I am using the MFJ 1979 with a loading coil, a small tuner and a tripod since years for my SOTA and GMA activations and normally it outperforms my linked dipole (configures as an iverted-V using a 6m-pole) at the same location. I have tested both antennas and the Buddipole in the field at a locations with bad ground values, which I have measured (I am geologist and can use professional equipment for testing ground resistivity at the working frequency - not at DC ! - and also permittivity or dielectric constant). The results are straightforward, if you think about antenna specifications:
The loaded vertical is used in the field with only 1 +/- resonant elevated radial. The hight of the elevated radial is - if possible - in the range of 0,5 to 1 m. Lesser is possible, but degrades efficiency very quickly especially on poor grounds like on most of our higher mountain tops.
A verical like this shows the upper-and-outer configuration and can be deployed within minutes. For short and medium range distances it is inferior compared to a dipole and an inverted V on my 6 m pole, but for DX it has shown to be unbeatable though overall radiation efficiency is clearly less than that of a dipole. All DX I made from summits is done using this antenna. The reason for DX performance is the well known low radiation angle. For short to moderate distances reception is 1 to 3 S-units less than that of my inverted-V, but I never had problems in working German or Central European stations. The signal strength of these stations is so high, that there won't be any problems. On the other hand DX with an inverted-V has been impossible becaus the signal strenght of these stations here is really low and the degradation of the regional signal coming under high angles is really appreciated by me.
I clearly prefer the dipole in 40 m and lower and will give it a try definitely on 60 m duringe one of my next activations. Especially on 40 m during daylight DX is impossible, low radiation is useless and steep radiation is needed for more or less local contacts.
If I am not using the MFJ whip I take a 6 m pole with me. It can be used to fix the inverted-V near the top and also to hoist up a loaded vertical made of wire. If I use it only for 20 m and higher there is no need for loading, but a small tuner (smallest available is ok for 5W only) is recommended. If the range of the tuner is sufficient, one can also match 30 m without coil, but in this case the feeding line between antenna and tuner should be as short as possible. Nothing degrades the efficiency of the whole antenna system more than long an mismatched feeding lines.
Earlier I mentioned the buddipole. I know that it is expensive and heavier, but I can easily carry it with me as long as there is no real climbing to be done to reach a summit. I'm using it with the long whips. So efficiency for 20 m and above is not as bad as one might expect. It has 2 pros:
- It is a verry "strong" and well designed antenna.If you fix it with 2 or 3 ropes to prevent falling down it will withstand neary all weather conditions under which SOTA activities are thinkable. Last year I took it up on the summits of our Hercynian Mountains and it worked under snowfall and so heavy winds, that I wouldn't even have thougt about any other antenna. I never had any difficulties ist the configuration of the antenna under whatsoever conditons weather and temperature conditions.
- It can be used from 40 m to 2 m with a lot of configurations in a very flexible way. The possibility to use it as a true vertical dipole - which I never tried on a summit, but at other portable locations - is a real pro for DX.
I think the most preferable way for a satisfiying activation is a short and lightweight (6 - 8 m) pole with it's possibility to use it as a vertical with elevated radials as well as the usage as a dipole. The additional weight for a second set of wires is negliable and the possibilities for local and DX traffic are somewhat maximized. At QRP-levels the most important thing is not to loose to much efficiency in matching feeding.