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Poor ground, better Beverage

Discussion on Top Band Antenna list, June 2000

Herbert Schoenbohm, Vigin Islands: I read sometime in the past that the necessary wave tilt that makes a Beverage develop its directional and performance criteria equates to the propagation of the incoming signal differently over the wire and the poorer conducting earth beneath it.
John B. Mitchell, USA: I can attest to the fact that poor ground seems to really help beverage performance.
Here, in SWVA, the Appalachians are mostly limestone, karst regions, with a thin overlay of mostly decayed matter representing the oak and maple hardwood forest floor.
I have three beverage antennas running tree-to-tree between 600-800 feet long.
I've done some limited modeling and read most of the literature, and everything confirms what I hear. I find no need for preamps, since most times the signal on the beverage is within 10-15 db of a full size inverted vee at 100-plus feet, or an inverted L, somewhat lower, which are my references.
The signal/noise ratio, of course, usually makes up at least 30 db of improvement, so the beverages are almost always better.

If my ground were better, the tilt angle no doubt would be significantly higher.
I estimate, from modeling, research, and on-the-air testing, that these beverages are most sensitive to an angle around 20-50 degrees.
While 20 degrees would not be considered "low-angle" on 20 M, it certainly is for Top Band. As a matter of fact, I question whether even transmit angles much below this are particularly useful under most practical conditions. (An exception might be a quiet January night in the middle of the sunspot minimum.)
There is much in the literature which indicates that transmit angles around 20-40 degrees are optimum for Top Band DX, since lower angles require the signal to traverse the D layer through a greater distance, thus attenuating the signal more. We've seen a lot of discussion about "high angle" conditions on Top Band, and since my Inverted Vee, because of terrain influence, is down only about 6 db at 30 degrees, it often outperforms the Inverted L on typical Eu-path DX from Virginia.
Of course, efficiency enters the picture, since the L doesn't have an ideal ground plane.

The individual who posted a few days ago about using a reflector with his high dipole resonated with me, also.
I believe experimentation with horizontal arrays, even at lower heights (around 100 ft) is warranted, and I intend to try this.
I placed a reflector directly below an 80 meter inverted vee at 50 feet (close-spaced, around 20 feet) and obtained 5 db improvement within 1000 miles and no change at 3000. I think this shows that close-spaced reflectors tend to widen the lobe, which, in this case is good, since it gives more useful radiation at lower angles than straight up.
So, even if it's tough to calculate the perfect length for a two-element array with both elements at, say 100 feet, I think it might serve to provide 10-12 db front-to-back at low angles, and lower the main lobe enough to pick up around 5 db at 30 degrees, which I have stated I believe is a more important angle than, say 10 degrees.
Poor ground actually may help here too, and sloping terrain always helps, so I'll experiment some next season.

Since most people have better ground than I do, I'd stay away from anything that raises the angles at which the receive antenna is most sensitive. By the way, my beverages are "short" for the Broadcast Band, but perform amazingly well, allowing the beverages to "capture" different signals on the same frequency by switching directions.

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