I would like to explain to a colleague why the noise floor on a SA does not look flat as it sweeps across a given frequency range after antenna factors, cable factors, external gain and external attenuation are programmed into its display function.
I think it breaks down to these fundamental points: 1. the SA receiver has noise in its attenuator, mixer and filter circuits (say -80 dBm, and maybe flat within a limited frequency range) 2. the external amplifier has some noise too, but its gain lowers the noise floor created by #1 (also flat within a limited frequency range) 3. the cables have losses which are frequency dependant, and those can be entered as loss factors into the SA (shapes the noise floor a little and those losses raise the noise floor) 4. the antenna has a gain which is frequency dependant with several dB of hills and valleys across its usable frequency range (that really shapes the noise floor more than 1, 2 or 3 above) 5. noise floor shape caused by #4 is the mirror image of the antenna factor vs frequency Is that a decent summary? . Ralph McDiarmid Compliance Engineering Residential/Commercial Solar Business Schneider Electric D +1 (604) 422 2622 x62622 E ralph.mcdiar...@schneider-electric.com 3700 Gilmore Way Burnaby BC Canada - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
