A beam switched log-periodic antenna for EMI measurement

In EMI (Electromagnetic Interference) test, the electric field intensity of radiated emission from EUT (Equipment Under Test) is measured. To find the maximum radiation by EUT, a receiving antenna is moved along a vertical pole, because the electric field intensity is seriously changed by the effect of ground reflection wave. In addition to this vertical movement, the main beam tilting is required to keep stable reception level from the EUT. A mechanical tilting is the current standard, however quick and fine adjustment is expected.