Normally the hardest probelms with pick-up are at HF - that is usually just one of the ham bands between 1.6 and 30MHz, mainly because the associated wavelength, some tens of metres, tends to be  comparable to the lengths of typical final circuits, which can then act as accidental monopole or loop antennas. Also HF antennas tend to be large, and therefore the 'near field' region around them, where the signal is not falling off as the inverse sqare of distance is also many metres.

It should be noted that a pass of the EMC standards required for CE marking is a very easy standard to pass, and does not require anything like enough protection to guarantee co-location of equipment. The prescribed levels are set so that you are unlikely to receive or cause trouble from or to the neighbours next door, rather than to prevent self interfernce between bits of kit on the same property, where supposedly you are able to do something about it yourself.

If you really want to test to levels that allow you to to co-site transmitters and potential victims, then a few more factors of ten are  needed, and you need to think not in terms of the Euronorm standards, but more like DefStan or MilStd, depending if you prefer MOD or NATO.

Designing to pass an immunity test at 200V/m from 10kHz to 6GHz  (the Def Stan) is far more demanding that one at 3V/m (CE marking for type B, domestic situations) or even 10 V/m (CE marking industrial), there is a reason that all the geen boxes are milled from solid metal and have EMC gaskets everywhere.

Some car safety standards are more sensibly exacting, and I suspect will tighten further with self driving cars.

Normally the hardest probelms with pick-up are at HF - that is usually just one of the ham bands between 1.6 and 30MHz, mainly because the associated wavelength, some tens of metres, tends to be  comparable to the lengths of typical final circuits, which can then act as accidental monopole or loop antennas. Also HF antennas tend to be large, and therefore the 'near field' region around them, where the signal is not falling off as the inverse sqare of distance is also many metres.

It should be noted that a pass of the EMC standards required for CE marking is a very easy standard to pass, and does not require anything like enough protection to guarantee co-location of equipment. The prescribed levels are set so that you are unlikely to receive or cause trouble from or to the neighbours next door, rather than to prevent self interfernce between bits of kit on the same property, where supposedly you are able to do something about it yourself.

If you really want to test to levels that allow you to to co-site transmitters and potential victims, then a few more factors of ten are  needed, and you need to think not in terms of the Euronorm standards, but more like DefStan or MilStd, depending if you prefer MOD or NATO.

Designing to pass an immunity test at 200V/m from 10kHz to 6GHz  (the Def Stan) is far more demanding that one at 3V/m (CE marking for type B, domestic situations) or even 10 V/m (CE marking industrial), there is a reason that all the geen boxes are milled from solid metal and have EMC gaskets everywhere.

Some car safety standards are more sensibly exacting, and I suspect will tighten further with self driving cars.