There was a thread on this some time ago and I think the consensus was that the -20 dBm limit must be a typo, or a misunderstanding by the sales dept that writes the catalog copy. if the switch is purely mechanical, the signal level shouldn't matter, except for here are some wool-gathering thoughts. If there is any kind of solid-state device in the path like a diode then there could be a lower limit to the signal that would be passed through. But also if it were a purely mechanical contact with any galvanic potential induced, that might inhibit the rf signal. -20 dBm is 87 dbuV which is about 22 mV (converting mentally) and perhaps a galvanic potential could corrupt signals at a level lower than that.
Maybe someone else will have a more definitive reply. > From: [email protected] > Reply-To: [email protected] > Date: Mon, 21 Apr 2003 13:27:38 -0400 > To: [email protected] > Subject: Low signal switching > > > Hello Friends, > > I have an application in which I would like to switch system signals on coax > cables. One system is 80 to 1000 MHz, the other is 1-2 GHz. I have found > coax switches by Narda, DB Products and Dow Key. Dow Key indicates that the > signals should be above -20 dBm to ensure that contact resistance doesn't > cause a problem. The others do not spec or address low signal issues. My > branches operate at -35 dBm, 0 dBm and 50 dBm. The 2 higher values are not > a problem, just the -35 dBm. Are there other companies that you are aware > of that make 50 ohm coax switches that are specified to operate at low > signal levels? Other ideas? > > Best regards, > > Don Umbdenstock > Sensormatic > > ------------------------------------------- > 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] > > Archive is being moved, we will announce when it is back on-line. > All emc-pstc postings are archived and searchable on the web at: > http://www.ieeecommunities.org/emc-pstc > 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] Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
