hi dears,
i have question if i have AP 5Ghz Radio9 chip AR9344 )can i change the band Frequency to 2.4Ghz ? because i read the datasheet For chip AR9344 support dual Band 2.4/5ghz.
You will need to provide more details, e.g. the exact device you're referring to.
Yes, the AR9344 does include a single 2x2 802.11n WAN MAC/BB/Radio and rf front end which can be run in either the 2.4 GHz band xor the 5 GHz band, it cannot do both at once. For concurrent dual-band support, the second radio needs to be supplied via PCIe and is accordingly unrelated to the SOC itself. While the AR9344 SOC internal radio hardware could run in either frequency band, this generally does not apply to the supporting rf hardware between SOC and antenna (e.g. external LNA and/ or analogue bandfilters, antenna multiplexer, etc.) for cost effectiveness reasons, nor would the wifi calibration data typically account for dormant band calibration.
The same principles basically apply to the second onboard PCIe radio, these decisions have to be made at the factory, in the board design and component selection phase.
For wireless routers and APs, the vendor typically opts for single band usage for their radios - both for cost reasons (much simpler and cheaper rf chains) and to achieve best signal quality without having to make compromises harming operations in the 'preferred' band. Wireless cards designed for notebook/ smartphone uses don't have that luxury, they need to do a bit of everything (but neither really well, as the requirements for 2.4 GHz, 5 GHz and 6 GHz operations are just too different to do this well with generic hardware (LNA/ PA/ rf frontend / antenna) designs).
tl;dr It depends on the exact hardware, but in general, no - you can't.
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