a Matlab package for phased array beam shape inspection

a Matlab package for phased array beam shape inspection a Matlab package for phased array beam shape inspection

07.07.2014 Views

36 A FIGURES TO CHAPTERS 2–7 D=0.1; θ = 60, θ = 60 0 g 90 1.5 120 60 1 150 30 0.5 180 0 Directivity 1.16 1.14 1.12 1.1 1.08 210 330 1.06 1.04 240 270 300 1.02 0 20 40 60 80 100 elevation polar angle (a) (b) 150 D=0.4; θ =60, θ = 60 0 g 90 2.5 120 60 2 1.5 1 30 2.5 2.4 2.3 2.2 0.5 180 0 Directivity 2.1 2 1.9 210 330 1.8 1.7 240 270 300 1.6 0 20 40 60 80 100 elevation polar angle (c) (d) Figure 2: Gain pattern and directivity of an vertical array of two isotropic elements. Panels (a) and (b) are for element separation d = 0.1λ, panels (c) and (d) are for d = 0.4λ. The beam steering in panels (a) and (c) has been to 60 ◦ from boresight (horizontal beam). The 3D gain pattern is obtained from the curves shown by rotating them around the vertical axis, which is also the direction of the array axis. The polar plots are labeled by the beam elevation angle, and the gain is in absolute units. Both of these arrays are dense (D < 0.5λ), so there are no grating lobes apart the main lobe, but there nevertheless is a rather well-developed ordinary side lobe in (c).

37 D=1.0; θ 0 = 60, θ g = −8, 60 120 90 2 1.5 60 3 2.8 2.6 150 1 30 2.4 0.5 180 0 Directivity 2.2 2 1.8 210 330 1.6 1.4 1.2 240 270 300 1 0 20 40 60 80 100 elevation polar angle (a) (b) d / λ = 1.8; θ 0 =60 ° , θ g = −53 ° −14 ° 18 ° 60 ° 90 2 120 60 1.5 150 1 30 0.5 180 0 Directivity 2.25 2.2 2.15 2.1 2.05 2 210 330 1.95 1.9 1.85 240 270 300 1.8 0 20 40 60 80 100 Elevation (c) (d) Figure 3: Gain pattern and directivity of an vertical array of two isotropic elements. Panels (a) and (b) are for element separation d = 1.0λ, panels (c) and (d) are for d = 1.8λ. The beam steering in panels (a) and (c) has been to 60 ◦ from boresight (horizontal). The 3D gain pattern is obtained from the curves shown by rotating them around the vertical axis, which is also the direction of the array axis. The polar plots are labeled by the beam elevation angle, and the gain is in absolute units. In (a), there are two grating lobes and one ordinary, but large, side-lobe, while in (c), all the lobes have equal directivity, and are grating lobes.

37<br />

D=1.0; θ 0<br />

= 60, θ g<br />

= −8, 60<br />

120<br />

90<br />

2<br />

1.5<br />

60<br />

3<br />

2.8<br />

2.6<br />

150<br />

1<br />

30<br />

2.4<br />

0.5<br />

180 0<br />

Directivity<br />

2.2<br />

2<br />

1.8<br />

210<br />

330<br />

1.6<br />

1.4<br />

1.2<br />

240<br />

270<br />

300<br />

1<br />

0 20 40 60 80 100<br />

elevation polar angle<br />

(a)<br />

(b)<br />

d / λ = 1.8; θ 0<br />

=60 ° , θ g<br />

= −53 ° −14 ° 18 ° 60 °<br />

90<br />

2<br />

120<br />

60<br />

1.5<br />

150<br />

1<br />

30<br />

0.5<br />

180 0<br />

Directivity<br />

2.25<br />

2.2<br />

2.15<br />

2.1<br />

2.05<br />

2<br />

210<br />

330<br />

1.95<br />

1.9<br />

1.85<br />

240<br />

270<br />

300<br />

1.8<br />

0 20 40 60 80 100<br />

Elevation<br />

(c)<br />

(d)<br />

Figure 3: Gain pattern and directivity of an vertical <strong>array</strong> of two isotropic elements.<br />

Panels (a) and (b) are <strong>for</strong> element separation d = 1.0λ, panels (c) and (d) are<br />

<strong>for</strong> d = 1.8λ. The <strong>beam</strong> steering in panels (a) and (c) has been to 60 ◦ from<br />

boresight (horizontal). The 3D gain pattern is obtained from the curves shown<br />

by rotating them around the vertical axis, which is also the direction of the<br />

<strong>array</strong> axis. The polar plots are labeled by the <strong>beam</strong> elevation angle, and the<br />

gain is in absolute units. In (a), there are two grating lobes and one ordinary,<br />

but large, side-lobe, while in (c), all the lobes have equal directivity, and are<br />

grating lobes.

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