If input VSWR for preamp and output VSWR for antenna are both bad, then it seems a simple solution is to connect preamp input to antenna output and let 50 Ohm output of preamp drive cable, solving two problems at once. Am I missing something?
---------- >From: "Pommerenke, David" <davi...@ece.umr.edu> >To: "'Ravinder Ajmani'" <ajm...@us.ibm.com>, marti...@appliedbiosystems.com >Cc: emc-p...@majordomo.ieee.org >Subject: RE: Pre-amps >Date: Thu, Nov 15, 2001, 7:49 AM > > > 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. > ------------------------------------------- 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.
