Application Note

RSS

There are many hazardous electrical events in the environment that can have adverse effects on the systems of a vehicle, causing potentially unsafe situations. These events can be generated by "off-vehicle" as well as "on-vehicle" sources and can either be natural or man-made. To protect against these events automobile manufacturers have developed ElectroMagnetic Compatibility (EMC) standards to test electronic components and whole vehicles. One known manmade event is the Radar Pulse used by military and airports to track aircraft. This high intensity RF field is directed up into the sky but sometimes can be detected on the surface where it could possibly affect the electronics of an automobile.

It has been found that vastly different results have been submitted from different test labs while all were found to be following correct testing practices. Error at this high a test field (600 V/m) can have a large affect on the actual fields. An error of 2 dB could change the actual fields by hundreds of V/m. In order to reduce error Ford has streamlined the test setup also.

The largest change to the setup was the removal of the ground plane. This removed any reflection off the surface and from grounding connections/straps, which improves the uniformity of the field. Any and all reflection can change the results so therefore measures should be taken to remove all reflecting materials that are not required. Since the ground plane is not required the test table becomes a larger factor in the test. This is why Ford is now requiring a low dielectric material. It is becoming a more of a requirement in the Radiated Immunity testing world where wood tables can no longer be used for testing above 1 GHz. Wood does contain some amount of moisture and will not be 100% permeable to microwaves. A suggested material would be rigid polystyrene.

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•Application Note: Automotive 600V/m Radar Pulse Test Solution