High Def Forum - Your High Definition Community & High Definition Resource - View Single Post - Antenna Selection Assistance (another one!)

gcd0865 · 05-21-2009, 10:55 PM

Libby:

The reason you are getting poor digital reception is because most of your digital channels are on UHF (channels 14-51), except for WXIA-NBC-11 (whose digital signal will be called 11.1, but will actually be on channel 10) and WGTV-PBS-8 (whose digital signal at 8.1 is already permanently on channel 8). Your Terk antenna is predominantly a VHF antenna (for channels 2-13 only). The pixelation you're experiencing can occur when you don't have enough signal strength, or your antenna is not aimed well toward the station, or your antenna simply does not have enough directivity (due to its design) to be accurately pointed toward the station no matter how you orient it.

I think you should be able to receive adequate signal strengths for most channels with an indoor antenna at your location, and without spending very much. However, indoor antennas (such as rabbit ears and other kinds) sometimes have problems because signals tend to bounce among the walls of houses/apartments/etc. and the rabbit ears don't have much directivity by their very design. Usually, the best reception from rabbit ears occurs from directions perpendicular to the extended elements themselves. Since your VHF digital channels 11.1/10 and 8.1/8 are to the south-southwest of you, you should be able to orient the extended elements of your Terk antenna in a west-northwest to east-southeast position, so that those two VHF digital channels should come in well. That should be the first test for that Terk antenna. In other words, you want the "V" shape of those elements in a plane perpendicular to the direction of your stations (which are south-southwest of you). Oftentimes, flattening the "V" shape of those antenna elements (by moving them each downward somewhat) so that they are closer to horizontal can help.

For all your other channels, which are on UHF, they might come in a little better with your Terk antenna if you were to shorten (collapse) the antenna elements to a shorter length (maybe only 8-10 inches long for each element; you'd have to experiment a little) and again orient those elements in the same west-northwest to east-southeast position (and preferably horizontally opposed from each other, as opposed to upright in a "V" shape). This is because UHF has a much smaller wavelength than VHF, and you want the antenna to match. You might find that (at least for some of your tv's, maybe the 2nd story ones) this works better. With some experimenting, you may even find some intermediate combination of length and direction that works well for all channels (VHF and UHF).

If not, the next step would be to add in a dedicated UHF-only antenna. If you want something simple for indoors, the Channel Master 4149 is inexpensive and has some directivity to it, due to its reflector:

http://www.summitsource.com/channel-...49-p-7193.html

I used to use one of these in my old apartment, and it worked very well on UHF for me. You would stand this near the tv somehow (usually, the higher the better), and face the bow-tie elements toward the south-southwest direction. But it must be combined correctly with your Terk VHF antenna when connecting to the converter box, which will have a single coaxial antenna input. Your current Terk VHF antenna should already have an adapter that converts its twinlead wire (300 ohm) to the threaded coaxial connector (75 ohm) that screws (or just press-fits) onto the antenna input of your converter box. The Channel Master 4149 UHF antenna is said to also include a similar adapter. Therefore, you will also need what is called a 75 ohm UHF-VHF signal joiner (or UVSJ), which is also inexpensive:

http://www.solidsignal.tv/prod_display.asp?PROD=UVSJ

Attach the Terk to the VHF input, then the Channel Master 4149 to the UHF input, and then you'd need a short coaxial wire (maybe you have one that came with your converter box, or one from former cable tv service) to attach the line output of the UVSJ to the coaxial input of your converter box. You'll probably have to play around with the positioning of the two antennas a little (they shouldn't be right next to each other, so they don't interfere), but with a little patience, you should be able to find acceptable positions for the two antennas. You may also find that this works better for some of your tv's compared to others.

I would try just one of the Channel Master 4149s first, and test it on all of your tv's. If it works, you have an inexpensive (less than $30) solution. Some people might try to talk you into buying a new amplified combination VHF-UHF indoor antenna (more than $30), but in my experience, you have plenty of signal strength at your location (your analog channels were fine before), so an amplified antenna is not what you need (and would be a waste of money).

Hope this is helpful...

05-21-2009, 10:55 PM	#10
gcd0865 High Definition is the definition of life. Join Date: Jan 2008 Posts: 31	Libby: The reason you are getting poor digital reception is because most of your digital channels are on UHF (channels 14-51), except for WXIA-NBC-11 (whose digital signal will be called 11.1, but will actually be on channel 10) and WGTV-PBS-8 (whose digital signal at 8.1 is already permanently on channel 8). Your Terk antenna is predominantly a VHF antenna (for channels 2-13 only). The pixelation you're experiencing can occur when you don't have enough signal strength, or your antenna is not aimed well toward the station, or your antenna simply does not have enough directivity (due to its design) to be accurately pointed toward the station no matter how you orient it. I think you should be able to receive adequate signal strengths for most channels with an indoor antenna at your location, and without spending very much. However, indoor antennas (such as rabbit ears and other kinds) sometimes have problems because signals tend to bounce among the walls of houses/apartments/etc. and the rabbit ears don't have much directivity by their very design. Usually, the best reception from rabbit ears occurs from directions perpendicular to the extended elements themselves. Since your VHF digital channels 11.1/10 and 8.1/8 are to the south-southwest of you, you should be able to orient the extended elements of your Terk antenna in a west-northwest to east-southeast position, so that those two VHF digital channels should come in well. That should be the first test for that Terk antenna. In other words, you want the "V" shape of those elements in a plane perpendicular to the direction of your stations (which are south-southwest of you). Oftentimes, flattening the "V" shape of those antenna elements (by moving them each downward somewhat) so that they are closer to horizontal can help. For all your other channels, which are on UHF, they might come in a little better with your Terk antenna if you were to shorten (collapse) the antenna elements to a shorter length (maybe only 8-10 inches long for each element; you'd have to experiment a little) and again orient those elements in the same west-northwest to east-southeast position (and preferably horizontally opposed from each other, as opposed to upright in a "V" shape). This is because UHF has a much smaller wavelength than VHF, and you want the antenna to match. You might find that (at least for some of your tv's, maybe the 2nd story ones) this works better. With some experimenting, you may even find some intermediate combination of length and direction that works well for all channels (VHF and UHF). If not, the next step would be to add in a dedicated UHF-only antenna. If you want something simple for indoors, the Channel Master 4149 is inexpensive and has some directivity to it, due to its reflector: http://www.summitsource.com/channel-...49-p-7193.html I used to use one of these in my old apartment, and it worked very well on UHF for me. You would stand this near the tv somehow (usually, the higher the better), and face the bow-tie elements toward the south-southwest direction. But it must be combined correctly with your Terk VHF antenna when connecting to the converter box, which will have a single coaxial antenna input. Your current Terk VHF antenna should already have an adapter that converts its twinlead wire (300 ohm) to the threaded coaxial connector (75 ohm) that screws (or just press-fits) onto the antenna input of your converter box. The Channel Master 4149 UHF antenna is said to also include a similar adapter. Therefore, you will also need what is called a 75 ohm UHF-VHF signal joiner (or UVSJ), which is also inexpensive: http://www.solidsignal.tv/prod_display.asp?PROD=UVSJ Attach the Terk to the VHF input, then the Channel Master 4149 to the UHF input, and then you'd need a short coaxial wire (maybe you have one that came with your converter box, or one from former cable tv service) to attach the line output of the UVSJ to the coaxial input of your converter box. You'll probably have to play around with the positioning of the two antennas a little (they shouldn't be right next to each other, so they don't interfere), but with a little patience, you should be able to find acceptable positions for the two antennas. You may also find that this works better for some of your tv's compared to others. I would try just one of the Channel Master 4149s first, and test it on all of your tv's. If it works, you have an inexpensive (less than $30) solution. Some people might try to talk you into buying a new amplified combination VHF-UHF indoor antenna (more than $30), but in my experience, you have plenty of signal strength at your location (your analog channels were fine before), so an amplified antenna is not what you need (and would be a waste of money). Hope this is helpful... Last edited by gcd0865; 05-21-2009 at 11:00 PM.