Two antennas
- Thread starter uno
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N_Jay
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uno said:
Connecting two antennas together will product random results depending on many factors.
Two identical antennas can be phased together but not across a wide band like scanning.
Two different band antennas can be connected together for wider bandwidth, but only if you understand how each will affect the other.
LarrySC
Member
Connect them together with a TV/VCR type splitter using RG-6 coax. Use F to BNC adp's as needed or twist on F/BNC for scanner. This also gives you the option to install an AB switch. The best switch should cost $12.00 or so. If this works good, and it should, then you could consider dumping more $ into the project by buying commerical grade splitters.
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N_Jay
Guest
LarrySC said:
And this brings the two signals into phase and cancels any random directionality, How??
If you realy want to do this buy 3 or more (odd number) of identical antennas and place them in a circle with a radius larger than the lowest frequency of interest, and then feed them into a multicoupler (backwards splitter) with identical length cable.
On the average you will get 3 dB of gain for each doubling of the number of antennas, and minimize the random directional effects (which will still be there to some extent) and only add minimal multipath fading.
AND IT STILL IS NOT WORTH WHILE! :evil:
Of ccourse the tower you want to hear might just fall into one of the random directions of gain at a particular frequency, and this coincidence will convince you all is well.
Tweekerbob
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Backwards splitter??????????????????????????????????????????
What exactly is a backwards splitter?
A splitter is a splitter. No matter if it is sideways, diagonal, frontways, slant ways, backwards, etc. A splitter is also a combiner as it is bi-directional.
I can find NO manufactuer of mutlicouplers who advocates the use of their product in a manner in which you describe.
An active multicoupler is nothing more than a preamp and a splitter. Possibly a band pass filter and Bias Tee as well. A passive preamp is just a splitter (both designs incorporate a design to provide better isolation between ports).
Can you provide me with a schematic of a multicoupler that effectively does what you intend it to do??
"Receiver only" mulitcouplers (as there are some transciever multicouplers that are very complex out there) are meant only to split (and amply in active ones) the signal for multiple receivers using ONE antenna and prevent receiver interaction. Again, I can find no reference other than in these forums, of a use other than those prescribed by the manufactuers of these products.
I bring this up, because I do not want to see someone spend 80 plus dollars on a piece of equipment to use it in a fashion that would best be served by buying a much less expensive and way more approriate diplexer. Or if they can live with the signal loss, and antenna interaction, a 3 dollar splitter.
Does anyone have any scientific proof that a mulitcoupler can be used as a "backwards splitter", i.e. test equipment results from a spectrum analyzer and/or signal generator? In addition any block diagrams and schematics to back this up? I don't have any proof that it wouldn't work well, simply because I never would have thought of using a multicoupler (a glorified splitter) in such an application as opposed to a diplexer (which works very well).
Thanks in advance,
Ryan
What exactly is a backwards splitter?
A splitter is a splitter. No matter if it is sideways, diagonal, frontways, slant ways, backwards, etc. A splitter is also a combiner as it is bi-directional.
I can find NO manufactuer of mutlicouplers who advocates the use of their product in a manner in which you describe.
An active multicoupler is nothing more than a preamp and a splitter. Possibly a band pass filter and Bias Tee as well. A passive preamp is just a splitter (both designs incorporate a design to provide better isolation between ports).
Can you provide me with a schematic of a multicoupler that effectively does what you intend it to do??
"Receiver only" mulitcouplers (as there are some transciever multicouplers that are very complex out there) are meant only to split (and amply in active ones) the signal for multiple receivers using ONE antenna and prevent receiver interaction. Again, I can find no reference other than in these forums, of a use other than those prescribed by the manufactuers of these products.
I bring this up, because I do not want to see someone spend 80 plus dollars on a piece of equipment to use it in a fashion that would best be served by buying a much less expensive and way more approriate diplexer. Or if they can live with the signal loss, and antenna interaction, a 3 dollar splitter.
Does anyone have any scientific proof that a mulitcoupler can be used as a "backwards splitter", i.e. test equipment results from a spectrum analyzer and/or signal generator? In addition any block diagrams and schematics to back this up? I don't have any proof that it wouldn't work well, simply because I never would have thought of using a multicoupler (a glorified splitter) in such an application as opposed to a diplexer (which works very well).
Thanks in advance,
Ryan
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N_Jay
Guest
Re: Backwards splitter??????????????????????????????????????
A passive multicoupler will work fine in either direction. (Splitter or combiner).
The term "Bacward splitter" was used because if you go into RadioShack, they call these things "splitters", not multicouplers.
I think if you read my whole post, you will find we agree.
I was using asburdity to emphasise my point that combining antennas is not a practical solution.
Tweekerbob said:
A passive multicoupler will work fine in either direction. (Splitter or combiner).
The term "Bacward splitter" was used because if you go into RadioShack, they call these things "splitters", not multicouplers.
I think if you read my whole post, you will find we agree.
I was using asburdity to emphasise my point that combining antennas is not a practical solution.
Tweekerbob
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Point taken, N-Jay. My main emphasis was on folks (there are many out there) that subscribe to the inappropriate use of expensive mutlicouplers (like Stirdberg, etc.) in a backwards ways (reverse of their intended use).
You are definitely correct in saying that Radio Shack uses improper terminology. They also have a VHF/UHF TV diplexer that they refer to as a "splitter". To the layperson using this product for the sole use of splitting a multi-band TV antenna to a (probably ancient) TV's seperate inputs of VHF and UHF (I think only the Smithsonian would have any use for this) would be OK. There is no need to confuse them with more terms. However, when someone like a scanner enthusiast mis-interprets their terms to mean something else, then problems arise.
Both of us will conclude that no one should use a splitter (or multicoupler) to combine two wide (or multi-) band antennas into one scanner. The result will in all but VERY few exceptions be DEGRADED performance. Especially when using a splitter.
I hope this helps out the original poster.
Ryan
You are definitely correct in saying that Radio Shack uses improper terminology. They also have a VHF/UHF TV diplexer that they refer to as a "splitter". To the layperson using this product for the sole use of splitting a multi-band TV antenna to a (probably ancient) TV's seperate inputs of VHF and UHF (I think only the Smithsonian would have any use for this) would be OK. There is no need to confuse them with more terms. However, when someone like a scanner enthusiast mis-interprets their terms to mean something else, then problems arise.
Both of us will conclude that no one should use a splitter (or multicoupler) to combine two wide (or multi-) band antennas into one scanner. The result will in all but VERY few exceptions be DEGRADED performance. Especially when using a splitter.
I hope this helps out the original poster.
Ryan
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N_Jay
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Tweekerbob said:
Unless the random combination accidentally helps reception, then the guy who did a genious and we are idiots! :twisted: :twisted:
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