Pet dual PIRs - radiation?

Hi. Does anyone know when they started using microwaves in PIRs used for pets ie with both IR and microwave?

And is the microwave only on when the alarm system is activated in the location of the pet PIR?


Hi Jess,

Welcome to the forum!!

I’m not too sure what you mean, do you have a pet sensing system? Or could you provide a link?
To figure out what is enabled you’d have to do a bit of reverse engineering, be weary opening up anything that plugs into the wall!

With most technologies I’d imagine it was developed by the military or another research body and gets phased into consumer tech. It would be hard tracking down a specific date though.

EDIT: Also the universe is a very radioactive place, I’m no expert but if you have a 2.4GHz headset you can hear crackling when your microwave is on - so there is likely some background radiation. If its WiFi enabled (The ESP chips are commonly used in ‘smart devices’ and emit 2.4GHz signals)


Hey Jess,

PIRs (Passive Infra-Red) sensors don’t use microwaves - I’m not sure where you got that from? They don’t even emit infra-red, they just measure the IR that comes in and detect when there is a change in the amount of IR they are receiving from the environment (which is what the Passive part of their name means).

The wikipedia article has a pretty good summary:


Thank you both. The information about pet PIRs having IR and microwave is here: The Beginner’s Guide to Motion Sensors | SafeWise

So I am concerned about the potential safety surrounding the use of microwave in a PIR.


Hi Jess,

I’m not trained in measuring the safety of a device or compliance for that matter, most movement sensors that I’ve come across just have a PIR, I;d imagine you’d be paying a bit more and the extra features would cost an extra $$$.

If you’re concerned about whats inside of it you could make your own!

If you’re after a more definitive answer it would be best to contact a professional that deals EMF it might cost a bit though and not sure where to start. As good as the forum is for answering electronics related questions this one is a bit outside the hobby realm.


I do very much appreciate all advice, hobbyist and otherwise. So will follow up with an expert as well. :nerd_face:


If this is the kind of device you are referring to it is passive for both IR and microwave detection.
The aim is to record constant background microwave radiation and ignore it, reducing false triggering.
BlueLineGen2_Data_sheet_enUS_2614480139.pdf (361.1 KB)

As far as I can tell, from the Bosh datasheet, it does not transmit even though the promotion pic shows that. If it is WiFi enabled then it would but the same as any other WiFi device. (no dangerous radiation)


Edit: Bosch is the only manufacturer I checked. The link you posted shows a device that transmits microwaves and looks at the refection returned. The level of these would be similar to WiFi signal from a phone and not dangerous, otherwise it would not pass RF standards and would not be sold.

If you can provide a link to the device you are referring to I could have a look at the datasheet and advise further.




Thank you for your detailed response, James - very much appreciated.


Hi Jess,

I came across this product today that might shed some light on the technology: 24GHz Microwave Radar Sensor | DFRobot SEN0306 | Core Electronics Australia

There arent any datasheets listed on it but it is available to the hobbyist!

1 Like