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Author Topic: What antenna do you use for backpack QRP?  (Read 32729 times)

cockpitbob

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What antenna do you use for backpack QRP?
« on: September 16, 2012, 11:49:31 PM »
Now that I've learned Morse well enough to get on the air, my next step is QRP, and especially for portable ops.  A QRP rig would also be a nice addition to the SHTF go-kit.  There are some really nice small QRP rigs, but what do most backpackers use for an antenna?  I mean, what's the point of putting the radio in an Altoids tin if the antenna is 65' of #18 wire, plus 50' of feed line, plus lots of 550 cord, plus a slingshot line launcher to get it up in the trees?

So, what do you use, or have heard that works and is compact and light?  If it's a wire, how do you get it up high?

gil

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Re: What antenna do you use for backpack QRP?
« Reply #1 on: September 17, 2012, 01:15:03 AM »
Hello Bob,

I made three...

- SOTA tuner from http://qrpkits.com with wires for 20m. I love the little LED that allows you to tune the antenna perfectly.

- 6-to-40m end-fed dipole, 35.5' long. http://www.earchi.org/92011endfedfiles/Endfed6_40.pdf

- 40m end-fed dipole, 66' long, with Tayloe SWR indicator from http://qrpkits.com: http://www.earchi.org/92011endfedfiles/Endfed40.pdf

I don't know how they perform on transmit yet (waiting for my call sign), but they receive very well.
Wire and toroids (T106-2) available from http://thewireman.com (I use wire #532 and #534).
The plastic boxes and hardware, I got at Radio Shack.

I also have a PAR End-Fed 40/20/10 (http://www.parelectronics.com/end-fedz.php). It's tuned for 20m, but I need to shorten it a bit for 40.

I might get a Buddistick (http://www.buddipole.com/buddistick.html) for when no vertical support is available, knowing full well performance is going to be limited..



By the way I am not associated with any of the above-mentioned manufacturers...

Gil.


cockpitbob

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Re: What antenna do you use for backpack QRP?
« Reply #2 on: September 17, 2012, 07:05:10 AM »
Nice collection of antennas!  I like the idea of an end fed 1/2wave antenna.  Only one end to get up in the air instead of 2 ends and a middle, plus the feed line will be much shorter.

Thanks,
--Bob

Mitch

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Re: What antenna do you use for backpack QRP?
« Reply #3 on: September 17, 2012, 10:37:26 AM »
After some experimentation I've settled on these choices for my outdoor expeditions:

http://www.eham.net/reviews/detail/8499

With a 16' extendable panfish pole as a mast for my VHF/UHF needs. The antenna can be hoisted into the trees for base station or used with the pole when on the move (if you really need some extra range over a duckie antenna). The super light weight fishing pole is also used as my walking stick as well as for a fishing pole of course!

http://www.eham.net/reviews/detail/3632 (Same as one of Gil's end fed antennas the 10-20-40 version)

Hoisted into a tree for all my QRP HF needs. I've experimented a bunch with portable antennas (I have a Buddipole, Buddistick, Miracle Whip, Homemade YoYotennas, and various lengths of wire with a tuner also) but my personal preference pared the equipment down to one small backpack for greater mobility/enjoyment. To that end; some of the lessons I have learned follow:

1. It's better to have portable antennas that are tuned/resonant without the extra weight/complexity/wiring of a tuner. (Unless you build/buy one of those minimalist tuners)

2. Nothing beats antenna height (unless you want an NVIS antenna) but it's darn hard to accurately throw stuff  high into trees and the time it takes will ruin the fun of portable operation. I've settled on a folding slingshot that slips onto a carry strap on the outside of my pack along with a fishing sinker.

3. Just stake a small spool of fishing line to the ground, unwind about 8 foot and make sure it's slightly slack between you and your target tree, then shoot your branch. You can then hoist your antenna or some 550 line to get your antenna up. It's so accurate that I can always get a line up to 60' in 2 shots.

4. Don't bother with a fishing reel attached to your slingshot (unnecessary weight/bulk), they tend to catch on something then your sinker shot comes back and pops you in the face. If your line spools from an area a few feet away you are much safer!

5. Use a good quality 20 foot section of coaxial cable as feedline with your end fed antenna because it's your counterpoise or radial. I still haven't figured out the difference between those 2 things...

6. It's much more enjoyable to hoist just one wire in the air. So many good antenna options need you to hoist more lines up. I don't really want to spend hours putting up a good dipole for a few hour operation in the evening.

7. Misc stuff- The buddipole is too bulky/heavy for what I wanted in nature. The buddistick is pretty nice but it's irritating to hear much more than you can work (although to some extent this is a built in feature of QRP operation). The Yotennas kept getting crossed and are so small it's difficult to tell that high up. The Yotennas were also heavy because I wanted the option to put as much wire as possible into the air. A slingshot also makes a nice bit of survival kit!

8. When camping keep all your components in ziplock bags or tupperware with a small dessicant pack to combat moisture. Most people will do this for their electronic components but some don't realize you need to keep your antennas, adapters, and coax in them too! This also keeps your wires from tangling in your pack.

9. Wind your wires on cardboard to save space/weight.



This just gives you my current experiences and will be in flux for the foreseeable future.
« Last Edit: September 17, 2012, 10:39:15 AM by Mitch »

gil

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Re: What antenna do you use for backpack QRP?
« Reply #4 on: September 17, 2012, 11:56:13 AM »
Great post Mitch, thanks.

I did order the Buddistick, though I certainly don't expect miracles..
What kind of contacts did you manage with it on 5W, 15W?

Thanks,

Gil.

cockpitbob

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Re: What antenna do you use for backpack QRP?
« Reply #5 on: September 17, 2012, 12:16:49 PM »
Mitch,
Thanks for the great reply.  One question.  If I read between the lines it sounds like you thing the Buddystick pulls in stations better than the endfeds.  True?

Mitch

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Re: What antenna do you use for backpack QRP?
« Reply #6 on: September 17, 2012, 01:26:44 PM »
Gil-
I'm 100% QRP for HF with an FT-817ND so you know where I'm coming from. I only operate when I'm camping for the most part (about once a month) so I'm not on the air a lot - my house is in an antenna no-fly zone. I don't keep a log currently (no it's not required); primarily because I don't talk much. I'm still soaking it all in with researching, tinkering, and listening. You can count the number of QSOs I've had with voice on one hand.

I'd recommend the reviews on eHam.net to get a better idea about how well something works. http://www.eham.net/reviews/detail/3870
After glancing at that review again I should also say that I've only operated my Buddistick from the tabletop position.

-> I'm still a radio noob! <-

I can say that the buddistick will get you contacts (Oklahoma, Tennessee, and Georgia for me), but if you use it QRP you'll need to learn good propagation technique (something I don't have) if you want to regularly get >1000 miles. I can talk over much of the midwest but have problems reliably hitting the coasts, but I hear those coastal stations well often. My Dad also lives in California so I'd like to hit that far!

I'm currently dabbling in digital hoping to squeeze more data per watt per mile out of my radio. One day I may try learning the code, just not anytime soon.



cockpitbob-
I'd have to say hands down the end fed receives better in my transient intallations so far, but I just attribute that to the height. What's around you matters a lot too... I'll say that if you are buying a buddistick to put up in your den and play radio you'll probably be disappointed unless your house is a lot more electrically quiet than mine!
« Last Edit: September 17, 2012, 01:42:13 PM by Mitch »

Paul

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Re: What antenna do you use for backpack QRP?
« Reply #7 on: September 17, 2012, 02:57:48 PM »
Just a few words about antennas in general.
The "ideal" antenna puts a signal where you want it to go.  That ability is usually referred to as it's radiation pattern.  It's also reciprocal, the 'reception' pattern is the same as the radiation pattern.  That radiation/reception pattern is a function of the antenna's length and 'shape'.  'Shape' in that a wad of wire seldom if ever performs like the same wire strung out, see what I mean?
There are particular lengths of antennas that produce a more usable radiation pattern than others.  All lengths produce a pattern, some just aren't very usable in particular circumstances.  The biggy with that is that as one of those particular antenna lengths is shortened, the radiation pattern changes.  What may be a very desirable pattern in 'full size' antennas degrades fairly quickly as it 'producer', that antenna, is shortened to a more convenient size/length.  A typical 2 meter rubberduck is a pretty good example of that. 
So, when talking about HF portable antennas 'size' definitely will make a difference.  Bigger/longer is better.  Certainly not very convenient.  But are you looking for convenience or performance?  That trade-off always means convenience is the 'short end' of the stick.  Then you get to balance the performance thingy with the practical thingy.  One of the two of those thingys will have to come up short, they are almost never compatible.
Another one of those 'general' thingys is that a 1/4 wave length antenna is the most common portable antenna.  That particular 'size' of antenna is the most easily used and usually has a usable radiation pattern.  For HF, any portable/mobile antenna you see will be a shortened version of a 1/4 wave antenna.  That's always frequency dependent, so the higher in frequency the less shortening required.
Nothing 'new' in any of that.  It's very handy to keep in mind when looking for portable/mobile antennas. 
 - Paul
 

Jim Boswell

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Re: What antenna do you use for backpack QRP?
« Reply #8 on: September 17, 2012, 06:06:22 PM »
Hello, I use a 20meter inverted vee or dipole. Just throw a rock over a limb and hoist the antenna up and tie off. Once you cut the length right, either CW or SSB then it is close enough to work reguardless of shape.
73'S   KA5SIW

Lamewolf

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Re: What antenna do you use for backpack QRP?
« Reply #9 on: October 10, 2014, 04:13:28 PM »
I built a mini T match tuner for field use and it has tuned any antenna I've connected to it so far - random wires, end fed half waves, verticals, mobile whips etc and its very compact.  You can see it here:
http://www.angelfire.com/electronic2/qrp/minit.html

Radio Preppers

Re: What antenna do you use for backpack QRP?
« Reply #9 on: October 10, 2014, 04:13:28 PM »