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There are APs that have dual band antennas and seem to offer simultaneous 2.4+5 GHz operation. I wonder how this simultaneous dual band operation technically works (2 radios using one antenna.) A sample AP may have 2x2 MIMO with two antennas altogether. Are the frequencies from the antenna filtered and then fed to the correct radio? Are APs with dedicated (single band) antennas better? (2x2 MIMO with 4 antennas in total.) If so, in which way?

These AP products seem to advertise combined 2.4+5 GHz bandwidth speeds which makes me feel it is possible to transmit different data on both frequency bands with single antenna.

Sample products:

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  • \$\begingroup\$ The main(only?) reason dedicated single band antennas MAY be better is if there was some compromise made in the dual-band antenna design in order for it to perform at both 2.4 GHz and 5.0 GHz. \$\endgroup\$
    – SteveSh
    Oct 16, 2022 at 20:54
  • \$\begingroup\$ Dunno about your example products specifically,but lots of wlan interfaces shamelessly advertise X+Y Mbps as if they were able to run on both bands in parallel while having no such capability (only one RF frontend). Those are client cards/dongles,I guess the situation is different among APs. \$\endgroup\$
    – TooTea
    Oct 17, 2022 at 5:27

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Are APs with dedicated (single band) antennas better?

Electric fields, magnetic fields and currents are linear, i.e. you can superimpose them without anything special happening. So, no.

Are the frequencies from the antenna filtered and then fed to the correct radio?

Yes. Explicitly through filter components before the mixers, and implicitly by not being mixed to baseband (in other words, filtered after the mixer or by inherent selectivity of components).

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