Radar and Communication Antenna Siting for Low-Angle Radiation at High Frequencies.

It is sometimes assumed that to obtain good low-angle radio transmission and reception at high frequencies one must use vertical polarization and have an extensive, horizontal, highly conductive foreground, such as an ocean surface. In the absence of such a surface, use may be made of inland sites having a sloping foreground, combined with distant level terrain. The theory presented here suggests that the angle of slope of inland sites should be four times the minimum angle of elevation for which coverage is required, so that coverage down to 1 degree requires a slope of 1 in 14. With the "pseudo-Brewster" angle of elevation for sea water as the cutoff angle for which the site is designed, horizontal polarization may be used at an inland site to obtain coverage down to the same angle obtained for vertical polarization over sea water with the antenna at the water's edge. 40 pp. Ref. (Author)