In the 78 issue there is one as you describe. The broadband torroid sensors
are about standard in the autotuners and in some radios because they tune up
at low power. They are small and don't add much inductance. You might even
build it into a qrp rig and use a multi function meter scrapped out of an
old tape recorder or a led bar graph.
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High intensity LEDs (for example those as used in traffic lights ,225 ea
per light) already light-up at 45 microampere and hence can be directly
used as a reflected power indicator instead of a meter.

Frank KN6WH