I was wondering how to set the antenna gain parameter for a device with an internal antenna. For the sake of discussion lets take a look at this unit: https://mikrotik.com/product/RBSXT5nDr2 (SXT5-Lite).
Is the value absolute, and do I thus enter +16dBi to transmit at the legal power level, or is it relative to the product default and I enter 0dBi assuming the antenna is not replaced by something else. I read the documentation but this is not clear. I always put +16, but today I noticed after a factory reset the default value is 0, so now I wonder.
You need to enter the absolute value of the antenna gain.
RouterOS when factory defaulted has no way of knowing what antenna is connected to it so you need to input this data. RouterOS is an operating system which is deployed across various boards, it isn’t device specific.
This is what I thought. Still, I think it is dangerous the default antenna_gain is set to 0, as that will almost always result in illegal operation if the setting is not changed, especially for products with built-in antenna (here you would not expect the need to change any configuration, if you attached the antenna yourself you would).
Maybe a better default would be a value that doesn’t allow enabling the radio unless you change it.
in the latest ros versions (i think >6.43) antenna gain is filled automaticaly when you set regulatory domain and your country. for example hap lite has antenna gain 2. rb951 has antenna gain 3. rb2011 has 4.