Author Topic: Wire Jungle Antenna  (Read 16073 times)

Offline Greekman

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Wire Jungle Antenna
« on: February 21, 2015, 01:04:40 PM »
ok...a fellow member here mentioned the Jungle Antenna the other day.
It so happened that I read this yesterday, h ttps://sparks31.wordpress.com/2015/02/17/squad-radio-considerations/
(notice: guerilla blog if it matters to you),
And I was thinking of a real fieid expedient ground plane antenna.

So I wonder how would one make a 1/4wave groundplane out of coax...

i.e. Strip l/4 of coax case and keep the center conductor with his case, and also keep a bit of a shield to attache regular wire.

Problem is...
Should one keep the insulation of the center conductor, and if yes, should he applly a velocity factor for it? (assuming one is going by math alone and no SWR metter is available)
also,
Any idea on making a good junction of coax shield and radials?

TNX...

Offline Greekman

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Re: Wire Jungle Antenna
« Reply #1 on: February 21, 2015, 01:58:44 PM »
PS, I am trying to avoid using any connector on the Coax-antenna junction.

Also, what kind of wire OTHER than the 50Ohm coax/ladderline/TV twin lead can one use for a feeder line?

Offline Carl

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Re: Wire Jungle Antenna
« Reply #2 on: February 21, 2015, 02:42:21 PM »
A field expedient Ground plane for which band?

If for 2 meters or 70CM I do not recommend you try without at least an SWR meter because it takes less than 1/4 inch to cause really dangerous changes in SWR that can damage your radio.

If the antenna is for HF...you have much less effect by an inch or so and so for HF(even 6 meters ) you can get by ok.

Insulation is not a problem.
Velocity factor is not an issue when coax is not coax.(separated,it is only conductors)

If you hang the antenna you would need stable (stiff wire ,or tied to ropes) ground plane and the angle of the radials and Length is important.

I would rather build and TEST a stiff antenna on ,at least ,an SO 239 chassis connector .

While it is fun and rewarding to build antennas...it is not so much fun when you SMOKE a radio.

Other feedline? A 50 ohm antenna and a 50 ohm radio just really expect a 50 ohm feedline.
For VHF/UHF you really need to stick to 50  or 70 ohm coax.

Here is the thread on my BIG STICK dual band antenna :

http://thesurvivalpodcast.com/forum/index.php?topic=49762.0








Offline Greekman

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Re: Wire Jungle Antenna
« Reply #3 on: February 21, 2015, 04:08:06 PM »
yes, I was thinking VHF.
and a construction along these lines
https://sparks31.files.wordpress.com/2014/05/jungle_ant.jpg?w=676

regarding feedlines I was carreid away by figures 7-13 & 7-14 in this
http://www.biggerhammer.net/manuals/23-10/ch7.htm

Offline Carl

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Re: Wire Jungle Antenna
« Reply #4 on: February 21, 2015, 04:45:55 PM »
Those are military radios for the 30 to 74 MHZ range and they are larger (at least twice as big) as two meter antennas and they also have antenna matching units built in...the WD-1 FIELD WIRE is two conductor wire with insulation on each wire (like power cord here in U.S.) and works with the tuning units built into the military radio....but that was before most solid state components and 50 ohm radios.

You might make it work...but not without a lot of work and wire trimming to reach the needed 50 ohms of your radio. Without a matcher ,you must match the antenna yourself...and that requires an SWR meter or more equipment. The higher frequencies are more and more dependent on exact dimensions and feed line matching.

Don't stop though,I want to know how it works out for you.

Offline Greekman

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Re: Wire Jungle Antenna
« Reply #5 on: February 22, 2015, 12:20:41 AM »
Those are military radios for the 30 to 74 MHZ range and they are larger (at least twice as big) as two meter antennas and they also have antenna matching units built in...the WD-1 FIELD WIRE is two conductor wire with insulation on each wire (like power cord here in U.S.) and works with the tuning units built into the military radio....but that was before most solid state components and 50 ohm radios.
ah! that brings us to the link you posted on Antennas and feedlines. It starts with the 50ohm and tunable radios...

Quote
Don't stop though,I want to know how it works out for you.

since i have a VHF meter and already doen a groundplane, this antenna can be doen in a Jiffy once I get the mod for it.
Primary reason is of course is emergency antenna...

One more question that spring up.
Assumming I do make and tune an antena with regular appliance electrical wire (1 or 1.5mm multistarnd) and record lengths...
How off can anew one be based on notes on the back of a HT?
Especialy changing wire thickness?
(Well that is an experiment easy enough to make myself)

Offline Carl

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Re: Wire Jungle Antenna
« Reply #6 on: February 22, 2015, 04:47:46 AM »
Wire thickness does not effect a VHF antenna,in my opinion. I have used 22 gauge wire to Metal alarm tape to 1/2" copper pipe and all worked well enough with length within an eighth of an inch and the ground radials at near the same angle(the droop angle does effect the loading and final tune of the antenna)

As small as a VHF ground plane is ,I would carry a properly built and tuned one with me rather than have to build one.
You could make one from expanding whip antennas and a fitting with a connector and SO 239 and it would fit in a pocket.
Or build a roll-up "J"Pole from ladder line like the link below.

http://thesurvivalpodcast.com/forum/index.php?topic=50529.0

In an emergency,you could look around for some 50 ohm coax and a connector to fit your radio(how is it you carry a radio and not antenna and coax?) and maybe have something that works....or you could pull an antenna out of your kit and have a known working antenna. You are not going to build one without wire cutter,wire,hardware and feedline,maybe even soldering iron,tape measure,and SWR meter...I would just carry one and save carrying a lot of weight.


Offline Greekman

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Re: Wire Jungle Antenna
« Reply #7 on: February 22, 2015, 07:00:35 AM »
well I already own a Slim Jim i bought before i got my SWR meter...
but since I cannot find 50Ohm twin lead locally in a hurry I am examining other options.

The expanding whip option I am saving for very latter to make a vertical dipole for VHF.

Meanwhile i have been reusing mobile VHF antennas as groundplanes for many years now...
When I traveled for work my leased appartment antenna was a 5/8 mobile hung from the balcony and converted to ground plane this way...
(early radial set version)
https://imagizer.imageshack.us/v2/720x479q90/r/854/webigp7153.jpg
(current version)
https://imagizer.imageshack.us/v2/640x640q90/r/850/igp6397n.jpg
https://imagizer.imageshack.us/v2/640x427q90/r/841/igp6395.jpg

But i love the joy of tinkering most!....

Offline Carl

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Re: Wire Jungle Antenna
« Reply #8 on: February 22, 2015, 07:13:36 AM »
I did think of a way that is not so critical to measure...a TWO METER DELTA LOOP. But why? do you insist on non 50 ohm feedline? it can work but the matching must be made with a shunt stub...just like a 300 OHM slim Jim.

Here is a version of the Delta Loop

http://www.k2zs.com/indoor-vhf-antennas/vhf-delta-loop

But you wanting to run other than 50 ohm feedline means you will need a matcher so the radio sees a 50 ohm load....and your experiments ,without an SWR meter ,are just likely to smoke your radio and that is a costly way to learn.


Offline Greekman

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Re: Wire Jungle Antenna
« Reply #9 on: February 22, 2015, 10:59:47 AM »
sorry, i was not that clear...
I was caried away by the military feedline, but not anymore.
rementioning the "50Ohm twin lead" was for making more SlimJims

Offline Carl

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Re: Wire Jungle Antenna
« Reply #10 on: February 22, 2015, 11:13:05 AM »
sorry, i was not that clear...
I was caried away by the military feedline, but not anymore.
rementioning the "50Ohm twin lead" was for making more SlimJims

Twin lead is 300 ohms in the US and 300 ohm ladder line works good too.  The 'match' to 50 ohm coax is made by the shunt at the bottom of the wire "J" pole.

Offline Greekman

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Re: Wire Jungle Antenna
« Reply #11 on: February 22, 2015, 02:07:16 PM »
you are right on the value..

PS i will have something to show in a while

Offline Carl

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Re: Wire Jungle Antenna
« Reply #12 on: February 22, 2015, 02:33:48 PM »
you are right on the value..

PS i will have something to show in a while

I envy your ability as I now have very little dexterity in my hands and have a difficult time doing the simplest work with them.
I can't even write with hands I used to repair watches with,my mind still knows what and how,just my body will not be controlled due to neuropathy or nerve damage ...I am loosing control of my muscles.

Offline Greekman

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Re: Wire Jungle Antenna
« Reply #13 on: February 22, 2015, 05:18:40 PM »
Oh! sorry to hear this...
i feel you, just yesterday my own father complained of aching hands not letting him do house chores...

BTW i did it, an ugly versin of it.
It is Too late in the night to post pics...
off i go to catch myzzzs

stay strong!

Offline Greekman

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Re: Wire Jungle Antenna
« Reply #14 on: February 23, 2015, 01:39:01 AM »
did it last night



Materials:
a meter (almost) of 1mm speaker wire
a electrical wire crimp connector
3 zipties
some heatshrink tubing
a length of RG-58 with BNC connctor I have for a future project

Did not want to remove 50cm of coax case to make the antenna vertical element, so i hooked up wire for it.



Messy job at the junction.



if you do a messy job, yuo will be spending alot of heatshrinking to reinforce it



as it is....

Now I SHOULD be getting out of the house one of the next days to set it up and tune it.

tonight I will calculate the string lines' length for 45 or 60degrees angle for the radials




« Last Edit: February 23, 2015, 01:58:46 AM by GreekMan »

Offline Carl

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Re: Wire Jungle Antenna
« Reply #15 on: February 23, 2015, 06:37:13 AM »
And you can name it "The Squid" Much better to have a pre-cut and tuned antenna in a pocket then try to build on the spot.

Offline Greekman

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Re: Wire Jungle Antenna
« Reply #16 on: February 23, 2015, 07:31:26 AM »
actually the next step is to make an l/2 version (with coax core as the vertical element) and put it in the radio kit.

Offline armymars

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Re: Wire Jungle Antenna
« Reply #17 on: March 02, 2015, 05:59:12 PM »
  You could make a  coaxial antenna all out of 50 ohm co-ax, but getting the shield to go back over the jacket is not easy. That's one reason the j poles are so popular. They use to make 75 ohm twin lead years ago, but I haven't seen it in a long time. Zip cord is about 50 ohms, but the lose is so high you wouldn't want to use it. 73

Offline Greekman

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Re: Wire Jungle Antenna
« Reply #18 on: March 03, 2015, 02:41:39 AM »
yes. i have seen designs of it....Also called bazooka antenna?

Till few years ago a guy in a HAM fest had soem cable to use.
Now my option is to buy twin-lead Tv antennas from ebay.
But price is close to getting a pre-made J-pole

Offline Carl

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Re: Wire Jungle Antenna
« Reply #19 on: March 03, 2015, 07:14:24 AM »
yes. i have seen designs of it....Also called bazooka antenna?

Till few years ago a guy in a HAM fest had soem cable to use.
Now my option is to buy twin-lead Tv antennas from ebay.
But price is close to getting a pre-made J-pole

The vertical bazooka or coaxial dipole...but still,without a matching unit (auto tuner) like those on military gear.
You are most likely to damage a radio with this experiment as measurements on VHF antennas are CRITICAL to 1/8 inch
for most antennas and radios are not so over-built to take mismatch abuse these days. You really need ,at least,an SWR meter to make a VHF/UHF antenna these days or the most careful of measurements.

Offline Greekman

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Re: Wire Jungle Antenna
« Reply #20 on: March 03, 2015, 10:13:23 AM »
I DO have a SWR meter and i also cross-checked it with another one.
remember the readings at the construction of my 1/4 wave groundplane?

The Bazooka antenna idea was just for reference.

Tomorrow I will be tuning the Jungle Wire antenna if I find the time to.

Offline Carl

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Re: Wire Jungle Antenna
« Reply #21 on: March 03, 2015, 10:30:06 AM »
I DO have a SWR meter and i also cross-checked it with another one.
remember the readings at the construction of my 1/4 wave groundplane?

The Bazooka antenna idea was just for reference.

Tomorrow I will be tuning the Jungle Wire antenna if I find the time to.

Good, I only find woods wire here in the South...maybe I can get some jungle wire on ebay?

Offline Greekman

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Re: Wire Jungle Antenna
« Reply #22 on: March 03, 2015, 05:03:21 PM »
nope...you won't find any...I am the sole provider  ;D ;D ;D

I can sell you some but it will cost you an arm and a leg.LOLOL  8)

Offline Greekman

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Re: Wire Jungle Antenna
« Reply #23 on: March 04, 2015, 06:49:42 AM »
She's Alive!

http://i176.photobucket.com/albums/w192/greekpreparedness/web-IGP1254-A_zpsf92zbchi.jpg~original

Best SWR measured was 1.04 @147MHz  ;D

explanation....The vertical element raises up to the uncliped ziptie. Rest is the Red string I used as a frame for the wire elements.

Full writeup tommorow....

Offline Smurf Hunter

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Re: Wire Jungle Antenna
« Reply #24 on: March 04, 2015, 10:00:12 AM »
She's Alive!

http://i176.photobucket.com/albums/w192/greekpreparedness/web-IGP1254-A_zpsf92zbchi.jpg~original

Best SWR measured was 1.04 @147MHz  ;D

explanation....The vertical element raises up to the uncliped ziptie. Rest is the Red string I used as a frame for the wire elements.

Full writeup tommorow....

Looks like something I'd expect was built by prisoners inside a North Korean labor camp.  :)

Offline Carl

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Re: Wire Jungle Antenna
« Reply #25 on: March 04, 2015, 10:51:40 AM »
Looks like something I'd expect was built by prisoners inside a North Korean labor camp.  :)

And later sold by MFJ?

Offline cpf240

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Re: Wire Jungle Antenna
« Reply #26 on: March 04, 2015, 02:17:27 PM »
And later sold by MFJ?

Only after serious cost-cutting measures are implemented in its materials and construction...    :D

Offline Carl

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Re: Wire Jungle Antenna
« Reply #27 on: March 04, 2015, 02:55:33 PM »
Only after serious cost-cutting measures are implemented in its materials and construction...    :D

Karma for someone who really does a beret justice.

Offline Greekman

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Re: Wire Jungle Antenna
« Reply #28 on: March 04, 2015, 03:55:54 PM »
Looks like something I'd expect was built by prisoners inside a North Korean labor camp.  :)

well that almost the idea...build an as-simple-as-it-gets antenna. Assuming one would use a no-solder UHF connector, just a knife would suffice to build it..

Offline armymars

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Re: Wire Jungle Antenna
« Reply #29 on: March 05, 2015, 08:52:10 AM »
  Carl,
  I was rereading reply 15 and I got to thinking. It's best to have what you need on hand, but it's good to know how to make it if something should happen. I build a lot of small radios so I know how. I use my IC 706, Paragon and Argonaut V ( on HF ) for my main stay radios. 73 ( Carl is one of my heroes. )