emcradiationsemiconductors
After the Fukushima nuclear disaster that took place in Japan in 2011, any imports from there are checked for nuclear radiations using radiation detectors.
I recently ordered components from Digikey but it will be tested for radiations because at the customs they suspect that one of the ICs is made in japan! Since I don't know much about how these radiation detectors work, Can they cause any type of harm to the ICs (Processors, FPGAs, memories, optocouplers, opamps, …etc) ?
It would help to see a picture, but in general antennas built into modules do not use the ground plane as part of the antenna. For a ground plane to be useful as a reflector, the antenna needs to be perpendicular to the ground plane. Think of the ground plane as a mirror. With a half height antenna sticking above it at right angles, it looks like a whole antenna when viewed from above the ground plane due to the reflection.
Usually the built in antennas of integrated modules are self contained. Look at the datasheets and there should be a spec about where there must not be a ground plane under the module. Some modules are arranged such that the antenna is at one end past all the mounting points so that it can stick out from the board. In any case, follow the spec about how far to keep the ground plane and other metal from the antennas.
Other than keeping the ground plain away from the antennas, the ground plane is a good thing. It is surprising that you would try to do something like this with only a two layer board. After the cost of the GSM and Zigbee modules surely the extra cost of 4 layers is negligeable. Unless you're making at least 100k of these things, trying to get away with 2 layers sounds like penny wise and pound foolish. I would use 4 layers with layer 3 being a pervasive ground plane except for where the antennas are, which should be cutouts in the ground plane at the edge of the board. Don't make the cutouts holes in the middle. This allows for putting parts on the bottom side easily.
For a compound box antenna the formula is similar and this might be useful: -
Obviously they are not using A and B to denote the aperture dimensions but, I suspect that "r" is going to be exactly the same i.e. distance between centre of aperture and measurement point.
Best Answer
They are looking for gamma radiation which is a result of certain decay chains. So it is a passive detection device, a gamma ray is very energetic photon.
That is what a rational person would use, but a rational person wouldn't be checking for radiation in electronics from Fukushima. Any radiation emission was extremely confined, there were no plants in the areas that possibly could have been exposed (The closest center of semiconductors to that locale is at Tskuba), even if there where production that was exposed they wouldn't be operational. Inputs into semiconductor plants are extremely pure. etc. etc.
Because you're dealing with an irrational actor, there is no possible way that we could know what type of detector they might decide is appropriate. And indeed they may take the shipment apart and ESD everything or they might be using some "special" machine that some charlatan has sold them, which might damage the chips.
It's best you ask them what they are using. It would be nice to know what country this is.