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Guest Message by DevFuse

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Omni Directional UHF Antenna


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9 replies to this topic

#1 OFFLINE   neogoten

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Posted 13 January 2011 - 12:08 PM

This is my first post in the forum so I apologize if I don't know all the rules. I have been reading posts from many people about different antennas and I seem to be at a loss and need some help.

The back story is I came from a family that always had cable or satellite and when my wife and I moved into our new home we had cable hooked up to it. Being that we're young and dirt poor (who isn't anymore) I want to cancel our cable and just go OTA. That be said I have been reading up and used antennasweb and TVfool and found that the stations we want are all UHF and all at about exactly 30 miles.

I have a two-fold problem. 1. Of the 9 or so stations that will come in great according to the websites and are about 30 miles out 2 are directly 180 degrees from the other 7. The problem is 1 of those two is NBC and my wife will kill me if we don't get that station, I of course don't want to miss out on the other 7. So, is there a good Omnidirectional antenna for this situation. I have been looking at the DB4 or Clearstream4, but most reports on here and other sites seem to be suggesting they are more directional that the manufacturer is letting on and would not serve my purpose. I have no problem mounting the antenna on my roof if that is what is required.
2. I am wondering if it is possible to connect the antenna to a preamp and then connect the coax to the splitter already installed in the house and send signals to the different rooms just like cable so I don't have to run a direct line from the antenna to only one TV in the house.

As you can tell I'm really new at this and have read all the primers and guides and now I'm looking for an antenna suggestion and a thought on the second problem before I buy and get rid of my cable. Thanks for the thoughts.

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#2 OFFLINE   bt-rtp

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Posted 13 January 2011 - 01:28 PM

You will need two antennas, one pointed in each direction. Then you use a standard splitter to combine the coax cable from each antenna into a single coax cable to connect to your TV. For this setup, each antenna should be directional (versus omni-directional) because this will help prevent bleed over of reflected signals into the antenna pointed in the opposite direction and visa versa.

Since the transmission towers are ~30 miles away, the signals should be weak enough that you won't need to use any UHF frequency filters.

I live is Raleigh and use this same setup to receive stations from the Raleigh transmission towers and also to get PBS from Durham. However, since I am only 14 miles away from each source, I had to purchase a UHF filter from Solid Signal. They call it a combiner, but you can use it as a band pass filter too. This prevents any reflected Raleigh sourced signals from the antenna pointed at Durham from being passed into the splitter and on to the TV receiver, which can cause signal lock problems in the receiver.

http://www.solidsign... Combiners&sku=
HR24-500 with AM21
HR21-200
HR20-700
HR20-100


#3 OFFLINE   Scott in FL

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Posted 13 January 2011 - 01:50 PM

If the transmitters are 180 degrees apart, there is another solution. Purchase a 4-bay bow tie antenna, such as the CM-4221HD, and remove the reflector screen. The pole holding the antenna elements is made to fit into a standard size mast.

http://www.channelma...p/cm-4221hd.htm

This will give you a bi-directional antenna with some gain and multipath rejection. The directional lobes are 180 degrees apart.

Be careful of connecting two antennas together. The gain for each individual antenna will decrease. No problem if you've got plenty of signal, but if your location is borderline you might have problems.

Plus one antenna is cheaper and smaller.

#4 OFFLINE   neogoten

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Posted 13 January 2011 - 01:52 PM

Thanks for the reply. So ideally mount the two antennas on the roof facing in opposite directions and run the cable into the attic and then join them? Do you think I would still want to put an amp on the line coming out of the joiner going to the splitter for the house? I guess a midrange directional will do the trick then. How will I know if I need a UHF filter?

#5 OFFLINE   neogoten

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Posted 13 January 2011 - 01:54 PM

Scott, just saw your reply. I guess I could always buy one antenna and try it and if it doesn't work buy another and join them. Humm.

#6 OFFLINE   Scott in FL

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Posted 13 January 2011 - 02:08 PM

It should work fine. I neglected to point out that when you remove the reflector screen you lose some gain. A 4-bay dipole antenna without a reflector screen will theoretically have a gain of about 6 dBd in two directions, 180 degrees apart.

The CM-4221HD has a gain of 11 - 13 dBd in its forward direction. So you lose about 6 dB.

When you combine two antennas pointed in different directions you lose 3.5 dB.

So actually the other suggestion has about 2.5 dB more gain (but requires two antennas).

Edited by Scott in FL, 13 January 2011 - 02:17 PM.


#7 OFFLINE   neogoten

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Posted 13 January 2011 - 02:14 PM

Good thoughts. I don't want to spend the money, but I don't want poor signal and wishing I had never canceled my cable. probably with a little bit more gain and an amp I think it may just work to join them and then split them out to the house. Now just to pick an antenna for 30 miles. Thanks guys.

#8 OFFLINE   Jim5506

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Posted 13 January 2011 - 03:20 PM

Depending on where you live in the Winston Salem area the signal may be strong enough for the one antenna trick to work fine. The further north east of W/S the better since the other towers are south east of town. If you are in SE W/S the signals will be more like 120 degrees from each other.

Go to www.TVFool.com and enter your exact street address or better still at that same page select the maps option in the right hand column and then enter your exact street address. When the map appears enter your proposed antenna height and check the box below the map that says "Show lines pointing to each transmitter". This will show you the direction to NBC north and all the rest south. There will be two tables below that that list the calculated signal strengths from all the transmitters - if they are all n the green, you should have no trouble with the one antenna trick.


Often joining two similar antennas together with a common splitter will cause both antenns to radiate at least 1/2 of the energy caught out the other antenna instead of down the pipe to your TV.

If the one antenna trick does not give you strong enough signal, try adding a Winegard HDP-269 pre-amp before messing with a second antenna.

Edited by Jim5506, 13 January 2011 - 03:42 PM.

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#9 OFFLINE   sum_random_dork

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Posted 13 January 2011 - 04:28 PM

Scott, just saw your reply. I guess I could always buy one antenna and try it and if it doesn't work buy another and join them. Humm.


While I am no expter on OTA I was in the same boat as you, most stations come from the SFO area........and about 180 degrees from that are the Sacramento stations. I mounted my antenna pointed towards the weakest stations (Sac) and in turn was also able to get a clear line from the back to SF. While it may not work for everyone it seemed to work for me, I have a ClearStream 2 antenna monted on my roof. I would get even better recpetion but I have pretty tall mnts (almost 1k ft) right in front of my antenna. Before investing a ton, I'd suggest getting one antenna and playing around with it a bit see what works best for you. Also double check all your channels are UHF, some channels are back on VHF after all the changes.

#10 OFFLINE   neogoten

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Posted 14 January 2011 - 07:12 AM

Thanks guys for all your help. So, I'm going to try the one antenna trick. I saw that the Channel Master 4221 was recommended and the most recent post was a clearstream 2. @Sum: Did you take off the reflector like Scott suggested?

Would anyone care to give their recommendation for this trick? I have been finding better reviews for the Clearstream 4 over the channel master 4221, but I doubt they involve this little trick in their reviews. Any thoughts from people more knowledgable than me is always appreciated :).

@Jim: I did go to TV fool and where I live is a Winston Salem address but technically a Walkertown location so I am NE of Winston. And yep NBC and one other station are at ~330 degrees and the rest are ~ 120 degrees. Here is the TV Fool: tvfool.com/?option=com_wrapperItemid=29q=id%3d3cf4da807c60da

Thanks so much guys.




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