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Built a DIY Coat Hanger Antenna - HOLLY - - - -

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Old 04-02-2010, 09:18 PM   #1
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Join Date: Apr 2010
Location: Winchester, CA
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Talking Built a DIY Coat Hanger Antenna - HOLLY - - - -

Ok, so I just built one of those DB4-like antennas and hooked it up. I am pulling stations out of Los Angele Mt. Wilson which is something like 70+ miles away with no preamp or anything. I'm blown away!

Click here to see a map of how far I am from the towers

And here are some pics:
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So yeah, just thought Id share! Thanks...
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Old 04-02-2010, 10:33 PM   #2
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How about you post your tvfool results.

I started with one of those and I was able to pull in WIVB 4.1 from a little over 100miles away. I got to watch the superbowl on a "real American" channel without the stupid Canadian commercials.

It had to be pointed just right and I could only get one other Buffalo station with it. My CM4228 works much much better.

Good start now imagine what you could do with a CM4228 or similar antenna. I don't think the coat hanger is gonna last outside anyways.

here's my tvfool and 100mile plus pull on wivb channel 4
http://www.tvfool.com/?option=com_wr...27eead661c837d
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Old 04-02-2010, 10:37 PM   #3
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Ohh and for more fun try making a reflector for it. That will improve your front to back ratio and make it more powerful in the forward facing direction. I made my reflector out of a large piece of cardboard and aluminum foil.
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Old 04-02-2010, 11:22 PM   #4
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Here's my TVFool Report...

http://www.tvfool.com/?option=com_wr...b7c8e8bfee8f3f
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Old 04-10-2010, 01:32 PM   #5
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Hi Daniel,
Sounds like you got some very promising results from your first effort - bravo! It's always nice to see someone trying to roll their own!

I do think you can improve on the both the performance and the longevity of the antenna out in the elements by re-building. A fellow called mclapp has done extensive computer modeling of the 4-bay bowtie design and fine tuned it for optimum performance. His improvements have been verified in real world usage. Do a little searching and you'll find all the details.

First is that wood is a no-no, especially outdoors - it holds moisture which will upset the impedance of the antenna. Use PVC pipe, galvanized elect conduit or alum tubing with insulating standoffs for the elements & phase lines.

Use either #8 or #10AWG aluminum ground wire or copper wire for the elements & phase lines - steel coathangers will rust outdoors and your performance will suffer.

The large fender washers you used for mounting also come relatively close to each other for the phase line spacing - try and use something smaller to avoid upsetting the impedance.

The whisker elements S/B 9.5" long spaced 9" apart, spread ~4" apart at the ends. I noticed you used a bit of a loop on the phase lines at the crossover points, which is good but being on one leg only it is messing with the phase balance of the lines. If you use standoffs on a pipe spline there will be room to do a nice smooth crossover while maintaining an ~1" space thru the crossover and keep the lines equal length. Phase lines S/B 1.25" apart otherwise, BTW.

Adding a reflector as LovesTheOTA has mentioned will improve both the gain over the UHF band and also give the antenna some positive gain over VHF-High too - use 1"x2" rectangular wire fencing with the horizontal wires in the 1" direction. It S/B 36"wide x 40" tall, spaced 4.5" - 5" back from the whisker elements.

Here's a video on a 4-bay build that follows the mclapp design:
http://www.youtube.com/watch?v=BcUSW2l6MSI
It uses reflector rods, but the wire fencing is (IMHO) easier and will achieve better results.

And one on straightening wire so your build comes out looking nice & professional and consistent:
http://www.youtube.com/watch?v=-8HoeP9beYE

Looking at your tvfool report I would aim the antenna @308 since that's where the bulk of your stations are, and you should be able to get RF12 @ 281 & RF26 @ 337 since they're strong. You should have a shot at RF 7, 9, & 11... RF13 becomes a bit more iffy. I notice you didn't put in a height for your report, which can make a difference. If you can mount the antenna on a piece of 1-1/4" galvanized electrical conduit 10' lg and get it above the roofline it should perform even better. (Putting a 20'-25' height in tvfool should improve signal strengths.) Be sure to use your exact address, or the tvmaps feature on tvfool to get as close to the actual location of the antenna as possible for the most accurate prediction.

If you find you have a solid lock on your stations but lose it due to weather, you can add an amp - a Winegard HDP-269 will give your lower level signals a bump and should bring them back from over the cliff with no chance of overload from any stronger ones.

Properly constructed a 4-bay mclapp should come very close to the performance of a CM4228 for a fraction of the cost - and you'll have the satisfaction of having done it yourself!

Hope this helps,
Hooper
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Some details on my DIY antenna builds:
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Some tips for newbies posting to the forum for the first time:
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