Making the Short dual wire Beverage better !
It was always the plan to bring both ends of the short Beverage into the shack and figure out how to make this thing adjustable. Further, since you have two coax that are receiving from two directions, it should be possible to make some sort of phase control device and combiner which allows you to “Steer” these antennas.
Victor Misek to the rescue ! Victor has written a book “The Beverage Antenna Handbook” , third edition which provides the state of the art in practical Beverage construction and use. Frankly, I found the information provided by the Antenna Handbook and Low Band DXing to be interesting but frustratingly incomplete. If you intend on building a short steerable Beverage, you want Victors book. You can get it from Radio Ware at www.radiobooks.com Very obliging chap runs this little store. Victor’s book is a self published job and gets out of stock. Charles at Radio Ware chased Victor down and got some more copies. Thanks Radio Ware !
Victor calls these shorter two wire antennas SWA’s, or Surface Wave Antennas. The traditional long and pointy Beverage are known as COS , or Cone of Silence, antennas.
Here comes the radical
challenge to conventional wisdom: Victor claims that a SWA with a steerable null is
more use to the amateur than a field full of
Most of us have a dream antenna setup consisting of a field full of long Beverage wires pointing all directions. Unfortunately, most of us also live on small pieces of urban land that preclude that dream from becoming a reality.
Read those two paragraphs again and let it sink in. Could the best of both worlds be had with a SWA and a steering device ? I now believe the answer is yes.
Victors book had very clear information on the transformers for the feedpoint and reflecting end of the SWA antenna. Yet again, I rewound my transformers and obtained better balance from my antenna. But, the last step of my short Beverage quest was at hand. I built one of the improved steering devices described in Vic’s book. Here is the schematic for it (reprinted from Vic’s book):
And, here is my first version of the device, shown in the following two collections of pictures. I thought I was being clever with the packaging, but of course, things didn’t quite work out the way I wanted. The next one will be about 50% of the effort of this MK1 version. This one includes a little sub box containing a port saver for the Pro3 rig. I have since removed it and mounted it closer to the Beverage port on the radio. My unit has 4 different phase shifter center frequencies that coincide to the 3 bottom ham bands and one for the broadcast band. Three would probably be enough in the MK2 unit ( VE1RGB’s unit ?)
However, together it went, and work it does !
Note the little sub board on the back of the band switch making a neat collection of my junk box coil and capacitor assembly. At this point, things look pretty good. Then reality set in !
However, the unit does what it was designed to do. The box was selected to sit near my right hand just starboard of the radio. The weight in the bottom is to aid anchoring the unit to the desk.
Inside got a little ratty. The next one could be greatly simplified by using one board to mount everything behind the controls. The board would be mounted to the controls by lead extensions from the controls themselves. Much easier and neater. I was trying to be too clever with this MK1 unit.
How does it work ?
! It works as advertised and then some. You can
literally steer a null around 360 degrees with this thing !.
Even in “
I suggest that this device makes the short SWA set up at least three times more useful than it was. Compared to a short single wire, I would say this is ten times more effective. Bold claims, I know, but I think they are justified.
Rumour has it that DX Engineering is going to offer a device like this to work with their commercial SWA parts.
The unit works by taking one of the signals and running it through a plus and minus phase shifter, and then subtracting the signal from the other signal via a hybrid combiner transformer. The Fet gives a little help to the lossy part of the signal after going through the phase shifter. There is also a control to provide an adjustable match to the other signal… a real boon to the balance issue on these antennas.
If you hate noise.. you will love this setup. A short two wire Beverage ,or SWA, and a null steering device.