Phased Arrays - MATLAB Simulations for Radar Systems Design - page 372

array boresight

plane
containing
the array

effective
aperture

steering
angle

effective
aperture

maximum effective aperture

effective aperture is reduced

Figure 8.51. Reduction in array effective aperture due to electronic
scanning.

The beamwidth at scan angle θ is

Θ broadside
θ

Θ θ = ------------------------

(8.86)

cos

due to the increased scan loss at large scanning angles. In order to limit the
scan loss to under some acceptable practical values, most arrays do not scan
electronically beyond about . Such arrays are called Full Field Of
View (FFOV). FFOV arrays employ element spacing of

θ = 60°

0.6λ or less to avoid

grating lobes. FFOV array scan loss is approximated by

) 2.5 L scan ≈ ( cos θ

(8.87)

Arrays that limit electronic scanning to under are referred to as
Limited Field of View (LFOV) arrays. In this case the scan loss is

θ = 60°

– 4

π d
λ

 

------

sin sin θ

 

-------------------------------

L scan =

(8.88)

π d
λ

------

sin θ

Fig. 8.52 shows a plot for scan loss versus scan angle. This figure can be repro-
duced using MATLAB program Ðfig8_52.mÑ given in Listing 8.8.