Study of an alternative method of indirect ESD test using folded-rhombic dipole-antenna

We focused on the problems of the indirect discharge specified in IEC 61000-4-2. In the standard, it is regulated that an equipment under test (EUT) shall be set 10cm apart from a vertical coupling plane (VCP). However, there is no information what kind of electromagnetic field is emitted from the VCP when the indirect-discharge test specified in the standard. Therefore, we considered how electromagnetic field strength changed with a separation distance between the VCP and an EUT increasing. In the consideration, we used a shielded loop-antenna for a measurement of magnetic fields emitted from the VCP. Moreover, we examined an alternative test method of the indirect discharge using a folded-rhombic dipole-antenna, which is a radiator instead of the VCP. As a result, decrement of the field strength for the separation distance was not steep in a case where the folded-rhombic dipole-antenna is used as the radiator comparing the case of VCP. This result shows the antenna has a possibility to be used as the radiator of the indirect-discharge test instead of using VCP.