Tuesday, January 03, 2017

Portable operations antennas

So with all the NPOTA operating and other portable operating that I've done over the years, you might think that I've become some sort of expert on portable antennas, right?

Nope - not even close.

I have become "expert" enough to tell you that there's no "one size fits all" or all purpose antenna that will work in every situation.  That antenna continues to be the "Holy Grail" or "Golden Fleece" of Amateur Radio.  It is rumored to exist and is still being searched for.  Some will tell you that they possess it, or a reasonable facsimile, thereof.

In my mind, it's a myth, a fairy tale, a legend.  I have found that in every situation, all portable antennas will work well, some better than others. It all depends on the situation and the circumstances of that particular day or event.

Do you have trees available?  Awesome!  I think back on Day One, the Good Lord knew that someday, radio would be discovered, and that our species of hobbyists would be spawned. So He created trees.  "The World" seems to think that trees were created for the purpose of shade, food, converting carbon dioxide to oxygen, as well as a source of wood.  We Ham Radio operators know better - that trees were created to hold our aerials up in the sky, away from the ground,  and that the other services that trees provide are just side benefits.

If you have trees available at your location, put them to their intended purpose ....... get wire in them, as high as you can get it.  Whether it be a dipole, doublet, end fed, zepp, or any other kind of wire antenna, get it up as high as you can.  Of course, for portable operations, you want to keep the antenna as uncomplicated as possible, while still maintaining the ability to work as many bands as possible. In my experience the W3EDP or an end fed wire connected to a 9:1 UNUN will give you the most bang for the buck.  These can be used as verticals or slopers. And if you have enough real estate and feedline, they can even be stretched between two trees, as high as you can get them.  In the five years of the NJQRP Skeeter Hunt, my best year was accomplished using a W3EDP strung between two trees in a horizontal configuration, about 40 feet up, or so.

But what if there are no trees; or only one tree?  If there's only one tree, then I would suggest using said arbor as a support for a sloper - again. getting the end up as high as possible.  If there are NO trees, then you have to become creative and a bit more flexible.  If you're at the top of a mountain, you might try taking an end fed and just allow it to dangle off the side of the peak. If that's not practical, or you're bothered by heights like I am, and will go nowhere near the edge of a cliff, then you have to resort to something else.

That something else might be something like a portable vertical. Portable verticals can work very, very well. But to work very, very well you need to lay down a radial field or use a counterpoise. When I used the PAC12 antenna, I used to lay down a set of 8 sixteen foot lengths of wire, arranged around the antenna in a wagon wheel fashion.  It worked well, but could become a nuisance if the radial wires became entangled.  Care had to be taken during storage to make sure that didn't happen. Also, the radials will work the best while being elevated, even if that means just an inch or two off the ground, which means some sort of radial support also becomes necessary.

If you operate from your car .... if you can operate from your car, the radial problem becomes much, much easier to deal with.  Put your vertical on a magmount and allow your vehicle to become the ground plane.  I was only so-so pleased with my Buddistick until Bob W3BBO recommended this to me.  After I abandoned using the Buddistick counterpoise wire, and let my Jeep fulfill that function, my Buddistick literally began to soar!  Over the years, I have worked over 60 countries and just about all 50 States using 5 Watts or less.  Having a huge hunk of metal under that vertical makes all the difference in the world.

That being said, does it work on ALL bands well?


The Buddistick on the roof seems to work well for me on 20 through 6 Meters.  If I want to hop on 40 Meters from the Jeep, I resort to a Hamstick.  The Hamstick, on that same magmount, works exceedingly well.  I suppose I could get the Buddistick to work decently, but I would need to add extension arms and figure out whip length.  It seems easier to just plop the Hamstick on for 40 Meters and the Buddistick for 20 - 6 Meters.  I have fiddled around with the Buddistick enough to find a tap setting that will allow me to work 20, 17 and 15 Meters without changing the physical configuration. The autotuner in my KX3 compensates as needed for each band, and minimally at that.

So what do you do, if you're away from your vehicle, there are no trees, and no way to support a wire with a portable mast; and you don't want to mess with a vertical and radials?  This is where a magloop can come into play.  The magloop is the newest antenna in my portable ops arsenal, and I have to admit that for a long time, I was doubtful of its capabilities.  But (there's always a but) I remained intrigued by the idea of having something like that and hoped against hope that the stories I had been reading were not just wishful thinking.

So far, I have found that the claims seem to have some truth to them.  From the limited use I have given my home brewed magloop, I have been quite pleased as well as surprised.  I have easily hopped the Atlantic several times with 5 Watts as well as crossing the Continental US to the west coast.  What has surprised me about the loop is that the noise floor, while using one, is so low that you may think you have it tuned wrong.  The incoming radio signals seem to jump out of nowhere and are quite loud. But using a loop takes some getting used to.  You have to teach yourself how to find the "sweet spot", which means turning the tuning capacitor for loudest ambient band noise. In an environment where there may be lots of traffic or people talking, that means resorting to using earbuds or headphones.  Once you carefully tune for that loudest band noise, though, means you are there - flat SWR.  But you have to be careful, though, because the tuning is very sharp and if you're even a tiny bit off, the SWR can be sky high.  If you're going to be frequency hopping a lot, this is a major pain.  Also, the tuning capacitor works best with some sort of reduction drive. As I've mentioned before, tuning can be tricky until you're used to it, and without the reduction drive, it can be difficult to find that noise peak.

The bottom line is that, if you're going to do a lot of portable operating, you really should have at least three or four options at your disposal. There is no situation where one antenna where work in all cases, either due to lack of set up time, real estate, available antenna hanging resources, etc.  Once you've gotten some experience under your belt you will be able to size up the situation and will be able to determine what option will work the best for that given day.

Always keep in the back of your mind the equation, "MOE = A + R + T" . That is, Maximum Operating Enjoyment becomes an art. It is a mixture of Antenna Efficiency  Resources and Set Up Time.  The desired outcome for an enjoyable outing is always using the most efficient antenna you can, using the resources you have at hand, with the minimal amount of set up and tear down time. After all, the idea is to be on the air making contacts, not silently cursing antenna wires or trees under your breath while simultaneously elevating your blood pressure.

A word of warning, though ..... this will become a lifetime endeavor and you will be constantly perusing the Internet and Ham publications looking for that "all purpose, all in one antenna".  I doubt that you or I will ever find it, but as they say, "The fun is in the journey, not the destination."

Have fun and see you on the air from the Great Outdoors in 2017!

72 de Larry W2LJ
QRP - When you care to send the very least!

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