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ASTRON building as Faraday cage

Submitter: Paulus Kruger & Mark Ruiter
Description: Very sensitive receivers are developed and tested at ASTRON, both in the Lab and next to the ASTRON building in the test field. In order to be able to test our receivers, radio frequency interferences (RFI) should not be too strong.

The figures above show the RFI measured in the test field and in the lab, and the red lines denote the maximum levels above which receiver measurements become very difficult. As we know from experience, the FM band (around 100MHz) and DVB-T&GSM band (0.6-1GHz) have too much RFI for our 'radio quiet' test field.

Looking at the measurement inside the building, we see that ASTRON itself is generating a lot of RFI. The strong peak just below 1 GHz is due to someone's phone inside the building, trying its best to communicate, and those at 2.4 GHz are the wifi signals.

Note that the ASTRON building acts like a Faraday cage: The RFI outside stays outside, and those inside stays inside (which is why GSM reception is so bad inside). The next step is to develop a RFI monitor inside the building to sound an alarm if people do not switch off their phone ... (knipoog).
Copyright: ASTRON
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