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Radar System Engineering

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SEC. 17.10] THE RADIATION PATH 715<br />

Diffraction Phenomena. —Whenever one of the relay stations is in an<br />

aircraft, especially if the transmission path is over water, interference<br />

-80<br />

-1oo<br />

-110<br />

.<br />

II ;<br />

,, .<br />

I /<br />

,.<br />

-120<br />

-130<br />

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‘1401<br />

10 20 30 40 .50 64) 70 80 90 100 1’: o<br />

Range in nautical miles<br />

FIG. 17. 15.—Field intensity vs. range for propagation of vertically polarized signals<br />

over sea water at various frequencies. Transmitter antenna height, 5000 ft; receiver<br />

antenna height, 75 ft.<br />

Range In nautical miles<br />

FIc, 17.16,—Field intensity vs. range for propagation of vertically polarized signals<br />

over sea water at various receiving antenna heights. Transmitter antenna height, 5000 ft;<br />

frequency, 300 Mc/8ec.<br />

between direct and reflected rays can occur. This subject. is treated<br />

in detail in l“ol. 13 of this series. Figure 17.15 shows curves of

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