Rich, I don't think you can use a filter in the restricted bands around 2400-2483.5 MHz. The reason for the filter is so that the fundamental emission does not over-drive your measurement receiver.
Without the filter, vary the input attenuation of the receiver to verify that the levels do not change. If they do, increase the input attenuation until you no longer are overdriving the receiver (levels remain constant). Hopefully your calibrated noise floor is still 6 dB or lower than the measurement limits. If not, I like Ken Javor's recommendation to terminate the antenna port. You will also need to determine the field strength from the conducted measurements in the restricted band (this assumes you know the antenna gain in the restricted band) and make field strength measurements of the transmitter enclosure. That should work for the first restricted band. For a 1 watt transmitter you will definitely want the filter for higher frequency restricted bands. so that you can minimize the input attenuation and use a preamplifier. Michael Peters -----Original Message----- From: [email protected] [mailto:[email protected]] Sent: Tuesday, September 10, 2002 9:07 AM To: [email protected] Subject: FCC Testing 2.45 GHz Transmitter Consider a 1W frequency hopping, spread spectrum transmitter operating at 2.45 GHz. The FCC released a Public Notice on acceptable test methods (Filing and Measurement Guidelines for Frequency Hopping Spread Spectrum Systems) where they "recommend" that the spurious radiated emissions in the restricted bands are to be measured with a high pass filter. There is a restricted band at 2483.5-2500 MHz. Given a 1W transmitter and a spurious limit of 500 uV/m at 3 m, it would seem that I need a very sharp high pass filter or a very good notch filter to measure in that band. Is this feasible? It would also seem that a notch filter or low pass filter is required for measuring spurious emissions in the restricted bands below 2.45 GHz. There is a restricted band at 2310-2390 MHz. Again, is a filter feasible? I am aware of semi-custom filter suppliers, but are there any off-the-shelf filters available? Richard Woods Sensormatic Electronics Tyco International ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [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://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [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://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
