Antenna Spreaders
from
Dale R Kubichek, N6JSX
on
March 20, 2008
View comments about this article!
HAM Builders: easy Antenna spreaders
[This article is directed to
old-fashion (nearly extinct) Antenna “builders”.]
Do you want to build a multi-element
fan dipole or Inverted “V”? Wonder where to get those spreader insulators that
WILL last for years? Easy answer is “MAKE THEM”!
You will need a ruler, table saw,
and drill. Yes, it’s that simple.
Go to your local hardware store and
buy outdoor "plastic" decking planks - 12”x36”x1”. Slice off a ½”
piece and take it to your kitchen microwave oven. Place upon a paper plate and
nuke it for >1 minute. Use either a thermometer (or the back of your hand)
to ascertain if the material has increased from its normal room temperature
right after the microwave stops cooking.
If it is HOT or warm to the touch
the material is NO good for RF use. Try a different decking type of planking
source hardware store and nuke again. If the piece remains at or near room
temperature to the touch it is good for antenna use.
Slice off as many spreaders as you
want – make the spreader depth near ½” to reduce wind loading and retain
strength. I use a metal de-burring tool that is fast and easy to use to remove
the rough plastic edges from the "new" spreaders. I use a drill press
to place a hole every 1.5”-4” leaving at least 1” of material on either end of
the spreader. Hole spacing and size is dependent to your antenna needs, remember
hole diameters larger than 1/4” reduce spreader material and strength to a 1”
crosscut. If you need more wires holes you can rip the plank the long way and
cut to your required size(s). I created a drill press jig (metal plate) to
insure all my holes are equally spaced to each spreader. I usually make 10-20
spreaders of various sizes [2, 3, 4, 5 or more holes each]. Jigs reduce my
setup time between antenna projects and provide consistency to my antennas.
Have fun – be creative!
***********************************************************************************************
My favorite all around wire antenna
is a multi-element/band “Inverted V”. Easy, cheap to build but one, and one of
the most effective antennas a HF HAM can install. It is a very forgiving; I’ve
bent my 75m legs 90º to make-fit to my property lot.
As you can see my home-made
spreaders did not greatly increase the ice loading to my inverted V week.
Actually the wires look to be more loaded that the spreaders.
This article has expired. No more comments may be added.
|
Antenna Spreaders
|
|
|
by N3AIU on March 20, 2008
|
Mail this to a friend!
|
I don't think that antenna home brewers are an extinct species yet. I have long given up building electronics circuits (although I still look at the circuit diagrams to see how they work), but give me some wire, insulators, coax, and a few trees and I can make very usable antennas.
Great idea for the spreaders.
73, Nick N3AIU/DL1NE
|
| |
|
Antenna Spreaders
|
|
|
by KB2DHG on March 20, 2008
|
Mail this to a friend!
|
nice article. GOOD IDEA about using a microwave oven to test for rf compatibility!
Wonder if PVC tubing works?
|
| |
|
RE: Antenna Spreaders
|
|
|
by K0BG on March 20, 2008
|
Mail this to a friend!
|
Well, I'm not so sure using a microwave to test the dielectric strength of any material is a safe practice.
Delrin, Teflon, and Nylon all exhibit good dielectric strength in their natural colors. However, introducing some color to them can turn them into fairly good conductors at gigahertz frequencies. So when you place them in the microwave they literally burst into flames, sometimes explosively. If you need proof, there are at least a dozen sites that list the dielectric strength of the various, commonly-used plastics. Some are good to several gigahertz, some are on par with salt water!
Personally, I would prefer knowing the exact dielectric strength of any material I was contemplating using, and the aforementioned sites is where I would start.
Alan, KØBG
www.k0bg.com
|
| |
|
RE: Antenna Spreaders
|
|
|
by AD5X on March 20, 2008
|
Mail this to a friend!
|
And if you do use a microwave oven, make sure you put a cup of water in the microwave with the spreader material. Otherwise, it would be like running the microwave oven with nothing in it (my microwave oven instructions say not to do this) if the spreader material doesn't absorb energy - which you are hoping for.
Phil - AD5X
|
| |
|
RE: Antenna Spreaders
|
|
|
by N2EY on March 20, 2008
|
Mail this to a friend!
|
Great article! A microwave is a good rough test for RF losses, but remember the cup of water, and use a small test piece.
Another material to consider is Corian and its cousins, if you can get scraps too small to be useful as countertops. Of course it needs to be tested.
btw, while nylon has good DC dielectric properties, its RF properties are poor.
73 de Jim, N2EY
|
| |
|
Antenna Spreaders
|
|
|
by W5FYI on March 20, 2008
|
Mail this to a friend!
|
|
Good and practical article. By using "outdoor" rated materials, you can be reasonably assured that they will stand up to the harsh weather and UV rays they are sure to encounter. However, I don't believe the microwave test is necessary for materials that are going to be used only at HF. It would be an interesting experiment to nuke a handful of wire insulation, capacitors, resistors, chokes, transistors and other components in a microwave oven as a way to rate their suitability for use in our HF radios. We also know that clear glass and quartz are excellent conductors of electromagnetic energy at light frequencies, but make great insulators at much longer wavelengths. Why not keep the tests relevant?
|
| |
|
RE: Antenna Spreaders
|
|
|
by KE3HO on March 20, 2008
|
Mail this to a friend!
|
Nice article. However, I will just say that the microwave test has no value. The loss tangent of a material at 2.45 GHz has no relationship to its loss tangent at HF frequencies. Just because it is good at 2.45 GHz does not mean it is good at HF, and being bad at 2.45 GHz does not necessarily mean it is bad at HF.
73 - Jim
|
| |
|
RE: Antenna Spreaders
|
|
|
by W4VR on March 20, 2008
|
Mail this to a friend!
|
|
Sounds like a lot of trouble to make spreaders...and using the microwave oven is probably not a safe practice. When I need spreaders or end insulators I buy a sheet of 1/4-inch plexiglass from the local hardware store, and have them cut it in 1-inch strips. I cut the strips at the required length with a hack saw and drill my own holes as needed for the application. I use these spreaders/insulators in 30 below zero weather and never had a problem....they last forever.
|
| |
|
Antenna Spreaders
|
|
|
by N0AH on March 20, 2008
|
Mail this to a friend!
|
|
Put a 20 meter dipole in a microwave oven set on the popcorn level and it will reduce it into a 6 meter dipole in 1:30-
|
| |
|
RE: Antenna Spreaders
|
|
|
by AE6RO on March 20, 2008
|
Mail this to a friend!
|
Gonna get in hot water with the XYL if you do that to the microwave oven. Gotta put that cup of water in the microwave so as not to blow the magnetron.
You could hack up old ballpoint pens for spreaders too. They are made from PVC and are lightweight and strong. Takes alot of them though. Just the thing for open wire line. Maybe even on 60 meters.
I'm not sure testing material for HF at microwave frequencies is helpful, except for microwave oven sales. 73, John
|
| |
|
RE: Antenna Spreaders
|
|
|
by N8QZ on March 20, 2008
|
Mail this to a friend!
|
|
PVC Tubing has very poor UV resistance and will break down within a few years if not sooner
|
| |
|
Antenna Spreaders
|
|
|
by WMCO on March 20, 2008
|
Mail this to a friend!
|
The microwave oven test is useless for materials used HF. The only time you would want to use the test is on materials you use on UHF and above. Material that test bad in a microwave will most of times work just fine on HF. This is like testing a lubricant that is used at room temperature at an elevated temperature of 1000F
John
|
| |
|
RE: Antenna Spreaders
|
|
|
by N2EY on March 20, 2008
|
Mail this to a friend!
|
"PVC Tubing has very poor UV resistance and will break down within a few years if not sooner"
That has not been my experience.
I have used "white" PVC DWV pipe for antenna insulators and trap forms for more than 20 years with no problems from UV at all.
73 de Jim, N2EY
|
| |
|
Antenna Spreaders
|
|
|
by WA7CS on March 20, 2008
|
Mail this to a friend!
|
The microwave method for checking the spreaders and insulators is a good valid check.
If a material does not get hot in the microwave, then it will not get hot at HF freqs. If the material gets hot in the microwave, that means it is absorbing a significant amount of the RF, and may also absorb significant amount of RF at your antenna.
Some confused commentors think this is a test for dielectric strength. This is not true, the microwave trick is for evaluation of the RF absorbtive qualities of the material.
WA7CS
|
| |
|
RE: Antenna Spreaders
|
|
|
by KB1LKR on March 20, 2008
|
Mail this to a friend!
|
"This is not true, the microwave trick is for evaluation of the RF absorbtive qualities of the material."
At least at High UHF/SHF frequencies. Value for HF is dubious, as microwave oven test is at ~2.45 GHz (~12.2 cm). Cool/cold should be good, but warm/hot is indeterminate.
UV resistant (often gray) PVC's (e.g. non metallic electrical conduit) may be a better choice than non-UV resistant (often white, also gray) PVC's.
See www.mcmaster.com or www.mscdirect.com etc. for UV resistant raw materials.
|
| |
|
Antenna Spreaders
|
|
|
by N3QE on March 20, 2008
|
Mail this to a friend!
|
There are lots of ways to make spreaders, and lots of materials.
The plastic decking certainly makes a heavy duty spreader. Most folks use something much more flimsy (e.g. PVC pipe, or strips of thin plastic sheet) and do just fine, and have less weight to suspend up in the aire.
But the real trick is attaching the wire to the spreaders (or the other way around) in a convenient way that will facilitate experimentation and maintenance. Len Cebik has some very good ideas on his web page about homebrew parallel transmission lines in figure 4: http://www.cebik.com/trans/par.html
Incidentally I think that the fan dipole is not the best approach. I tried it, was very unhappy with the results, and ended up doing an all-band doublet fed with homebrew parallel transmission line and a tuner - Len Cebik has a wonderful introduction at http://www.cebik.com/wire/abd.html
Tim.
|
| |
|
RE: Antenna Spreaders
|
|
|
by W5GNB on March 20, 2008
|
Mail this to a friend!
|
Personally I like the old method of using wooden dowls boiled in hot parifin wax. I have had some of these up for over Ten years and no problems as yet in the HOT New Mexico sun.
Also, the plastic spreaders present such a high impedance to the line that there is really no measureable loss even if it does fail the microwave oven test.
You are looking at low frequency RF on the line and the RF will follow it least resistive path, making the loss in the spreaders somewhat mute.
If you are using 2.4 Ghz and building radomes or such which will be near that frequency, the microwave test will be a good indicator of the properties for that frequency range but that is about it.
73's
Gary - W5GNB
|
| |
|
RE: Antenna Spreaders
|
|
|
by W9OY on March 20, 2008
|
Mail this to a friend!
|
I made some spreaders out of some corrugated plastic tubing. Super light weight, cut it with a pocket knife, and poke holes in the same spot on each part by counting the corrugation. I made some light weight open wire line using the same technique.
I use the Microwave to heat my Latte
73 W9OY
|
| |
|
RE: Antenna Spreaders
|
|
|
by W6TH on March 20, 2008
|
Mail this to a friend!
|
.
I still use wood for insulators and spacers. Today one can buy dowels, boil them in paraffin; A waxy white or colorless solid hydrocarbon mixture used to make candles, wax paper, lubricants, and sealing materials.
Cut the length and drill the holes before the paraffin dipping. This is what we old timers used back in the early years of ham radio and using the spreaders for open wire line.
When I returned home from Burma, after WW2, I brought back with me Teak wood and have boiled them in paraffin and had used them for over 45 years with my horizontal antennas and never had a problem, no arcing, fire and what not.
Microwave ovens are used for cooking and heating food please don't defeat its purpose.
W6TH
.:
|
| |
|
RE: Antenna Spreaders
|
|
|
by N1LO on March 20, 2008
|
Mail this to a friend!
|
Nicely written article and well illustrated.
I like those fiberglass driveway marker sticks from Lowe's. Some are 1/4" and some are 5/16".
Very light and durable.
If you just drill 1/16" holes through them, you can use wraps of #18 solid copper wire to attach the antenna wires, like making parallel line spreaders.
Very little work, and you don't have the tedious job of threading the antenna wires.
--...MARK_N1LO...--
|
| |
|
RE: Antenna Spreaders
|
|
|
by AC7ZL on March 20, 2008
|
Mail this to a friend!
|
Jim-
I gather that you live in PA. At that latitude, you might get away with using PVC in the manner in which you describe.
At my QTH, in Arizona, the UV will eat up exposed PVC pipe in months-- if not weeks.
Pete
AC7ZL
========================================================
N2EY said:
"PVC Tubing has very poor UV resistance and will break down within a few years if not sooner"
That has not been my experience.
I have used "white" PVC DWV pipe for antenna insulators and trap forms for more than 20 years with no problems from UV at all.
73 de Jim, N2EY
|
| |
|
RE: Antenna Spreaders
|
|
|
by W6TH on March 20, 2008
|
Mail this to a friend!
|
.
At my QTH, in Arizona, the UV will eat up exposed PVC pipe in months-- if not weeks.
Pete
AC7ZL
In California, the Mojave desert, the PVC will start to lose the gloss and then the gloss turns to powder and in the summer months, July, August, the PVC will disintegrate.
W6TH
.:
|
| |
|
RE: Antenna Spreaders
|
|
|
by N6AJR on March 20, 2008
|
Mail this to a friend!
|
|
plastic coat hangers.. just don't let the wife catch you cutting up HER hangers
|
| |
|
RE: Antenna Spreaders
|
|
|
by W8JI on March 20, 2008
|
Mail this to a friend!
|
Nice article but just one area of caution.
Microwaves are at 2 GHz, and only test for absorbtion of EM waves at 2 GHz. They can't test for voltage breakdown, leakage resistance, or any number of other critical characteristics.
HF Radios are at 30 MHz. Voltage breakdown and surface leakage when wet are critical. EM wave absortion at 2 GHz isn't very important.
An insulator that fails a microwave test at 2 GHz can be anywhere from very good to very bad, especially at 30 MHz or lower. An insulator that passes the microwave test can be anywhere from very bad to very good in the real world.
73 Tom
|
| |
|
RE: Antenna Spreaders
|
|
|
by N2EY on March 20, 2008
|
Mail this to a friend!
|
AC7ZL writes: "Jim-I gather that you live in PA."
That's correct, Pete. Suburbs of Philadelphia.
AC7ZL: "At that latitude, you might get away with using PVC in the manner in which you describe."
I've had antennas with insulators and trap forms made from white PVC DWV pipe and never had problems. This was in locations that got lots of sun, wind, acid rain, etc. The pipe loses its glossy finish in 5 years or so but is just as strong as new.
This may not be true of all types of PVC pipe, though.
AC7ZL: "At my QTH, in Arizona, the UV will eat up exposed PVC pipe in months-- if not weeks."
Interesting! Have you tried it? I mean, just putting a piece of pipe out in the elements?
What do they use for plumbing vent pipes in newer houses in AZ? In my old house on RadioTelegraph Hill, the vent pipe was cast iron, but in my present house and all the newer/renovated houses I see, the plumbing vents sticking out of the roofs are just white PVC. Is something else used where you are?
That white PVC DWV-type is the kind of pipe I use for antenna work.
73 de Jim, N2EY
|
| |
|
RE: Antenna Spreaders
|
|
|
by KG6WOU on March 20, 2008
|
Mail this to a friend!
|
I made up a two band parallel dipole using wood dowels because after looking around for alternate materials, I could not find anything that gave the same strength, light weight and small diameter [wind loading!] as wood. I painted mine with several layers of Krylon to make 'em disappear. Boiling in wax is also a good treatment.
I've seen some nifty pulsetruded stuff but most of it these days is carbon fiber, which I assume is not suitable for antenna use, but you could use fiberglass just as easily. With this type of material it becomes a question of how do you attach to the wires. It can be done but dowl with holes is faster I think, particularly if you have a drill press.
|
| |
|
Antenna Spreaders
|
|
|
by KI6JUU on March 20, 2008
|
Mail this to a friend!
|
|
Good Article...I wish I had thought of using the mw to check the material...At my age none of my legs, 75 meters or otherwise, will bend 90 degrees! Too soon old, too late smart.
|
| |
|
RE: Antenna Spreaders
|
|
|
by AC5UP on March 21, 2008
|
Mail this to a friend!
|
Next time you're at your local big box handy guy store, stroll over to the plumbing section and eyeball the C-PEX tubing. It's used as a semi-flexible pipe for rigging up water coolers and such. I've used it for spreaders and home brew ladder line spacers. Light, strong, cheap.
The 1/4" flavor makes good ladder line spacers. Use a tubing cutter to chop it to length then a 3" black Ty-Rap threaded dog-bone style around the wire and through the center of the tubing.
No problems with UV deterioration after ~10 years, no RF issues noted at HF.
|
| |
|
RE: Antenna Spreaders
|
|
|
by N4BWV on March 21, 2008
|
Mail this to a friend!
|
|
I agree. Pex rules. My mutiband doublet has been up for 5 years without problems.
|
| |
|
RE: Antenna Spreaders
|
|
|
by KC6KIM on March 21, 2008
|
Mail this to a friend!
|
doublet on the lowest band, 300 or 450 parallel line, 4:1 balun.... easy just be sure to have a good ground and a good tuner! Nothing could be easier!
Anthony
AKA The "Anthonator"
|
| |
|
RE: Antenna Spreaders
|
|
|
by N3QE on March 21, 2008
|
Mail this to a friend!
|
|
On the subject of deterioration in UV and high-ozone environments: it's remarkable how fast things like synthetic rubber will deteriorate in smog-zone areas in the summertime. Just sunlight seems OK, just ozone seems OK, but put some plastics or synthetic rubber under both sunlight and smog/ozone and kaboom, they're gone in weeks.
|
| |
|
RE: Antenna Spreaders
|
|
|
by K0VVX on March 21, 2008
|
Mail this to a friend!
|
|
My exsperace with uv and pvc is this. In South Dakota it's not much of a issue but in AZ with in 2 years it starts to discolor. But a easy fix is a uv resistance paint.
|
| |
|
Antenna Spreaders
|
|
|
by W1AEX on March 22, 2008
|
Mail this to a friend!
|
|
Nice article! I used the same thing AC5UP used, the 1/4 inch C-PEX tubing found at Lowes to build a 20-10 meter fan dipole. It worked great and has survived two years of New England weather. To fasten the wires, I cut a notch on each end of the tubing then held it against the wire and filled the end of the tubing with glue from a hot glue gun. Locks it right up and it holds everything together very well. I'm going to make new open wire line for my 160 meter antenna with the same stuff.
|
| |
|
RE: Antenna Spreaders
|
|
|
by K4JSR on March 22, 2008
|
Mail this to a friend!
|
G3LBS inquired, "Have any hams been boiled in paraffin?"
The answer is no. They only WAX POETICALLY.
|
| |
|
RE: Antenna Spreaders
|
|
|
by AE6RO on March 23, 2008
|
Mail this to a friend!
|
All this reminds me of an old Russian proverb:
"M'yagko s'dyelat da zhostka spat."
In English, "Easy to spread but hard to sleep."
Must be talking about 160 meters. 73, John
|
| |
|
RE: Antenna Spreaders
|
|
|
by G3LBS on March 23, 2008
|
Mail this to a friend!
|
W1AEX said 'To fasten the wires, I cut a notch on each end of the tubing then held it against the wire and filled the end of the tubing with glue from a hot glue gun'
Is it possible then to get glue from a glue gun which is waterproof please - I have always found that it deteriorates outdoors in wet weather?
|
| |
|
Antenna Spreaders
|
|
|
by K0RGR on March 24, 2008
|
Mail this to a friend!
|
I like the idea of using a tough plastic for the spreaders. I haven't used home-built spreaders myself, but my father did. When I was a teenager, I got the job of melting the paraffin wax. This is a dangerous process - paraffin is flammable, and it's possible to get it to explode when it's in liquid form. You have to create a 'double boiler' - I used Mom's big canning pot with the largest sized coffee can we could find inside it, with water in the canner. I wouldn't even attempt this on a gas range! And, it's a good day to send Mom and the kids to the movies, as long as you have a reliable way to call 911 yourself if needed.
We'd boil those wooden spreaders in the paraffin for a long time. They did provide good service, but when they got old, they got brittle and would break easily.
|
| |
|
RE: Antenna Spreaders
|
|
|
by KT8K on March 25, 2008
|
Mail this to a friend!
|
I had an old green plastic deck chair that had a leg broken off of it. I hid it from my wife in the lawnmower shed and later cut it into half inch strips with my jig saw. I melt holes in the strips as needed with a 100w soldering iron (using an old tip) and then attach wires to them with 18 gauge solid magnet wire. It seems like a bit of overkill, but it's definitely strong, and seems to work at my power levels (100w max, 5w 99% of the time). Before this I always used old toothbrushes with holes melted in the ends (and always leave the bristle-end on so the little birdies can brush their teeth when they sit on my antennas).
I don't know if it's a great dielectric, and it's certainly not the "glass doobies", but the antennas are working. Best rx & 73 de kt8k - Tim
|
| |
|
RE: Antenna Spreaders
|
|
|
by KE7NVY on March 26, 2008
|
Mail this to a friend!
|
|
I used the plastic coat hangers for my first multiband dipole a few months ago, and it's worked well. But that antenna was built using 22ga insulated wire, and after having the wire break a couple times I'm going to rebuild it. This time I bought a spool of 16ga insulated speaker wire, and it's big enough in diameter that drilling holes in those plastic coat hangers big enough for it to feed through will leave precious little of the spacer left. So I was looking through Home Depot a while back for a solution, and found some 3/8" OD translucent polyethylene tubing used for piping water to refrigerator built-in ice makers and the like. Is that the same stuff as the C-PEX that a couple people have mentioned?
|
| |
|
RE: Antenna Spreaders
|
|
|
by W4LGH on March 28, 2008
|
Mail this to a friend!
|
The easiest thing to do to build spreaders, end insulators is to use 1/2" PVC electrical conduit. This is the gray stuff, hides better than the white.
Cut it the length you need for wire spacing, then use a hacksaw to cut grooves into the side of the pvc. This will provide a nice snug fit for your wire. You can also use nylon wire ties to snug it up even more.
You can also cut 8" pieces for your end insulators.
For your center insulator, I have found that a piece of 1/4" thick plexiglass. Cut it to whatever size you need to handle the number of wires you are using,
73 de W4LGH - Alan
http://www.w4lgh.com
|
| |
|
RE: Antenna Spreaders
|
|
|
by K9GLN on March 30, 2008
|
Mail this to a friend!
|
|
All I have ever used at my station are parallel dipoles. I use small diameter PVC. Only tools needed are a hacksaw and a drill.
|
| |
|
RE: Antenna Spreaders
|
|
|
by WB0ETN on April 5, 2008
|
Mail this to a friend!
|
I use pexiglass. 1/4 inch is best. It is kinda pricy new, but I can always find some around that is too scratched up for normal use, and is being tossed out. Try your local sign shop. Cut and Drill as necessary.
I also check the local tanning salons. The pexiglass on the beds gets changed often because it cracks. One sheet 3' x 6' will make lots of spreaders. 73
|
| |
|
You must be a single man . . .
|
|
|
by KE5BCG on April 7, 2008
|
Mail this to a friend!
|
I'd be afraid to consider the consequences my XYL would come up with for using "her" microwave oven to test insulation materials.
It would certainly be worse than the time I used "her" dishwasher to clean my blackpowder pistols.
Good Luck!
Pete
K5BCG
|
| |
|
Antenna Spreaders
|
|
|
by K3SI on April 7, 2008
|
Mail this to a friend!
|
|
Ha anyone else thought of using spreaders cut from one of these synthetic cuting boards or nmc( non metallic conduit) the nmc is rated for exposure to sunlight and weather.
|
| |
|
Email Subscription
You are not subscribed to discussions on this article.
Subscribe!
My Subscriptions
Subscriptions Help
Related News & Articles
6-Meter Square Copper Dipole
Wire Antenna in Trees with Crossbow
The 'Lazy 7'
Where Do I Go from Here?
Other How To Articles
Measuring a Solid-State PA’s Zs
How to Help in an Emergency...Tools
6-Meter Square Copper Dipole
|
