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Author Topic: Tape Measure 2 Meter Antenna  (Read 5090 times)
KB1OCC
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Posts: 172




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« on: March 19, 2007, 12:04:10 PM »

Does anyone know where I can locate plans for an antenna that utilizes a tape measure as the basis for its contruction?  I've seen yagis for RDF using tape measure parts (tape), but I have yet to see an antenna for omni-directional coverage.

I would like to incorporate this into my "go" kit for a 5W HT.  And yes, I also have a roll-up J-pole with the kit too.

I remember in the past seeing one for VHF Marine radios (emergency use), but I've never seen one for 2 meters use (or 70cm for that matter).
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KE4DRN
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Posts: 3714




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« Reply #1 on: March 19, 2007, 04:28:18 PM »

hi brian,

fun to build and easy to use.

http://home.att.net/~jleggio/projects/rdf/tape_bm.htm

take a look at the Moxon for 2m, nice antenna direct fed and you can
make one with thhn # 12 wire or aluminum rod.

http://cebik.com/moxon/moxbld.html

73 james
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K2GW
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Posts: 535


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« Reply #2 on: March 20, 2007, 05:42:10 AM »

>I remember in the past seeing one for VHF Marine radios (emergency use), but I've never seen one for 2 meters use (or 70cm for that matter).

I know the marine emergecny antenna you're thinking of.  It's designed for sailboats that get dismasted and lose their regular antenna as a result.  The rollup feature allowed it to be easily stored when not in use, which was virtually never.

However, it's been my experience that just sticking an 18" piece of wire out of the SO-239 on the back of a VHF radio doesn't work particularly well.  Not much of a signal gets out and a lot of RF gets back into the rig.  I suspect that's why most hams would use a roll-up J-pole seperated from the radio by a short coax run instead.

73

Gary, K2GW

 
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KC0SHZ
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Posts: 373




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« Reply #3 on: March 21, 2007, 06:43:01 AM »

I made a 2 meter moxon with tape measure.  I used PVC for a frame, so it was heavy.  The calculations for dimensions was tricky.  I used moxgen and had to use 1/2 the width of the tape measure for the dimension and the tape curves.  

The result was an antenna that had a peculiar pattern.  It was almost omnidirectional except for a narrow, but very deep notch in the direction of the reflector.   Sort of like cutting a thin slice of pie out of the north end of a whole pie.  

I could get full quieting in Benson on 5 watts (about 10 miles away from my location) when the notch was pointed elsewhere, and was not heard when the notch was pointed there.

I would recommend a moxon be made of something rigid enough to be self supporting.
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KE4DRN
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Posts: 3714




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« Reply #4 on: March 21, 2007, 02:54:56 PM »

hi,

I used 3/16" aluminum rod for the first 2m version,
worked great with no adjustments needed.

I build another for 6m using thhn #12 solid,
worked nice and build a second with 3/8"
aluminum tubing.  WOW nice antenna, takes up
less space then a yagi and similar gain with
no match needed, direct fed 50 ohm coax to radio.

73 james
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KC8VWM
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Posts: 3124




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« Reply #5 on: March 21, 2007, 08:00:49 PM »


Why a tape measure antenna?

I would prefer to use something more powerful such as a folding 3 element yagi antenna designed from a piece of ordinary cardboard with wire glued on it.

Cardboard yagi's are pretty small, lightweight and rolls up rather nicely.

Just place a few thumbtacks on it to secure the 3 element cardboard yagi antenna to the side of a tree or simply make a couple of "cardboard legs" on it that will permit you to stand the cardboard yagi up on it's end such as a table or even on the roof of your vehicle for example. The cardboad could be water proofed and stored or the cardboard could be scrounged from practically anywhere when you actually need to use the antenna.

A small roll of duct tape in your go kit can fix many other things besides just holding up your cardboard yagi antenna in the desired direction.

The antenna sure beats the pants off any roll up jpole or any other similar "emergency antenna" designs I have seen before.

Heck, if a person just kept the basic dipole and other wire elements rolled up and stored inside a film canister for the cardboard yagi and kept it in your go kit, you could always construct a 3 element yagi on the fly. It could be constructed on the side of an existing wall or other flat object using thumbtacks or duct tape. In fact, the entire yagi could be made out of duct tape for that matter.

You could write the antenna spacing dimensions and instructions on the roll of duct tape itself. The roll of duct tape could be marked at intervals and serve as an effective tape measure. I would imagine the entire 3 element duct tape yagi would weigh practically nothing at all. Probobly weighs less than most HT antenna's.

Have fun with this one.  Smiley

73 de Charles - KC8VWM
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KB1OCC
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Posts: 172




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« Reply #6 on: March 22, 2007, 05:06:05 AM »

Thanks for everyone's fine responses.

I think I wasn't clear enough in my original post...
I'm looking for a non-yagi, non-directional antenna design.  

However, I do like the cardboard yagi suggestion and may also look into that.

73's
Brian
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N7IOH
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Posts: 116




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« Reply #7 on: March 22, 2007, 11:58:02 AM »

Hi Brian, here is a link to what I think you are looking for.  I also have some additional information that is not posted from emailing Joe Leggio, WB1HO directly ref the antenna should you want more information.  

   http://home.att.net/~jleggio/projects/rdf/tape_bm.htm

    Al, n7ioh
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KC7VTR
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Posts: 26




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« Reply #8 on: March 22, 2007, 12:29:09 PM »

But the Leggio antenna is directional. Brian is specifically looking for NON directional.
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N7IOH
Member

Posts: 116




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« Reply #9 on: March 22, 2007, 02:38:10 PM »

Just remove the reflector and the director and you can use it vertical or horizontal.  The formula used in this antenna is, Driven= 433.84/f MHz, Hairpin= 61.55/f MHz.
There is no magic here.  You will still have to check it out for resonance where you want it if you are moving it much from the design frequence.  

      Al, n7ioh
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KE4DRN
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Posts: 3714




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« Reply #10 on: March 22, 2007, 02:42:36 PM »

hi brian,

I did not read your post, my error !

how about 1/4 wave ground plane using tape measure material for
the element and radials attached to SO-239 connector ?

http://www.qsl.net/wrav/2mground.htm

73 james
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ONAIR
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Posts: 1735




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« Reply #11 on: March 25, 2007, 01:14:10 AM »

    I once saw a 2 meter dipole taped onto a yardstick, with an SO-239 mounted in the middle!  The ham kept it in his car trunk, and he said that it worked fine for portable use.
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WB6BYU
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Posts: 13007




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« Reply #12 on: April 06, 2007, 02:48:50 PM »

Tape measure works like any other sort of conductor for building
antennas.  If you are modelling it, it is roughly equivalent to a round
antenna with a diameter of half the width of the tape.  So for 1" tape
I model it as a 1/2" diameter round element and it comes out pretty
close.

Given that you can make any sort of antenna using it.  For example,
it can form the radiator section of a J-pole, a dipole, the radiator for
a ground plane, or a quarter wave whip for an HT.  To connect it to a
SO-238 jack, solder a couple inches of #14 wire to the jack then scrape
the paint off of the concave part of the tape and solder it to the wire.
(Or perhaps in reverse order, since soldering to the tape may  melt
the other solder joint.)  Another way to connect to it is to use a brass
threaded standoff and cut a slot in one end with a hacksaw.  Slip the
end of the tape element into the slot and solder it.  The element can
then be screwed onto the exposed end of a matching bolt.  With a small
tuned circuit you could build a half-wave end-fed antenna like a HotRod
using the tape measure element.

Although I've built a lot of tape measure antennas, they do have limitations.
The main one is stability in the wind:  I often have to use double (or
even triple) thickness tape measure near the base of an element to make
it stiff enough to hold its own weight, and wind will usually blow it over
unless it is very stiff.  Trying to get a 2m half wave to stand up straight
in a breeze will take some work - it probably will require at least 3
pieces of varying lengths to make the bottom stiff without making the
top too heavy.  You might even use two different widths of tape.

I've often found 16' tape measures at a Dollar store, and that will give
you material for a lot of experimenting.
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N2IK
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Posts: 220




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« Reply #13 on: April 06, 2007, 07:47:43 PM »

My emergency antenna is a cheapy 1/2 wave 144/440 NMO base and Mag mount base and cable assembly. The antenna is a low quality Chinese copy of a Larsen design. I fake a ground plane from one of several choices, any available found metal, a big square of aluminum foil, a steel baking pan or a steel electrical box with solid copper radials. the electrical box has a U bolt for fixing to the top of 1 1/4 inch light gauge TV mast sections. I keep the antenna and mag mount assembly in the car at all times and add whatever I need to it as necessary.

Also see the Ed Fong designed roll-up J pole in a very recent QST as unlike many J poles it is a good performer on both 144 and 440. Very low cost, highly compact, and portable. The article is on the arrl.org website as a TIS article.

73 de Walt N2IK
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K1LDS
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Posts: 20




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« Reply #14 on: July 04, 2007, 10:30:58 PM »

Instead of kludging, military tape whips from PRC-25 / -77 VHF radios are all over the surplus market.

I've replaced the whip on my MP-1 Superantenna with a whip and flex joint from a PRC-77, for whichever of my HFPack rigs (an FT-897 and FT-817) I'm using for a particular session.

Keith K1LDS
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