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Homemade HD Antenna

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Old 12-03-2007, 10:39 AM   #31
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Listen I'll give it a try still don't worry.. Your heart was in a good place to share this info and real images with us.. Pictures tell more than the eye can see as the mind really can't see. Like I had said prior I use to do things like this well not building stuff for HD yet but I would like to see for myself if it really works as you say.. But you know it works and that's good enough for me!
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Old 12-03-2007, 04:43 PM   #32
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Quote:
Originally Posted by XDRoX View Post
Just wanted to point out amongst some of the confusion that this antenna does get High Definition for free.
When hooked to my TV, I get the following extra digital stations:
6.1 (fox)
8.1 (CBS)
10.1 (ABC)
15.1 15.2 (KPBS)
39.1, 39.2 (NBC)
51.1 (KUSI)
69.1 (???)
and many other Spanish stations (possibly coming from Mexico, I live 30 miles from the border).

Amongst these digital stations, yesterday I saw high definition being broadcasted in 16:9 picture ratio on:
6.1 (fox)
8.1 (CBS)
15.2 (KPBS)
I don't know how many other of these digital stations broadcast in HD, but I know at least these one do.

Everything that has been posted above by Loves2watch and BrianO is very true and worth pointed out, I just didn't want any new readers misinterpret and think that the antenna did not get HD.
It is a UHF antenna, but it can handle both analogue and digital (including) HD broadcasts. It is not designed to handle VHF broadcasts, but it might work for some nearby strong VHF stations.

VHF is channels 2 to 13
UHF is channels 14 to 69 (14 to 51, starting Feb 18, 2009)

The channels that you have listed are virtual channel numbers that do not tell you what actual RF channel is being used for digital broadcasts by those stations. The number before the decimal point in a digital virtual channel number usually corresponds to the analogue channel number of the station. Consequently you cannot tell whether the digital broadcasts are on VHF or UHF just by looking at the virtual channel number.

I can not find any technical info for the Fox channel, since I believe it is located in Mexico. However, all of the other channels you have listed currently broadcast their digital programming on UHF but two of them will switch to VHF in 2009.

KFMB (CBS) broadcasts its analogue on channel 8 and its digital on channel 55. ie. Virtual channel 8.1 is actually broadcast on channel 55. In 2009 KFMB will switch its digital broadcasts to VHF channel 8.

KGTV (ABC) broadcasts its analogue on channel 10 and its digital on channel 25. In 2009 KGTV will switch its digital broadcasts to VHF channel 10.

KPBS (PBS) broadcasts its analogue on channel 15 and its digital on channel 30. It will keep its digital broadcasts on channel 30 after the analogue shutdown.

KNSO (NBC) broadcasts its analogue on channel 39 and its digital on channel 40. It will keep its digital broadcasts on channel 40 after the analogue shutdown.

KSWB (CW) broadcasts its analogue on channel 69 and its digital on channel 19. It will keep its digital broadcasts on channel 19 after the analogue shutdown.

KUSI (Ind) broadcasts its analogue on channel 51 and its digital on channel 18. It will keep its digital broadcasts on channel 18 after the analogue shutdown.

Although I have posted this info for San Diego before, I am repeating it here so new readers do not get the impression that the antenna can handle VHF (channels 6, 8 and 10 have been mentioned) well. All the stations mentioned broadcast their digital TV on UHF channels.

Last edited by BrianO; 12-03-2007 at 04:49 PM.
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Old 12-03-2007, 04:53 PM   #33
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That makes perfect sense and thank you for the info.
One more question, is there any way of knowing whether or not channels will continue to broadcast in HD? It seems that people using antennas are a thing of the past. So why would companies still broadcast in HD if they don't have to?
I understand that companies have to switch to digital, but why are they broadcasting in HD if they don't have to, will it last?
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Old 12-03-2007, 05:45 PM   #34
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so will you still be getting the same channels starting feb 08?? with this antenna??
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Old 12-03-2007, 05:55 PM   #35
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BrianO's post above explains what stations you will get after the switch over. As long as the channel is a UHF station you will get it.

But now a new question, is it just as easy to make a VHF antenna???
My guess is no, or someone would have already chimed in, but I'll research it.
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Old 12-03-2007, 06:11 PM   #36
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But now a new question, is it just as easy to make a VHF antenna???
Nope, they get real BIG in comparison.

Look at the old rooftop units. all of those huge elements are there for VHF. All of the bow-tie or other funny shaped tiny elements are for UHF.

Actual antenna size is a function of wavelength and wavelength is inversely proportional to frequency.
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Old 12-03-2007, 06:23 PM   #37
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Quote:
Originally Posted by XDRoX View Post
BrianO's post above explains what stations you will get after the switch over. As long as the channel is a UHF station you will get it.

But now a new question, is it just as easy to make a VHF antenna???
My guess is no, or someone would have already chimed in, but I'll research it.
Yes, it is just as easy, but the elements are longer.

Perhaps 10 times as long.

Otherwise, yagis are yagis.

Depending on your distance to the transmitter, you might consider a simple dipole (two elements). Perhaps good for 2-6 miles if mounted outside, or 1-2 miles if mounted in the attic.

There comes a point (and VHF antennas approach it), where it is simplier and just more practical to buy the antemma.

Google "VHF antennas for TV" and you'll see what I mean.

(Bedsprings will work if you're close!)

Best of luck, my friend.
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Old 12-03-2007, 06:39 PM   #38
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Default A little more about antennas.....

Most antenna manufacturers design and test their antennas in an anechoic chamber like this one:



The higher the frequency (UHF) the more accurate the element length and spacing needs to be. The lower (VHF) frequencies are more forgiving.

VHF is easy.

Microwave is more precise.

Antennas are fun and easy to build. I encourage you to try!

(I try and stumble with them every day! LOL)
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Old 12-03-2007, 09:10 PM   #39
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Can't find copper at Home Depot rods or ground wire use in electrical wiring.. I might have to back and look. Our HomeD is mix up in the aisle.. Took forever to find DAP..
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Old 12-03-2007, 10:14 PM   #40
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Quote:
Originally Posted by pearltone View Post
so will you still be getting the same channels starting feb 08?? with this antenna??
Yes and no. It depends on where you live.

In the San Diego example above, 2 stations that are now broadcasting their digital programming on UHF channels 55 and 25 are switching their digital programs to the VHF channels (8 and 10) that they are currently using for analogue. This antenna is not designed to pick up those VHF channels, but it will continue to receive the other stations..

In many other areas all stations will be broadcasting digitally on UHF and an antenna of the type being discussed (4 bow tie UHF) will suffice.

BTW, it's February 2009 rather than 2008.
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Old 12-03-2007, 11:00 PM   #41
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Quote:
Originally Posted by Scottnot View Post
Nope, they get real BIG in comparison.

Look at the old rooftop units. all of those huge elements are there for VHF. All of the bow-tie or other funny shaped tiny elements are for UHF.

Actual antenna size is a function of wavelength and wavelength is inversely proportional to frequency.
Wasn't that old "bow tie" shaped antenna on our roofs a UHF receiver ?

A question: Are the lengths of wire in this homemade antenna required to be exact to receive the DTV stations correctly, how far the V's stick out fromthe center of the board ?
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Old 12-03-2007, 11:12 PM   #42
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Quote:
Originally Posted by XDRoX View Post
I just did a search on Yahoo and here is a much better one:

Hey HDRoX, in this photo is that an old fridge's cooling/condensing coils with a copper UHF annached ? I don't see any notes to go along with the photo, do you think the DTV copper ant part was attached to the cooling coils or were they using it as a seperate VHF antenna ?
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Old 12-04-2007, 05:31 AM   #43
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Quote:
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Hey HDRoX, in this photo is that an old fridge's cooling/condensing coils with a copper UHF annached ? I don't see any notes to go along with the photo, do you think the DTV copper ant part was attached to the cooling coils or were they using it as a seperate VHF antenna ?
Any copper will do ... Don't use alumin it won't work.. I had made a an alumin tree using a real tree to house stran 3 years ago. Then I made a quick root ANT using 6 old rabbit years from some family members who wanted some very cheap.. That worked for ANTV.. Still up there on the roof today!

Last edited by tipstir; 12-04-2007 at 05:39 AM.
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Old 12-04-2007, 06:43 AM   #44
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Quote:
Originally Posted by hdgtx View Post
Wasn't that old "bow tie" shaped antenna on our roofs a UHF receiver ?
Yes.

Quote:
A question: Are the lengths of wire in this homemade antenna required to be exact to receive the DTV stations correctly, how far the V's stick out fromthe center of the board ?
They should be "relatively" exact, since they determine the frequeny of the antenna, but basically, the design should center them near mid-band (remember, UHF is 470MHz - 890MHz), so it does not have to be "exact", just close.

Distance off of the board is not critical, the board is only there as a support structure, not a reflector.
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Old 12-04-2007, 06:52 AM   #45
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Quote:
Originally Posted by hdgtx View Post
Hey HDRoX, in this photo is that an old fridge's cooling/condensing coils with a copper UHF annached ? I don't see any notes to go along with the photo, do you think the DTV copper ant part was attached to the cooling coils or were they using it as a seperate VHF antenna ?
Note that the UHF elements are insulated from the cooling coil by wood "standoffs". I suspect the refrigerator coil is intended as a reflector to increase the gain of the antenna.
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