A Study on Characteristics of 10 MHz to 30 MHz in CISPR 25 ALSF Method CISPR 25 Annex J Reference Data Verification of Long-wire Method

in this paper, Absorber-lined shielded enclosure (ALSE) method and newly added Annex J described in CISPR 25 Edition 4 revised in 2016 is analyzed in order to make proposals for a test setup improvement. Analysis was made on the monopole antenna band (150 kHz to 30 MHz) to clarify the ground plane resonance generated between 10 MHz and 30 MHz. In addition, it will be shown that to improve the differing characteristics at each site, an improvement of the test setup is necessary. Then, as for improvement of a test setup, it will be shown that by adding grounding to a ground plane or a counter poise, even at a site where grounding is made to a floor, measurement results within +1- 6 dB of the reference values can be obtained.