scampbell: your idea is not working because that is a low band (2.4G) and hi band (5G) filter inside.
Ndor: yes, i can be done with bandpass filter - but that would really limit the usage.
For example: radio port1 filtered to 5500-5650
radio port2 filtered to 5750-5900
Again: Mimosa connect 2 radios onto 1 antenna. Those radios can work in very near freqs, like
radio1: rx on 5500-5540
radio2: tx on 5550-5590
both radios can be tx or rx only, or both can be bidirectional.
Also, there is a multiplexer for Ubiquiti AirFiber: AF-4x4 or 8x8 (2 or 4 radios connected).
(2 radio - 4dB insertion loss, 4 radio - 8dB insertion loss)
Syncing of radios are a must for this i think - without that, you have to have big isolation between radios. But with proper sync - local radio will not transmit when other local radios receive - so will not interfering ownself.
The bandpass filtre will not limit the spectrum in that case.
Take your example: radio 1 - 5500 - 5750 and radio 2 - 5550 - 5590.
That means you need a 150 Mhz bandpass filtre for each radio port . If we choose the channel set at 40 Mhz , it can be seen clearly that we have space insside for 3 (3.75) radio channels , every 40 Mhz ,and we can set the Rx or Tx ,without interference between them. The advantage of such setup, can be compatible with any equipment .
We can't compare with equipments which has been designed from the beginning with filters insside them like Mimosa or AirFiber 5x.
The UBNT multiplexer NxN 4, is nothing more than a hybrid coupler and cannot operate with anything else than AirFiber 5 .
But, with a hybrid coupler and bandpass filters we can do the same thing with any other equipment .
And, -4 dB means nothing when it is known this thing from the beginning, and will take into account when calculate the link.
In fact ,I observe that Netmetal has 31 dBm in Tx and AirFiber 5x has only 26 dBm in Tx. Netmetal advantage, if you want to use them in such setup .
You can do full duplex link with one antenna and two wifi cards with that , without any problems.