“For example, radar uses an ionizing tube to block high power radar waves from the magnetron and allows the low power reflected waves to use the same antenna and waveguide.”
Source?
I’m an electrical engineer with attack radar repair training. In radar repair training, we went through every circuit on the radar. Even though it was 37 years ago, I specifically remember the special section of waveguide that ionized when the radar transmit pulse struck it to allow the same waveguide to be used for both transmit and receive.