External wireless front door guest presence sensor to sounder alert

[mp]

Anyone know if there are any narrow angle, short distance, thermally stable wireless sensors available to use externally directly in front of a front door?
The application is to activate a loud sounder when a courier or guest has reached the front door without them having to use the doorbell.
I tried creating this with a PIR sensor however there were too many false alarms due to outside heat variations and individuals close by despite using black tape on the PIR sensor.

[phil from seattle]

Try a Lidar sensor.  Expensive though there are modules in the 50ish USD range.  Maybe ultrasonic sensors?

[edit] This one looks easy to use.https://www.sparkfun.com/products/15776

[Whales]

Automatic doors use "microwave motion detectors" for this situation.

Not sure of pre-made options that come with wireless comms and battery, however.  Generally speaking: most active sensing methods require something more than batteries if you don't want it to be a PITA.

[nfmax]

You can get little 5GHz doppler radar modules designed to operate a relay for automatic light switching: on the ones I have, you can disable the light sensor, so it will detect any motion. The sensitivity and 'on' period are also adjustable. They will 'see' through a wooden door quite easily, so can be mounted inside. They came installed in some Osram automatic LED luminaires. I have these set up in pairs, so a couple of the modules were surplus. I set up one to turn on the light in the front porch when someone approaches, though it occasionally gets triggered by by large vehicles (horse boxes!) passing in the road. The other one is in a box somewhere. I can't remember the manufacturer name though, it wasn't Osram.

[cv007]

Search for RCWL-0516.

There is quite a bit of info out there on this thing, so should be easy to figure out if its suitable. Or spend $5 to find out. I do have some of them, although have not tested them yet.