I kind of agree with this. I just happen to play around with the Zigbee radio and pay a bit attention to their datasheet.
Zigbee radio can transmit up to +20dbm. In USA, the transmit power on channel 25 and 26 should be less than +20dbm.
Most Zigbee radio without dedicated power amplifier can push a lot less than 20dbm. For example, plain old CC2530 can only push 4.5dbm. An NRF52840 (much newer radio) push max 8dbm. Anything comes between those MCUs will have roughly similar power. If I were to build firmware with those radios, I would not reduce the power on the 2 said channels.
It is kind of expensive to validate. I would not even dream buying test equipment to test the antenna. But, I suspect there could be something in the antenna that is not as efficient at the 2 channels for the smaller repeater out there.
Thanks for sharing. The real world of user experience at the end of the day is what's count.
