Mr. Woodgate's comment about the the electric field probe needing to be several meters long needs some amplification.
There are two different types of 41" rod that have varying degrees of sensitivity. An active model, where the base of the rod drives a FET-input amplifier, can be very sensitive (0 dB antenna factor), but is easily overloaded outdoors on an OATS. It is best used in a shielded chamber. A passively matched 41" rod antenna uses a series of inductors to tune out the 10 pF source capacitance of the rod, and uses six or more bands (inductors) to get from 150 kHz to 30 MHz. These antennas do not overload, but antenna factors are higher. Antenna factors decrease with increasing frequency, with a typical antenna factor at 150 kHz being 40 dB and 25 dB at 30 MHz. With a receiver of noise figure of 20 dB or less, these antenna factors are good enough to allow measurements to any reasonable radiated emission limit. This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
