The importance of measuring performance is often underestimated.
I tried out a few directional couplers, but I was never satisfied.
In my opinion, I needed something with greater precision and, above all, a linear frequency response from 1.8 MHz to 70 MHz.

I developed a directional coupler based on a Sontheimer-Frederick directional coupler with two AD8307 logarithmic amplifiers from Analog Devices.
This gave me the necessary linearity, and the output voltages for the outgoing and reflected power can be processed directly with an AD converter.

Directional coupler with 2x AD8307