Years before the internet we obtained a small handheld meter intended to determine the safety of microwave radiation outside of microwave ovens. It is a Tenma #72-220 from MCM Electronics and has a meter divided into a band of green and red. The green portion is marked SAFETY and the red part CAUTION. There is a numeric scale ranging from 0 to 2.7, with 1 right in the center. Later I'll dig into our back-files to find the application sheet to learn what the numbers signify. This morning I held the device close to the transmitting antenna of our TP-WT02 2.4GHz Transmitter and the meter rose to a number of 0.5 on the green scale. Next we held the meter close to the antennas of the Wi-Fi router and saw no reading, realizing that our router is operating at 5GHz. We do not know the actual range of the small device. It responds entirely to the radiant power of whatever's being measured and uses no batteries nor power connection.
It was designed specifically for microwave ovens and they run on exactly 2.4 GHz so wi fi and cell phones wouldn't show accurately with that meter. 5GHz won't show with that. Also 5G isn't 5GHz it's 5th generation as I read. You know my feelings about microwave radiation. It's not the same as FM and AM bands. Also Amazon has many inexpensive meters just for cell phone and Wi Fi measurements. For some reason Amazon won't let me post a link here!
Try this.. https://www.cnet.com/tech/mobile/cell-phone-radiation-detection-app-comes-to-android/
Mark and I agree that microwave radiation is harmful to human health but I have been drawn in to a few devices because they are low power RF goodies that provide wireless connections and I am old enough that I figure I'll die from eating too many potato chips before the Wi-Fi gets me.
And an interesting thing comes up in the conversation... I think the term '5G' in cellphone terminology means '5th Generation' whereas the 5 G in Wi-Fi is the 5 GHz Wi-Fi Band, a second band in addition to the 2.4 GHz Band.