Resonance free operation of the rod antenna for 1 m distance testing up to 30 MHz

The electric field distribution generated by the CISPR 25 fixture named 'long wire antenna' is here investigated both in the case where the fixture is placed on the floor of a semi-anechoic chamber or on an elevated ground plane as in 1 m distance testing with rod antenna. The analysis of the electric field distribution suggests two options for rod antenna placement and electrical operation. These two options are not presently considered by the standards but can produce resonance free response and measured levels compatible with current standard test setups. Experimental results are offered that confirm predictions and that are obtained in both semianechoic and fully-anechoic facilities.