Abstract:Experimental m easuremen ts usi ng scale model techniqu es ha ve been carried o u t to determine t he effectiveness of a ground system of lon g-wire radials to obtain low a ng les of dep ar ture of t ra nsmission . Since transmission was to be in one direction only, t he gro und wires were laid out to form a g round-plane sector approximately 18° wide cen te red i n t he direction of trans mi ssion. The antenna was a base-driven vertical monopole. Measurem en ts were made of t he relative respon se in decibels… Show more
“…On a number of occasions it has been suggested that low-angle radiation froill ground-based h.f. antennas can be enhanced by the use of large ground planes (Wait 1956(Wait , 1963Wilson 1961;Andersen 1963). T o be effective, these must reduce significantly the surface impedance of the foreground out to distances froill the antenna comparable with or greater than a Fresnel zone.…”
FIG. 1. A linear antenna erected over a sector ground system whose surface impedance differs from the surrounding ground plane.IThis work was carried out while the author was a visiting professor a
“…On a number of occasions it has been suggested that low-angle radiation froill ground-based h.f. antennas can be enhanced by the use of large ground planes (Wait 1956(Wait , 1963Wilson 1961;Andersen 1963). T o be effective, these must reduce significantly the surface impedance of the foreground out to distances froill the antenna comparable with or greater than a Fresnel zone.…”
FIG. 1. A linear antenna erected over a sector ground system whose surface impedance differs from the surrounding ground plane.IThis work was carried out while the author was a visiting professor a
“…One method of obtaining an improvement in the reception at low angles is to use an extended ground-wire system in the direction of propagation (or reception) (A.C. Wilson;1961) . Another method would be to chuose the antenna site near a coastline in order to utilize the high conductivity of sea-water wherever it is possible.…”
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