The PREDator

The PREDator (Portable, Resonant, Elevated, Directional) is an elevated vertical antenna for 40M-6M sitting on a tripod (or an extended ground spike) with the feed point about 5’ off the ground and two elevated radials. I've modeled it extensively in 4NEC2 (including the tripod) and calculated optimal whip and elevated radial lengths below. You will have to experiment in your own yard to finetune these, but I typically get better than 1.1:1 SWR on all bands. I've found through my computer modeling and real experience in the field, this elevated vertical is more efficient than any ground-mounted version with two radials. You can certainly use this type of antenna for 40M with a coil (like the WRC Sport Forty) and get similar results but elevating two 33' radials is a bit cumbersome in the field. Alternatively, you can combine the two 20M 16.5' radials end-to-end to have one 40M radial (that's what I do on POTA).

The two elevated radials are 90 degrees apart to provide some directionality (about 8-12dB or up to 2 S-units) within the 90-degree span. If you prefer an omnidirectional pattern, you can place the two elevated radials 180 degrees apart. Having your radials elevated dramatically reduces near-field ground losses and increases gain versus a purely ground-mounted vertical. This really is a fantastic POTA activator antenna - easily portable and highly efficient. I regularly get comments like "you're the loudest signal on the band" from hunters. It's also a great DX antenna when conditions are right with a very low angle of radiation component around 12-15 degrees.

Here are the components I use (you can substitute as you wish):

Above are the 4NEC2 calculations but, through experimentation, I found that you will need an individual set of radials for 20M, the 17M radials could work for both 17M and 15M, the 12M radials could work for both 12M and 10M, and you'll need an individual set for 6M. So, if you want to save on packing, you will only need 3 sets of pre-cut radials (20M, 17M, 12M) which will cover 5 bands: 20M, 17M, 15M, 12M and 10M. You tune the antenna with an analyzer by slightly adjusting the length of the whip up/down once you attached the right set of radials. You shouldn’t need an external antenna tuner of any kind.

Here are 4NEC2 computer model graphics showing the directionality (vertical, horizontal plane) and reflection coefficient (RC) for 20M. Note the SWR = 1.00:1 at 14.250 MHz with an RC of -70dB.

And here are a few photos of the PREDator in my backyard 'antenna proving ground' to show you how the tripod elevates the feedpoint up 5' and the 3' fiberglass stakes elevate the end of the two radials 90 degrees apart. I insert the radial fiberglass stakes at a 60-degree angle into the ground for stability.

The PREDator is my primary POTA portable antenna, but it could also be used at your home QTH. Keep in mind, you'll have to keep adjusting the whip length and the set of radials for the band you want to operate on. While that's easy for POTA use, it may be inconvenient for you at home. Of course, if you only want to primarily run on a couple bands (e.g. 20M-15M) that would be easy to manage.

Greg Mihran, KJ6ER