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Topic:
Homemade HD antenna..any help?
This thread has 18 replies. Displaying posts 16 through 19.
Post 16 made on Wednesday September 5, 2012 at 19:27
WoundedKnee
Lurking Member
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September 2012
2
I'm no expert, but at this link are some measurements you'll probably find helpful to answer your questions 1,2 and 3:

http://www.tvantennaplans.com/

4 - If it were me, I'd put it in your attic, not the roof (others here can advise better)
5 - vertical, facing SE
6 - Flat works fine for me, but I've read that some have better reception if the left and right edges of the plate are bend forward a bit (others here can advise better)

Good luck!
Post 17 made on Sunday January 27, 2013 at 02:13
BIGCROW
Lurking Member
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January 2013
1
... i think crossing the 'joining' wires is important, as this may optimize the impedance of the signal carried by the current. It harkens a log-periodic broadband design, although the only thing that i can see that would make this antenna broadband would be:1. an increased thickness of the 'ear' metal,2. having the metal bare, and 3. non corroding element and lead wires, like aluminum or stainless steel. Whereas having thicker elements would make the antenna more receptive to various frequencies, it is important to note that the majority of the signal moves along the periphery of the metal, so no coatings and no corrosion will be best. Also, the vee shape of the elements accommodates broadband reception because of the 3 inch gap at the ends, the current 'seeing' a broader periphery than the actual thickness of the element wire.

Old analog tv had 6 MHz bandwidth to facilitate analog broadcasting of three or more separate signals, and i haven't studied digital, but maybe digital stations wouldn't require as much bandwidth, as a whole big analog wave for each television function, ie: audio, colour, actual picture, etc., would now me reduced to digital pulses instead. Hopefully someone here knows about these intricacies...

Another reason, probably, for this 4 tiered arrangement would be it's space saving property. A big, long yagi log periodic might make the neighbors jump...
Post 18 made on Sunday March 31, 2013 at 13:30
Ernie Gilman
Yes, That Ernie!
Joined:
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December 2001
30,104
On January 27, 2013 at 02:13, BIGCROW said...
Whereas having thicker elements would make the antenna more receptive to various frequencies, it is important to note that the majority of the signal moves along the periphery of the metal, so no coatings and no corrosion will be best.

Why? A coating will simply be a (likely) non-conductive cover over the actual outer diameter of the element. It should not interfere with the signal at all. On the other hand, corrosion will indeed interfere with the operation of the antenna as a)it could well be non-conductive variety of the metal, such as rust, which might actually act as a shield (just guessing) and corrosion will reduce the diameter of the conductive part of the antenna, sharpening its tuning, i.e. making it less broadband.

Also, the vee shape of the elements accommodates broadband reception because of the 3 inch gap at the ends, the current 'seeing' a broader periphery than the actual thickness of the element wire.

Makes sense.

Old analog tv had 6 MHz bandwidth to facilitate analog broadcasting of three or more separate signals,

Sorry, wrong; the analog signal occupied 6 mHz of bandwidth, including a dead band on each side to reduce co-channel interference.

and i haven't studied digital, but maybe digital stations wouldn't require as much bandwidth, as a whole big analog wave for each television function, ie: audio, colour, actual picture, etc., would now me reduced to digital pulses instead. Hopefully someone here knows about these intricacies...

The channel frequencies have not changed, leaving 6 mHz betweeen carriers, so even if that's true, it has no effect on the situation. And digital signals need to be "condensed" because they have so many more individual signals than analog signals.

Another reason, probably, for this 4 tiered arrangement would be it's space saving property. A big, long yagi log periodic might make the neighbors jump...

Nope. This is four individual antennas, their signals adding up for more output, their vertical arrangement making them more vertically directional, that is, more sensitive to pointing up or down than a single element would be.

I'm surprised that there's no reflector on the back of this antenna. The screen you usually see on the back side of a commercial antenna of this sort increases the signal at least a couple of dB as well as increasing directionality.
A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
Post 19 made on Sunday December 15, 2013 at 15:48
ota_user
Lurking Member
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December 2013
2
I need help building a single channel yagi for Channel 14 (470-476 Mhz). I've been all over the internet and have downloaded many different yagi calculators. Problem is every program gives me different numbers. I've never built an antenna before but I've installed my current system (i.e. stacked 91xg's on 50 foot tower).

Can someone direct me how to build a 10 element yagi with a strict 5 Mhz bandwidth for RF14? I need help with diameter of directors, impedence, place to purchase supplies, balun, etc. I need to make sure RF15 doesn't interfere with the narrow band I need to get channel 14.

The reason for this is that Hamilton Mountain (South) has completely lost reception for WUTV because of CHCH now broadcasting on RF15. CHCH's adjacent signal is effectively acting as a jammer for Fox 14 and Zuus 14.2. Where Fox used to be a consistent signal, Hamilton Mountain is now getting no signal bars for WUTV. I used a notch filter and a quarter stub notch to block out CHCH but to no success. I'm hoping a single channel yagi pointed precisely a Grand Island will get me my original reception for Fox and Zuus.
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