Hi Vic, I am not sure of the reduction that was done to reach the formula stated by the RS report [SQRT(Po x R)/D], but the root of the formula must come from the relationship for electric field strength: E=SQRT(Zo*Pd) where Zo is the wave impedance and Pd is the power density of the wavefront. Without going through the whole iteration, for free space this simplifies to E (V/m) =SQRT (30*Pt*Gt) / d where Pt = transmit power in watts Gt = numerical gain of the transmit antenna and d = distance in meters I do not know how the relationship simplifies to the formula SQRT (Po*R) / D, but hopefully this gives you a little background on where the E field formula comes from. Over a ground plane things may get a little more complicated. Best regards, William M. Elliott (Mac) Staff Engineer- Wireless Testing Bluetooth Qualification Body HYPER Corporation 1279 Quarry Lane, Suite B Pleasanton, CA 94566-8499 +1 925.462.9105 (Office) +1.925.280.7751 (Fax) +1 925.577.5518 (Mobile) mailto:[email protected] www.hyperinterop.com
<mailto:[email protected]> -----Original Message----- From: Gibling, Vic [mailto:[email protected]] Sent: Mon 6/2/2003 11:11 AM To: EMC-PSTC (E-mail) Cc: Subject: What is the background to the formula.... Hi, The following formula was stated in a report covering Radiated Spurious Emissions: Field Strength = SQRT(Po x R)/D Where R was given as 50ohms and D as 3 metres. Can someone please give me some background to the formula? Many thanks Vic Gibling ------------------------------------------- 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
