I have bought a linksys EA8500. Flashed OpenWrt and so far I'm happy with it.
I'm now trying to optimize the wifi coverage and trying to get more information about the radio part.
This router is dual band (2.4Ghz and 5Ghz) and the instructions manual state that have 5 antennas (4 external and 1 internal - this one must be PCB-based). Anyway, I'm trying to understand if all the antenna ports are dual-band or if some are 2.4Ghz and others 5Ghz. I read somewhere that even though the physical antenna could be multi-mode, the port it attaches must be either 2.4GHz or 5GHz. I'm not sure it would be like that.
The TOH doesn't state it and does neither the linksys documentation...
This is one of those "If you have to ask, you shouldn't be..." questions.
Modification of antenna systems (or any part of the transmitter chain) for transmitters requires an appropriate technical license in most jurisdictions. Even with those licenses, modification of any part of the RF chain at 2.4 GHz and 5 GHz requires advanced knowledge of microwave circuit design and fabrication skills far beyond that which most computer hobbyists possess.
Yes, typically there are separate 2.4 GHz and 5 GHz RF chains, even if the antenna covers both bands.
My "radio optimization" is limited to choose how to place the antennas. The router is in the attic and the antennas are spreaded across it with sma cable extensions. Since I'm just using 2.4GHz a good starting point would be to know which antenna ports should I connect it. I'm not planning to modify the radio part or anything...
Unfortunately, by the photos and documents in that site, I'm not able to identify which ports are 2.4GHz and what are 5Ghz but I'll continue looking for it.
That's really not going to work well at all. Signals at these frequencies travel very poorly through any coaxial cable that would cost less than buying another AP for the other side of the house.
To answer the original question, the unit uses all four external antennas for both bands. The two radios each have four transmit-receive chains. One signal for each band is combined to each antenna.
I have this linksys EA8500, I would like to know what is the purpose of the internal antenna. Does it fulfill the Radar function?
or is it just a normal antenna, because I have seen the router inside and it does not look like a dual band antenna.