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Author Topic: Best way to mount EndFedz 10-20-40  (Read 3873 times)
AF6WI
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« on: December 05, 2011, 04:26:58 PM »

I'm adding this to my wishlist, and I'm reading different statements on radiation over on the product review side. My goal is to have it radiate as near to 360 degrees around my house as possible; the other preference is to have it radiate east/west. I have no trees, and no yard (I'm in a condo), but I can mount it vertically on the side of the condo, inverted L up the side and across the roof, or as a sloper from eaves to chimney top.

Any discussion on how to have a full 360 or 180 would be appreciated, as would references to articles on how to mount an end fed antenna for directionality or lack thereof.
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WB6BYU
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« Reply #1 on: December 05, 2011, 05:29:45 PM »

The buildings will make more difference in the pattern than you can by changing the
way you mount it.

Ideally you would mount it vertically for best omnidirectional coverage - on top of the
building if you want to keep it out of the pattern.  If you string it up horizontally then
radiation will be maximum broadside to the antenna (though there will be some in other
directions as well.)

Anything else will be some combination.  This is a trapped end-fed half wave antenna,
right?  Then if you install it as an inverted L the 10m and 20m sections are likely to be
primarily vertically polarized, while the 40m one may be mixed (depending on where you
put the bend.)  That's not a bad combination.

The truth is, just about anything you do will work in most directions, though some may be
better than others.  The amount of directivity you can get from a half wave antenna is
limited:  slopers may have a slight bit of directivity, but it depends on the radiation angle
and earth characteristics, and other wires and structures in the vicinity will probably make
more difference to the patterns than that from the antenna itself.

So just put it up and use it.  Hang it form whatever high support you can manage and try
to keep it away from the building if possible.


As far as articles on directivity of an end-fed antenna:  if it has traps the pattern will be
the same as for a half wave dipole.  You should find lots of information about that.

If it doesn't have traps, but uses the 40m wire as a full wavelength on 20m and 2 wavelengths
on 10m, then it gets more complicated.
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AF6WI
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« Reply #2 on: December 05, 2011, 05:48:47 PM »

> So just put it up and use it.

Y'know, that's always good advice. :->

Thanks.
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KQ6Q
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« Reply #3 on: December 06, 2011, 10:37:18 AM »

Basic rules on optimizing an antenna - higher is better.
A Clear shot at the horizon without going through buildings is better.
It sounds like running from eaves to chimney top would be worth a shot.
Since it's just a wire antenna, you could try it in a couple of configurations
and see which works best. Best time to test is during a contest or other
activity when there will be lots of stations to work easily. 10m contest
this weekend, SKN coming up in a few weeks, or some of the SKCC weekend
sprints would be good times.
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AF6WI
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« Reply #4 on: December 07, 2011, 11:42:17 AM »

> Since it's just a wire antenna, you could try it in a couple of configurations and see which works best.

Eeeeh -- I'm in a condo, and it's three stories high. So 'just a wire' is right, but climbing out on to a sloping roof 3 floors to asphalt (I'm mid-60s, too) several times to try different configurations gives me pause.

That's one of the reasons I'm hoping there's a generalized answer to the questions: is an inverted L more or less directional than a sloper? I understand there's no specific answer given too many unknowns, which is why references to materials I could read would also be appreciated. My google-foo is failing me on that search, and I could read up on all the variables and see how they might apply to my townhouse life.
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WB6BYU
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« Reply #5 on: December 07, 2011, 12:31:04 PM »

See if this helps you understand the sloper...

http://www.cebik.com/content/a10/wire/sloper.html
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AF6WI
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« Reply #6 on: December 07, 2011, 01:22:27 PM »

See if this helps you understand the sloper...

http://www.cebik.com/content/a10/wire/sloper.html

His site is subscription-only now. I paid for a subscription once and either lost it or let it expire. I appreciate that his heirs want to make some money off his site, but I'm not sure I want to support his heirs, as opposed to the world-renowned Mr. Cebik himself. shrug -- anyway, I can't get into any pages of his that you link to.
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WB2WIK
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« Reply #7 on: December 07, 2011, 01:30:20 PM »

What's the building exterior material?

Around here a lot of condos/town houses as well as private homes are "stucco."  If yours is stucco, anything placed alongside it won't work well at all.  In that case, I'd use the roof idea (eave to chimney top) to get it above the stucco.

If it's just "wood" or something that isn't a terrible dielectric like stucco is, then the vertical orientation will probably work pretty well.
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WB6BYU
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« Reply #8 on: December 07, 2011, 01:59:03 PM »

Quote from: AF6WI

His site is subscription-only now...


Actually there is no charge for a subscription to his site.  You just have to sign up.

It is run by Antennex magazine, which does charge for subscriptions to other content on their own site.
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AF6WI
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« Reply #9 on: December 07, 2011, 07:08:32 PM »

On the other hand, maybe I could just tune up this chair: http://gizmodo.com/5865994/sat-chair-hides-your-satellite-dish-in-plain-sight.

> If it's just "wood" or something that isn't a terrible dielectric like stucco is, then the vertical orientation will probably work pretty well.

Yep, wood shingles. Thanks for the suggestion.

> Actually there is no charge for a subscription to his site.

Great -- many thanks for clearing up my confusion.
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