Antenna design and its application for near field disturbance measurement in upper VHF band

An undersized biconical antenna for radiated disturbance measurement nearby the equipment under test (EUT) is described. Considering mutual coupling effect on its antenna factor, which one expects to be reduced by downsizing elements, it is confirmed that such antenna can be used for accurate measurement in MIL standard and in some standards of automotive and aerospace EMC. It is found that an antenna factor of the proposed antenna, derived from the two antenna method using a separation distance of 1 m, is very close to the one calculated in free space and measured by the three antenna method. The accurate measurement with more than 6 dB S/N margin to the severe limit in the upper VHF band of CISPR 25 class 5 test is discussed and illustrates the possible applications of the proposed undersized biconical antenna.