Radio Preppers

Recently there has been some discussion on-line in other fora soliciting suggestions for "portable" antennas. Admittedly my idea of portable is thrown wire that travels in a ziploc bag. But, in the vein of never-say-never, there could be a time one isn't afoot all the time, or has some hirelings, and could tote something larger to their favorite spot . But the spot has no vertical structure of any kind, although there is the means to guy-off something if needed.

Does anyone here have experience with any of the popular push-up verticals or dipoles that could be toted in a bag under the arm and set up, say, on a beach somewhere?  The Buddipole is one common one I hear about; the Superpole is another. Buddipole (and Buddistick) have long-standing reputations; the other uses no coil clips but rather slides to adjust roughly for the band.

Just wondering if anyone has ever been in that situation, what was used, and what were the results.
Just to keep the size parameters reasonable, we're talking 20-17-15m, that kind of thing, 30m would be dessert. Antenna tuner is available.

Thanks!
:)

I've had good luck with my Buddistick... Even made contact with Ray 830 miles away once on 30m with the stick inside the house and 2W power!

Gil.

I have a buddipole and it works great. The standard kit with 2 additional counterpoises makes a great NVIS antenna.

Resurrecting an old thread again, that's me.  :)  I have a Superantenna MP-1, and it works great on 40-10. Haven't tried it on 6, but it shows acceptable SWR. I've had this antenna for a few months but have only really started using it a lot in the last few weeks. So far, so good.

I've got High Sierra Sidekicks on my truck and motor home and love 'em. I've also got a collapsible tripod to which I can attach one of the screwdriver antennae with three wire counterpoises. An MFJ 12 foot collapsible whip allows it to tune 160 thru 6 meters without a dedicated tuner. It's not as inexpensive as a roll of wire but it's pretty cool :)

@@ BlackBerry 10 Mobile Messaging @@

I'm still planning a 20m magnetic loop, that will be portable...

Gil.

I'm enamored with 1/2 wave end feds and have had great results.  I love an antenna that fits in a ziploc, but they need trees.  What I really want to get into next is mag loop antennas.  Though a bit pricey, the AlexLoop Walkham  (http://www.alexloop.com/index.html)covers 40M-10M at 10W CW and gets great reviews  (http://www.eham.net/reviews/detail/9012)(5.0/5.0 from 36 reviews!).

You don't need to spend that much Bob. You can get a high voltage air capacitor for about $70, and a thick 10ft coax patch cable to use for the loop. Use a toroid core for feeding, and you'll get your Alex loop for about $100. That's what I'm going to do..

Gil.

Quote from: gil on September 04, 2013, 10:42:56 PM
You don't need to spend that much Bob. You can get a high voltage air capacitor for about $70, and a thick 10ft coax patch cable to use for the loop. Use a toroid core for feeding, and you'll get your Alex loop for about $100. That's what I'm going to do..

Gil.

Great!  Me too.

In my backpack portable rig I've got a YoYo-Tenna, two buddiestiks center-fed on a homebrew feedpoint I found on YouTube and an Opek HVT-400b...along with 50' of RG8X

Dear friends.

I casually stumbled to this forum browsing the internet and I found it interesting because it deals with radio-hiking, which is an activity I like a lot.
My name is Davide, I'm from Italy and my callsign is IZ2UUF. I live in Milan but I have a little house in the middle of the Alps, near the border of Switzerland, where I spend a lot of time.
I work mostly HF in CW only. When the trip altitude gap is below 1200m (4000 ft), I can afford to carry my FT-817, a little tuner and a 10m fishing pole in my backpack.
Initially I was using a vertical antenna but, after some reasoning and simulations, I decided to switch on a dipole.
In order to keep the dipole high on the 10m fishing pole and almost horizontal, I feed the dipole with a 450-ohm window line directly to the tuner (without balun). Then a very short run of RG-58 connects the tuner to the radio.
In this way, being this dipole very light, I can keep it at almost 10m from ground without overloading the fishing pole.
The dipole can be of any lenght and it works on all bands. With a 16m long dipole (8m/26ft each side) I have optimal results in all bands from 15m to 40m, while it still works reasonably well in 12 and 10m.
The dipole has two 20m thin strings on each side: in this way, pulling the strings far away, I can obtain a very open inverted-vee shape (140°).

This is how the antenna looks:


This is a view from one of the strings:


This is me operating with a view of the entire antenna:


This is the connection to the tuner, directly to the ground/wire input (which is the same as the ANT SO-239) and not to the 4:1 balun:


Below the diagrams of this antenna (blue) compared with a 10m vertical pole (red) in same portable condition explain numerically why this antenna works so well.

This is in 40m, where this antenna is omnidiretional and good for a 1000km range:


This is in 20m, where it is directional:


Tis is in 10m, where lobes are not so good. To work 10m a shorter dipole would be better.


I would like to recommend this solution because results, as predicted by computer simulation, has been astonishing.
This antenna requires a lot of estate to pull the strings, but space it is one of the few resources available with abundance in this kind of activity.
Although the dipole performances are well known, this kind of solution is seldom considered for QRP/P activity, mostly for the weight of the balun and coax that can't be suspended at the top on a thin fishing pole.
This solution solves both the weight and the multi-band issues.

I hope this solution has been of your interest.

73 de Davide IZ2UUF

Davide, welcome to the forum, glad to have you aboard. Awesome photos, thanks for sharing.

Beautiful Photographs, David! Thank you for posting. You are very welcome aboard here.

Hello Davide,

Awesome photos! Thank you, and welcome aboard  :)
Maybe we could schedule a QSO some time using CW...

I should look into this antenna. Ray has been telling me the same thing. I have never used ladder line to feed an antenna, but it looks more and more interesting...

Gil.

Thank you for your warm welcome.

I can indeed have a schedule for a CW QSO: better when I am at my QTH because in my QRP/P activity it don't know whether and when I can be on air. I usually walk maybe 3/4 hours and when I find a nice spot I might have just 30' on-air.
Open-wire (aka window/ladder lines) are an ancient type of transmission line, unfortunately unknown to many OM.
Their strong point is the ability to deal with greatly mismatched antennae with a negligible loss, while coax, due to its low characteristic impedance, pays great losses. This allows using random-length dipoles, like in my case, with an overall loss due to line and tuner around 0.3 dB.
Their weak point is that the RF energy is carried outside the line and not confined within the shield: this means that they interact with every object they encounter and their path must be carefully planned. Nov.2009 QST has a very interesting article on the interaction an open-wire line has with wet/dry soil when laid on ground.
However, in this kind of portable antenna, as long as the fishing pole is made of non-conductive fiberglass, it is very easy to find a convenient path for the window line down to the tuner and the QRP low power will be grateful of the added efficiency. :-)

73 de Davide IZ2UUF

Welcome Davide, very interesting, all the information presented. A SOTA person I've had contacts with before swears by his telescoping jackite pole, and a dipole fed with 300-ohm twin lead. He very seldom sounds "QRP" even though he is.
72

I think the reason a lot of hams are reluctant to use  balanced feed line is because they're scared from all the horror stories they've heard. Most bad things that a majority of hams have heard regarding balanced line are either blown way out of proportion or just dead wrong. Balanced feed line is lightweight, very low loss even with an obscenely high SWR and best of all it's dirt cheap compared to most coaxial feed lines. I've been feeding my main antenna here at the shack - a 140' dipole - with cheap 300 ohm TV twin lead for about 10 years now........... you couldn't get me to replace it with coax if you gave it to me for free.

Quote from: KK0G on September 08, 2013, 06:42:50 PMI've been feeding my main antenna here at the shack - a 140' dipole - with cheap 300 ohm TV twin lead for about 10 years now........... you couldn't get me to replace it with coax if you gave it to me for free.

If that's what you're normally using with your 3w to me I can attest that is one barn-stompin' antenna.
;)

Quote from: KC9TNH on September 08, 2013, 06:56:38 PM

Quote from: KK0G on September 08, 2013, 06:42:50 PMI've been feeding my main antenna here at the shack - a 140' dipole - with cheap 300 ohm TV twin lead for about 10 years now........... you couldn't get me to replace it with coax if you gave it to me for free.

If that's what you're normally using with your 3w to me I can attest that is one barn-stompin' antenna.
;)

That's the one.

QuoteTheir weak point is that the RF energy is carried outside the line and not confined within the shield: this means that they interact with every object they encounter and their path must be carefully planned.

My issue would be getting the line inside the house. Right now I use RG-174 and it goes through an aluminum window frame where it makes two 90deg bends. Very bad, I know... Due to the aluminum, could I route open line the same way, or would I be better off going through the wall? I do have two 50-Ohm 8" barrel plugs that I could use to turn the balanced line into coax, but what would I need to do and would that even be  good idea? The open line would have to turn into a short coax somewhere, right? What if the tuner is inside the radio?

Gil.

For me there is that RF issue at a fixed location; it's a personal nit that I pick. With the various wires that end up in my shack I definitely prefer coax.  But they do make great portable outfits where proximity to metallic and other such objects aren't an issue. What has been told to me about the twin-lead is: don't loop it, don't let it lie ON the ground (draping across the tops of bushes/tumbleweeds totally allowed).  The folks I know that use it regularly come to a very short length of coax, a jumper really, via a 1:1 or 4:1 current balun (ratio depending on length or config of the antenna). The SOTA guy I mentioned before runs 44' per leg, sometimes Inverted-V but flat-topped as much as he can reasonably do it, then about 30' of twin-lead to a baby-sized 4:1 current balun.  That's just one way to do it I guess. He is running a KX3 with ATU by the way, and runs 80-10 with that.

Perhaps Davide can speak some more to that or KK0G on how that gets handled for the fixed location.

Quote from: KC9TNH on September 08, 2013, 06:34:42 PM
Welcome Davide, very interesting, all the information presented. A SOTA person I've had contacts with before swears by his telescoping jackite pole, and a dipole fed with 300-ohm twin lead. He very seldom sounds "QRP" even though he is.

I really believe that: the antennae commonly used for QRP activity are so inefficient that something as simple as a dipole gives unbelievable results. The classic 30 ft "fishing pole" antenna in 40m gain is -10 dBi or less, never mind those 5 ft "miracle" sticks.

73 de Davide IZ2UUF

QuoteI really believe that: the antennae commonly used for QRP activity are so inefficient that something as simple as a dipole gives unbelievable results.

Depends on what you call a "commonly used QRP antenna..." If you mean a Buddistick or something similar, sure, though they do work. I use end-feds, and they are as god as a dipole. In fact they are dipoles of a sort, end-fed dipoles. Performance is really a matter of size (that's what she says ;-), no escaping that. The only exception might be the magnetic loop, but you get extremely narrow bandwidth as a price.

Gil.

From my home station when I was a novice and general class way back when, I used an end-fed zepp that was 65 feet in length and fed it with 300 ohm open wire ladder line, the old style ladder with glass insulators and heavy wire. I ran a KW from it once. It worked very well on 40 meters  and up. I have used the same length wire using 300 ohm TV twin lead using lower power and it works the same. Fantastic. 300 ohm tv line can be gotten at Radio Shack :) Just don't bother telling them why you want it. You will be in for a whole lot of nonsense talk about antenna installations and why you should buy coax line instead, unless your guy at Radio Shack is a ham.  :) 
Anyway, the end-fed zepp is Easy to put up in the woods. Easy to carry. Once I decide on a QRP rig it will probably be the end-fed Zepp antenna for me once again like my novice days. There certainly is nothing wrong with the 1/2 wave dipole, it just takes more room to string it up. That fiberglass pole that David is running is a great idea for a center point to hang a dipole on. The pole would be pretty Light in weight, I reckon. Caution: If you use open wire ladder line like I did in my earlier days, DO NOT touch the wire while transmitting. Don't ask why I know this.   :)  but there are such things as scars.

Quote from: gil on September 08, 2013, 07:04:27 PM

QuoteTheir weak point is that the RF energy is carried outside the line and not confined within the shield: this means that they interact with every object they encounter and their path must be carefully planned.

My issue would be getting the line inside the house. Right now I use RG-174 and it goes through an aluminum window frame where it makes two 90deg bends. Very bad, I know... Due to the aluminum, could I route open line the same way, or would I be better off going through the wall? I do have two 50-Ohm 8" barrel plugs that I could use to turn the balanced line into coax, but what would I need to do and would that even be  good idea? The open line would have to turn into a short coax somewhere, right? What if the tuner is inside the radio?

Gil.

This is one of those things I was referring to that while true is blown way out of proportion. The twin lead leaving my tuner passes all kinds of metal objects including several other feed lines, accessory cabling, power cords, metal desk, steel mast, etc. on it's way up to my dipole, in several places it's in direct contact with them. Is there interaction with these things? No doubt there is but it's never been anywhere near enough to cause any problems.


As far as feeding the feedline goes, the long answer is it depends on what antenna you're trying to feed. The short and simple answer is get a cheap MFJ tuner with a built in 4:1 balun.

Quote from: KC9TNH on September 08, 2013, 07:33:37 PM
Perhaps Davide can speak some more to that or KK0G on how that gets handled for the fixed location.

I have a big dipole at home fed with an home made ladder line. The ladder line enters a wooden window through two little holes in the frame. On the inside, immediately nearby the window, there is a tuner with "balanced" ports (internally connected to a balun); then regular coax goes to the radio.
I totally agree with KK0G about what many OMs think about twin-lead and me too would never give away my ladder line fed dipole.
It is absolutely true that twin-lead is not easy to deploy: my apartment in Milan covers 8th and 9th floor, which is the roof: so my radio station is literally on the roof, which is an ideal position. In most other cases, when line has to run inside walls, using a twin-lead line is very hard, if not impossible.

However, there are other ways to take advantage of twin lead lines. For example, one could install a cheap automatic tuner well protected in the attic or near the window and use twin-lead from the anntenna to the tuner; then normal coax to run to the station. This solution has the same performances of a mast-mounted tuner but cheaper.

Internal ATUs and twin-lead - I read a question about using internal tuners. In theory, a 1:1 or 4:1 balun at the end of the twin-lead would do: tuners with "balanced" entry are normal tuners with a 4:1 balun in them. However, there are two issues with internal tuners:
1) many of the tune only in TX: this is ok for almost resonant antennae, but these random antennae are completely deaf if not tuned;
2) often their tuning range is too restricted: they are designed to tune antennae slightly out of the resonance point, not random wires.

Balun - Normal tuners have this setup: twin-lead -> 4:1 balun -> tuner -> coax -> radio. This is the only option for this kind of multi purpose tuners. However I think that the best setup would be: twin-lead -> tuner (ungrounded) -> 1:1 balun -> coax -> radio. This is because in this way the balun (that can be a current choke) works without SWR, reducing its power dissipation.
In QRP/P I use this setup: twin-lead -> tuner -> very short coax -> radio. The tuner/coax/radio assembly is so short (compared to wavelength) that doesn't unbalance the line.

73 de Davide IZ2UUF

Quote from: gil on September 08, 2013, 07:04:27 PM
My issue would be getting the line inside the house. Right now I use RG-174 and it goes through an aluminum window frame where it makes two 90deg bends. Very bad, I know... Due to the aluminum, could I route open line the same way, or would I be better off going through the wall? I do have two 50-Ohm 8" barrel plugs that I could use to turn the balanced line into coax, but what would I need to do and would that even be  good idea? The open line would have to turn into a short coax somewhere, right? What if the tuner is inside the radio?

The best solution is probably to run the line outside keeping it reasonably far from everything. Then entering the house somewhere and putting an automatic tuner right there; then regular coax goes to the radio.
In theory the line could enter aluminum or other conducting objects as long as they are symmetric to the line: if the field disturbance is symmetric, it does not unbalance the line.

As I wrote in my previous post, most radio tuners do not have enough tuning range to tune this kind of mismatch. Also, many of them tune only when transmitting.

Davide

Quote from: gil on September 08, 2013, 08:00:07 PM
Depends on what you call a "commonly used QRP antenna..." If you mean a Buddistick or something similar, sure, though they do work. I use end-feds, and they are as god as a dipole. In fact they are dipoles of a sort, end-fed dipoles. Performance is really a matter of size (that's what she says ;-), no escaping that. The only exception might be the magnetic loop, but you get extremely narrow bandwidth as a price.

Gil

I totally agree with that, except that it is matter of size... and height.
If you are working 20m or higher bands, you can afford a vertical end-fed half-wave antenna, whose performances are more or less the same of a vertical center-fed dipole. The problem with it is that is too near too ground, which causes a great attenuation.
This is the horizontal dipole I've shown and an end-fed 1/2 wave antenna on 20m, both on the same type of ground and 10m pole:



As you can see, the horizontal dipole gains 6 dB more than the vertical dipole; ok, the horizontal dipole is directional, but in its nulls has almost the same gain of the vertical. I mean, vertical 1/2 wave is not bad at all, but the high horizontal dipole seems to be significantly better.

If we go down to 40m, the situation becomes dramatic. The vertical 10m pole is 1/4 wave and behaves as a Marconian antenna: the ground now has a much greater influence:


I tried to center-feed a 10m pole on 40m to make it behave as a shortened Hertzian dipole using 300-ohm twin-lead up to half-way the pole and then continuing with a single conductor. It is a zepp-like feeding: it works, with performaces similar to the 1/4 wave with several radials, but nothing comparable to the dipole.

73 de Davide IZ2UUF

Quote from: Archangel320420 on September 08, 2013, 09:20:18 PMJust don't bother telling them why you want it. You will be in for a whole lot of nonsense talk about antenna installations and why you should buy coax line instead, unless your guy at Radio Shack is a ham.  :)

LOL, true. Plus they want to sell you a phone plan. I got some (in brown, for the fashion conscious) to cut up for some roll-up J-poles for 2m from an old TV repair fellow who was closing the business. The best source I've found is a smaller-town hardware store (a true one) who stock this stuff on reels with the rest of their wire.  Many folks in rural areas still run this to an aerial on an old tower, bolted to their old house, going to their old converter box - because they don't have cable TV.  So it's stocked by any hardware or farm supply store worthy of the name. They unspool it & measure against the dimension of the floor tiles. And it's cheaper than Radio Schtick. I seem to recall there are even little center-insulators sold somewhere with cutouts to allow for strain relief of twin-lead as the feedline, although they could certainly be made.

I think I'll get that SOTA-type dipole I mentioned up to the hunting property and see how it does. The attraction for me at QRP levels is that twin-lead helps with an issue that downsizing coax doesn't - loss, in a system where every milliwatt is precious.

Quote from: gil on September 04, 2013, 09:08:37 PM
I'm still planning a 20m magnetic loop, that will be portable...

Gil.

If you're going to DIY a magnetic loop antenna, you could also DIY the variable capacitor...
http://www.alexloop.com/artigo21.html

Sent from my Transformer Prime TF201 using Tapatalk 4

Hello Davide,

My 40m end-fed is a half wave. The bottom it about ten feet from the ground. Now, the length of it is 40ft, because of the choke. It's a 40/20/10m model. It must work pretty well because I worked Estonia on 1.2W on 40m, 5200 miles. I do get Russia regularly using from 3 to 6W...

Nice graphs, what program do you use?

Gil.

QuoteIf you're going to DIY a magnetic loop antenna, you could also DIY the variable capacitor...
http://www.alexloop.com/artigo21.html

Well, sure... Or I can work an hour or two and make enough to buy one... I love building stuff, but even though it isn't always cheaper, I try to consider the labor cost benefit...

Gil.

If you are car camping, a lot of this sounds good, but I wouldn't want to hump the fishing pole, tuner, stakes and guy-lines for the pole and a long feed line.  My end-fed has a tiny coupler and the feed line can be just a few feet long.  I only have to get 1 end of it up in a tree.  I do bring a spool of mason's string, a slingshot with a fishing reel hose-clamped to the side and a few 1oz weights.  After set-up the sling shot has other fun uses.

Quote from: gil on September 09, 2013, 10:52:14 AM
Nice graphs, what program do you use?

Hello Gil.

I'm using 4NEC2 (http://www.qsl.net/4nec2/), a free frontend based on the classic NEC-2 (http://en.wikipedia.org/wiki/Numerical_Electromagnetics_Code) engine.

Davide

Thanks!
Gil.

Quote from: cockpitbob on September 09, 2013, 10:56:13 AM
If you are car camping, a lot of this sounds good, but I wouldn't want to hump the fishing pole, tuner, stakes and guy-lines for the pole and a long feed line.  My end-fed has a tiny coupler and the feed line can be just a few feet long.  I only have to get 1 end of it up in a tree.  I do bring a spool of mason's string, a slingshot with a fishing reel hose-clamped to the side and a few 1oz weights.  After set-up the sling shot has other fun uses.

You are right but the situation is not as bad as you are depicting it: I'm also very concerned about weight, since I have to carry it for hours.
- the "long feed line" is 450 ohm window line, which is very light; it could be 300-ohm twin lead, even lighter;
- I carry no stakes, just one fishing pole;
- to hold the fishing pole, I have velctro ties in case I find a little tree or other suitable fixed structures; otherwise I use what I find, like stones;
- the setup time ranges from 10 to 15 minutes, depending on what kind of support for the fishing pole I find.

Finally, my altitude usually is so high that there are no trees:




Davide

Is it just me, or is IZ2UUF the kind of person we need to come to the USA?  :)

Quote from: IZ2UUF on September 09, 2013, 04:56:55 PM
Finally, my altitude usually is so high that there are no trees:

Which brings up a good point; sometimes we forget that our environment can have a huge impact on how we operate portable. Here in the midwest there are tall trees everywhere it seems and my end fed works perfectly in that environment. When I took a trip to Las Vegas last year and went into the mountains and desert to do some portable operating one day, I quickly discovered that I wasn't prepared very well antenna wise for that environment - in many places finding a suitable tree was very difficult to impossible in some places.

Quote from: Archangel320420 on September 09, 2013, 05:10:58 PM
Is it just me, or is IZ2UUF the kind of person we need to come to the USA?  :)

Seeing his photos, I am tempted to go there.   :)

Quote from: Geek on September 09, 2013, 08:43:08 PM

Quote from: Archangel320420 on September 09, 2013, 05:10:58 PM
Is it just me, or is IZ2UUF the kind of person we need to come to the USA?  :)

Seeing his photos, I am tempted to go there.   :)

Don't, it's a dangerous place: there are wild and ferocious animals that like to tear down antennae!  ;D



Davide

Maybe she smelled your socks from a long way off...  ;D

Gil.

Quote from: gil on September 10, 2013, 03:45:24 AM
Maybe she smelled your socks from a long way off...  ;D

This is a very good point to be remembered for the future: never put boots and socks near the antenna!  ;D

Cow pies surrounding the spot you left your shoes!   :(

Quote from: Geek on September 10, 2013, 08:33:41 AM
Cow pies surrounding the spot you left your shoes!   :(

That would be a real nightmare! When I'am surrounded by cows or goats I choose an high and flat stone, something I can defend like a bastion. I've seen cows eating shoes, socks and t-shirts: they chew them for a while, then they spit them out all green colored. Glad that weren't mine! :-)

Davide

Quote from: KK0G on September 09, 2013, 07:31:48 PM

Quote from: IZ2UUF on September 09, 2013, 04:56:55 PM
Finally, my altitude usually is so high that there are no trees:

Which brings up a good point; sometimes we forget that our environment can have a huge impact on how we operate portable. Here in the midwest there are tall trees everywhere it seems and my end fed works perfectly in that environment. When I took a trip to Las Vegas last year and went into the mountains and desert to do some portable operating one day, I quickly discovered that I wasn't prepared very well antenna wise for that environment - in many places finding a suitable tree was very difficult to impossible in some places.

Yep, there it is. As Davide points out, lichen do not count as vertical structure.  ;D
Those who go above the tree line regularly - or for "that guy" luxuriating on the beach with his Buddipole & KX3 - either accomodates based on what's at hand; rocks, tie off to a shoe & bury in the sand, etc.  Being in a situation like "that guy" is on my bucket list but further down. In my real-life I'm blessed like KK0G with lots of antenna supports that give off oxygen. We seldom get the fantasy, it's what we do with what's in the windshield that defines.

HAAAAAAAAAAAAAAAAAAAAAAAAAAAA  David.  Have YOU found a home here. We are all a bunch of nuts.

Quote from: Archangel320420 on September 10, 2013, 01:27:30 PM
HAAAAAAAAAAAAAAAAAAAAAAAAAAAA  David.  Have YOU found a home here. We are all a bunch of nuts.

Better not to take life too seriously!  :)

IZ2UUF:  Thanks for sharing those pics and welcome.

IZ2UUF Davide,

Is it permitted for you to milk a free grazing cow when camping/hiking in the Alps? Thanks.

Terry NN0AA

Probably not, for fear of escalation...  ::)

Gil.

Quote from: Archangel320420 on September 17, 2013, 02:50:43 PM
Is it permitted for you to milk a free grazing cow when camping/hiking in the Alps? Thanks.

Hello Terry.

I don't think so. I have never taken into consideration to milk a grazing cow: probably you can do it as long as you are out of the shepherd's sight! :-)
By the way, on the Alps camping is forbidden almost everywhere: you can "emergency" camp overnight everywhere, but you have to be gone by early morning.

Davide

Quote from: cockpitbob on September 04, 2013, 10:57:33 PM

Quote from: gil on September 04, 2013, 10:42:56 PM
You don't need to spend that much Bob. You can get a high voltage air capacitor for about $70, and a thick 10ft coax patch cable to use for the loop. Use a toroid core for feeding, and you'll get your Alex loop for about $100. That's what I'm going to do..

Gil.

Great!  Me too.

If you are running QRP power levels, you don't need the high voltage cap.  Google the Rockloop antenna, its made of wire with a small air variable and will work several bands, and you can make it bigger for use on lower frequencies.  Just make some sort of collasible frame for it from wood or PVC pipe and you have a portable antenna that will knock down to a small package.  Good thing about magnetic loops is that they will work well even at low heights !

Quote from: IZ2UUF on September 08, 2013, 07:52:55 PM

Quote from: KC9TNH on September 08, 2013, 06:34:42 PM
Welcome Davide, very interesting, all the information presented. A SOTA person I've had contacts with before swears by his telescoping jackite pole, and a dipole fed with 300-ohm twin lead. He very seldom sounds "QRP" even though he is.

I really believe that: the antennae commonly used for QRP activity are so inefficient that something as simple as a dipole gives unbelievable results. The classic 30 ft "fishing pole" antenna in 40m gain is -10 dBi or less, never mind those 5 ft "miracle" sticks.

73 de Davide IZ2UUF

There is no need to worry about RF in the shack from balanced feedline, since it is balanced, the fields in the feedline cancel each other.  Coax on the otherhand is more likely to radiate RF unless some means of choking is used to keep RF off the outside of the shield, ie: current baluns, RF choke, ferrite beads.  I call the problem of RF on coax the "3rd wire syndrome", you have the inner conductor, then the shield, and then the outside of the shield that does sometimes look like a 3rd wire to RF !

Quote from: IZ2UUF on September 09, 2013, 04:56:55 PM

Quote from: cockpitbob on September 09, 2013, 10:56:13 AM
- I carry no stakes, just one fishing pole;
- to hold the fishing pole, I have velctro ties in case I find a little tree or other suitable fixed structures; otherwise I use what I find, like stones;
- the setup time ranges from 10 to 15 minutes, depending on what kind of support for the fishing pole I find.


Davide

I just carry a big screwdriver that the handle will fit in the butt end of the fishing pole, stick the screwdriver in the ground, unscrew the buttcap off the pole and slide it down over the screwdriver.  Works like a charm !

Quote from: Lamewolf on October 10, 2013, 01:56:41 PM
There is no need to worry about RF in the shack from balanced feedline, since it is balanced, the fields in the feedline cancel each other.  Coax on the otherhand is more likely to radiate RF unless some means of choking is used to keep RF off the outside of the shield, ie: current baluns, RF choke, ferrite beads.  I call the problem of RF on coax the "3rd wire syndrome", you have the inner conductor, then the shield, and then the outside of the shield that does sometimes look like a 3rd wire to RF !

Well, actually you might still have RF in the shack even from balanced feedlines. This happens if load is not balanced: currents in the feedline would not be the same and they would not cancel. In this case, we would need a balanced tuner, i.e. a tuner able to force equal currents with 180° phase even on unbalanced loads.
This is a good reason to aim to symmetrical aerials, like the dipole I have described.
The balanced/unbalanced tuners on the market (like many MFJs) force balancing by mean of a 4:1 wideband balun: ANT->LINE->BALUN->TUNER->COAX->RIG.
The problem is that the BALUN, at that position, is working where SWR is very high, reducing its efficiency.
There are some tuners (like Double-L Networks) that are able to force equal currents by design without the balun workaround. However, using a balanced antenna, i.e. offering the same impedence on both sides (electrically symmetrical), we can use ANT->LINE->TUNER->BALUN->COAX->RIG, where the BALUN can be a simple choke. In this case, the TUNER does not need to be balanced, since currents are balanced by themselves due to the symmetrical load.
If COAX is short and RIG is not grounded, the path COAX->RIG is so short that its impedance at HF frequency is very high, so we can get rid of the BALUN. This becomes a very simple setup.

I also would like to add some calculations about efficiency of the whole system comparing a 16m long horizontal dipole fed with 20m of 450 ohm window line and a tuner and two resonant single-band dipoles in 20m and 15m fed by 20m of RG-213 without tuner, all mounted at 10m on the same ground.

• radiation diagrams and antenna feed point calculation is done using 4NEC2 (http://www.qsl.net/4nec2/‎);
• feedline impedance transformation and loss over mismatched load is done using Transmission Lines Details 2.0 (http://www.ac6la.com/tldetails1.html) by AC6LA;
• tuner dissipation is calculated using T-Network Tuner Simlator (http://fermi.la.asu.edu/w9cf/tuner/tuner.html) by W9CF; its calculated results match pretty closely the measurement I made myself on my tuners;

This is the situation at 14 MHz (multiband dipole is red, monoband resonant dipole is blue):



Non resonant 16m-long dipole
Impedance ad feed point: 449+j1044 
Transmission line 20m 450-ohm: loss 0.21 dB 
Impedance at tuner: 1910.240+j1477.946
Tuner loss: 0.3 dB
Total antenna system gain: 6.32-0.51 = 5.8 dBi

Resonant 14 MHz dipole
Impedance ad feed point: 73.1+j0       
Transmission line 20m RG-213: loss 0.46 dB
Total antenna system gain: 5.62-0.46 = 5.16 dBi


This is the situation at 21 MHz (multiband dipole is red, monoband resonant dipole is blue):



Non resonant 16m-long dipole
Impedance ad feed point: 499+j1534 
Transmission line 20m 450-ohm: loss 0.430 dB 
Impedance at tuner: 5057.142+j288.847
Tuner loss: 0.5
Total antenna system gain: 8.81-0.5-0.43 = 7.88 dBi

Resonant 21 MHz dipole
Impedance ad feed point: 70.7+j0       
Transmission line 20m RG-213: loss 0.544 dB
Total antenna system gain: 6.37-0.544 = 5.826 dBi

These figures seem to prove that some very common ham myths like "the ideal solution is a single-band resonant dipole, multi band dipoles are just compromises", or "a tuner will dissipate most of your power" are just... myths.
A setup made of a longer dipole, open-wire and tuner outperforms any single band tuned dipole on a frequency range of about F to 2*F, where F depends on the length of the non-resonant dipole.

73 de Davide IZ2UUF

Quote from: IZ2UUF on October 16, 2013, 05:29:12 AM

Quote from: Lamewolf on October 10, 2013, 01:56:41 PM
There is no need to worry about RF in the shack from balanced feedline, since it is balanced, the fields in the feedline cancel each other.  Coax on the otherhand is more likely to radiate RF unless some means of choking is used to keep RF off the outside of the shield, ie: current baluns, RF choke, ferrite beads.  I call the problem of RF on coax the "3rd wire syndrome", you have the inner conductor, then the shield, and then the outside of the shield that does sometimes look like a 3rd wire to RF !

Well, actually you might still have RF in the shack even from balanced feedlines. This happens if load is not balanced: currents in the feedline would not be the same and they would not cancel. In this case, we would need a balanced tuner, i.e. a tuner able to force equal currents with 180° phase even on unbalanced loads.
This is a good reason to aim to symmetrical aerials, like the dipole I have described.
The balanced/unbalanced tuners on the market (like many MFJs) force balancing by mean of a 4:1 wideband balun: ANT->LINE->BALUN->TUNER->COAX->RIG.
The problem is that the BALUN, at that position, is working where SWR is very high, reducing its efficiency.
There are some tuners (like Double-L Networks) that are able to force equal currents by design without the balun workaround. However, using a balanced antenna, i.e. offering the same impedence on both sides (electrically symmetrical), we can use ANT->LINE->TUNER->BALUN->COAX->RIG, where the BALUN can be a simple choke. In this case, the TUNER does not need to be balanced, since currents are balanced by themselves due to the symmetrical load.
If COAX is short and RIG is not grounded, the path COAX->RIG is so short that its impedance at HF frequency is very high, so we can get rid of the BALUN. This becomes a very simple setup.

I also would like to add some calculations about efficiency of the whole system comparing a 16m long horizontal dipole fed with 20m of 450 ohm window line and a tuner and two resonant single-band dipoles in 20m and 15m fed by 20m of RG-213 without tuner, all mounted at 10m on the same ground.

• radiation diagrams and antenna feed point calculation is done using 4NEC2 (http://www.qsl.net/4nec2/‎);
• feedline impedance transformation and loss over mismatched load is done using Transmission Lines Details 2.0 (http://www.ac6la.com/tldetails1.html) by AC6LA;
• tuner dissipation is calculated using T-Network Tuner Simlator (http://fermi.la.asu.edu/w9cf/tuner/tuner.html) by W9CF; its calculated results match pretty closely the measurement I made myself on my tuners;

This is the situation at 14 MHz (multiband dipole is red, monoband resonant dipole is blue):



Non resonant 16m-long dipole
Impedance ad feed point: 449+j1044 
Transmission line 20m 450-ohm: loss 0.21 dB 
Impedance at tuner: 1910.240+j1477.946
Tuner loss: 0.3 dB
Total antenna system gain: 6.32-0.51 = 5.8 dBi

Resonant 14 MHz dipole
Impedance ad feed point: 73.1+j0       
Transmission line 20m RG-213: loss 0.46 dB
Total antenna system gain: 5.62-0.46 = 5.16 dBi


This is the situation at 21 MHz (multiband dipole is red, monoband resonant dipole is blue):



Non resonant 16m-long dipole
Impedance ad feed point: 499+j1534 
Transmission line 20m 450-ohm: loss 0.430 dB 
Impedance at tuner: 5057.142+j288.847
Tuner loss: 0.5
Total antenna system gain: 8.81-0.5-0.43 = 7.88 dBi

Resonant 21 MHz dipole
Impedance ad feed point: 70.7+j0       
Transmission line 20m RG-213: loss 0.544 dB
Total antenna system gain: 6.37-0.544 = 5.826 dBi

These figures seem to prove that some very common ham myths like "the ideal solution is a single-band resonant dipole, multi band dipoles are just compromises", or "a tuner will dissipate most of your power" are just... myths.
A setup made of a longer dipole, open-wire and tuner outperforms any single band tuned dipole on a frequency range of about F to 2*F, where F depends on the length of the non-resonant dipole.

73 de Davide IZ2UUF

I agree with everything you said, but I do know that onece I switched to balanced feedline, all my RF problems ceased.  With the coax fed antennas I was using, nothing I did seemd to help at all.  I used ferrite beads on everything, 1:1 current baluns at the feedpoint of my antennas, multiple grounds rods all bonded together, nothing seemed to help.  The problem wasn't all that bad, but it was there in the form of RF on your audio reports constantly.  Then one day when experimenting with a doublet fed with balanced feedline, a friend told me to take down all my other antennas and use that one because my RF problem was gone !  I've never used coax on a doublet since !  I do use an unbalanced tuner, but I don't use the built in 4:1 balun.  I do have a 1:1 current balun right outside the shack with about 6 feet of coax entering the shack and connecting to the tuner.  The antenna is a 40 meter extended double zepp 178' long and fed in the center with 450 ohm window line about 40' long and via the tuner it will work 10 thru 160 meters.  I also have a homebrew Zmatch tuner Iuse sometimes but that requires running the balanced feedline all the way in, but either way I don't have the RF problems I had with a full coax feed.

Quote from: Lamewolf on October 16, 2013, 08:30:06 AM
I agree with everything you said, but I do know that onece I switched to balanced feedline, all my RF problems ceased.  With the coax fed antennas I was using, nothing I did seemd to help at all.  I used ferrite beads on everything, 1:1 current baluns at the feedpoint of my antennas, multiple grounds rods all bonded together, nothing seemed to help.  The problem wasn't all that bad, but it was there in the form of RF on your audio reports constantly.  Then one day when experimenting with a doublet fed with balanced feedline, a friend told me to take down all my other antennas and use that one because my RF problem was gone !  I've never used coax on a doublet since !  I do use an unbalanced tuner, but I don't use the built in 4:1 balun.  I do have a 1:1 current balun right outside the shack with about 6 feet of coax entering the shack and connecting to the tuner.  The antenna is a 40 meter extended double zepp 178' long and fed in the center with 450 ohm window line about 40' long and via the tuner it will work 10 thru 160 meters.  I also have a homebrew Zmatch tuner Iuse sometimes but that requires running the balanced feedline all the way in, but either way I don't have the RF problems I had with a full coax feed.

I bet it works, you did one of the best and most efficient wideband antennae you could make!
Your setup is very smart, since you are not using the internal 4:1 balun but you placed a choke-balun between the tuner and your rig.
Also, you are feeding your doublet at its center: thanks to this, currents will be balanced enough to avoid line radiation.
However, even though there might still be some unbalance on the line due to real-world differences between the two arms, the choke-balun will stop any common mode current that could run to your rig.
Therefore, the little unbalanced currents that still might be running on the balanced line will never reach your rig, as you experienced.
At home I have the same setup you have and I'm extremely satisfied.

73 de Davide IZ2UUF

Quote from: IZ2UUF on October 16, 2013, 09:05:45 AM

Quote from: Lamewolf on October 16, 2013, 08:30:06 AM
I agree with everything you said, but I do know that onece I switched to balanced feedline, all my RF problems ceased.  With the coax fed antennas I was using, nothing I did seemd to help at all.  I used ferrite beads on everything, 1:1 current baluns at the feedpoint of my antennas, multiple grounds rods all bonded together, nothing seemed to help.  The problem wasn't all that bad, but it was there in the form of RF on your audio reports constantly.  Then one day when experimenting with a doublet fed with balanced feedline, a friend told me to take down all my other antennas and use that one because my RF problem was gone !  I've never used coax on a doublet since !  I do use an unbalanced tuner, but I don't use the built in 4:1 balun.  I do have a 1:1 current balun right outside the shack with about 6 feet of coax entering the shack and connecting to the tuner.  The antenna is a 40 meter extended double zepp 178' long and fed in the center with 450 ohm window line about 40' long and via the tuner it will work 10 thru 160 meters.  I also have a homebrew Zmatch tuner Iuse sometimes but that requires running the balanced feedline all the way in, but either way I don't have the RF problems I had with a full coax feed.

I bet it works, you did one of the best and most efficient wideband antennae you could make!
Your setup is very smart, since you are not using the internal 4:1 balun but you placed a choke-balun between the tuner and your rig.
Also, you are feeding your doublet at its center: thanks to this, currents will be balanced enough to avoid line radiation.
However, even though there might still be some unbalance on the line due to real-world differences between the two arms, the choke-balun will stop any common mode current that could run to your rig.
Therefore, the little unbalanced currents that still might be running on the balanced line will never reach your rig, as you experienced.
At home I have the same setup you have and I'm extremely satisfied.

73 de Davide IZ2UUF

I had a 135' doublet setup the same way before I made the 40M EDZ, and when I switched to the EDZ, folks that I normally talked to on 75 meters thought I had bought an amp !  I never run more than 100 watts and even prefer QRP when on CW, but the EDZ made such a big difference in my on the air reports over the 135' doublet, I could hardly believe it !  It is a good antenna for all bands if you only have room for one antenna !

You guys want a good portable antenna, try the Eagle One Vertical at www.w8afx.com Its basically a 40 meter quarter wave vertical (33 feet tall) and works great on that band without a tuner but will work other bands with a tuner.  I have one up at home with an Icom AH4 tuner at the feedpoint and it works 10 thru 80 meters via the tuner.  The good thing about the Eagle One is that it is telescopic and collapses down to 44 inchs when not in use !  The guy that makes them, Steve Sheers is a super nice guy to deal with and sells them by itself, with a tripod mount, or a ladder mount kit for RV's and motor homes.  I think he also sells a mount that goes on a trailer hitch for stationary mobile operation.  Check them ot.

Quote from: SGO on November 13, 2013, 01:53:14 AM

Quote from: Lamewolf on November 12, 2013, 11:50:07 AM
I don't get the theory behind the Chameleon antenna ?  It states it has a "special matching device" but you must use a tuner.  If you must use a tuner which is a matching device, why not just use a plain whip and skip the "special matching device" which would eliminate some losses from the system ?  IN a manpack station the antenna is going to be a compromise anywaay, so why not eliminate as much loss as possible ? A 10' to 15' telescopic crappie fishing pole with a light wire hellically wound around it would be just as effective when fed by a tuner and would cost a lot less !

To understand what you can do with that product maybe you should watch their YouTube videos: http://www.youtube.com/user/ChameleonWalker/featured?view_as=public

I guess I should elaborate a little on what I mean.  What I can't figure out is why folks will spend so much money on something that really isn't all that special.  I mean $100 is a lot of money for a whip when there are alternatives out there that will work as well or even better for a lot less.  When I see and advertisement that the antenna will work all bands with a special matching device at its base, but you must still use a tuner, I tend to get leary of it.  If its has its own matching device, then why does it need a tuner ?  Eliminate the special matching device and you eliminate some losses in the system.  Since you must use a tuner anyway, depend on it for the matching instead of having double the losses of the special matching device and a tuner combined.  To me it sounds like the special matching device does no real matching in the first place.  Its probably really nothing more than a simple balun or unun of some sort and those can help sometimes if you are using an autotuner that is built into the radio that has limited matching range, but if you use a good outboard tuner that has a wide matching range, the unun or balun simply isn't needed and can even degrade your signal output.  What it basically boils down to is when using a compromise antenna such as when using a manpack station, you want to eliminate as many losses as possible.  Those whips are really nothing more than a fiberglas tube with wire inside, and I can make that myself for a lot less money using a simple telescopic fishing pole and some cheap wire.  I have 3 of them I have made, one is 10' long, one is 20' long, and the other is 31' long and they all work really well and I don't think I have $100 in all 3 of them !
And maybe join their Yahoo Group and chat with their members: http://groups.yahoo.com/group/ChameleonAntenna/

If you never tried to use one those antenna maybe you should.

SGO

Quote from: KC9TNH on June 18, 2013, 03:08:46 PM
Recently there has been some discussion on-line in other fora soliciting suggestions for "portable" antennas. Admittedly my idea of portable is thrown wire that travels in a ziploc bag. But, in the vein of never-say-never, there could be a time one isn't afoot all the time, or has some hirelings, and could tote something larger to their favorite spot . But the spot has no vertical structure of any kind, although there is the means to guy-off something if needed.

Does anyone here have experience with any of the popular push-up verticals or dipoles that could be toted in a bag under the arm and set up, say, on a beach somewhere?  The Buddipole is one common one I hear about; the Superpole is another. Buddipole (and Buddistick) have long-standing reputations; the other uses no coil clips but rather slides to adjust roughly for the band.

Just wondering if anyone has ever been in that situation, what was used, and what were the results.
Just to keep the size parameters reasonable, we're talking 20-17-15m, that kind of thing, 30m would be dessert. Antenna tuner is available.

Thanks!
:)

I'm getting together the parts to build a "vertical half rombic" antenna that needs no tuner for 10 thru 160 meter operation and can be used as a portable field antenna.  You can make it smaller if all you need it say 40 thru 10 or 30 thru 10 and it only needs one support for which I'll be using a 31' Jackite pole.  The antenna is fed at one end near the ground by a 9:1 unun and it terminated on the other end by a 470 ohm non inductive resistor to ground that is rated at least half the power of the transmitter's output.  Or you can terminate it with another 9:1 unun that goes to a 50 ohm dummy load.  For 10 thru 160 meters, the wire needs to be about 100' long but will work at shorter lengths with reduced efficiency or just use shorter lengths for higher bands if that's all you need.  Also in dry climates a counterpoise wire is laid out under the antenna and attached to the ground at each end.  Here's a good writeup on the antenna: http://www.korpi.biz/hr.pdf

Why is it that every comm forum I visit, SGO is there pushing that shitty antenna?

Quote from: cockpitbob on September 04, 2013, 10:27:50 PM
I'm enamored with 1/2 wave end feds and have had great results.  I love an antenna that fits in a ziploc, but they need trees.  What I really want to get into next is mag loop antennas.  Though a bit pricey, the AlexLoop Walkham  (http://www.alexloop.com/index.html)covers 40M-10M at 10W CW and gets great reviews  (http://www.eham.net/reviews/detail/9012)(5.0/5.0 from 36 reviews!).

I always take my tree with me !  Its a 31' long Jackite pole....

Quote from: KC9TNH on June 18, 2013, 03:08:46 PM
Recently there has been some discussion on-line in other fora soliciting suggestions for "portable" antennas. Admittedly my idea of portable is thrown wire that travels in a ziploc bag. But, in the vein of never-say-never, there could be a time one isn't afoot all the time, or has some hirelings, and could tote something larger to their favorite spot . But the spot has no vertical structure of any kind, although there is the means to guy-off something if needed.

Does anyone here have experience with any of the popular push-up verticals or dipoles that could be toted in a bag under the arm and set up, say, on a beach somewhere?  The Buddipole is one common one I hear about; the Superpole is another. Buddipole (and Buddistick) have long-standing reputations; the other uses no coil clips but rather slides to adjust roughly for the band.

Just wondering if anyone has ever been in that situation, what was used, and what were the results.
Just to keep the size parameters reasonable, we're talking 20-17-15m, that kind of thing, 30m would be dessert. Antenna tuner is available.

Thanks!
:)

You know, I was just thinking about this and MFJ sells a 17' telescopic whip antenna that can be adjusted to full quarter wave on 20, 17, 15, 12, and 10 meters, and with a small loading coil at its base you could add 40 and 30 meters to it. 

My Buddistick works well down to 30m.. 40m, not so much...

Gil.

I use hamsticks on my car.  20M tunes and works great.  40M is useable, but doesn't like to tune.  I'm getting the idea that short whip antennas bottom out at 30-40Meters

Quote from: cockpitbob on October 10, 2014, 02:27:29 PM
I use hamsticks on my car.  20M tunes and works great.  40M is useable, but doesn't like to tune.  I'm getting the idea that short whip antennas bottom out at 30-40Meters

I agree, the Hamsticks are ok on the higher bands but 30 meters and down they are crap.  I use an MP-1 portable antenna with a flexible stainless steel whip on it for portable operation and it works great on 40 - even on low power (10 watts from an old Yaesu FT-7) ssb.  I have a 24" x 3/8" stainless shaft on the bottom and a 52" stainless whip on top of the MP-1's adjustable coil.  For those that aren't familiar with the MP-1, its basically a manually adjustable screwdriver antenna made for portable operation but I use it mobile on a big 3 magnet mount.  They make an 80 meter add on coil for it but I like 40 for mobile operations.