On the amps: For emissions there are the following electrical criteria:
- Noise figure expect about 4 dB for a broadband amp 30 MHz - 2 GHz. The noise figure is often larger at the lower frequencies if the amplifier goes up to many GHz. - Input SWR. This is important. Most broadband amps (especially if they go up to many GHz) have a bad input match at low frequencies. As the log-per antennas have a bad mismatch too, you will have multiple reflections on the cable between the antenna and the pre-amp. This reflections will influence your measurement and cannot be corrected for by the antenna factor. They may be as large as a few dB below 100 MHz. For that reason, you may be forced to add a 3 dB attenuatore at the antenna. This increases your noise figure by 3 dB. - Gain. Of course, you need only as much gain as is needed to overcome the cable loss (cable to the spectrum analyzer) and the noise figure of the spectrum analyzer. More gain will not help you. David Pommerenke -----Original Message----- From: Ravinder Ajmani [mailto:ajm...@us.ibm.com] Sent: Wednesday, November 14, 2001 1:27 PM To: marti...@appliedbiosystems.com Cc: emc-p...@majordomo.ieee.org Subject: Re: Pre-amps Joe, HP (Agilent) make good Pre-amps for different frequency ranges. If you are looking for an economical solution then you may try Com Power Corp. at (949) 587-9800. Regards, Ravinder PCB Development and Design Department IBM Corporation Email: ajm...@us.ibm.com *************************************************************************** Always do right. This will gratify some people and astonish the rest. .... Mark Twain MartinJP@appliedbiosyst ems.com To: emc-p...@majordomo.ieee.org Sent by: cc: owner-emc-pstc@majordom Subject: Pre-amps o.ieee.org 11/14/2001 10:14 AM Please respond to MartinJP I am having some difficulties locating manufacturers that provide preamps with a 20-22dB gain. What manufacturer/model do you recommend? Why? Your assistance is appreciated. Regards Joe Martin Applied Biosystems ------------------------------------------- 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: pstc_ad...@garretson.org Dave Heald davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server. ------------------------------------------- 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: pstc_ad...@garretson.org Dave Heald davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server. ------------------------------------------- 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: pstc_ad...@garretson.org Dave Heald davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
