Brian, I perform this calibration without automated positioning equipment with only 32 probe position changes covering both vert and horiz polarizations. This data is usable for generating uniform field levels from 1 to 20 V/m at ANY level desired. The trick is to follow the 61000-4-3 par. 6.2 procedures, calibrating at 10% steps using a level in the range of 3-10 V/m (no leveling required). You should record fwd. pwr. delivered to the transmit antenna, rather than sig. gen. output power. Record data for each frequency step, before changing probe position. Once all the data is recorded, use the relationship between fwd. pwr. and field strength to determine the forward power required to get at least 12 of the 16 locations in the required range for each frequency step. This relationship is: E2 = E1 * (FP2)1/2 / (FP1)1/2 where E = field strength in V/m and FP = fwd. pwr. in mW
Use of spreadsheet software will greatly simplify your data calculations. Additionally, once you determine the appropriate fwd. power levels (for (12/16 position field uniformity) for, say 10V/m; using the above relationship with FP as the variable, you can calculate the appropriate forward power level for a uniform field strength at any V/m level! Good luck. Doug Frazee Lead Compliance Engineer Windermere Military/Commercial Compliance Laboratory Annapolis, MD USA [email protected] -----Original Message----- From: [email protected] [SMTP:[email protected]] Sent: Wednesday, December 02, 1998 11:42 AM To: emc-pstc Subject: EN61000-4-3 Hints and Tips It's that time of year again where our lab must perform the dreaded "Calibration of Field" test for the EN61000-4-3 standard "Radiated Immunity". If you performed the test as explained in the standard (section 6) moving the Field Probe to each of the 16 positions for each frequency for both vertical and horizontal and for us at 3V/m and 10V/m power levels, you have to go inside the chamber over 17,000 times. Because this is not practical, I assume that most labs measure all frequencies at each of the 16 positions. This reduces the number of trips into the chamber to only 64, but you still have to deal with over 17,000 pieces of data. What we currently do is level at each frequency to the desired field strength (lets say 3V/m) and store the output level of the Signal Generator. Repeat this for all 16 positions. Then for each frequency throw away the 4 highest values and keep the fifth. This is the data that we will use during the test. This will take us anywhere from 3-5 days to gather and calculate all the data. There is got to be a better way, hopefully easier and quicker. I'm very interested in how other labs perform this annual procedure. Any hints or Tips would be most appreciated. Thanks in advance, Brian --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators). --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
