Hello as all things said below, there is one more item to be added. The formula is right for the power deliver to the antenna terminal and the field probe sitting direct opposite the transmitting antenna with not influence due to the chamber and antenna polarisaton and free space conditons. Said this, for at least up to 1 GHz according to EN 61000-4-3 the homogenous field is defined as 1.5 x 1.5 m. And the calculated reference calibration file is calcutated with 12 out of 16 points. And for this 12 out of 16 points the resulting field strength may be - 0 dB to + 6 dB from the reference point. Nothing is said about the remaining 4 points. Therefore you may find for 10 V/m CW measured voltages at least from 10 V/m to 20 V/m, and then some more for the remaining 4 points. Of course if space allows it's possible to move the antenna further away, which will reduce the field variation, just a bigger amplifier or better antenna is needed. Slightly different above 1 GHz, since smaller windows can be used. Here smaller window and large EUT goes to very large testing time. Hope you charge by the hour, otherwise by bigger amplifier. The stated values may be ok for CW but not for 10V/m and 80 % AM Cable loss between you amplifier out and antenna are a very distinct factor depending on the cable length and cable type. 3 - 6 dB or more are easy, spend money on good cable or much better move the amplifier into the test chamber Regards Markus Plangger ----- Original Message -----
From: Grace Lin <mailto:graceli...@gmail.com> To: emc-p...@ieee.org Sent: Thursday, June 08, 2006 9:24 PM Subject: RF Power Amplifiers Dear Group Members, Please help me to determine specification for RF power amplifiers for 61000-4-3 and 61000-4-6 tests. I found an equation to calculate power required (ETS-Lindgren Antenna Catalog, page 71): PdB(W) = 20 log10 (Edesired(V/m)) +20 log10 (d m) ・20 log10 (fMHz) +AFdB(m-1) +15 Based on this equation, my calculated results are: For 10V/m @ 3m at 80MHz by using ETS-Lindgren 3149 antenna: P(W) = 111.7018 For 10V/m @ 3m at 80MHz by using Schaffner CBL 6140 antenna: P(W) = 22.2874 For 10V/m @ 3m at 1000MHz by using ETS-Lindgren 3149 antenna: P(W) = 12.0016 For 10V/m @ 3m at 1000MHz by using Schaffner CBL 6140 antenna: P(W) = 7.1489 For 10V/m @ 3m at 1GHz by using ETS-Lindgren 3115 antenna: P(W) = 7.1489 For 10V/m @ 3m at 4GHz by using ETS-Lindgren 3115 antenna: P(W) = 4.4681 Do these mean that a 150 watts amplifier is enough for the frequency range 80MHz-1000NHz, and a 10 watts' is enough for the frequency range 1-4GHz? Is a 75 watts' good enough for 61000-4-6 test? Is there any other factors, such as cable loss, etc., that I have to include in the calculation? The measuring system will include a dual directional coupler and a power meter. I have received different recommended specifications. Different specifications mean different prices. The price difference is huge between wattages. Your help is highly appreciated! Best regards, Grace Lin Crestron Electronics, Inc. New Jersey, USA www.crestron.com <http://www.crestron.com/> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.org Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.org Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
