Topband: Shorty Beverages

[Larry Molitor]

Recent experiments with short beverages have proved interesting and 
informative. Since all the positions and combinations possible on my little 
piece of ground have been tried, I've had to quit before all my questions 
were answered. Some of the following observations may be based on 
incomplete data and as such are subject to debate.

Six beverages were constructed. All were 270 feet in length. One was 30 
inches above ground and inside the TX antenna elevated radial circle. The 
rest were laying on the surface of the earth or on top of the dead grass. 
These were placed from inside the radial circle to as much as 60 feet 
outside the circle (in my neighbors yard). Galvanized fence wire and #24 
insulated copper wire were both used.

As was expected, interaction between the TX system and the beverages inside 
the radial circle occurred. Unexpectedly, the amount of interaction was 
nowhere near as great as computer modeling predicted. Useable results were 
obtained from even the worst case placement.

As has been noted on this list in the past, placement near and PARALLEL to 
a metal fence caused no noticeable degradation. However, fences near the 
ends of the wire, and nearly PERPENDICULAR to it, caused quite a bit of 
pattern distortion and loss of F/B. Modeling the fences did not show this 
effect. There was only so much real estate to work with, so no more could 
be done to explain this. This effect caused me a great deal of confusion 
initially, because there was still a lot of degradation when the TX antenna 
system was removed from the picture.

The 270 foot BOG (beverage on the ground) has a "gain" about the same as a 
FLAG.

While my rotatable Flag has a real cardioid pattern (easily observed back 
null about 30 dB), none of the beverages had a good null off the back in 
spite of the model predictions. The F/S was better and the front lobe 
seemed to be narrower than predicted in all cases. The 30 inch high wire 
under the elevated radial system had a null off to one side. It was very 
deep and I first mistook it to be a figure 8 pattern similar to what 
appears in "Low Band DX'ing".

A/B switching between the Flag and the various wires produced a tie in 
performance on 160. At times one would have a much better S/N, then other 
times the reverse would be true. I'd like to believe that the beverages are 
responding to lower angles better, but I have no way to prove that. On 80, 
the BOG's are way better than the Flag and are even pretty good on 40 
compared to my poorly phased 4-square.

My Flag has the advantage because I can turn it. It also suffers far less 
from interaction with the other antenna systems on the property. The shorty 
beverages are much simpler and cheaper to construct, but require a long 
straight clear run of real estate to get the best out of them. However, 
even when placed poorly, they are quite useable, if you can point them in 
the right direction.

The "elevated" wire had a measured surge impedance of 450 ohms. The BOG's 
were all 300 ohms +/- 10%. This is over my excellent ground; wet, highly 
alkaline, old farm ground. (Of course, it's now all asphalt and concrete 
outside the subdivision)


While not nearly as good as a longer version, these "shorty's" are 
certainly worth putting up. I would go so far as to say that modeling these 
wires close to the ground gives misleading results and you are better off 
trying it to see if it works for you. You might be surprised.

73,

Larry - W7IUV