All, It might also be necessary to look at the VSWR or match of the intervening connections between the antenna and amplifier. The VSWR of the antenna is taken into account when the gain is measured. However, the match at the cable connector interface and, where used, the bulkhead connector may reduce the power delivered to the antenna. Standard match calculations need to be applied to be certain of sufficient power. Regards Tim
_____ From: [email protected] [mailto:[email protected]] On Behalf Of Mowbray, John H Sent: 08 June 2006 20:56 To: Grace Lin; [email protected] Subject: RE: RF Power Amplifiers *** WARNING *** This mail has originated outside your organization, either from an external partner or the Global Internet. Keep this in mind if you answer this message. Grace For the 80-100 range the power sounds about right, but be careful many amplifiers will ouptut reduced power if the VSWR at their output exceeds 2:1. For the other ranges the 75 W should be more like 25-50 W, again depending on the amplifier and VSWR. The high frequency amplifier should be at least 30 W to account for the higher cable losses. The best approach is to try a demonstrator before you buy. I have seen amplifiers that would only produce 1/2 of their rated output power in my test setup. John Mowbray, P. Eng. Senior EMC Engineer NCR Canada, Ltd. 580 Weber St. N. Waterloo, Ontario N2J 4G5 519 884 1710 X5371 [email protected] _____ From: [email protected] [mailto:[email protected]] On Behalf Of Grace Lin Sent: June 8, 2006 3:24 PM To: [email protected] 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 [email protected] 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 [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] 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 [email protected] 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 [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] 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 [email protected] 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 [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
