such a way that the exit path of the returning

energy is in a direction reciprocal to that of the incident

energy.

3.4.3.2

The polar diagram

Figure 3.22 gives the theoretical polar diagram, and

Figure 3.23 shows its practical effect when applied to a

buoy. It should be noted that in the horizonta