How To Receive Ota Hd Below Channel 14 Uhf

[logandiana]

While tuning in my over the air channels for HD, I found there is one channel that won't get a good signal. I have two UHF antennas

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=15-2160

and I used the antennaweb.org to point them in the correct directions. All channels are on just two vectors (69degrees & 77degrees) and come in great with strength levels about at 80 and higher on the STB. The only channel that doesn't come in great is the local ABC which is normally analog channel 8 but with a Digital channel of 9. The best signal I could pick up after an hour or two of tweaking was a strength level of about 30. The channel finally tuned in but barely and would break up all the time. Then it occured to me that the antennas that I have are UHF for channels 14-69. Is this the reason why I can't pick up digital channel 9??? This is the only channel that is below 14 on the list of channels in my area. What can I do to pick up this channel better???
The antennas are mounted in the attic and I am between 23-24 miles from all stations. Should I add a pre amp? If so which one?

Thanks

[Ratman]

You will probably need a VHF antenna.

[mjones73]

Second that, it's a VHF channel, you need a combo VHF/UHF antenna...

[logandiana]

is there a small inexpesive vhf that I can be recommended?

Thanks

[mjones73]

Small and VHF don't go together... At your range, this might do the trick.. It should be able to do what your Yagi's are doing now also...

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=15-2151

How are you joining the two Yagi's you have now by the way?

[Ratman]

You could also try this for your VHF channel. If it doesn't work, return it.

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F003%5F001%5F001%5F000&product%5Fid=15%2D1864

But... as mjones74 suggested, a combo antenna is the best option.

[D.Russell]

What does HDTVPUB have your channels listed at? See if it's a Digital coming off a VHF Frequency? Or it just might be Re-mapped to Channel 9 ?

http://www.hdtvpub.com/

[Ratman]

The only channel that doesn't come in great is the local ABC which is normally analog channel 8 but with a Digital channel of 9.

If this is accurate... it looks as if the digital is in fact channel 9.

[logandiana]

I got a pair of plain rabbit ears from radio shack on the way home.

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F003%5F001%5F001%5F000&product%5Fid=15%2D236&hp=search

I just zip tied the small plastic piece to the mast that supports my UHF antennas. The I just extended the antennas as far as they would go out to each side and viola. I only needed to pick up the one channel. Before I was getting a signal strength on the channel 9 of about 25 -30. After it is more like 80-85. Picture on digital channel 9 comes in great. And all my other channels are the same as before.

Thanks

[Ratman]

Super! Good job!

[huhl118]

While tuning in my over the air channels for HD, I found there is one channel that won't get a good signal. I have two UHF antennas
....

The antennas are mounted in the attic and I am between 23-24 miles from all stations. Should I add a pre amp? If so which one?

Thanks

May I know your setup of the antennas? Do you need an A/B switch to switch between the two antennas?

[logandiana]

I have two 15-2160 UHF only antennas

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F003%5F001%5F002%5F000&product%5Fid=15%2D2160&site=search

that I purchased from radio shack. According to antennaweb.org. all my digital channels are either at 77 degrees or 69 degrees. I mounted a 5 foot mast in my attic and aimed one antenna at 77 and one at 69 using a compass. The antennas have a couple of screws that you connect one of these to:

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=15-1230

Then I connected coaxial cable to this part on both of the antennas. The two coax cables are about 4 feet long and come together in a splitter/combiner,

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=&product%5Fid=15%2D1234&site=search

where they are combined into one coax that goes into the back of the hd box.
Except for the 1 vhf channel that wasn't coming in, everything was getting high strength signals around 85-90 on my hd box. By the way the vhf antenna that I bought also has a twin wire lead which I connected to the terminals on one of the UHF antennas. I will try and email a picture on here if possible or if anyone is interested.

Thanks

[huhl118]

I have two 15-2160 UHF only antennas

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F003%5F001%5F002%5F000&product%5Fid=15%2D2160&site=search

that I purchased from radio shack. According to antennaweb.org. all my digital channels are either at 77 degrees or 69 degrees. I mounted a 5 foot mast in my attic and aimed one antenna at 77 and one at 69 using a compass. The antennas have a couple of screws that you connect one of these to:

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=15-1230

Then I connected coaxial cable to this part on both of the antennas. The two coax cables are about 4 feet long and come together in a splitter/combiner,

http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=&product%5Fid=15%2D1234&site=search

where they are combined into one coax that goes into the back of the hd box.
Except for the 1 vhf channel that wasn't coming in, everything was getting high strength signals around 85-90 on my hd box. By the way the vhf antenna that I bought also has a twin wire lead which I connected to the terminals on one of the UHF antennas. I will try and email a picture on here if possible or if anyone is interested.

Thanks

Hmm, sounds like you are doing exactly what I was adviced not to do by one of my coworkers... two antennas combined into one coax. I guess I will have to try it out myself. Thank you very much for the reply.

[Ratman]

Hmm, sounds like you are doing exactly what I was adviced not to do by one of my coworkers... two antennas combined into one coax.


Ha-ha.. yeah. That's the general concensus. And that's usually the correct advice.

With two antennas pointed in different directions, you can increase multipath and make reception worse. Also, using a combiner (hybrid splitter/conbiner) you will halve the signal.

But! That's what experimentation is all about. There are no 'hard/fast' rules when it comes to OTA reception. What works for you may not work for the guy next door!

[huhl118]

Ha-ha.. yeah. That's the general concensus. And that's usually the correct advice.

With two antennas pointed in different directions, you can increase multipath and make reception worse. Also, using a combiner (hybrid splitter/conbiner) you will halve the signal.

But! That's what experimentation is all about. There are no 'hard/fast' rules when it comes to OTA reception. What works for you may not work for the guy next door!

Yeah, I will try it out and see how it works. Hopefully, with two antennas points to the opposite direction, multipath may be a less problem, or is it?

[mjones73]

I'd worry about it being more of a problem with the antennas pointing opposite directions, if the signal your aiming at bounces off anything past your house and gets reflected back, your other antenna would get it also causing multipath..

[hd4me2]

By having two broadbeam antennas pointed in almost the same direction with equal lengths of coax to the combiner he has built a two element phased array. If he were to increase one of the coax's by a half wavelength, 180 degrees, the two would cancel, destructive interference vs. constructive interference with equal lengths.

The combiner will not attenuate the signal by 3 dB it just serves to add the two incoming, in phase, signals together. I believe he could get away with only one UHF antenna to get his UHF channels, that beam isn't that narrow.

But I agree: if it works, don't fix it!

[Ratman]

By having two broadbeam antennas pointed in almost the same direction with equal lengths of coax to the combiner he has built a two element phased array. If he were to increase one of the coax's by a half wavelength, 180 degrees, the two would cancel, destructive interference vs. constructive interference with equal lengths.

Nice description... what are you really saying?

The combiner will not attenuate the signal by 3 dB it just serves to add the two incoming, in phase, signals together.

Sorry, but a combiner/splitter will cut the signal by -3dB. In a 'stacked' antenna configuration (both antennas aimed/pointed in the same direction) you can effectively narrow your beamwidth and double the power (+3dB). Adding a 'traditional' combiner will reduce the power. A joiner can provide a more effective solution with less loss.

I believe he could get away with only one UHF antenna to get his UHF channels, that beam isn't that narrow.

In the case of the opening post, you're correct. But in hulh118's case, it doensn't apply.

[logandiana]

I also was told that as long as the coaxes from the antenna to the combiner were the same length then it should not be a problem. And yes both of the antennas are pointed relatively in the sam direction with only 8 degrees difference. The sweep on the antenna is supposed to be like 25 degrees, but I wanted to make absolutely sure that I got all my channels. So I went ahead and went with two. All my digital channels are coming in with high strength signals of like 85-90 and up. Only one channel is coming in with a strength of 60-65, but it still looks as good as the others and its a channel that I don't normally tune in to either.

Thanks for the help
Logan

[Ratman]

You should probably be able to use one antenna and split the difference (aim at midpoint).

Your decision... but you may find that one antenna works better.
It may be worth the effort to test.
(or... let sleeping dogs lie)

[huhl118]

I'd worry about it being more of a problem with the antennas pointing opposite directions, if the signal your aiming at bounces off anything past your house and gets reflected back, your other antenna would get it also causing multipath..

Thanks for the advice. I guess I will have to try it and see what happens.

[hd4me2]

Sorry, but a combiner/splitter will cut the signal by -3dB. In a 'stacked' antenna configuration (both antennas aimed/pointed in the same direction) you can effectively narrow your beamwidth and double the power (+3dB). Adding a 'traditional' combiner will reduce the power. A joiner can provide a more effective solution with less loss.


The two ports that the two antennas are attached to are isolated from one another. If what you said was true then you could never double the power by using 2 antennas because the splitter would negate it.

[Ratman]

http://www.tvantenna.com/support/tutorials/combining.html

http://hdtv.forsandiego.com/messages/1/438.html?1055857409

http://hdtv.forsandiego.com/messages/1/37.html?1035585294

http://www.satelliteguys.us/archive/index.php/t-12594.html

[hd4me2]

If you're links are trying to say there is loss, I agree there is no such thing as a lossless RF device. While there is always insertion loss with any device my point was that when the signal from one antenna enters the splitter half of the signal doesn't go to where the other antenna is connected, it goes to the single port of the splitter.

You didn't answer the question about two antennas connected together through a splitter. You said the total gain would be 3 dB higher than one antenna but according to your theory it's cancelled out by the 3 dB loss of the splitter. We both know that's not right.

[Ratman]

Only one of us...