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kadhim09
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Coaxial Adapter

Mon Jan 04, 2021 7:41 pm

Hi every one
so I wonder can I use the Coaxial Adapter | SMA male to 2 x SMA female to connect two of the RB 912 to one sector or not why I can not
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sindy
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Re: Coaxial Adapter

Mon Jan 04, 2021 8:14 pm

I would be afraid of frying the output amplifier of one of the devices by the other one, this adaptor seems too small to me mechanically to be a proper power divider/combiner with isolation between the radio ports. So it may act as a divider for the receive direction (antenna port to radio ports), likely with quite a lot of impedance mismatch, but not as a proper combiner with isolation between radio ports for the transmit direction.

But I may underestimate recent advance of microwave technology, so if you can measure the actual attenuation between the radio ports with an antenna connected to the antenna port, you may prove me wrong.
 
mistry7
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Re: Coaxial Adapter

Mon Jan 04, 2021 11:27 pm

@ kadhim09
Two radios on one Antenna is not possible with an Cable connection like SMA.

What you want to do?

Why you want do connect an Second radio to one Antenna, why an old RB912?
 
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k6ccc
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Re: Coaxial Adapter

Tue Jan 05, 2021 1:48 am

Nope. Doing so would likely release the magic smoke that makes all electronics work. Combining transmitters into a single antenna can be done, but it's not something that is plug and play - or inexpensive.
 
r00t
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Re: Coaxial Adapter

Tue Jan 05, 2021 4:02 am

Yeah, this will not work.

What will happen is one of the radios will be transmitting while other one is receiving. They will probably survive this, but there is no amount of filtering on normal boards that can reject another transmitter on nearby frequency.
To combine multiple radios like this, you would have to use two band-pass filters, each selecting just a channel(s) where one specific radio operates. This is for example how Audience splits the 5G band into low and high portions, feeding each part into different radios.

And if you may ask how more complex radio systems like cellphone towers or satellite links can share same antenna:
They use device called "circulator", it works as a one-way splitter for microwave frequencies.
So you split antenna into separate TX and RX ports and then combine them separately so the radios can't see each other.

So yes, this problem is solvable, but not in that simple way...

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