OTA antenna combiner same as splitter?

[tazzmission]

I am going to be setting up two OTA antennas and combining them into one cable run. I need to do this because I can not pickup my OTA WTAE 4.1 with one antenna and still pickup all of the rest of my locals OTA. WTAE is in the total opposite direction from the rest of the locals in my area. I can combine two antennas.. Aim one at WTAE and the other at the rest of the channels and get all the channels. The rest of the channels are all in the same direction.

My question:
is a splitter and combiner the same thing? Do I need a 1GHz or 2GHz? I know I will loose about 3db with combining the signals, but I am close enough for this to work.

I get 90+ signal strenght when I aim at WTAE only. I get 90+ signal strength when I aim at all of the other channels too.

[DavidS]

Here is a response (http://www.avsforum.com/avs-vb/showthread.php?p=6090038&&#post6090038) I received when I asked a similar question in a related form. Don't know how well this addresses your situation, but I thought I'd pass it on.

[A J Ricaud]

They are different. A splitter joins the 2 inputs together, which may cause mutual interference. A combiner has circuitry that prevents the inputs from interacting with one another. You only need a splitter that goes to 1 GHz for OTA.

I would try the splitter first beacuse it is the cheapest and may work for you.

If it doesn't then try a "jointenna" search in this forum.

[TyroneShoes]

They are different. A splitter joins the 2 inputs together, which may cause mutual interference. A combiner has circuitry that prevents the inputs from interacting with one another...
Not exactly. A hybrid splitter evenly power-divides signal among outputs (or evenly combines signals among inputs), and being a passive device, can be inserted into a signal chain in either direction, depending upon the application. So a typical 2-way splitter can be characterized as a "combiner", and quite often is, especially when combining signal from two or more antennas. Depending upon the application, a 2-way splitter will have one input and two outputs down 3 dB from the inputs, or one output and two inputs, if you take the exact same device and simply turn it around. So a "splitter" is indeed a "combiner", since the same exact physical device is used for both jobs.

There are also frequency-split combiners that allow a UHF and a VHF antenna to be combined without "mutual interference" (and even those can be turned around and used in the other direction, say if you wanted to connect an all-channel antenna to separate VHF and UHF inputs such as found on an old TV set from the 70's). But a hybrid splitter/combiner will not reject such interference.

The confusion may come from a third device, normally referred to as a "directional coupler". It has one port normally used for input, another port normally used for output, and a third port normally used for a reduced-level output (sometimes used as an input). It looks very much like a hybrid splitter, but there is one critical difference in that the down-leg is isolated from the output, or "through" leg. IOW, signal entering the typical "input" port will emanate from the other two ports, but signal injected into the down-leg, while it will naturally return to the "input" port, will not go to the "output" port, and signal injected into the "output" port, while it will return to the "input" port, will not appear at the down-leg port. It can be used to combine antennas of different signal strengths together to match levels and provide some isolation from "mutual interference", but is more typically used in loop-type MATV construction and for 2-way cable TV.

[jcoulter]

I used an antenna joiner from Warren Electronics. Here (http://www.warrenelectronics.com/Antennas/joiners.htm) is the link.

I have the same problem you do. 4 channels one way, one channel 160 degrees the other. Just make sure you get the right joiner, i.e. UHF/UHF, VHF/UHF.

[tazzmission]

I used an antenna joiner from Warren Electronics. Here (http://www.warrenelectronics.com/Antennas/joiners.htm) is the link.

I have the same problem you do. 4 channels one way, one channel 160 degrees the other. Just make sure you get the right joiner, i.e. UHF/UHF, VHF/UHF.
That is the exact same site I found. going to order one of those tomorrow and 2 DB2's from antennasdirect.

I have a DB4 from antennasdirect, but don't want another DB4 since it is a rather large antenna. The two smaller ones should work fine and I can probably put them both on the same mast.

I will update when I have these installed.

[RBMD]

I joined my two antenna downfeeds (uhf/vhf-uhf) with a simple $2.95 splitter turned upside down which worked with only a very slight drop in signal strength from 92 to 88-90. I also tried an expensive $20.00) audiophille spliter with a much higher bandwith ( up to 2300mhz or something) rating that would not work at all. Try a simple splitter first and watch your signal meter for effect. My antennas are very directional and therefore I think I avoid interference.
Rich

[tazzmission]

Anyone know where I can get a join-tenna other than warrenelectronics? I called them and there is a two week wait for them to get them in stock plus the time for them to deliver it to me.

[A J Ricaud]

Here's a Channel Master distributor list fo PA.


Maybe you can find 1 thru 1 of them.

Distributor Locator

Results for Pennsylvania


Available at Participating Ace & True Value Stores
Contact Your Local
Store, For More Details
Phone: ___________


Available at participating Lowe's
Contact your
local store, for more details
Phone: ___________


Cumberland Electronics
1748 Sixth Avenue
York, PA 17403
Phone: (800) 632-9025
Phone Number 2: (717) 848-1511


Cumberland Electronics
622 Columbia Ave.
Lancaster, PA 17603
Phone: (800) 242-3703
Phone Number 2: (717) 393-8304


Cumberland Electronics
642 South 20th St.
Harrisburg, PA 17105
Phone: (800) 223-3221
Phone Number 2: (717) 232-9715


DSI Systems Inc.
810 Plum Industrial Ct.
Pittsburgh, PA 15239
Phone: (800) 888-8876
Phone Number 2: (724) 325-4606


HBF Electronics
6900 New State Road
Philadelphia, PA 19135
Phone: (215) 338-1100
Phone Number 2: 0


Moyer Electronic Supply
310 North 2nd Street
Sunbury, PA 17801
Phone: (570) 286-6707
Phone Number 2: 0


Moyer Electronic Supply
758 North Locust Street
Hazleton, PA 18201
Phone: (570) 455-3631
Phone Number 2: 0


Moyer Electronic Supply
330 East Norwegian Street
Pottsville, PA 17901
Phone: (570) 622-7866
Phone Number 2: 0


Perfect 10 Satellite Distributing Company
2780 Commerce Drive, Suite 300
Middletown, PA 17057
Phone: (717) 939-0523


State Electronics
60 West Fayette Street
Uniontown, PA 15401
Phone: (412) 437-6110
Phone Number 2: 0


The Hite Company
1800 Warren Road
Indiana, PA 15701
Phone: (724) 349-5260
Phone Number 2: 0


The Hite Company
420 Napolean
Johnstown, PA 15901
Phone: (814) 535-1589
Phone Number 2: 0


The Hite Company
2402 W. 15th Street
Erie, PA 16505
Phone: (814) 455-3923
Phone Number 2: 0


The Hite Company
Beale Ave. & 31st St.
Altoona, PA 16603
Phone: (814) 944-6121
Phone Number 2: 0


Tri State Electrical
1809 Olde Homestead Lane
Lancaster, PA 17601
Phone: (717) 291-1861
Phone Number 2: 0

[RBMD]

You can't lose more than a couple of bucks trying my above suggestion. No wait or shipping as splitters are found everywhere. You may not need the fancy stuff. If it works, it works.
Rich

[A J Ricaud]

I'm with RBMD. Try a <$5 Radio Shack or other splitter first.

[tazzmission]

I will try that first.

[tazzmission]

Regular Rat Shack splitter/combiner did not work.

[RBMD]

Sorry to have wasted your time. My $2.95 splitter worked fine, although it may not have been a RS brand, it was an old one I had laying around with the price tag still on it.
Rich

[tazzmission]

I also heard that both antennas cables need to be the same length. In my situation they are not. But they can be if I set it up that way.

[TyroneShoes]

Unlike 300 ohm twinlead, coax cable in this application is transmission-line technology. IOW, it sees a 75 ohm load impedance as if it were an infinitely long coaxial cable, no matter how long it is, just as if it were a waveguide. As long as the cables are terminated in 75 ohms (which every OTA tuner does) received signals, antennas, and tuners both can't care and can't tell how long the cables are. If CATV/MATV technology relied on matching the cables to precise lengths, CATV may well never have been implemented, or at the very least would cost about 3 times as much as it does.

[TyroneShoes]

Regular Rat Shack splitter/combiner did not work.
Tazz:

If channels in one direction are all VHF and channels in the other are all UHF you should probably use a UHF/VHF hi-lo splitter. That way off-axis interference at the same frequencies entering the opposite antenna will not pass into the tuner, improving directionality at frequency.

[RBMD]

My cable lengths before the splitter are very different lengths. One of my antennas is uhf only and one is uhf/vhf. As I mentioned above I tried one splitter which did not work, then tried another which did. The one that did was rated to 900 mhz the one that didn't was rated to 2300mhz. Don't know why, that's just the results. Perhaps trying another brand would be worth a go. Both my antennas are pointed in different directions with the big combo antenna aiming at towers 54 miles away and the smaller antenna 7ft below the taller one aiming at a tower 23 miles away. Maby the smaller one below can't pick up the distant tower because of the distance and because it's a directional antenna. Proper spacing of the antennas is supposed to be important also. I also placed an preamp on the 54 mile antenna then combined the signals which didn't work, then put the amp on the combined line after the splitter which did work and improved the signal on both lines. A lot of trial and error was done to get my best signals. Placing the preamp on the lower antenna alone also didn't work. Perhaps someone is smart enough to explain my results, but these are my findings. Hope it helps.
Rich

[TyroneShoes]

All of your hypotheses seem to be right on.

Some sat-freq splitters have problems at frequencies lower than 950, which could be part of why that one didn't work, or it just could be bad.

I assume that in one direction you need both U and V, and just U in the other. Otherwise, see my post to Tazz above.

Spacing is indeed important. Separate masts are best, but usually not practical. If antennas are within a wavelength or so of each other, it tends to detune the directional pattern. This is also why it is good technique to adjust a bit, step away, readjust, step away, etc. (just a warm body being close to the antenna can affect its performance).

As you indicate, "a lot of trial and error" is the answer...an object lesson for everyone.

[bdlucas]

The length of the lines from the antennas to the combiner matters if both antennas are picking up signals from the same transmitter because the signal takes a finite time to travel from the antenna to the combiner and so the length of the line affects the relative phase of the signals when they arrive at the combiner. For example if the signals arrive at the two antennas in-phase but the length of the lines from the antennas to the splitters differs by one-half wavelength they will arrive at the combiner 180 degrees out of phase and so cancel. The transmission line characteristics of coax vs twinlead doesn't change this (except perhaps to affect the speed that the signal travels in the line which affects the relative phase delay introduced by different length lines).

However if the antennas aren't aligned just right (pointed in the same direction and in the same plane) some of the signals are arriving at the antennas out-of-phase with respect to each other anyway, so as has been pointed out you're in the "try it and see" regime anyway, so an uneven line length from the two antennas could actually work to your advantage.

If the antennas are pointed in different directions and are fairly directional then to some degree they aren't both picking up signals from the same transmitters, in which case all of the above is less important.

[TyroneShoes]

I accept your phase theory (and stand corrected on that count), but it doesn't apply in the slightest to consumer antenna reception. This is not a scenario where two antennas are used to receive the same signal with a similar output level, so any cancellation would be either insignificant, or unimportant. Probably both. Normally two different antennas are used in two separate directions for two different signals or groups of signals, so one can't cancel the other, only attenuate it minimally due to sidelobes, and much less than the combiner would normally do, anyway, potential net cancellation which would mean very little to modern tuners that can AGC 30 dB or more. The output levels of both antennas for any specific carrier would have to be within about 2-4 dB of each other as well as the lead length would have to be very close to half a wavelength longer on one of them, neither of those likely with this kind of system. And that half a wavelength is different for every channel.

Phasing identical antennas to increase gain from the same source is common for MATV and CATV receive situations (created a few 4-antenna arrays a few times myself) but other than cutting the leads the same length it more importantly means the antennas must be physically placed very specifically with regard to each other, and pointed in the exact same orientation, and must have the same identical gain characteristics to be effective (IOW, be identical antennas). That is a very different situation than two usually-different usually-directional antennas facing two very different directions for two very different purposes.

[tazzmission]

I don't need VHF at all. I need one UHF antenna aimed at the city of Pittsburgh (312-320 degrees) for about 6 local channels and the other UHF antenna aimed at channel 51 WTAE's tower which is at 187 degrees.

I am going to try a Join-Tenna that allows ch 51 only on one side and blocks all other channels on that side, and blocks channel 51 on the other side but allows all the rest.

That should work.

[TyroneShoes]

Sounds like a plan. It should preserve the directionality of both antennas, or at least most of it.

[tazzmission]

I have been waiting almost three weeks now for the join-tenna to arrive and it is back ordered. Any other places to buy it online?

[RBMD]

If your wait goes on I'd try another brand of a cheapie splitter. As I said, one I tried didnt work and one did.

[tazzmission]

I tried every splitter that I own and bought three more. None worked.

[RBMD]

Sorry about that. I assume you have tested each antenna seperately,thus you can pin down the problem to the splitter?. Any chance your signals get too strong and need attenuation? In my case I needed a preamp after joining the antennas with the splitter to bring the signals from 70's to 88 or 90 but I have long cable runs to my TV's and split to two sets.

[tazzmission]

I got (2) DB2 antennas from AntennasDirect and a ChannelMaster JoinTenna. This is now working perfectly for me. Now I have DirecTV coming out to install a multiswitch with an OTA input so that I can get OTA on both of my HR10-250's.

[Tom J]

So Tazz, how long did it take to get the Join-tenna from warrenelectronics? I need to order a couple of UHF Join-tennas but they have to tuned to order which I'm sure takes longer. Considering the sudden interest in UHF reception issues I'm surprised there aren't more e-tailers selling Channel Master and Blonder-Tongue products.

Tom J

[tazzmission]

It took me nearly a month to get the JoinTenna I ordered. It took me another month or so to get good weather and the time to install it. :-)

[timmy1376]

I know it's bad to bring back a dead thread, but I wanted to say that after reading this thread I tried just a plain splitter to join my two UHF antennas, for most of my channels to the East, and one lone channel to the West, and it worked great. I get the same signal readings as I did with just using a rotator. El cheapo splitter turned around worked great!