Graybeard,
Perhaps not 'modern', but years ago I worked on one that used a Travelling Wave Tube with 275kV on the collector, was 13 feet long, water cooled, and lived in a concrete pit lined with lead. Even with a .001% duty cycle, there was 5kW of RF, which would cook you!
When I did my radhaz course back in the '90s, we did an exercise on a 2MW S band radar of using a 'ball on a stick' to run along the waveguide looking for leaky joints. I found it was just as effective and quicker to run your hand along feeling for the spot where it was warm. A procedure heartily disapproved of officially by the lecturer!
Surprisingly, in pacemakers, where the battery power limits you to no more than 1mW out of the transmitter, you have to have some sort of small radome around the antenna to ensure you meet everybodies requirements on SAR. There we are talking generally of transmissions of a few seconds a month or less. becasue of battery life.