Custom Search
Over 10000 Pages Indexed
Your Host
Click here to read about RF CafeKirt
Blattenberger

... single-
handedly
redefining
what an
engineering website
should be.

View the YouTube RF Cafe Intro Video Carpe Diem!
(Seize the Day!)

5CCG (5th MOB):
My USAF radar shop

Hobby & Fun

Airplanes and Rockets:
My personal hobby website

Equine Kingdom:
My daughter Sally's horse
riding business website -
lots of info

•−•  ••−•    −•−•  •−  ••−•  •
RF Cafe Morse Code >Hear It<

Job Board

About RF Cafe©

RF Cafe E-Mail

noise source for transmission measurement - RF Cafe Forums

Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views. It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if you would like to post something on RF Cafe's Facebook page, please do.

Below are all of the forum threads, including all the responses to the original posts.


 Post subject: noise source for transmission measurement
Posted: Wed Nov 01, 2006 4:09 pm 
 
Captain

Joined: Mon Aug 21, 2006 11:52 am
Posts: 6
Hi all,

I have a question regqrding noise sources.

I would like to do some measurements of RF devices from MHz up to a few GHz. The best would be of course to have a network analyzer. For the near feature I was considering another option: use a spectrum analyzer that is already available, combined with a broadband noise source. Of course, I will miss the phase information and also I cannot measure reflection. I would greatly appreciate any advice on this. Also, do you know how easy it is to get a noise source at a decent price? Someone warned me that a good noise source can also be quite expensive (though I hope it is not that bad, since I do not need a very flat spectral density and large power for example).

Any tip is greatly appreciated,

Adi


 
   
 
 Post subject:
Posted: Fri Nov 03, 2006 5:24 pm 
 
Site Admin
User avatar

Joined: Mon Jun 27, 2005 2:02 pm
Posts: 406
Location: Germany
Hello,

Don't mix between the use of Network Analyzer and Spectrum Analyzer. Network Analyzer won't help you to measure noise. Please provide information on what kind of parameters you want to measure?

In the RF world one should have a deep pocket for purchasing test equipment. There are no cheap solutions for getting accurate and reliable test results. Any compromise in the price will come on the expense of quality :!:

_________________
Best regards,

- IR


 
   
 
 Post subject:
Posted: Sun Nov 05, 2006 11:47 am 
 
Captain

Joined: Mon Aug 21, 2006 11:52 am
Posts: 6
Hello IR,

Thank you for your reply. I see that I did not manage o explain very well what I wanted to do. The idea is that I want to set up a measurement system and for characterization I want to to measure transmission of various two port components (amplifiers, transmission lines, etc). Of course, I would normally use a network analyzer, which gives both the amplitude and phase of the transmission. The problem is that we do not have a network analyzer. But, since we have a spectrum analyzer, I was thinking of a different solution: use a noise source to inject some broadband noise at one port and the spectrum analyzer to measure the transmitted noise at another port. This measurement would give me the amplitude of the transmission for that two port system (unfotunately I will still miss the phase).
So in the end I would need a noise source to do the measurement. The requirement would be that it generates noise in a broadband (say from a few MHz to a few GHz) and that it has an output impedance which is 50 ohm over this band.


Quote:
In the RF world one should have a deep pocket for purchasing test equipment. There are no cheap solutions for getting accurate and reliable test results. Any compromise in the price will come on the expense of quality

I completely agree with you.

Adi


 
   
 
 Post subject:
Posted: Sun Jan 14, 2007 2:18 pm 
 
Captain
User avatar

Joined: Thu Jan 11, 2007 12:59 pm
Posts: 16
Hi,

if I understand you right you want to see for an example a filter-curve on your spectrum analyzer. This is possible. You will not, as you mention your self, see the angle information.
What can be tricky though is to have enough power from the noise source since these often have very low output power. If you amplify this noise you must be sure to have a good output match!

Hope this helped.
Regards
Jens




Posted  11/12/2012
A Disruptive Web Presence

Custom Search
Over 10,000 pages indexed! (none duped or pirated)

Read About RF Cafe
Webmaster: Kirt Blattenberger
    KB3UON

RF Cafe Software

RF Cascade Workbook
RF Cascade Workbook is a very extensive system cascaded component Excel workbook that includes the standard Gain, NF, IP2, IP3, Psat calculations, input & output VSWR, noise BW, min/max tolerance, DC power cauculations, graphing of all RF parameters, and has a graphical block diagram tool. An extensive User's Guide is also included. - Only $35.
RF system analysis including
frequency conversion & filters

RF & EE Symbols Word
RF Stencils for Visio

Product & Service Directory
Personally Selected Manufacturers
RF Cafe T-Shirts & Mugs

RF Cafe Software

Calculator Workbook
RF Workbench
Smith Chart™ for Visio
Smith Chart™ for Excel