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Guest Message by DevFuse

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Combining antennas aiming opposite locations.


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14 replies to this topic

#1 OFFLINE   bulltdave

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Posted 23 April 2013 - 11:37 PM

How is the best way to do it?

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#2 OFFLINE   P Smith

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Posted 23 April 2013 - 11:42 PM

better use active combiners to avoid mismatching impedance ...



#3 OFFLINE   AntAltMike

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Posted 24 April 2013 - 01:01 AM

Wrong Forum.  Try  Local HDTV Info and Reception or HDTV Technical.


Edited by AntAltMike, 24 April 2013 - 01:02 AM.


#4 OFFLINE   sregener

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Posted 24 April 2013 - 04:22 AM

In the old days of analog reception, or the early days of digital reception, this was a major no-no.  It would introduce multipath into the signal, causing ghosting on analog and complete loss of signal in digital.  However, modern digital tuners (5th generation and newer) handle static multipath perfectly, and such a solution can work, although not as well as a single antenna aimed in the proper direction.

 

The easiest way to combine signals is to take the coaxial feed from the two antennas and run it through a splitter in reverse.  Any garden variety splitter will do the job - they're easily found for under $10.  If there's only one channel you want from the "wrong" direction, Channel Master made filters that would allow you to block the rest of the channels from one side, but you'd have to get one specific to the channel you're after, and there's some bleed-over 2-3 channels either way of the "proper" channel.  Not sure if they still make them or where you could buy one.

 

Note, however, that any results you get will be unpredictable.  Be prepared to fiddle, including aiming your antennas in counter-intuitive directions.



#5 OFFLINE   Jim5506

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Posted 24 April 2013 - 06:23 AM

Be aware that with this type of setup, 1/2 of the signal from each antenna is re-radiated out the other antenna, so you are cutting the signal from both in half at the outset, weak signals become very weak, you need strong signals to pull this one off.


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#6 OFFLINE   gov

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Posted 24 April 2013 - 06:24 AM

I've had better luck with the 2.4 GHz splitters (as combiners) over the 900 MHz or 1000 MHz units. (your results may differ, LOL)  If you're lucky and have a VHF ATSC channel in one direction and UHF ATSC in another, you can use the VHF/UHF splitter/combiners (with the appropriate antennas)  I also use the 2.4 GHz units to add NTSC modulators to an ATSC system.

 

The 2.4GHz splitters seem to have more 'directionality', that is, less of the signal inputted on one leg of the splitter appears on the other leg, and more of it turns up on the common port.



#7 OFFLINE   bulltdave

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Posted 24 April 2013 - 06:28 AM

Thank you. I am learning a lot!

#8 OFFLINE   SayWhat?

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Posted 24 April 2013 - 07:39 AM

Combing antennas aiming opposite locations.

 

I don't find it necessary to comb mine.  I might brush them occasionally though.


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#9 OFFLINE   gov

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Posted 24 April 2013 - 08:08 AM

I have glued  a few rubber snakes to areas around antennas and dishes to cut down on bird poop problem.  (Seems like the birds get used to the snakes pretty quickly)

 

So I have snaked some antennas.

 

 

 

:coffee



#10 OFFLINE   veryoldschool

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Posted 24 April 2013 - 08:12 AM

Be aware that with this type of setup, 1/2 of the signal from each antenna is re-radiated out the other antenna, so you are cutting the signal from both in half at the outset, weak signals become very weak, you need strong signals to pull this one off.

 

 

I've had better luck with the 2.4 GHz splitters (as combiners) over the 900 MHz or 1000 MHz units. (your results may differ, LOL)  If you're lucky and have a VHF ATSC channel in one direction and UHF ATSC in another, you can use the VHF/UHF splitter/combiners (with the appropriate antennas)  I also use the 2.4 GHz units to add NTSC modulators to an ATSC system.

 

The 2.4GHz splitters seem to have more 'directionality', that is, less of the signal inputted on one leg of the splitter appears on the other leg, and more of it turns up on the common port.

The idea of the signal being divided by 2 and re-radiated doesn't have much merit.

The isolation of a splitter is going to be greater the 20 dB.  


A.K.A VOS

#11 OFFLINE   veryoldschool

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Posted 24 April 2013 - 08:25 AM

As others have posted, there are a lot of variables to this.

The direction of the channels, the beam width of the antennas, and what band/frequency the channels are using.


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#12 OFFLINE   Rich

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Posted 24 April 2013 - 10:12 AM

I have glued  a few rubber snakes to areas around antennas and dishes to cut down on bird poop problem.  (Seems like the birds get used to the snakes pretty quickly)

 

So I have snaked some antennas.

 

You'll probably find that getting rid of birds is almost impossible.  We had that problem in a factory I worked in and we did everything we could think of to get rid of birds roosting in/on a huge wooden water cooling installation.  Glue didn't work.  Fake owls didn't work.  Poisoning them didn't even work.  We even considered shooting them.

 

Finally the whole water cooler burned down.  That got rid of the birds.  Rather draconian solution, tho.   :yesman:

 

Rich



#13 OFFLINE   gov

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Posted 24 April 2013 - 01:42 PM

Birds that are permitted to be 'deleted' (English Sparrows come to mind) as opposed to all the other birds you can get in trouble for messing with, can be 'deleted' from roosting inside farm buildings and garages and gazebos and such by simply pulling their nests down.  You don't have to kill any of them. You do need to be relentless, however.

 

Amazing to me at least, you get the same ones back every year.  As it turns out, natural attrition (cats and Silverado radiator grills around here) weeds out 1/3 to 1/2 or them every year.  If a nest isn't up long enough for mommy bird to even get a chance to lay an egg, the problem will take care of itself in just a few years.

 

You do need to be relentless, one egg, and you reset the clock.  Once problem is abated, just do a quick inspection during nesting season for 'colonizers' and you won't have the darn things in your buildings. I've seen a couple of them get VERY determined and they attempt a nest outdoors.  They make really crappy nests, you have to hurry to knock them down as even a slightly windy day usually dislodges them.

 

If these are the birds on your antenna (don't get your hopes up!) you'll prevail.

 

I generally don't like working on antennnas covered in bird droppings, psitticosis, for one, and histoplasmosis IIRC.  looks nasty too.  Still, we gotta do what we gotta do, bird poop or not.

 

Haven't seen bird residue corrode splitters and such outside, but it can't be a good thing.  And as some of you might be gathering, many of my antenna installs can be a tad complex from splitter/combiners, amps, arrays, ground blocks, arrestors, etc.



#14 ONLINE   kenglish

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Posted 30 April 2013 - 07:31 AM

When you ask for the "best" way, here's the "best".....but it costs several hundred dollars:

 

http://www.johansson.../PROF/PROF.html

 

The Profiler series, and other similar equipment, is designed for MATV systems. It allows you to set up different channel bands for each input. Sort of a "mini Cable TV Head End in a box".

NAS Products, in New York, carries one version that will operate on USA standards.

Solid Signal was also carrying them once, and might still have them.


Edited by kenglish, 30 April 2013 - 07:37 AM.


#15 OFFLINE   Michael Hilley

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Posted 03 May 2013 - 12:26 PM

0005 DBS Dish Mount Left Close-Up.jpg

 

You don't indicate whether you need VHF-Lo and/or VHF-Hi & UHF, and the distance from the broadcast towers.

The WineGard MS-1000 is an Omni-directional / non-powered that covers both VHF-Lo and VHF-Hi/UHF, up to 40/50 miles or so, the MS-2000 is a powered version.

Easily mounts to the mast of a SlimLine SWM, both DTV and OTA fed into each line of a dual coax for HR20 or AM21 OTA.

I've seen paired long range ~100 mile outdoor aerials, on 65' masts, and if the broadcast towers are distant, the Omni's aren't going to do you any good, but if the towers are less than 50 miles, this is a lot cheaper, $30-$40, compact, and cleaner than a paired antenna solution.






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