There is some 1930s bell labs paper on coaxial cables that considered available materials and concluded 30 ohms was best for power handling, 77 ohms was best for low loss, and 50 ohms was selected as a manufacturable compromise. The publication I'm thinking of would have been by Espenschied most likely.

Edit: ah, I see the fine article also says this-- in any case the name might be helpful to someone looking up the citation.

The article is about the 50 Ohm impedance of coaxial cables, not the 50 Hz frequency of the power grid in many countries.

Of some coaxial cables. Back in the 90s I just accepted every terminator was 50hz, and the only coax I really dealt with was ethernet. In the 00s I got into television and almost every terminator was 75Hz, with 50hz being specially marked.

I can't remember the last time I saw a terminator. I still deal with plenty of coax, but it's from one piece of active equipment to another and they self terminate.

(thinking about it I do see some specialised terminators on N type connectors on spectrum analysers, but I don't really do satellite so never deal with them)

I know that, I'm a HAM radio operator.

I was just using the 50 Hz as an example of something that was chosen pretty arbitrarily. I always thought the 50 Ohm was also chosen like that. I had no idea there were serious technical considerations in choosing it.

I should have written 50 Ohm, not Hz in the first sentence of my post though, that was a mixup. But I'm very aware of it.