In the US what frequencies does Zigbee use?
I have read in the USA Zigbee uses 900 MHz range,
Then I read it also uses 2.4 GHz....
How do you know what frequency the device is on when looking to purchase a Zigbee device?
Z-wave definitely has regional restrictions that require deconflicted frequencies that are all within the vicinity of 900 Mhz. When purchasing a ZW device, you will often be offered a regional selection choice.
For North America, ZW uses 908-916 MHz for mesh and 912-920 MHz for LR.
Painting with a broad brush, Zigbee should be the same everywhere (2.4 Ghz band), but there are some unique zigbee channels bands set aside for North America, Europe and China... But in general those shouldn't be in play with respect to smarthome gear.
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The zigbee devices used with Hubitat (or Home Assistant, SmartThings, zigbee2mqtt etc.) are all in the 2.4 GHz range and cover zigbee channels 11-26. Channel 26 is a lower power channel.
Zigbee channels 1-10 are in the 900 MHz range. There are regional restrictions on their use. I am mentioning this as an aside. These lower channel zigbee devices are typically found in proprietary solutions (eg. ecobee sensors that only pair with their thermostats and not with any other zigbee controller).
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Digging through my scrap pile I found a quantity of 2 dBi 902-928 MHz antennas that might be useful on the Z-wave side of C8-Pro
The antenna originally came with 902-928 MHz spread spectrum data radios.
The antenna has a RP-TNC connector but an adapter will make it RP-SMA for Hubitat C8-Pro
The stock C8 pro antenna according to FCC ID specs is less than unity gain (0.8 dBi). Whereas this antenna is 2 dBi gain. Will give it a try to see if worth using with the Z-wave side once I get the adapter.
I probably have over a dozen so if they work, maybe someone may want one on the cheap ... LoL
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I am using different antennas as well but just a word of caution of something I didn't notice for a bit:
If you encounter anything weird with zwave after using your antennas switch back to the stock ones or ones recommended in the above post.
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I've used a 3 dBi L-Com antenna for z-wave. It worked really well. Although truth be told, the stock antennas also work fine.
For zigbee I've used a 5 dBi 2.4 GHz antenna from an old router .....
So does that mean that the C8-PRO never uses the Zigbee 900 MHz band at all?
Look for “zigbee 3.0” or “ZHA 1.2” in the product literature. Those are the zigbee profiles that are compatible with Hubitat (although some devices may still need a custom driver to actually function as intended with Hubitat).
The zigbee spec includes other profiles, including at least one that uses 900 MHz spectrum. But not the zigbee profiles that Hubitat supports.
Yes. All hardware generations of the hub, from the original C3 through the most recent model C8 Pro have zigbee radios that transmit and receive on 2.4 GHz.
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AFAIK, that's correct. I don't remember which zigbee 3.0 SOC is used in the C-8 and C-8 Pro. But even if it is capable of using zigbee ch 1-10, that capacity isn't used.
You'd also be hard-pressed to find zigbee devices that use the lower channels. Such devices all use proprietary encoding, even though they use zigbee as the transport. And again, the example would be ecobee sensors.
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