Microwave Oven door attenuation in dB?

[NTL2009]

I recently made a repair to the door switches/bracket on our microwave oven (MWO). All is well, but later, after reinstalling a trim piece and checking the fit, I noticed that with the door closed and latched, that there was a bit of play (1/8"?) - I could push the door a bit further closed, and it would spring back when I let go.

It probably was like this before and I just never noticed. But, I had some concern that it could be leaking. How to test this? My first step was a basic one, I took my phone, started a youtube video over WiFi (I made sure I was on the 2.4G WiFi band, which is close to the 2.45G MWO), turned the sound up, set it in the MWO, closed the door - and it kept playing.

If I opened the door and quickly looked at the WiFi antenna icon, it was at the lowest bar. Then I thought of a way to increase the information - I went into my router's admin page, and sure enough, it shows the signal strength of each wireless device. It indicated about -55 dBm with the door open, and about -88 dBm with the door closed. I had my wife push the door closed that last bit, and I maybe saw ~ 1 dB more attenuation. I repeated that with my tablet.

So I'm convinced the little bit of looseness on the door is no issue (it's probably acting as a wave-guide attenuator, rather than needing direct contact, and the length/width of any gap provides effective attenuation?). And with about 33 dB attenuation, a 1000 watt MWO would be below 1 watt total, in the range of a cell phone. So I think that is good, but the only specs I could find were rated in mW per cm^2.

Does 33dB attenuation seem right?

 

[anorlunda]

A software designed radio (SDR) would be a great way to test it. Radios of course, are very sensitive.

I recall a SDR demo video (sorry, no link) that showed a man in an apartment building claiming to hear the noise of all the other tenant's microwave ovens turning on and off.

 

[nsaspook]

Yes, the door likely has a choke flange. The door gap is not very critical as the 1/4λ sections of the RF trap are fixed on the door structure usually.



https://www.physicsforums.com/threads/microwave-faraday-cage.650830/post-4162799

33dB attenuation seems about right.

 

[NTL2009]

Yes, the door likely has a choke flange. The door gap is not very critical as the 1/4λ sections of the RF trap are fixed on the door structure usually.

....

https://www.physicsforums.com/threads/microwave-faraday-cage.650830/post-4162799

33dB attenuation seems about right.

Thanks, that's along the lines of what I was thinking about. Good info in that older post.