Tape measure vertical antenna

Tape measure vertical antenna DEFAULT
WØIVJ's Portable Antenna Project
(Click on pictures to enlarge)
Email: [email protected]

With the increase in travel and deed restrictions, portable antennas have become more attractive.  This is an attempt to construct a portable antenna that can work as low as 40 meters without sacrificing a lot of performance.  The idea behind this antenna is to construct a dipole for 40 meters.  One side of the dipole is 33 feet and will stick out the window.  The other side is adjustable up to 12 feet and is loaded with a high-Q coil to compensate for not being a quarter wavelength like the other side.  A tape measure is used to adjust for resonance at various frequencies within the band.  A small antenna tuner is used for the final matching.  Antenna modeling shows this antenna to have a free space gain of less than 3/4 of a db below a full size dipole using # 14 copper wire and an uH coil with an unloaded Q of about

Small HF rigs make it possible to carry a complete station on an airplane.  Photos A and B show the travel case packed complete with transceiver, power supply, Clear Speech speaker, antenna analyser, and antennas.  MFJ makes a telescoping mast (part number MFJ ) that extends to 33 feet and collapses to about 48 inches and weighs about 3 pounds.  This pole is made out of an insulating material much like phenolic.  The mast is shown in the collapsed position attached to the travel case handle in photo A and by itself in photo C.  I pushed a piece of #14 wire  into the small section of the telescoping mast until it was tightly wedged.  I  cut it off so that it extended out the insertion end about 1/4 inch.  I then soldered a female, cylindrical electrical diconnect terminal to the protruding end of the #14 wire as shown in photo D.  I  drilled a hole in the rubber end of the mast that is on the large end.  The rubber peice may be removed by unscrewing the base ring.  Be careful to hold the mast horizontally so all of the sections don't fall out.  I then took about 35 feet of # 14 Flexweve wire and soldered a male disconnect connector to one end.  I threaded the wire through the retainer ring and the hole in the rubber end and reattached the retainer ring.  I telescoped the mast, pulling the Flexweve wire through until the mast was fully extended.  I  cut off the Flexweve with about an inch protruding from the bottom and soldered on another male connector.  An uH coil was constructed as shown in photos M and N.  This coil was wound on a 3" OD, thin-wall, polycarbonate cylinder.  The cylinder was scored in a lathe so that the coil has 16 turns in 2 inches.  The measured Q of the unloaded coil is   A cheap, locking 12 foot tape measure was modified by cutting off the tab and screwing a male connector on to the end.  The male connector is the right size to be tapped with a tap, so that it can be secured to the end of the tape measure.  Photo J shows this connection, as well as the current balun.  The balun was an absolute must.  My measurements made no sense without it.  The balun consists of 14 turns of RG on an FT core.  Photos E through G show the extended mast outside a second story window.  Photo H shows the arrangement inside the room, and photo I shows the base anchored to a chair.  The chair must be very heavy, especially if there is any wind outside.  Photos K and L show the tape measure counterpoise.  Photos M and N show the loading coil for 40 meters.  The coil can be shorted and a shorter wire threaded through the mast for use on the higher frequency bands.  Finally, photo O shows the rig used in the 40 meter test.

 Figures P and Q show the free space comparison between the portable antenna and a dipole using #14 copper wire. P is the dipole and Q is the portable.  As you can see the difference in gain is only db. Figure R shows what you might get in a hotel on the 15th floor.  Don't you love that low angle of 13 degrees!  The analysis was done using EZNEC by Row Lewallen.

I used an MFJB antenna analyzer to tune the antenna.  It can be resonated (zero reactance) between about 5 and 10 MHz with the 12 foot tape fully extended to fully retracted.  About six feet of tape is used for 40 meters.  The actual length will vary with the location of the antenna.  On the air tests show between 5 and 10 db difference between my home station using a 40 meter kit on a Cushcraft A4-S up about 40 feet.  Of course the building blocks radiation in one direction and that was the direction that I was talking.  Further tests are needed and the results will be reported as the tests are done.

The mast can also be erected vertically as a quarter wave vertical by extending two radials in opposite directions, or it can be used to support the center of a full size inverted V. When used as a vertical, the antenna must be either mounted over a near perfect ground like sea water or elevate into the air at least 30 feet. The two radials will give a return current path, but they do not do much for lossy ground shielding.






I took my portable system to Oklahoma over a weekend and made some comparison tests with a flat top dipole strung in the trees at about 20 feet.  Photos A, B, and C show the arrangement of the portable antenna.  On 40 meters the difference was about 6 db with some reports indicating that the portable antenna was stronger.


I recently took a trip to Dedham, MA where I got to try out the portable setup from the third floor of a building.  Photos A through G show the operation there.  The building is an old mansion with wooden floors, so the counterpoise can rest on the floor as shown in B.  I got good reports on 40 and 20 meters.


Sours: http://tomthompson.com/radio/PortableAntenna/portable.html

Like many amateur radio operators, I live on a small lot surrounded by neighbors, utility lines, and civic-minded citizens concerned about the "attractiveness" of my community. &#;Whether by design or outright fear, I've adopted the "stealth" approach to ham radio antennas. &#;It's the old "out of sight, out of mind" idea applied to amateur radio antennas. The amateur radio press is full of articles describing the struggle of amateur radio operators to pursue their hobby under the burdensome regulations of CC & Rs, HOAs, and other civic minded citizens who object to antenna farms. &#;So far, my modest verticals, loops, and inverted vees have blended well with the vegetation and trees bordering my small backyard. &#;Vertical antennas have always been a problem because of the limited space for a radial system. &#;There are times, however, where a shortened vertical for the lower HF bands (such as 80/75 meters) is necessary where horizontal space is lack

Sours: https://www.simplehamradioantennas.com//11/hf-tape-measure-horizontal-dipole.html
  1. Zoo coloring page
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  3. Elmos world birds

        |QST TBD |  -- 2m Copper Tape and PVC Helical Antenna
            Amazingly simple and inexpensive 2 Meter base station antenna
            Ideal new ham's first home-brew antenna. Excellent radio club DIY meeting project.

        |QST TBD |  -- Design Your Own Coax Choke Balun
           Easy, yet a mystery to many hams.

        | TBD |  -- Double inverted Delta All-Band HFVertical
            30 ft, low noise, horizontally polarized vertical with the azimuth gain of a small beam.
            Less noticable than a beam on a tower. Excellent for Field Day and portable operation.

        |QST September |  -- The Roostertenna, a Weather-Vane-Disguised 2m Antenna (Second Model, see below)
            You Neighbors will love it and may even want one themselves.
            Your HOA will never know it's an antenna.

        |TBD |  -- The 2nd Law of Dropped Screw Dynamics
            They have a mind of their own, like buttered toast.

        |QST December |  -- 6m Slot-Cube Antenna
            50 MHz version of 2m Slot-Cube below
            Remarkably small size
            QST Cover Plaque Award

        |Rev. |  -- The Cavity Duplexer Book
            Home-brew design and modification princiiples

        |QST November |  -- Frankenkey
            QST Key Competition Entry

        |QST September |  -- Rugged 2m Base Station Antenna
            Ideal for remote mountain tops or just long lifet
            Small compared to a J-pole

        |QST July |  -- High-performance HF no-radial Kite-shaped Vertical
            Superior permance compared to equal size vertical with radials

        |QST June |  -- Improved 3D- Printed VHF/UHF S Groundplane
           3D printed ruggedized ground plane antenna using a chassis-mount SO connector
        |QST March |  -- 3D-printed Coax to Wire/Open-Line Connerctor Blocks
        |QST January |  -- 2m Slot-Cube Antenna
            Copper pipe J-pole builders, eat your heart out
            QST Cover Plaque Award

        |QST May |  -- Durable lightweight HF Antenna Traps from PC Board
            |PCB etching patterns|  -- .pdf files, actual size

        |QST April |  -- Ultra Simple Coathanger 2m antenna, ideal club project.
            QST Cover Plaque Award

        |QST March |  -- Low Profile 2m Mobile, First Place ARRL Antenna Design Competition

        |QST tbd|  -- The Small Wonder 2m Stealthy Base Station Antenna

        |Not Published|  -- Wearable 2m Lincoln hat antenna

        |QST March |  -- 2m Slot Antenna Disguised in a TV Dish Antenna

        |Not Published|  -- Rain Gutter HF Loop Antenna

        | QST February |  -- High-Efficiency 40m Vertical Without Radials

        |QST October |  -- Cookie Can Portable Antennas

        |QST January |  -- T-hunt 2m Loop Antenna

        |QST TBD |  -- 2m 70cm Gentleman's Walking Stick

        |QST March |  -- Best Mounting Position for a 2m car antenna

        |Not Published |  -- Why Nets Succeed

        |QST January |  -- 2m 70cm Tape Measure Beam

        |QST June |  -- Two Small 2m Helical Antennas

        |ARRL WEB March |  -- The Getoutometer

        |QST February  -- Better Coax Traps

        |QST March |  -- Thinning RTV, Hints and Kinks

        |QST October |  -- The Quadrafiler Helix (QFH) as a 2 Meter Base Station Antenna
            QST Cover Plaque Award

        |QST July |  -- Homebrew Coaxial Dipole for VHF or UHF

        |QST October |  -- Go Portable with an MFJ Rotatable Mini-dipole, Hints and Kinks

        |QST March |  -- Compact 40 Meter HF Loop for Your Recreational Vehicle

        |QST August |  -- A Weather Vane Antenna for 2 Meters

        |WORLD RADIO May |  -- An Efficient Portable Dipole from Mobile Whips

        |WORLD RADIO January |  -- An Efficient HF Antenna for your RV

        |73 Magazine July |  -- Garbage in -- No Garbage out ( MHz Cavity for APT Satellites)

        |ELEMENTARY ELECTRONICS May |  -- You Can Custom Build Transformers

        |ELEMENTARY ELECTRONICS May |  -- Dickey Flasher (Neon Party Novelty)

        |POPULAR ELECTRONICS June |  -- Active Filter Sharpens CW Reception

Sours: https://w6nbc.com/published.html

My take on the WB2HOL tape measure Yagi

So I want to work some satellites with my handheld radio, and I couldn't hear any of the packets from the ISS using a Nagoya whip on the radio, a 1/4 wave ground plane, a magnet mount mobile antenna, or a TV twin lead slim jim. granted, the passes were not optimal. But I have been wanting to try this antenna for a while so I finally got the parts yesterday and built one.

Here is the link I used for the instructions:


All of the element lengths and spacing are taken right from these plans, along with the length of the wire used for the hairpin match.

The plans call for attaching all of the elements using stainless hose clamps, but the author does mention that he would use screws to attach the director and reflector to reduce weight and bulk. He also states that the screws would weaken the tape. Additionally, he mentions some builders using rubber washers as spacers to help the tape match the radius of the pipe fittings.

I decided to use some industrial strength Velcro to mount the director and reflector elements, and reinforce the joints with nylon zip ties. This seems to work well, and doesn't weaken the tape by putting holes in it. It also has the added benefit of making a better match to the radius of the pipe, similar to the washers described in the original article.

I then went one step further and added velcro bits to hold the elements in a folded configuration for easier storage and transport. I have seen some guys roll them up individually but that seems to be too fiddly and time consuming. folding the elements and detaching the director makes the whole thing collapse down to a very reasonable size.

To mount it I used a CB antenna mirror mount that I drilled and tapped with 1/ threads to mate with a standard camera tripod. It is light enough not to tip over, and this tripod has a hook for hanging a sandbag to add weight if needed. If the antenna needs to be stiffened up for windy conditions, you could just stick some PVC into the sides of the fittings and tape the elements down (or use more velcro).

The hardest part of the whole operation was holding solder, soldering iron, hairpin match, and cable all at once. My 'helping hands" were not enough. Just as was advised in the article, I tinned everything first. However, the article advises against soldering everything in place because it could melt the PVC fittings. I found that slipping a scrap piece of tape measure under the piece being soldered, and loosely clamping them both onto the fitting allowed me to solder the connections in place without melting the pipe, though the insulation on the hairpin took a beating.

I will probably eventually get a 1"-3/4" reducer and an end cap and mount an SO in the end and route the cable through the inside of the mast. I also want to get some plasti-dip for the ends of the elements. For now I used electrical tape covered with heat shrink but the dip would be a more streamlined solution. I looked 4 places and nobody stocked it.

The match is not perfect but it is good enough to satisfy me. It is under SWR from to MHz, and under at as verified with an MFJC.

Here are a few pics. It is my first scratch built Yagi so go easy on me! :D

Fully deployed:

Elements folded:

Detail of director mounting with Velcro and zip ties:

Connections and hairpin match:

Velcro tabs to fold elements:

Detail of mount:

End protection:

Thanks for looking!


Sours: http://forums.radioreference.com/threads/my-take-on-the-wb2hol-tape-measure-yagi/

Vertical tape antenna measure

This page lists many resources for all of us that dream, design, and build the last piece of gear that our signals touch as they race out of the shack.

Your First Antenna

This article from the Radio Society of Great Britain (RSGB) talks about building your first HF antenna. This page goes through the theory, design, and construction of a 1/2 wave dipole.

Two Meter Vertical Loop Antenna

Andrew VK1AD has a great example of building a two-meter vertical loop. His version is meant to be a portable antenna that easily slips on a vertical rod&#;s top. However, this antenna would also work great in a permanent installation.


There&#;s a Tram antenna page at https://www.cheapham.com/tram that details all of the different ways to mount something to a vehicle.

6 Meter Squalo Antenna

Dwayne Rogers KC5GGH of Louisiana posted his version of a 6-meter Squalo Antenna on Facebook. A detail of this build is available by clicking here.

W2BLC Antenna Links

Our own Gary Skaggs WB5ULK says, &#;I cannot say enough about this website! There are truly DOZENS of build-it-yourself antenna projects on this site. But for those of you who cannot or do not want to build your own antenna, there is an extensive listing of antenna manufacturers listed at the bottom of the page. You can also learn a lot more about &#;why&#; an antenna is built that way it is, how much, if any, gain you can expect, and with a little research, you should have an excellent antenna to meet your own needs for not a lot of money – if you build it yourself. And I’m a great believer in build-it-yourself-if-you-can antennas!&#;

Stealth Vertical Antenna

This has to be the original Flagpole Vertical Antenna. This antenna disguises a vertical inside the pole. This is from , and what&#;s old is new again!

ZeroFive Flagpole Antenna

Tom Leakakos N9ZV produces a flagpole-style antenna that can be used in HOA applications. He produces these antennas out of Brookdale, IL, and sends them out to the world. Take a look at his ZeroFive Antenna website and see if this is for you.

Oblong Vertical Loop for 6M or 10M

VK3YE shows us how to build some easy-to-build vertical loop antennas for either 6M or 10M. These loops can hang off of a tall fishing pole.

Yagi Antenna For Space Reception

Diana Eng has a great article on Make Magazine that talks about building handheld Yagi antennas that can be used to listen, and talk, to the orbiting space satellites, including the International Space Station. Take a look here, to see how to build your own VHF / UHF antenna setup.

Another $4 Yagi Antenna For Space Reception

Are you looking for an inexpensive VHF/UHF antenna for space operations or direction-finding? Zed Zed has a great VHF / UHF antenna setup that you can build for cheap.

VHF or UHF &#; PVC Using 3D Printer

So, you have access to a 3D printer and you&#;re looking for something to build? How about building a VHF or UHF beam with a stick of 1&#; PVC and a few 3D printed parts. Here on Thingiverse is one that you can build for cheap.

Cheap and simple VHF/UHF Yagis

The three previous entries show you four different ways to build a VHF or UHF directional yagi antenna. Once you figure out a construction method, here&#;s a great resource to determine an antenna&#;s wire length and spacings. DK7ZB has a great VHF / UHF antenna design page on QSL.net that you can use to calculate the details. It&#;s not very clear, but if you click on the yellow bar items at the top of the page, you can select the number of elements and band that you want to build. You&#;ll see an expected SWR chart, a picture of the assembly, detailed lengths and spacings, and expected gain and pattern charts on these pages. Additionally, you&#;ll see how to stack a pair (or more) of these to increase the gain/pattern effect. He&#;s also got a great balun designer at this link.

J Antenna Audio Discussion &#; Denny WA6DKD

Our own Denny WA6DKD is one of our local Antenna Elmers, and he always does a great job of helping us with different antennas. On January 1, , Denny and DJ walked through the setup of a J Antenna on the MHz repeater. This minute discussion walks through the design, implementation, theory, and construction of one of our favorite antennas.

J-Antenna Wire Lengths

In order to make a J-Antenna of your own, you might use this page for your calculations for 2M through 40M versions.

G7FEK Limited Space Antenna

We have no personal knowledge of this antenna, but it appears to be a great 80/40/30/17/15/12 and maybe 20/10 in only 46&#; of space. This antenna looks interesting, and we&#;d love to see it built. If you make this work, let us know at [email&#;protected].

VHF Tape Measure Yagi

This information is from an ARRL antenna document, which says&#; The tape measure antenna is a simple, hand-held 2 meter Yagi; that is fun, inexpensive, easy to build. The tape measure antenna is a &#;homebrew&#; 2-meter antenna made out of PVC pipe and a steel tape measure.

This antenna is useful (especially if you want a portable antenna for backpacking, etc.) for any radio or satellite use that uses 2-meter frequencies. Here&#;s a great example, thanks to the photography of Michelle Carey W5MQC and the modeling by Victor McDaniel K5VL:

These tape measure antennas are similar to the ones shown at local SCARS meetings and can be built for about $ Take a look at the SCARS version at this link.

Bent Dipole Simulations

Let&#;s say you want to put up a dipole antenna, but your property, trees, or other obstructions mean you have to bend the perfect dipole to fit your area. Dick Reid KK4OBI has a great website that lets you visualize how your antenna will transmit given a ton of variables, like frequency length, height above ground, and bends in the wires. Here you might get some ideas about why your favorite antenna works and why others don&#;t work so well.

Non-Resonant Wire Lengths

Are you working with an end-fed halfwave antenna? Or, do you need a non-resonant length of wire or coax? Take a look at the University of Delaware&#;s random wire length web page. On this page, you will be able to find random lengths of wire that are not resonant on given bands.

London, Ontario, Temporary Car Mount

John Visser, VA3MSV of London, Ontario, and his crew provided this wonderful idea for a temporary antenna. Details are available on this page.

SCARS Suction Cup Mount

We&#;ve built a suction cup-mounted antenna based on the above mount for the Bike MS and other mobile events. Our antenna is detailed on this page.

Almost Wire Antennas for Amateur Radio

Iulian Rosu YO3DAC has a great collection of Amateur Radio goodies on his site at QSL.net, but this page gives almost different wire antennas for you to review, covet, and build.

G5RV Information

The G5RV antenna has been around for generations,  and it is a non-resonant antenna that requires a tuner. This link talks about how to build one and use it. They also talk about the theory behind this piece of wire that performs on 5 bands.

Ed&#;s Antennas

This antenna showed up on the SCARS Facebook page from Chuck Crawford, and it interested me. Ed&#;s Antennas have exterior vertical antennas for dual VHF/UHF and the ham bands. These antennas are about $ What&#;s interesting is that Ed Fong WB6IQN is a university professor and has sold 16, of these antennas over the past ten years, and the profits go to help his student group. He&#;s even got a +5dB patented gain UHF antenna for $ All kinds of crazy cable, cable length, and connector options. You pay the actual shipping from Santa Monica, CA. Jump on our Facebook Group and ask how it works. There are a couple of these in town!

Using RG-6 for Amateur Radio Feedline

In rebuilding his radio shack, Mark Kleine N5HZR started using quad shield RG-6 coaxial cable for his amateur radio antennas and reported good results.

F to PL

The pros of using this cable are that it is relatively cheap (about $ per foot) and available everywhere, even at Home Depot. It is also UV resistant, and it&#;s cheap ($40 for a crimper, toner, and connectors), and easy to crimp F connectors as you need them. There&#;s even F female to PL adapters available for a couple of bucks each to let you connect directly to your radio or antenna. You can get F female to BNC male adapters if you need those connections. A toolkit is about $33, and you can even directly crimp BNC jacks to the quad shield RG

Cable companies use an RG-6 cable with frequencies up to 3 GHz. The cable also has low loss numbers in the ham bands. For example, this chart shows that at 10 MHz, RG-6 loss is .6 dB / , RG is dB / , and RG-8X loss is dB / We recently used a foot segment of RG-6 at Field Day, and the system performed without any issues. Loss figures at 10 MHz would be dB, slightly lower than the dB of RG-8X, or dB of RG

The cons of using RG-6 are that the characteristic impedance of this cable is 75 Ohms, and hams typically use a cable with a characteristic impedance of 50 Ohms. Most radio gear transmitter ports state that they have a 50 Ohm output. Since all antenna work is a compromise, this difference may be more academic than problematic. For example, a 1/2 wave dipole, mounted 1/2 wave above ground, presents a 72 Ohm load. So, even using 50 Ohm cable presents issues with impedance mismatch. Belden, a major cable manufacturer, has a page describing why 50 Ohm cable was selected.

So, like everything else with amateur radio, it matters less what you use; it matters more that you DO something.

Coaxial Transmitting Chokes

The practice of installing chokes on antenna feedline is about 1 part science and 8 parts religion. Here&#;s a great PowerPoint by Jim Brown K9YC, that talks about all of the different methods to connect a radio to an antenna, and how to make that connection work efficiently. Um, yes, this is pages of fun!

Vertical Loop Antenna Construction

Vertical loop antennas work well to get efficient / low-noise wire antennas. Steven Culp W5SDC has a great page to show you how to design and build these.

Horizontal Loop Antenna Construction

Horizontal loop antennas are a great way to start building your wire antenna farm. The idea of these antennas is to build a wire loop that connects your coax tip with the coax shield and hang that wire in the air. This works best when you capture the largest area inside the loop. By the math, this means a circle, but those get hard to hang. Typically you&#;ll find square and triangular (delta) loop antennas are the easiest to hang. Other irregular forms are very acceptable. Randy Davis K5RCD, from the San Antonio, TX area, has a great web page that explains how to design, build, and operate this type of antenna.

Yet Another &#; Loop Installation

Gary Marbut K7GMM put up a loop antenna and did a great job documenting its installation at https://marbut.com/Loop/.

Skywire Loop Antenna

Some call it a Skywire Loop Antenna, some call it a W0MHS Loop Skywire Antenna, nowadays it&#;s called a Full Wave Loop Antenna, but it still is a powerful antenna. &#; of wire for a M full wave antenna that tunes M through 10 M. With a remote tuner attached at the feed point, this antenna tunes it all. Jason Buchanan has a great page that explains his efforts in building one of these antennas.

Effects of Radials on an Antenna

Have you ever wondered what effect that radials have on an antenna? Colin Summers M6NLC did a quick test and reported the results here on an 80 meter vertical.

Resonant Wire Antenna Efficiency

Our own Kenn Goodson KA5KXW found a white paper by David J. Jeffries that was published in the antennaX journal in Issue No. – March This PDF version talks about the different materials that can be used to build amateur radio antennas. Here he compares these different materials: silver, copper, steel, gold, aluminum, brass, tin, lead, stainless steel, tin-lead solder, and zinc. The Jeffries article shows the power loss per watts in each of the different materials. The results are fairly obvious, BUT what you&#;ll find is that there are only a couple watts per difference between the best copper and the steel/aluminum wire that you may be tempted to use. So, like the rest of amateur radio, use what you&#;ve got.

Home Made PVC Antenna Tee

We are always looking for a new way to connect the center of a dipole to the coax. This PVC method looks easy, and we will make this one for the next dipole.

PVC/Copper Pipe 2 M Vertical Dipole

Jim Feldman W6JMF builds an odd 2-meter vertical dipole that can be portable or mount permanently on a vertical surface. Everything you need to build this antenna can be found on this page.

Moxon 6 Meter 2 Element Beam Plans

Michael Martens KB5VBR has several great antennas and plans. His version of the Moxon dual-element 6-meter beam looks great. Easy to build out of wire and PVC, you can mount this permanently or use it as a temporary antenna for mobile events. This beam should get you 6 dBi of forward gain and a 25 dB front to back ratio. Click here for a link to his site.

Rhombic Math

W5EDI has a great Rhombic calculator.

Vehicle Antenna Placement Chart

Car Mount

Build a NOAA Weather Radio Antenna

The National Weather Service (NWS) has a great article on building an external antenna for your weather radio. A number of these radios have an RCA jack that can be used for this purpose. An RCA jack to F connector will make the connection easy. These connectors are available from the Norman Emergency Manager, David Grizzle, or through various Internet sources.

Wire Weight per Foot

When you are building an antenna, you might need to consider the weight of the wire. Click on this link to see a chart of wire weights.

Mag Loop Antennas

Magnetic loop antennas seem to have an attraction that keeps drawing in more and more people. Thomas Hays KI5AIF has a great page about Capacitor Selection and Design for Magloop Antennas and a page about First Check of Big Loop Components.

And, when you get the loop up and running, Dave Trewen G7IYK has a digital magnetic loop tuner that will tune the capacitor automatically.

Sours: https://w5nor.org/antennas/
Using Tape Measures for Radials?? Big Upgrade for the Wolf River Coils!!

Introduction: The Tape Measure Antenna

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 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

Step 1: Cutting the Elements and Assembling the Boom

You’ll need to cut two pieces of PVC pipe. One piece will be 17 1/2”. The other 7”. This, along with the PVC connectors, will form the frame of the antenna.

Assemble the pipe to form the frame ("boom") of the antenna. Gluing each piece together, the 17 1/2” piece connects between the tee and the first cross. The PVC tee is the front of the antenna. The 7” piece connects between the first and second tees.

Disassemble the tape measure by pulling the tape out of the case. If you pull the tape past it’s end, you’ll find that it’s connected to a spring. Simply twist the tape so it disconnects from the spring.

Cut the tape at 35 1/8”. This will be the director of the antenna and will attach to the front of the antenna.

Cut two 17 3/4” long pieces of the tape. These will serve as the driven elements.

Cut an additional element from the tape. This will need to be 41 3/8”. This is the reflector element.

Sand all the ends of the elements so they are smooth to the touch. These are extremely sharp if left un-sanded. Also sand off about 1/2” of paint on the ends of the bottom side of the driven elements. This will be where you will solder the wires later.

Note: If you are going to mount the antenna, set it up so the antenna will be forward of the mounts. Yagi antennas may suffer in performance if mounted elsewhere, like the center of the boom.

Step 2: Installing the Elements of the Antenna

Slip the hose clams over the PVC tee at the front and slip the Director element under it. Tighten the hose clams so it is secure.

Attach each of the driven elements to the frame of the antenna with the sanded sides facing each other. Before securing the elements, space the elements 1” apart and tighten the clamps.

Finally, attach the reflector element at the rear of the antenna and tighten the clamps.

Step 3: Soldering the Wires

Now you will tin the ends of the driven element. Simply heat the soldering iron and apply solder to the tape measure at the sanded spots. Make small pads where you can solder two wires to each side of each driven element.

Strip the end of the RG cable and isolate the outer and inner wire. Solder one side of the RG to a driven element and the other to the opposite driven element.

Strip the 5” piece of 18 gauge (or whatever wire you have) and solder a side to each of the driven elements.

I chose to add an optional piece of PVC and an elbow at the rear of the antenna to make it easier to hold and/or mount. I also chose not to glue the PVC together so the antenna can be broken down for storage.

Step 4: Adjusting the Antenna

Adjusting the antenna is very simple. Simply attach a SWR meter between the antenna and the radio. Adjust your radio to mhz and check your SWR reading. If the reading is more than to 1, turn off your radio and adjust the driven elements by loosening the hose clams and moving the elements toward each other. Turn on your radio and check your SWR again. Repeat until your SWR is at an acceptable level. I was lucky and my antenna registered extremely close to 1 to 1 without adjustment.

When adjusting the driven elements make sure your radio is off.

Step 5: Technical Notes

Software modeling programs show that this antenna should have a gain of dBd.

Real world experience: Running a HT at 5 watts, my nephew and I were able to use a repeater miles away, with reports of a clear signal. We were also able to access several other repeaters that are 40 to miles away. Performance will vary based on your location. 

While this antenna is designed for VHF two-meter operations, it can easily be redesigned for other frequencies like meter, 70 cm or 33 cm. There are many websites that will calculate the length of and length between the elements on a Yagi-Uda antenna. You can try Martin Meserve's (K7MEM) online calculator here. 

Additional information on this antenna

The original plans for this antenna are available at Joe Leggios (WB2HOL) website. A link to the plans is here.

Additional plans are available from KC0TKS' website here, as well as from NT1K's website here.

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