YG520C Desktop shielded chamber

[TopQuark]

Not sure how much interest there is in this kind of equipment, and not sure if this strictly qualifies as test equipment, but I thought this is quite test and measurement related so I'd thought I'd place this here.

Recently I was developing a very low noise circuit that I have to characterise properly and I had a lot of trouble isolating the DUT from external EMI to make accurate measurements.

Also I haven't been very happy with the noise floor of my conducted emission measurements, as doing such measurements in open air picks up a lot of EMI not originating from the DUT.

I have tried DIY solutions with various metal boxes/enclosures, but I haven't been happy with the results. There's always some leakage into the test chamber, and EM reflections within the chamber messes up the measurements I am trying to make.

So I decided to "invest" in a more proper and professionally made solution, and I found these desktop sized shielded chambers for sale on Taobao. These shielded chambers are marketed towards portable RF equipment (smartphones, radios etc.) testing and characterizing.

I settled on the YG520C model, with the following specs:
- Outer dimension: 380x340x260mm
- Working volume: 350x320x240mm
- Weight: 12kg
- Shielding performance: >80dB (800 MHz to 6 GHz)
- Ports
  - 2 x SMA
  - 2 x N
  - 1 x DB9
  - 2 x USB
  - 1 x RJ45
  - 1 x DC barrel jack

The unit cost around 450 USD and is also quite expensive to ship around, so it is not an insignificant purchase for a home lab. However, with the time and effort I have sunk into making a proper shielded chamber, I think this is a sensible purchase if it performs as well as it advertises.

I'll be testing the chamber more and documenting the results.

[TopQuark]

So some rough measurements just to see how well the shielded chamber shields against external wireless signals.

I used a wideband antenna, and made some measurements with the antenna inside vs outside the chamber.

Trace A is antenna outside of the chamber, Trace B is noise floor of SA with no antenna attached, Trace C is antenna placed inside the chamber. Pos peak detector is used, traces are max hold results from around a minute of measuring.

While I am not able to verify the 80dB shielding performance spec, what I got is already a huge improvement compared to my previous DIY attempts.

[TopQuark]

The other application and test I have in mind for this shielded chamber is for conducting conducted emissions EMC measurements. 

I performed two conducted emissions test, one inside and one outside of the chamber. I used a 12V battery as a power source, and a power potentiometer as the DUT to make sure I am measuring the noise of the setup itself, not the power source or DUT. The LISN and battery was placed on a continuous conductive surface, the DUT (potentiometer) is placed on a 5 cm tall block of foam above the conductive surface.

Trace A is test done in open air, Trace B is test done in the shielded chamber. I couldn't be happier with the results.