Instructables
Picture of The Tape Measure Antenna
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Are you looking for an easy kid friendly project? Are you looking for a project to encourage a new generation of ham radio operators?

This project is unusual, so it’s something that will certainly capture the attention of anyone, particularly a kid. It’s an antenna built out of PVC pipe, a tape measure and a handful of hose clamps.

This antenna is designed for two-meter operations, which, for a newbie ham operator, is one of the bands available under the Technician license in the US. Plus it’s easy to build and gives a great opportunity to teach several subjects with a hands-on approach.

Disclaimer: This project isn’t new; it’s not even my idea or design. I used the design from Joe Leggios (WB2HOL). The plans to his antenna are here.

Project Background

My nephew recently expressed interest in earning his Technician class amateur radio license. While some people discount the Technician level license of amateur radio as “ridiculously simple”  (including a well known conservative talk radio personality) it’s not so easy for an eight-year old. It requires comprehension of concepts that they still have yet to cover in school. Topics like basic algebra and principals of electricity.

When I set out to find a project, I was looking for something unusual that would grab his attention but something that was easy, fast and required few tools or skills. And I wanted it to be cheap. There is a total of $20 in materials in this antenna, assuming everything is purchased specifically for this project and not scavenged or salvaged parts.

The fundamentals of antennas is the one area I’ve been finding difficult to teach my nephew. Mostly because I refuse to “teach the test”. I want him to fully understand the material, not just pass a test. And I have found that I have had to teach him basic algebra in the process.

This project was perfect as I could scale it up or down as a lesson in a number of ways. Which is to say you can use the plans to build a perfectly workable antenna, or, you can use the formula for a Yagi antenna to modify the design. In my case, my nephew and I used the plans from WB2HOL, but we worked through the math to come up with element lengths.

And, in the end, we built something useable for when he earns his Technician class license.

Materials List

3/4” Schedule 40 PVC Pipe - at least 25”
6 hose clams big enough to fit around the PVC pipe
1 3/4” PVC tee
2 3/4” PVC crosses
8’ RG-58 cable with a connector attached to one side. I soldered a female BNC to mine.
5” wire. I used 18 gauge solid copper wire, but I’m told anything works.
Rosin core solder
Tape measure with 1” wide tape
PVC glue

Tools Needed

Soldering iron
Tape measure
Pipe cutters
Wire stripper
Shears or scissors
Sand paper
SWR Meter
Screwdriver or wrench for tightening the hose clamps
 
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MrSquare made it!2 months ago

My first homebrew antenna and my first Instructable build. Super easy and fun to build! Tested it out on a Baofeng UV-5RAX handheld and was able to pick up a friend on the same model radio about 6 miles away. I just used regular CATV coax. I have a friend with SWR meter... will have to run it through to see if it needs any tweaking. Thanks for the Instructable!

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MikeWA6ILQ4 months ago

Safety feature: The locals that have used these for transmitter hunt antennas for the last decade or so discovered something a long time ago... The edges of the tape measure section can be VERY sharp and can cut a gash faster than you can blink. I'd do two things: first, use a file on the sharp ends to reduce the sharpness as much as possible... Second, cover the ends with something - the most common thing you see around here is a piece of cloth duct tape folded over each end of each element.

BTW, if you have a Harbor Freight in your area, walk in and sign up for the snail-mailed coupons Every so often their monthly snail-mail flyer includes a coupon for a free 25 foot (by 1 inch) tape measure just for walking into the store (no purchase required). Two other frequent freebies are a low-end-DVM or a 6-piece screwdriver set (both of which live in my ARES go-bag).

kc8hps8 months ago

Ive seen a number of antennas such as this. Im curious where and why the 5" piece of wire is used. Is the wire a matching section or impedance balance component?

jcoman (author)  kc8hps8 months ago
You are absolutely correct, it's a hairpin match. It's the simplest match for this type of antenna, with the added bonus that it is light weight and compact as compared to something like a Gamma match.
kc8hps jcoman8 months ago

Thanks so much for the clarification.

zawy11 months ago

I guess the camera "fish-eye" effect is making the top length look longer than the middle length. At least I can count the inch marks and see the top length is off-center by 1 inch, having 18 inches to the left and 16 inches to the right. I assume you've caught that by now and adjusted it.

jcoman (author)  zawy11 months ago
If I remember correctly, it was actually 2" off. The photo was pre-SWR meter testing. I'm surprised you caught that; Even though it was new, I cut the tape a foot in from the front so I didn't have holes in the element. Thanks!
zawy jcoman11 months ago
It is important where the 2 cut pieces meet in the middle to be as close as possible. The total length of the two lengths plus the space should probably be 17.5" in order to be ideal according to the software that the original designer was using. I would trim off 1/16" from those pieces to see if it improves. Car anteneas use a spiral groove to add inductance and a metal ball at the top to add capacitance which matches with the characteristics of the surrounding air better. So I bet there's a way to improve upon even yagi designs.
jcoman (author)  zawy11 months ago

An inch between the ends of the driven elements seemed to work pretty well for me in this design. When I moved the driven elements closer or father from each other, the SWR changed, and not in good ways. At exactly an inch, I had just a touch over 1:1 but under 1.1:1 on the SWR meter at the frequency the elements were cut for. It's the best I was able to achieve and really good considering. Funny you mention car antennas, I actually scavenged several yesterday because I was thinking the next project with my nephew would be a Yagi built out of them.

profpat11 months ago

nice instructables!

spark master11 months ago

Copper cacti were used by Hams in apartments with terraces and a no external antenna rule (of any kind). So you plop it in a Ceramic Vase and call it sculpture. (fer real).

Ladder line hard to get (jpole) Take a piece of plastic corrugated "cardboard" shove the appropriate pieces of "12 solid down two of the corrugations at the right distance from each other (parallel)make the connections take silicone sealant and squirt into the open ends of corrugations. There will be 2 or 3 empty channels near the middle pull some fishing line through them to make a nice hanger. while this will not roll up it is also light and you can with aid of rope pull it up into a tree.

Get dimensions for ladder line from the net. Alternatively you could just glue the wire to anything for the spacing add a hole to the "backer board" add the string.

Then you can build the attic antennas! (quaggie)

Ciao

chris

spark master11 months ago

OH I fergit, let him make a Jpole and a Copper Cactus. The CC will let him/her use flames. Nothing better'n flames and ham radio. Sometimes the radio provide both!

jcoman (author)  spark master11 months ago

Interesting idea! I think I'll do that. One can never have enough antennas and I'm sure I have some copper laying around somewhere. Thanks for the idea.

FN6411 months ago

Glad to see another "Elmer" in the mix. I made one of these a few years ago from Joes plans. Works quite nicely!

All my best to the young fellow working on his ticket.

Here's a look-see at the one I put together.

http://www.instructables.com/id/Radio-Direction-Fi...

jcoman (author)  FN6411 months ago

Thanks! These things work really well; of course why wouldn't they? Yagi's are pretty amazing antennas.

I didn't find yours until well after I posted this one. These are fun because they are so simple to put together. Definitely a great project.

spark master11 months ago

2 meters?

how about 6 meters?

nice instructable and Kudo's as well to the guy who thought it up! (WB2HOL)

the new 1 inch wide rulers really can work well and being able to roll them up is a hoot.

Great for a back pack if you use "rollers" to roll them up to stay put and then get to top of say Bear Mountain in NY and fire up the Limark repeater system! I did it with a crappy rubber duck on an HTX 202 on Lo Power, dfq even. This would make it even better!

Height makes mite they say! so put it in a tree.

ciao

Florizzz11 months ago
good hunting! 73
jcoman (author)  Florizzz11 months ago

Thanks! That's one of the things I plan to try to get him into when he gets his ticket. 73!