Looking for a good single wire antenna solution for 10-20m. I normally use a 40 efhw and it works great , but with the higher bands being so good lately , it would be nice to not have to string a ~66 ft wire if I just want to focus ln the upper bands
Id like the antenna to be as efficient as possible so that’s to me leaves out a random wire with a 9:1 transformer.
Someone mentioned sota beams traps.
Make a 20/10 meter EFHW (about 33’). Then wind it on a winder and find the resonant point for 17 and tie a knot in the wire. Do the same for 15 meters.
Then just wind wire out to that point and tie it off as normal.
The “cap hats” the coiled wire makes will not cause much change and you can tune it out when finding the right length with your analyzer.
You get your short wire, with no splices or traps. I’ve been running this way for years.
That’s a great idea. I’m thinking of also trying a paint pen instead of a knot…:.
I tried paint, tape and heat shrink tubing. They either wore off or slid off the mark.
Come to think of it, you could just mark your 40m EFHW in the same way and just need one wire for all bands.
I even used mine for 2 meters once!
I recently build a 3-band vertical EFHW with traps for 20-17-15m for my MTR5B for this purpose. The traps are Picotraps from SOTABeams; thanks to the inductors in the traps, the total wire is less than 9.5m, which fits nicely on the DXwire 11.5m mast. Then feedpoint is hence ca. 2m above the ground.
While the mast is not really super-portable, the antenna should play very well for DX - no need for radials (and resulting heavy ground losses).
73 de Martin, DK3IT
Presuming you have an antenna analyser of some kind, my suggestion would be to build a linked dipole for the bands needed - the calculator for lengths is under “EXTRAS” at sotamaps.
SOTABeams also build a commercial version of this for certain bands but not perhaps for the bands you want.
My modified SOTABeams one now covers 80,60,40,20,17 &15m.
I have added a 1:1 balun from a SOTABeams kit (and their current product comes with this) but it is not essential when running low paper (say up to 20w).
For some time I’ve been using a very compact antenna for casual “fair weather” radio while hiking on the surrounding hills. This fits well in a Deuter Speedlite 15 liter backpack and looks like this:
- A nominally 6m long carbon mast DAIWA COMPASS Mobile Telepole 600 (6m/0.42m, 330g) with a classic wire GP antenna mounted about 1m elevated, together with 2 horizontal radials (each 3.1m long, about 1m above the ground and attached to the hiking poles)
- The resonant antenna wire length for 14 MHz, when wrapped around the mast 3 times, is reduced to just 4m and is therefore perfect as a monoband antenna for a small QRP transceiver without ATU such as a mountain topper
- To keep it strictly simple and to omit any unwanted feedline effects the radio is also attached to the mast at the antenna feedpoint
- 14-28 MHz multiband operation is possible with the help of a suitable ATU at the antenna feed point, e.g. with an Elecraft KX2&ATU. This variant was used in Oct. 2021 for SOTA HB/BE-150 activation because the terrain there offers slightly elevated seating (for the lower bands, a small matching unit with switchable toroidial wound loading coils was used)
- The vertical radiation characteristics calculated by EZNEC are shown below. The antenna radiates omnidirectionally.
73 gl, Heinz
I tried this and could only get resonance on 10m. Back to the drawing board for the other bands
Don’t neglect 12m, when ten is good 12 can be better!