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[Articles Home]  [Add Article]  

Inexpensive 17-Meter Vertical

Darrin (K5DVW) on February 26, 2006
View comments about this article!


A low cost, low profile DX antenna

We hams love our antennas. So much so that it's not unusual to see an amateur erect a 100 ft tower and sprinkle it with beams, and wires. Unfortunately for most of us, we either don't have the space, funds, or accommodating neighbors for such a system. But, all isn't lost when it comes to chasing DX. This article focuses on one way to accomplish a decent inexpensive antenna that is capable of 17 meter DX.

It's well known that a properly installed vertical antenna has low angle radiation to the horizon, the favored direction of DX propagation. It's also well known that a horizontal dipole will have excellent low angle radiation too, but only if it's high enough off the ground. One half wavelength or higher is the target for a DX oriented dipole. On the higher HF frequencies, that's not usually a big issue as � wavelength on 10m is only 15 feet. But, a horizontal dipole will need three tall support structures spaced at proper horizontal distance and may not be so neighbor friendly. Enter the vertical.

I've used a ground mounted HF vertical for years with good success. The secret to a good ground mounted vertical is to put many, many radial wires from the feed point along the ground like spokes of a bicycle wheel. This has the effect of reducing the ground loss in the near field of the antenna by shielding the antenna's image from lossy soil. These ground losses can be significant and reduce a vertical to little more than a dummy load if they are not reduced. On the order of fifteen 0.1 wavelength radials are the absolute bare minimum if you don't want to lose a lot of signal to the earth below. Hardcore vertical users put upwards of 100 half-wavelength radials to squeeze the last dB out of their installation. Still, I like verticals. My main HF antenna is a popular commercial trapped model and it doesn't cover 160m, 60m or the higher WARC bands (17m, 12m). So, I set out to develop a simple antenna to fill in the gaps in my HF coverage. I wanted to focus on the higher HF band coverage for the time being, leaving the low band challenge for later. Specifically I wanted to target 17m.

Fortunately there is an alternative to good vertical performance without all those radials. An often used technique to making a vertical work without a massive radial system is to elevate the entire system, radials and all, off the lossy ground.. As little as 0.1 wavelength separation from earth does wonders for efficiency. In fact, at such a height or higher, the number of radials required can be reduced significantly without much performance degradation compared to a ground mounted system with 100 radials. Believe it or not, at sufficient height, reasonable performance can be had with only two tuned radials! The height target for good ground decoupling is greater than 0.1 wavelength high and at 17m that's only a little higher than 5 ft off the ground. That's to say that the ground radials must be 5 feet or higher off the ground at their lowest point.

With the idea to develop an elevated vertical for 17m that is not too complex or expensive as my goal, I started reasoning through my options. If you are anything like me, you've probably tried HF mobile before and you may already have the main piece to build this project; a hamstick antenna. The hamstick is a mobile style HF antenna for single band HF coverage. The price is right and every hamfest I've been to has a vendor selling them inexpensively. The hamstick construction is that of a bottom loading coil section wound on a � inch fiberglass tube with a resonating whip above. The total length is about 7 feet and the base is a 3/8 inch 24 TPI (turns per inch) bolt with male threads. These antennas are built to take abuse, so they're not fragile and a good candidate for outdoor use.

Now I had the idea that I could build an elevated 17m vertical using a hamstick as the main element, it was time to design and test it.

Construction

PVC drain pipe is a wonderful material to homebrew with. It's lightweight, strong, and inexpensive, plus, your local hardware store has plenty of it. It just so happens that the cap for the 1 1/2” drain pipe is flat on the top which makes for a great mounting surface, the smaller pipe caps are curved and would be difficult to use without sanding them flat. I started the project by obtaining 10' and 5' sections of SCH 40 PVC, 1 1/2” drain pipe, a pipe coupling, and a cap. I also picked up a 1” long 3/8” 24 TPI bolt, a couple of washers, a �” 24 TPI threaded coupler and an electrical eyelet large enough to fit over the bolt. For feed line I decided on a 15' length of RG58 with a PL256 connector on one end. Any length is fine as long as it reaches your radio. The radial system is made using #14 solid copper wire which can also be found at the hardware store. Any gauge of wire is fine, but the thinner stuff can be fragile. Be sure to have at least 30' of it on hand for this project. It doesn't matter if it's insulated or not. Figure one is a diagram of the cap and feed point.

0x01 graphic

Figure 1. PVC pipe cap and feed point detail

The PVC cap I found had raised lettering on the top of it which disturbed the flatness of the surface, so I first sanded it down flat using sandpaper. I then drilled a 7/16” hole in the center of the cap. I also drilled two 1/8” holes for the radial wires on opposite sides of the top of the PVC cap about �” down and a 3/8” hole about 1ft down from the top on the 5' PVC pipe to route out the coax feed line along the outside of the pipe.

The coax feed line is prepared by placing the free end through the hole in the side of the 5' PVC pipe section and bringing it out the top open end. Strip the jacket insulation off the free end about 1.5” and separate the shield from the center conductor. Strip the center conductor insulation back about �”. The electrical eyelet should then be soldered on to the center conductor.

Next, prepare the feed point by inserting a 1/2 foot section of the stripped #14 wire through the two drilled radial holes in the pipe cap. The idea is to connect the radials later, but to have a continuous length of wire running through the pipe cap for mechanical rigidity. Solder the radial wire inside the pipe cap to the shield of the coax cable. Be sure to not let the wire get too hot as it will melt the PVC material.

Insert the 1” long 3/8” 24 TPI bolt through the eyelet on the center conductor, through a washer, then into the hole in the pipe cap. The head of the bolt should be inside the pipe cap with the threaded end sticking out the top. Place a washer on the bolt on the outside of the cap and using a wrench, tighten the spacer onto the bolt. It's a good idea to wrap the radial wire with electrical tape where it is soldered to the coax shield so that it doesn't contact the bolt head. Place the pipe cap onto the 5' section of PVC pipe, and your antenna feed point is now finished! Figure 2.

0x01 graphic

Figure 2. Pipe cap assembly with radial pig tails

I added some RTV to the holes where the radial wire and feedline comes though the pipe cap but I did not glue the pipe cap onto the pipe. I don't think it's necessary to use glue since the downward weight and pressure of the antenna and radial wires should hold it in place and it's a snug fit. Tie wraps are a good idea for keeping the feedline from blowing around in the wind.

With the remaining #14 wire, it's time to make radials. Since we're just using two, cut them to the appropriate length for the band your hamstick is designed for [L=243/(MHz)]. In my case the radial lengths for 17m are 13.5 feet each. Strip back and solder the radials onto the wires which come out of the pipe cap again being careful not to melt the PVC. The 5' section of pipe can now be connected to the 10' section by use of the pipe butt coupler. Now you have your mast. Again, I don't see the requirement to cement them together, but you certainly can. You can even paint the pipe. Next, screw the hamstick onto the 24 TPI coupler. I decided to use the coupler for two reasons. One, the thread on the antenna didn't seem long enough to go thru the pipe cap and washer and, I could change antennas without disturbing the feed point connection inside the pipe cape. Your antenna is now complete! Figure 3.

0x01 graphic

Figure 3. Complete antenna hidden by a tree.

Installation

The hardest part of this project is deciding where to put the antenna. A site clear of metal obstructions and far from the house is best. A bonus would be if it could be hidden from view. Wooden fence posts make an excellent mount and the radials can be anchored to the fence itself. I decided to strap my antenna to a short tree and let the radiating element protrude above the tree top. My radials are anchored to a nearby wooden privacy fence. In this configuration, I didn't need to guy the mast since the tree and radials did that for me. For best results and a better SWR match, the radials should be angled down from the feed point and kept symmetrical. Angles from 30 to 60 degrees provide a good match, with 45 degrees usually being optimum. Of course, you will need to adjust the whip on the hamstick to tune to lowest SWR. My SWR plotted over 17m is shown. Due to the low feedpoint impedance of a shortened antenna, you can expect SWR to run a bit higher than with a full sized version. In other words, don't expect to find a 1:1 SWR match.

Simulation

Always curious how my antenna designs perform, I like to simulate them. Using NEC-2, I simulated a wire structure representing my antenna with the feedpoint 15 feet over average ground. I used distributed loading to approximate the bottom loading section of the antenna. Since I couldn't measure the value of the loading coil directly, I played around with the simulation values and found where it would resonate at 18.1 MHz with a 3.5 foot whip by adjusting the loading inductor value. I then noted the simulated feed point resistance at resonance in the simulation was lower than the 35 Ohms I measured with my impedance bridge, so I added resistive losses to my loading coil until the simulation predicted a feed point impedance of 35 ohms. The final values for the distributed loading coil are 1 ohm in series with 0.42 uH. My simulated SWR curve matched very closely the measured data.. NEC predicted that the maximum gain direction is at a low elevation angle with approximately 0 dBi. Recall that a dipole should have about 2.4 dBi, so it's reasonable to expect we're losing a bit of gain over theory with this setup, and this simulation doesn't include any effects of the transmission line, or unbalanced radial current, but it does show a trend. It shows that most of the RF energy is at low angles leaving this antenna! Just what we want for DX. Figure 4

0x01 graphic

Figure 4. NEC simulated pattern

0x01 graphic

Figure 5. Measured SWR

Operation

Now I'll be the first to admit that this is a compromise antenna and it's not meant to perform like a tower and beam or a high dipole. There are plenty of discussions around about how inefficient verticals can be, and especially bottom loaded verticals. On the other hand, you'll see some of the best low band DXers using verticals, so they can and do work very well with low angle skip. By elevating the radials from ground as in this design, one major source of loss has been reduced, the dirt below. The loss of the loading section is still there, but I think it can be tolerated; after all, thousands of mobile stations make excellent contacts with these same antennas. The elevated vertical explained here should operate certainly as well as if not better than a mobile installation. So, how has mine worked?

As for on the air results, within the first 30 minutes of operation I made contacts to Portugal, Ireland, Argentina and Azores from my central US location. I'd say the low angle skip is definitely being worked!

Conclusion

The benefits of the antenna that I have presented here are a simple construction technique, easy match to 50 ohm cable, good low angle omni-directional performance, portability and ability to install most anywhere. Drawbacks are certainly the lossy nature of a short, loaded vertical when compared to a full sized vertical antenna, or a dipole up � wave length.

Please treat this article as only one suggestion and expand on the idea. Try different mounting locations, modify the construction techniques and play with the radial orientation. Try it camping or at your next field event. Experiment and have fun! Hamsticks are available for any HF ham band so it's possible to go lower than 20m with this idea. One note of concern, however, is that going below 40m in frequency may reach a point where the loading coil losses become very large, but the low angle radiation pattern will be the same. If anyone tries it, please write me with the details! Sixty meters anyone?

Member Comments:
This article has expired. No more comments may be added.
 
Inexpensive 17-Meter Vertical  
by AE5X on February 26, 2006 Mail this to a friend!
The photos need to be re-sized so that horizontal scrolling isn't necessary.
 
Inexpensive 17-Meter Vertical  
by K0RFD on February 26, 2006 Mail this to a friend!
The biggest problem with this antenna is efficiency. If you look at your radiation pattern plot, notice that the maximum contour on the plot is -.13 dBi. That means that even though your antenna is putting out all its radiation in favorable places, it's less radiation than the mythical isotropic antenna puts out. Pattern isn't everything. Efficiency counts a bunch.

I have a similar elevated ground plane antenna I use on 20 meters. However, I used more radials. They're cut to resonant length and are used to guy the pipe the antenna is U-bolted to. It models at about +1.1 dBi, which is at least positive gain instead of negative. You wouldn't hear the difference, but I'm just using the statistic to make a point. More radials are better, even if they're elevated. Just use the radials as resonant guys to hold up whatever structure you have the antenna sitting on. The efficiency of the antenna will improve.
 
RE: Inexpensive 17-Meter Vertical  
by K5DVW on February 26, 2006 Mail this to a friend!
Sorry about the photo size... not sure why it's that way. Maybe the eham folks can fix it?

As far as the antenna not being highly efficient and being a few dB below a full sized antenna, I mentioned that several times in the text. The point is that it's not a full sized vertical, it's a "gets you on the air" type of antenna. It's also not entirely the number of radials effecting the gain, it's mostly the fact that the helical base loading on the hamstick is lossy. That's what the model is responding to.

Thanks for the comments.

K5DVW
 
RE: Inexpensive 17-Meter Vertical  
by VA7CPC on February 26, 2006 Mail this to a friend!
Thanks for the article. I've been thinking about "stealth" antennas, and using a Hamstick as the vertical element is very neat. It cuts down the height considerably, and avoids the need for a top support.

A 3-db loss isn't a bad compromise, given the nice vertical take-off angle.

A question:

What assumption did you make about the quality of the ground around the antenna when you set the model up ?

Thanks again -- it's always nice to read about inexpensive, effective solutions.

Charles VA7CPC
 
RE: Inexpensive 17-Meter Vertical  
by K5DVW on February 26, 2006 Mail this to a friend!
Charles VA7CPC,

When I made the model, I used the average ground selection. Altho, I think what you'll find is with elevated radials, the type of ground you have has less of an impact, especially the higher you get the radials off the ground.

Good luck with it!

K5DVW
 
Inexpensive 17-Meter Vertical  
by AF0H on February 26, 2006 Mail this to a friend!
I'd be curious to see how this one compares to a full-length ground mount vertical. Ground losses are introduced, even with a decent radial system, but having a full-length radiator should help compensate for some of this loss. At a little over 13' tall, it would not be hard to hide either.

I homebrewed a 20-meter ground mount vertical (full 1/4 wave) and it worked great! Even with only 12-radials under it, I always got great signal reports with only 100-watts on SSB. For that matter, I worked all over with my Rockmite 20 (500-mw) using this antenna.

73 de
af0h - Rob
 
RE: Inexpensive 17-Meter Vertical  
by KT4XF on February 26, 2006 Mail this to a friend!
Who is going to waste their time scrolling back & forth to read this article?
 
RE: Inexpensive 17-Meter Vertical  
by K5UJ on February 27, 2006 Mail this to a friend!
Thanks for taking the time and trouble to communicate your antenna idea. since 1/4 w. on 18 mhz is i'm guessing, around 14 or 15 feet, why not get rid of the loaded ham stick and use a small diameter aluminum pipe? you can get aluminum stock from vendors such as Penninger Radio (http://www.penninger.com). If you don't want the antenna to go as high as it would with this, you could shorten it with top loading i.e. a capacitance hat. either way, you would have a more efficient antenna. I would also add more radials to the counterpoise; at least two more at 90 deg. to the two you have.
 
RE: Inexpensive 17-Meter Vertical  
by ERNESTTHOMPSONEXK4EAT on February 27, 2006 Mail this to a friend!
Next time FORMAT correctly - after about the third sentence my hand was tired...
 
Inexpensive 17-Meter Vertical  
by K0PD on February 27, 2006 Mail this to a friend!
What a pain in the Rumpus trying to read this article. definately need's to be resized......
 
RE: Inexpensive 17-Meter Vertical  
by KG6WLS on February 27, 2006 Mail this to a friend!
WHOOOOOOAAAAAAAAAAHHHHHHHHH. This makes me dizzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzy
 
Inexpensive 17-Meter Vertical  
by KD5PSH on February 27, 2006 Mail this to a friend!
I'm with KT4XF; what a pain to read such an article, scrolling back and forth.

However, I've done exactly this kind of antenna with a Ham stick on top and used various radials (102" whips or other Ham sticks x3) and had immediate success. Running three watts CW last field day, I had contacts out from 400 to 1200 miles on low power.
The best performance is to use guy wires as radials (about 1/4 wave plus 10%) and three or four of them.
At any rate, it is a cheap vertical and easy to hide.
Finally, you can make a dipole with two Hamsticks, and that can work like a champ as a horizontal dipole.

K5CO (former Kd5PSH)
 
Inexpensive 17-Meter Vertical  
by KD5PSH on February 27, 2006 Mail this to a friend!
I'm with KT4XF; what a pain to read such an article, scrolling back and forth.

However, I've done exactly this kind of antenna with a Ham stick on top and used various radials (102" whips or other Ham sticks x3) and had immediate success. Running three watts CW last field day, I had contacts out from 400 to 1200 miles on low power.
The best performance is to use guy wires as radials (about 1/4 wave plus 10%) and three or four of them.
At any rate, it is a cheap vertical and easy to hide.
Finally, you can make a dipole with two Hamsticks, and that can work like a champ as a horizontal dipole.

K5CO (former Kd5PSH)
 
RE: Inexpensive 17-Meter Vertical  
by K5TR on February 27, 2006 Mail this to a friend!
The formatting and image sizes have been fixed.

It should be much eaiser to read now.

Thanks
 
Inexpensive 17-Meter Vertical  
by N5UV on February 27, 2006 Mail this to a friend!
Nice article...I have the 6BTV, so it doesn't have 12m or 17m bands to work with, and this would be a good alternative if I have the space...and I'm sure you could do one Hamstick for each band and switch as needed from 17m to 12m.

For those hams looking for a slightly more expensive alternative, you can't go wrong with the Cushcraft MA5V (or now the MA6V, with 6 meters added). That ant. covers 20/17/15/12/10, all in one vertical. It will cost you about $100 to $125 more than 2 Hamsticks and assorted wire, but it has an elevated counterpoise/ground plane (of sorts), and it worked great for me for 3 years just being mounted to a 3ft. section of pipe in the ground. You can't run over 300 watts, but it'll "get 'er done." Honestly, I'd still be using it if I weren't doing more 40/80 ops. (and QRO at that).

Regardless, tnx. for the article...and it's very easy to read now, tnx. eHam for correcting that.
 
RE: Inexpensive 17-Meter Vertical  
by KT8K on February 27, 2006 Mail this to a friend!
At 20m and up you can make a vertical dipole and not need radials at all. The only catch is, you have to take the feedline away at 90 degrees to the vertical for at least a half wavelength or more. The results are quite good, though.

I put the driven element from an old tribander in one of my backyard trees, throwing a line over the top of the tree and pulling the center bracket of the dipole up as high as it would go. Then I tied the bottom end of the dipole to a branch a couple of feet out from the trunk (but still vertical - the tree tilts a bit) and voila! I have a very good triband vertical with no radials to worry about.

It might be a little bit more lossy when all the leaves are around it, but it is especially good in Winter. The tradeoff is that it is hidden in the tree in the Summer when my neighbors are out and about. Nobody has said anything about that thin aluminum tube sticking out of the top of the tree.

I have heard that I can use a tuner to resonate it on 12 and 17m without too much loss of efficiency, but haven't tried it yet.
Happy antenna building and good reception to all de kt8k - Tim
 
RE: Inexpensive 17-Meter Vertical  
by KA0GKT on February 27, 2006 Mail this to a friend!
From a simplicity point of view, why not make the antenna a full length 1/4 wave vertical? At the middle of 17 meters (wavelength, not frequency) the total length of the radiator would be 13' 7". This could be made with aluminum tubing or 3/4 or 1" copper refrigeration grade tubing (which comes in 20' lengths)

Another possibility would be a sleeve dipole which would allow the coaxial cable to leave through the bottom of the antenna.

All that said, the Hamstick seems to work reasonably well and it is an interesting article.

73 DE KAGKT/7

--Steve
 
RE: Inexpensive 17-Meter Vertical  
by W6TH on February 27, 2006 Mail this to a friend!
.

Someone asked to compare to a full size vertical for the 17 meter band.

Here is the gain at the radiation angle of 32 degrees and 12 radials a half wave long lying on the ground.

...................3.58dBi..............

...................5.54dBd.............

Verticals are the way to go for DX at a low price, simple antenna.

73, W6TH.

.:
 
RE: Inexpensive 17-Meter Vertical  
by W6TH on February 27, 2006 Mail this to a friend!
.

Try this as the cost will be less and also the workmanship less.

Vertical height of vertical 12.5 feet long.

Radials: 12 at the same length of 12.5 feet, quarter wavelengths.

No matching network needed using 50 ohm coax if vswr is 1.5/1 or lower.
Should be 1.5/1 with no tuning.( 50 divided by 32 = 1.562/1 ).

W6TH

.:
 
RE: Inexpensive 17-Meter Vertical  
by RobertKoernerExAE7G on February 27, 2006 Mail this to a friend!
Great article.
TKS for taking the time.
73
Bob
 
Inexpensive 17-Meter Vertical  
by WB5PDW on February 27, 2006 Mail this to a friend!
Great article! Verticles do work for DX. I've worked a JA on 10m at 5 watts with two phased verticles.
 
RE: Inexpensive 17-Meter Vertical  
by WB8RFB on February 27, 2006 Mail this to a friend!
Great article Darrin and thanks for taking the time to share it with all of us. You are to be commended for your efforts!

I had a somewhat similar experience building and operating a "low-profile - neighborhood friendly" quarter-wave ground plane vertical made out of a chassis SO-239 connector and speaker wire.

This was going to be an antenna to use for a "weekend" of operating under the picnic table canopy and then toss. It took all of an 90 minutes to build and hang from a tree branch and it has now been up for over 8 months and still going strong.

The radiating element is 13' long as are the 4 radials. The 4 radials are soldered to the 4 screw-holes in the SO-239 and the vertical element is soldered to the center pin. I used a random length of ratty old RG-58 from the junk box, with the shield soldered to the radials and the center conductor soldered to the radiating element.

The base of the antenna is suspended about 7' in the air with the radials drooping at roughly a 45 degree angle and fastened to 4 plastic tent pegs pounded in the ground. The top tip of the antenna is knotted and tied to a manila line thrown over a tree branch to hold it vertical. My rig is a 20+ year old Kenwood TS-440 feeding a Heathkit SA-2060 manual antenna tuner and I'm running about 100W, but who knows what amount of power is making it to the antenna. Never measured it. I can tune it on 30, 20, 17, 15,and 10 meters and have made contacts on all these bands. Even managed to squeak a few watts out of it on 40 and worked 3 European stations!

Here's a "sampler" of the DX I've worked over the last eight months with the most recent contacts coming from last weekend's ARRL International DX Contest - LZ, EA8, EA6, I, G, GI, GM, SM, S50, DJ, OM, Z33, EA, F6, J7, T9, OE, HB, UA9, YQ, EW1, UN9, OH, LY, RG9, OH0, TF, SP, YL, KH6, KL7, 9A, LU, ZD, JA, 5B, CU2, 6V, S9, etc. I won't list all the Caribean locations, but suffice to say I have worked most of them from here in Illinois.

All in all, verticals DO work albeit not in the most efficient manner. But, when that's all you can string up, you gotta go with what you've got. I used to pooh-pooh them too until I had no choice. If I wanted to opeate, this is what I could/can use. So far it seems, it's worked out to be a pretty good antenna for me. For the time and expense involved, it's worth a try. You might be as surprised with results as I was!

73 from WB8RFB
 
RE: Inexpensive 17-Meter Vertical  
by K5UJ on February 28, 2006 Mail this to a friend!
BTW, if you use a 16' Al pipe instead of the hamstick you will have a 1/4 w. vertical on 20 m. that will take legal limit power if you use large enough feedline. if you don't want to run high power, you can use that to your advantage by installing an automatic matching network at the feedpoint, the type that is in a weatherproof enclosure, and then your vertical can be tuned to give you a 50 ohm load with a 1/4 to 1/2 wave radiator on 20 to 10 meters.
 
Inexpensive 17-Meter Vertical  
by KG6WLV on February 28, 2006 Mail this to a friend!
Great article. These are the stories I like to read on eham.com. I love to read the "brainstorming" responses, also.
I have a sturdy patio cover (wood frame; I can walk on it) covered in corrugated aluminum panels. It's approximately 12 by 20 feet and about eight to ten feet above ground (it slopes). I'm thinking of constructing an HF vertical there and using the cover for a ground plane. I've been wondering how that would play. You've given me food for thought.
I know the panels aren't at the optimum angle, but I figure the efficiency of the panels tied together electrically would make up for that.
I like messing around with PVC, too. I've just homebrewed a mast for my Elk VHF/UHF log periodic out of it, and I've achieved a mast that is modular, dirt cheap, light, reasonably strong, and about 11 feet high. None of the pieces are longer than 16 inches, so they fit in my backpack easily. My goal is to backpack to a local state park's camping grounds (about four miles and a vertical climb of about 1800 feet), camp overnight and hilltop.
Anybody have any real world experience with antennas built with copper plumbing pipe or electrical aluminum conduit? How well do they tolerate high winds?
 
RE: Inexpensive 17-Meter Vertical  
by KG6WLS on March 1, 2006 Mail this to a friend!
Thanks to the fine folks at eHam, it's much easier to read this article. I always like reading hombrew antenna ideas that pertain to limited, and/or restricted space.

"Anybody have any real world experience with antennas built with copper plumbing pipe or electrical aluminum conduit? How well do they tolerate high winds?"

I've used 1/4", 3/8", and 1/2" copper for homebrew loops and hentennas for VHF. If you have limited/restricted space, they work OK and tend to hold up well with the winds. I'll defend my case on the copper loops, because there will most likely be some nay-sayers that will comment. They're not a high gain beam by any means but, they do work.

Working with verticals higher than 12 feet with 1/2" or 3/4" (copper or alum. pipe) you will need guy rope/wires so the wind and weight doesn't make it fold over on itself. Or even worse...on somebody.

73
Mike
 
Inexpensive 17-Meter Vertical  
by KE4ZHN on March 1, 2006 Mail this to a friend!
Wouldnt it be easier to simply hang a dipole vertically from a tree limb and achieve the same results?
 
Inexpensive 17-Meter Vertical  
by K0ZN on March 1, 2006 Mail this to a friend!
Hi.

Good article. It will help some newcomers. I am sure the antenna works well as a basic antenna. Some people are so perfectionist that they miss the point of "BASIC, simple antenna".

One other possible thought is that one could easily put a short (one or two ft. long) length of threaded 3/8" brass rod stock between the antenna base support and the antenna, thus slightly lengthening the whole antenna and raising the radiation resistance/efficiency a little. i.e. raising the inductive loading coil up off the base helps a fair amount because the bottom of a vertical antenna is the highest current portion. Obviously, you would need to reduce the length of the whip section slightly to compensate/tune it.

I have been meaning to build something similiar but make it a coaxial antenna... just a "for fun project". In theory, a coaxial is a tiny bit more efficient than a Ground Plane but I am sure it will be a little harder mechanically to tune the sleeve to resonance. The beauty of the GP is mechanical simplicity.

Last summer I put up (mainly out of curiosity) a full size 20 M Vertical Folded Dipole fed with ladderline (via an antenna tuner) and it worked very well on 20 and 17 M.

73, K0ZN
 
RE: Inexpensive 17-Meter Vertical  
by WA2JJH on March 4, 2006 Mail this to a friend!
Nice job. You put much effort to publish this.

I am sure your antenna is far better than anything GOTHAM verticals ever made!
 
RE: Inexpensive 17-Meter Vertical  
by DD3LY on March 10, 2006 Mail this to a friend!
This article is great for those who have this mobile antenna anyway. For the rest I recommend to build a J-pole antenna made from wire and some homebrewed plastic spacers. Such a J-pole has an efficiency of 95 percent, has 3dB gain compared to a quarterwave antenne (the mentioned mobile radiator is even a shortened quarterwave radiator!) and costs just next to nothing if you dig into your junkbox. And you ALWAYS will be able to find a point where to feed this antenna, which has a good VSWR. If you paint the antenna in a dark color you may disguise it when hung up in a tree. What else do you want?
 
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Feeding an LPDA Beam Antenna
The REMBLA
An Automatic Motor Controller for Small Loop Antennas