All vertical monopoles of 5/8-wavelength __and less__ radiate (launch) their maximum relative field (E/Emax) in the horizontal plane. This is true no matter what the loss in the r-f ground connection they use.
A lossy ground connection will reduce the gain of the antenna system, but it will not change the relative fields they radiate. IOW, their pattern shapes remain the same regardless of the loss in the ground connection, be that to salt water, or dry sand. The link below leads to a plot of the radiation patterns and directivities of several monopoles. These are the shapes of the radiation patterns leaving the monopole as they exist at the beginning of the far field of the radiator. These patterns were calculated for two ohms of loss in the r-f ground connection - which is about the loss that 120 x 1/4-wave buried radials provides even in poor soil. If fewer/shorter radials are used, then loss increases and the directivities (gains) of these patterns would be reduced -- but the radiation pattern shapes would remain the same. Many amateur radio operators consider only the far-field pattern of a monopole antenna as shown by NEC and in textbooks, without realizing that this is not the shape of the radiation leaving the monopole. It leads to the concept of a "takeoff angle" where radiation apparently was maximum from that monopole. However the elevation field radiated by a monopole always is maximum in the horizontal plane, and always is less than that at the elevation of an assumed takeoff angle. A NEC analysis including the surface wave from the monopole will show this. Some of that low-angle radiation can reach the ionosphere and produce skywave service, even though according to a NEC far-field analysis, the fields are approaching zero at those low angles. This doesn't mean that radiation at and near the "takeoff angle" does not provide significant skywave service, but it does mean that significant skywave service can be generated by radiation at much lower angles than commonly believed. http://i62.photobucket.com/albums/h85/rfry-100/MWElPatComparison.jpg _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
