S/m does actually make sense (to me) as the antenna factor units for getting magnetic field strength. Since the input to our SA or receiver measures voltage, we get back to current by multiplying the voltage times the conductivity, or 1 over the impedance. That doesn't directly get you to Teslas, but Amps/m.
Brent G DeWitt, AB1LF Milford, MA From: Ed Price [mailto:edpr...@cox.net] Sent: Monday, February 27, 2017 5:35 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Passive Loop Emissions [General Use] Ralph: I'm afraid that your explanation didn't get through to me. When I think of an electric field, I think of two voltage levels separated by a distance, so Volts per meter seems very descriptive. For instance, two plates, one meter apart, with one plate at 5 Volts and the other plate at 15 Volts, yields a field strength of 10 Volts per meter. Going logarithmic is simply a convenience for thinking about widely differing voltage levels, so again, very straight forward. Of course, you have to set a reference foe the log scale, so Volts or microvolts are equally valid. OTOH, mho/cm for a field is pretty obscure to me. Who uses that metric, and how? Ed Price WB6WSN Chula Vista, CA USA It's about as obscure as using "dBuV/m" for field strength Ralph McDiarmid Product Compliance Engineering Solar Business Schneider Electric From: Ed Price [ <mailto:edpr...@cox.net> mailto:edpr...@cox.net] Sent: Monday, February 27, 2017 5:37 AM To: <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] Passive Loop Emissions [General Use] Andrew: I thought that S/m was a unit of electrical conductivity, defined as 0.01 mho/cm. This seems like a useless unit for magnetic field strength. I did find one site: <http://www.mdltechnologies.co.uk/wp-content/uploads/2012/05/6512-datasheet. pdf> http://www.mdltechnologies.co.uk/wp-content/uploads/2012/05/6512-datasheet.p df which provides a side-by-side chart for "dBS/m" and Electric Field Strength in "dB/m". At 10 kHz, the antenna factor in db/m is about 86 dB, while the antenna factor in dBS/m is about 35 dB. This sounds like the old relationship of magnetic field strength, in dBuA/m, to electric field strength, in dBuV/m, of 51.5 dB. Ed Price WB6WSN Chula Vista, CA USA -----Original Message----- From: Price, Andrew (Leonardo, UK) [ <mailto:andrew.p.pr...@leonardocompany.com> mailto:andrew.p.pr...@leonardocompany.com] Sent: Monday, February 27, 2017 4:16 AM To: <mailto:EMC-PSTC@LISTSERV.IEEE.ORG> mailto:EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] Passive Loop Emissions [General Use] Hi All I need some help in obtaining the correct result. The customer has requested an extended magnetic field emission test over the range 100kHz to 2MHz with a limit defined in dBpT. The antenna to be used is an EMCO 6512 which has it correction factors provided in dBS/m which the emission software used does not recognise. So is there a conversion factor that enables the right correction factor to be entered or is the conversion factor only used once a result is obtained?? 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