Haven't followed the other sensor threads I guess...
Yes, totally possible and I can trigger the Linptech sensor from behind.
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At least haven't followed them at the level of detail you have. 
I hadn't seen this mentioned. I've been monitoring mmWave more at a "skim" interest level until I noticed discussion of this particular sensor that met my basic criteria - available from Amazon, <$30, confirmed 24GHz, not "chatty," and (subjective) nice looking so my wife would be more accepting.
This opens up some interesting (and obviously sometimes annoying) possibilities w/these sensors. On the interesting side - placement on a wall to track movement in two separate rooms. This info should be in the OP for folks who haven't been deep diving in the mmWave topics. For mmWave noobs the idea of sensing movement behind the sensor is going to be a big surprise.
the sky isn't falling
OK,
Here is a sensor's preferences:
And here is an installation details:
-
Sensor location in the kitchen are:
Plastic plate covered with copper foil is behind the sensor. -
View fro kitchen to the Living Room:
-
And view from Living Room to the Kitchen:
Sensor is behind the rack on the right side.
Occasionally (I am glad is not always) sensor is picking up us siting at the dining table or
getting closer to the bar.
I have another one installed in the Bathroom (different style, square shaped). Behind the wall
where sensor is installed is a closet. This one is ALWAYS triggered by someone in a closet
but this is not a big deal.
I'd drop the static sensitivity. I'd maybe also drop the distance to 2 meters. Doubt copper would do much of anything.
Believe or not I tried many different combinations of settings.
What I ended up seems to be the best.
Coper foil does the job. Without it and different settings sensor either always triggered from
behind or not triggering at all when it should. Thank to coper foil primary triggering is near
ideal but from the behind the triggering is very seldom which is acceptable and yes, waf is high.
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I don't think I suggested that anyone panic, I have my towel and I'm quite calm.
This is important info for folks considering these sensors to be aware of, the idea that a sensor can trigger from behind is just not "normal" for users of traditional motion sensors. I know I never would have considered it if my sensor had been triggering when no one was in the room in front of it.
Again, this really isn't a big deal. I can trigger mine 8" behind in free air. The sensitivity and distance settings probably influence that a bit. Most of the time these are mounted at a perimeter location while the best location is up high.
I have many MS scattered around apartment. The idea is to automate lighting in different areas
(I guess, the goal is achieved). I replaced MS with mmWave only in a Bathroom and Kitchen.
These two areas are very waf-sensitive (specifically Bathroom). MS will stay everywhere else
just because it is relatively easy to install them to see just a very specific area. This is absolutely
impossible with mmWave unless it must see the entire area (Bathroom and Kitchen cases).
BTW, I experimented with FP2 (bought 2 of them) but they are nice toys to play with but
absolutely useless for any automations (just flipping a coin produces better results).
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Oh, I believe you. What is static sensing getting you in the kitchen? If you turn it way down does the sensor not stay active with people standing in the kitchen?
Yes, this is a case. Before I was using MS in a Kitchen assuming it is impossible to be motionless
in this area. Well, my wife managed to do something being almost motionless. To deal with this
issue I had to install 2 MS and set lights off delay time to 15min. The same was done in a Bathroom.
(except it was 4 MS and even bidet seat sensing was involved).
Now single mmWave are doing very nice job in both places. And off delay time is down to 1min.
It's is a big deal if you're unaware that it's possible. If you don't know something is possible, you're not going to know to look for it if you're troubleshooting activations when there is no one in the room or next room in front of it. A central purpose of this forum is to make it easier for folks to adopt and use HA. There are a lot of people w/out experience w/mmWave sensors that are going to come across these topics and aren't going to know/expect that a sensor can sense "backwards," so sharing that info is a very good idea. Last I'll say on this.
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Settle down there camper. I'm not sure I'm taking away your rights or trying to silence you. I'm simply saying for the rest of us we know that most any sensor has bleed and a little sensing 8" behind the Linptech for the most part isn't going to impact much. You are breaking out the big guns here when they are not needed.
Well, I did not test Linptech for back sensing in deep details but square shaped sensor
has about the same sensitivity from both sides (front and back). This makes perfect
sense because internal patch antenna is facing front but has no any shielding from
the back. And that is why putting relatively big metal plate (or plastic covered with
coper foil) behind the sensor makes a difference (but unfortunately does not remove
back sensitivity completely).
Yea, I saw your other thread when you are showing pics of the same location with the 5.8ghz sensor.
How does this one do for you?
As I mentioned before I am/was experimenting with many different mmWave sensors.
Few already thrashed. I am still keeping 2xFP2 (too expensive to trash) but very unlikely
these will be ever used (they produced very unreliable results). I have very good
experience with these square sensors but they don't like C8 altogether. I replaced one
in a Kitchen with Linptech only because Linptech has no pairing problem with C8.
In a Bathroom I will keep a square one because it looks much better (near unnoticeable).
After all these trials I ended up with single Linptech in a Kitchen, single square one in
a Bathroom plus one Linptech and two squares in a spare drawer. Because of very high
back side sensitivity I don't see where these spare sensors could be used.
Cool graphic - what's the scale for distance?
No scale given. —- I would guess that rings are 1/2 meter on 6 meter setting. —-
I put my sensor on one side of an uninsulated drywall wall.
It sensed me on the other side, BUT Motion was not triggered.
Motion was only triggered when I was on the front side (and sides) of the sensor.
The distances reported on the back side, through the wall, were about a meter too far.
Not a rigorous analysis.
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This is only half of it. Unless backside is shielded, patch antenna doesn't know what is front and what is back. And this is a reason why these sensors have backside sensitivity.
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