Microwave Proximity Sensor RCWL-0516 radiation pattern - Page 1
Forum section: electronics / projects

author: beduino
author_rank: Regular Contributor
timestamp: November 16, 2019, 11:48:49 pm
content: Hello,I've found this RCWL-0516 microwave proximity sensor very interesting, since I'd like to use it to detect movements in house rooms and controll lights as well to create standalone map to log activity in rooms when at work outside house to connect with custom security alarm system.It is said that movement detection range is about up to 7 meters, but what about radiation pattern of this 3.1GHz radar?I've watched this very interesting video with attempt to reverse engineering PCB, but not too much about radiation patterns and what happends when for example we will try run eg. two of such modules not far away a few meters distance in a few rooms with open doors?The same question is in open space maybe I'd like to make something like rotating radar with this thing, than try to detect something and send back movement data with angle, but is it directional sensing.Maybe someone already made such experiment with this module to find out radiation pattern ?

author: rhodges
author_rank: Frequent Contributor
timestamp: November 17, 2019, 12:48:01 am
content: I have played with this some. I think it is more sensitive than optical PIR.What I read is that it sends out a microwave signal, and if there is a change in the return signal, it calls that "motion". It is NOT RADAR. So I would expect two or more in the same room to be fine. They would receive each others' signals and that would be the normal pattern. Any motion would disturb that pattern, so the network might be even more sensitive to motion. I have not tried this, I am just going logically from what I read.Rotating a sensor would be futile. It would trigger continuously.

author: beduino
author_rank: Regular Contributor
timestamp: November 17, 2019, 07:15:17 pm
content: Quote from: rhodges on November 17, 2019, 12:48:01 amYep, If we knew its radiation pattern one could put few such sensors rotated by given angle to cover 360 deg.Another story is, trigering of this sensor is caused by any moving object or maybe when focused somehow we can make detection at larger distance?I mean, for example mirror at some distance and sensor put in the focus of parabolic mirror to try make its detection more directional?As I heard it works at 3.1GHz microwave range, so its wave length is ~10mmI believe in that maybe by using mirrors we could somehow guide this microwave signal and by mirror make something like invisible line where when crossed by someone it will disturb reflected microwaves?It is quite cheap and much more compact design than many PIR sensors and probably transaparent to glass?BTW, rotation could work this way that we turn at some step or to predefined angles and stop rotation for lets say a few seconds, than scan other location.

author: beduino
author_rank: Regular Contributor
timestamp: December 10, 2019, 12:21:05 am
content: OK, I've a few such sensors to play with mirrors and electromagnetic wave guidesCan anyone confirm is it fine power this thing from 12VDC ?

author: bingo600
author_rank: Super Contributor
timestamp: December 10, 2019, 03:57:59 pm
content: AFAIK they radiate ~ equal power on both sides.Depending on your (wall) mount , it might "look" through the wall to the next room.Someone mentioned they need several (like 5) layers of tinfoil to shield the backside , and there must be some distance to the "shield".Andreas Spiess made a youtube video playing w. those./Bingo

author: beduino
author_rank: Regular Contributor
timestamp: December 18, 2019, 11:13:20 pm
content: Quote from: bingo600 on December 10, 2019, 03:57:59 pmThanks, I've already watched this video and it was surprising that they were not able detect human movements while playing with glassAdditional thing missed in those experiments is response time to movement - it is interesting how much time it takes from detection to outputAnyway, I've steel radiowaves guide like shown below and idea is put inside this thing at lets say some distance from its square bottom 5mm plate to try reflect those microwaves.Not sure what about distance - maybe assuming it is 3.181GHz calculate electromagnetic wavelength in air and try sdjust distance from this steel wall in a way that reflected wave will not cancel another one from other side of this PCBUpdate: It looks like wavelength should be around 0.094m (9.4cm) in airIt could be interesting to see if we were able eg. detect mouse and catch it alive in this steel pipe to release outside house in its natural environmentThat is why response time of this microwave sensor can be critical while mouse is very fast