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Author Topic: Can a 24-30 foot fiberglass flagpole be used to support wire antennas?  (Read 489 times)

WA7OPV

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I am looking for a way to put up my 80 meter horizontal loop.  I have recently learned about 25 to 30 foot tall flagpoles that are self supporting.  Could they support a wire antenna like that without guys?  I simply don't have enough room for guys and just barely enough for an elongated rectangular loop. 

Has anyone tried this idea?

-david BTW
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KH6AQ

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Without one back guy line on each flagpole I would use #26 copperweld such as Wireman 534 wire to keep forces down.

Wire https://thewireman.com/product/antenna-wire-26-awg-copper-clad-steel-stranded-jacketed/


This 28' fiberglass flagpole tapers to just 0.87" diameter at the top.

https://www.flagsimporter.com/28ft-fiberglass-telescoping-flag-pole?gclid=Cj0KCQjw8e-gBhD0ARIsAJiDsaXenwbzEn9pl8QMLd7kUpt60etK4zxLPiEgyebJLd8sw5XXQA82CUEaAiQPEALw_wcB#product.info.description
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W6SWO

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I used an MFJ one to support an end-fed wire, but after only a couple of weeks in the desert southwest, it crumpled and put my antenna on the ground.  If intense sun/UV rays aren't a big consideration, you might get away with using a fiberglass mast if you find a heavier duty one.
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WB6BYU

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Depends on the wire size, wind load, and how much bending
you are willing to tolerate on the supports.

The weight of the wire between supports causes a sideways
force, even without wind loading.  The greater the tension
on the wire, the less sag, but the more the poles will bend.

You can get a sense of the amount of bend by looking at how
it reacts with a flag on it in the wind.  They should be better
than the top section of some of the telescoping fishing poles.

Lighter wire certainly helps - I  use #26 stranded, insulated
hookup wire, although sometimes I have had to replace the
wire every couple of years, as the insulation provides much
of the strength, and some types will crack out in the sun.

Of course, when a hawk or owl lands in the middle of the
wire, that will bend the supports even more!

Feeding the loop in a corner (so the weight of the feedline
is on one of the masts, rather than hanging in the middle)
will reduce bending as well.


There are various ways that you can reduce the size of the
loop for 80m without affecting the radiation too much.  The
wires can be folded (which requires more wire), or loading
coils added (again, preferably at the supports, to minimize
the weight hanging between them).  It will also depend on
the reason for choosing a loop, and of that particular shape,
in order to maintain the desired qualities.

For example, by bow-tie figure-8 loop is designed to maintain
high angle radiation on both 80m and 40m (which isn't always
the case with other loops shapes).


Meanwhile, you might consider a "back stay", as often used
on a sailboat.  Basically it is a back guy to stiffen the mast
that is attached near the top, goes over a spreader of some
sort, and ties back to the base of the mast.  It provides some
rear support without taking up any ground space (although
a bit of overhang if you are at a property boundary).  However,
it can require quite a bit of tension, and using wire with a
turnbuckle is often a good approach.  (And the mast has to
be able to support the extra downward pressure without
buckling.)

Otherwise, a prop on the inside of the corner may help since
it doesn't extend beyond the loop, although that will need to
be pretty long.

W6MK

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I support my doublets with 30 ft. fiberglass telescoping poles, available from DX Engineering or MaxGain Systems. The poles need to be of sufficient OD; a minimum of 1.5 in. OD for the top pole which means a 2.5 in. OD bottom pole for a 30 ft. mast composed of four 8 ft. sections.

I support my feed line with a pole at the center of the antenna. I use #24 steel core copper-plated stranded antenna wire for minimum side loading.

Bottom line: if the masts are sufficiently robust and the wire load minimized AND the feed line is fully supported at the center of the antenna, you will have a very durable, long-lasting antenna.
The masts themselves need to be well-supported. I strap them to properly-installed 4x4 fence posts or to a pair of steel wall brackets.
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WA7OPV

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The flagpoles I refer to are MUCH stronger than the telescoping flagpoles.   I know for sure the telescoping poles even at just 25 feet would need guys. I was referring to something like this:  https://www.united-states-flag.com/25ft-residential-fiberglass-pole.html

4.25 inches at the base for example.  Top is 2.75 inches.  Expensive for sure, but maybe it might work?

-david BTW  WA7OPV

« Last Edit: March 23, 2023, 12:42:11 PM by WA7OPV »
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W6MK

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I know for sure the telescoping poles even at just 25 feet would need guys.

From my perspective using a very robust, expensive flagpole simply to support a piece of wire at 25 ft. is excessive and far too expensive. I didn't look at the type of foundation that needs to be
prepared, but it would need to be substantial (and costly).

My suggestions for telescoping masts for supporting wire antenna at heights up to about 40 ft. are based on getting more than adequate performance at reasonable cost and ease of installation.
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WA7OPV

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Hello W6MK.  I quite understand your comments. The cost is very high.  If I could figure out how to use fiberglass telescoping I would use it, with the knowledge that they will require a backstay of some kind. 

-david BTW
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AC6LA

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For example, by bow-tie figure-8 loop is designed to maintain
high angle radiation on both 80m and 40m (which isn't always
the case with other loops shapes).

I'm wondering if Dale meant to show this link to a page on his Practical Antennas site:

Bow-Tie Horizontal Loop

Dan, AC6LA
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WB6BYU

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    • Practical Antennas

Thanks, Dan.

Yes, I got interrupted and didn't get the link inserted properly.

W6MK

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Re: Can a 24-30 foot fiberglass flagpole be used to support wire antennas?
« Reply #10 on: March 23, 2023, 08:51:57 PM »

I quite understand your comments. The cost is very high.  If I could figure out how to use fiberglass telescoping I would use it.

No backstay is needed if the fiberglass tubing is of adequate size for its height, the size of the antenna wire is appropriate and the mast is adequately secured to a sturdy existing structure or mounted on a metal post properly set in the ground.
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KD6VXI

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Re: Can a 24-30 foot fiberglass flagpole be used to support wire antennas?
« Reply #11 on: March 24, 2023, 04:01:39 AM »

I've had a 32 foot DX Commander vertical in the Caribbean for a year.

No degradation in the fiberglass noted thus far.  It came down for a week during tropical storm Fiona, was laid next to the house.  Other than that, has been standing for a year.

I took it down Thursday to look at the base / clean some vegetation that had grown up into the feed point area and there was no degradation in the fiberglass noted.

--Shane
WP2ASS / ex KD6VXI
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WB8PFZ

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Re: Can a 24-30 foot fiberglass flagpole be used to support wire antennas?
« Reply #12 on: March 24, 2023, 04:51:49 AM »

Not sure how this pole is constructed, would it be possible to fill it with fiberglass resin to make it stronger?
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N9SD

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Re: Can a 24-30 foot fiberglass flagpole be used to support wire antennas?
« Reply #13 on: March 24, 2023, 05:45:06 AM »

Absolutely you can.

Personally, I use a 24’ fiberglass extendible painters pole from Home Depot. It holds up an 80m doublet just fine. With that support holding up the doublet, I parked mobile and came in second place single op low power in the WIQP about 3 or 4 years ago. Plus we use it for field day every year.

If you don’t like the color, extend it out and paint it. I use three camouflage colors so you can’t even see it from 10’ away when it’s erected in the woods.
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WA7OPV

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Re: Can a 24-30 foot fiberglass flagpole be used to support wire antennas?
« Reply #14 on: March 24, 2023, 12:46:42 PM »

Thanks for all the comments.  This will be installed in my back yard using metal fence posts, most of which are properly cemented into the ground for all four corners.  I have also considered using aluminum pipe for the bottom part of the masts with fiberglass on top where the loop in supported.  I want to avoid metal around the tie points in the four corners.  in addition, for a large part of this there is an 7 foot high chain link fence.

And as I posted before on the forum, there will be a Zero Five 80-10m Ground Plane (GP-43) inside the loop mounted 8 feet off the ground.

These antennas will have to last me as my last ones for retirement. 

-david BTW
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