Possibly one or more PIN diodes, cheap and cheerful if not particularly sensitive: https://www.maximintegrated.com/en/app-notes/index.mvp/id/2236 https://www.m

Possibly one or more PIN diodes, cheap and cheerful if not particularly sensitive: https://www.maximintegrated.com/en/app-notes/index.mvp/id/2236 https://www.maximintegrated.com/en/app-notes/index.mvp/id/22...