Question about microwave sensors detecting very small objects

I have a very weird project. I have a neibour and I am worried that he is 110% motivated to rob me. I have looked over my apartment for weaknesses. I already made a motion activated esp32 cam that emails me if anyone enters my room. I have one more concern I am worried about my ceiling as a easy place to break in. Recently there was construction on my building and the workers left a hatch that goes into above my ceiling. I live in a shady part of town and my neibour is an apartment rober So I am taking all precautions. I want to make a sensor that's attached to a servo that sweeps my roof back and forth looking for any breaches or hopefully holes.

I have some of these

https://www.google.ca/search?q=DIYmall+RCWL-0516+Motion+Detection&hl=fr&tbm=isch&source=lnms&sa=X&ved=0ahUKEwjf-o-lxcvwAhVH-J4KHfWmBugQ_AUIhAIoAQ&biw=1920&bih=927#imgrc=ReRMqovJ1lNV1M

I first thought about using Pir sensors but they wont do enough, then I thought ultra sound but all of my ultrasound sensors only detect from a straight line of sight. so they wont do much then I saw microwave sensors and did not read any absolute facts but I have seen images and advertisements that says stuff like range for some microwave sensor is 30 degrees * 70 degrees and all. In my mind that says that they have not only a single line point to work with but an area. This sounds like what I need. I would imagine I need to use very high frequencies to detect small objects. I have used a lot of sensors but for this topic I wanted to ask more because this is an uncommon project and I don't want to bend over backwards for criminals. Hopefully someone has some more experience with sensors detecting very small objects in large enough areas.

You are spending entirely too much time thinking and not enough studying the data sheets describing the operation of your various sensors. They ALL have a cone of response, perhaps 15 degrees. NONE operate in only a direct line, from where, you don't describe.
Paul

1 Like

Holes and objects are obviously very different. But might I ask why you want to detect very small things? Presumably the only threat to you is when someone enters the roof space above your apartment? In which case a PIR sensor should be sufficient to detect them, I would have thought.

I'm struggling to understand why anyone would want to make a very small hole into your roof space. What would be the point?

1 Like

Another approach might be to get a webcam with a wide angle of view, and place it in one corner of your roof space so that it can "see" the whole area. Make sure it's a type where you can switch the IR illumination on and off.

Then, you can check it regularly for changes in the roof space. For example, you could manually switch off the illumination and look for new points of light coming through where a hole has been made. You can also connect it to the appropriate server software and use it for movement detection.

1 Like

I am not sure what they would do exactly but I am guessing that they would start off making a small hole to look around. I would want to catch that process before people enter the unit. can microwaves detect small objects anyways? and how small. I am guessing if someone makes a small hole it will be with a tool, the tool will poke through microwaves will see that

Ok I have ultrasound sensors I have used the before I find that they only detect something that right infront of them. Is there a command you can give them to change their beam dimensions. I have lots of these Ultrasonic Sensor - HC-SR04 - Elmwood Electronics

They can only detect what exactly in front of them. Are there any other sensors that use ultrasound that have a wider area than the ones I am using or am I missing something
? thanks

Sorry, can't help any more - I have no knowledge relevant to what you want to do.