The "Fishing Pole" Vertical antenna
(a very simple 1/4wave ground plane for 20m)
After reading up on lots of antenna ideas that use the same fishing pole approach (St. Louis Vertical, etc.), I realized a couple of things:
-I don't operate below 20m (occasionaly on 30m)
-1/4 wave on 20m is about 17ft (about 5.3m) in free space, and shorter when built as a dipole
-this is less then 20ft! (go figure :-) )
-I can use a 20ft crappie pole to raise my antenna vertically!
Therefore, this antenna is basically a 1/4 wave vertical ground plane antenna. Rather simple, but effective.
What you need:
Take a piece of wire of about 8ft3", strip it apart, solder it together so the total length is16ft 4". Now solder a clip on both ends. You can use electrical tape of heat shrink tube to sturdy the center joint and the clip joints and keep the wire from breaking off. Needless to say, you can also use a single piece of 16ft
Through the top ring of the crappie pole, tie the piece of nylon wire such that it makes a loop. You will clip/hang hand the vertical radiator onto this.
Putting it together:
Clip on vertical radiator to the loop at the top of the pole. Extend the pole. Put it over the mount.
Clip the BNC female chassis adapter to the vertical radiator. See photo 1.
Put the coax into the BNC connector.
Clip all 4 radial pairs clips onto the connector; spread out the 8 radials as evenly as possible in a circle around the antenna. (You can obviously make more radials, this will probably improve performance somewhat. Going beyond 16 radials, i.e.. 8 pairs, will probably not help much)
After this, I use some velcro tape to hold this concoction to the pole, but this is optional.
Now you basically have a 1/4 vertical with ground plane for 20m. (see photos 2&3) I have successfully used this antenna in my back yard, and around a few campgrounds (photos 4&5.)
Several times I have gotten an SWR of around 1.5:1 and needed no tuner to operate. Running low power, I have made lots of interesting contacts around the country and the world with this! Because the angle of radiation angle is low, this is a good DX antenna!
I have tuned this antenna on 30m and 15m and made satisfactory contacts. For permanent use on 30m you can lengthen the ground radials. You can also hang 17m, 15m, 12m and 10m vertical radiators on the same pole by soldering then onto the same clip on one side of the 20m radiator. (Use 12.9ft, 11.1ft, 9.3ft, and 8.3ft respectively) Then tape them to the longer wire where they end (since these are shorter). This should allow for a relatively decent multi-band ground plane antenna, while keeping construction and cost low. Due to interaction of the various vertical pieces, you will either have to tune the lengths of these somewhat, or use a tuner to satisfy your transmitters input impedance.
The whole antenna, apart from coax and pole, easily fits into a zip lock bag for transportation!