I recently tested a little wireless device in a chamber to get its radiated output power. The DUT sat on a pedestal with a ring of antennas all around it. The antenna is a little pcb slot antenna, that's supposed to have a uniform gain of 2dBi all around it in the X-Y direction. It sits off to the side of the product with the pcb behind it.
When I look at my X-Y plane measurements for the TX power I see a lot of the energy shifted to the side away from the PCB. I assume this is either reflected energy or my PCB is changing the performance of the antenna as a whole system, but I'm not sure.
I put in 5dBm of power and after subtracting the loss for free space from the measurements at the antenna ring I got 11dBm on the right side, and 2dBm on the left side (that's blocked by the PCB). Can I assume if I increase my TX power to 20dBm that my output power will also increase by 15dBm. So I'd see 17dBm, and 36dBm accordingly?
I'm assuming I can just do all this as addition and subtraction since it's DB but I'm new to wireless and not entirely sure.