A proposed setup to meet the new CISPR 25 Annex J Long-wire method: Adverse Effect Analysis of Antenna Cable Wiring in the Band below 30 MHz

This paper discusses CISPR25 edition 4 Annex J and reports the effects on the measurement results of the connection between a monopole antenna and a ground plane due to the connection symmetry of an antenna counterpoise and a ground plane, the placement symmetry of a jig for a long wire antenna, and the wiring placement of a coaxial cable connected to an antenna. From the experiment, it is shown that the placement symmetry and the resonance of a ground plane make a measurement value smaller than that of a reference setup. As for the wiring placement of a coaxial cable, the Backside Cabling is proposed to minimize the effects of itself on measurement results. The method is then verified based on experiment results. Finally, it will be shown that the measurement results least affected by the wiring placement correlate with the calculation results of an electromagnetic field simulator modelling an actual setup. The analysis results considering the size and connection method of a ground plane at each test site are the appropriate reference data for the long wire antenna method.