Electronics World articles Popular Electronics articles QST articles Radio & TV News articles Radio-Craft articles Radio-Electronics articles Short Wave Craft articles Wireless World articles Google Search of RF Cafe website Sitemap Electronics Equations Mathematics Equations Equations physics Manufacturers & distributors Engineer Jobs LinkedIn Crosswords Engineering Humor Kirt's Cogitations RF Engineering Quizzes Notable Quotes Calculators Education Engineering magazine articles Engineering software Engineering smorgasbord RF Cafe Archives RF Cascade Workbook 2018 RF Symbols for Visio - Word Advertising RF Cafe Forums Magazine USAF Radr Shop Sponsor RF Cafe RF Electronics Symbols for Visio RF Electronics Symbols for Office Word RF Electronics Stencils for Visio Thank you for visiting RF Cafe!
Triad RF Systems Amplifiers - RF Cafe
RIGOL Technologies (test equipment) - RF Cafe

About RF Cafe

Kirt Blattenberger - RF Cafe Webmaster

Copyright: 1996 - 2024


    Kirt Blattenberger,


RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.

My Hobby Website:


withwave microwave devices - RF Cafe

Microwave Noise - RF Cafe Forums

RF Cafe Forums closed its virtual doors in 2012 mainly due to other social media platforms dominating public commenting venues. RF Cafe Forums began sometime around August of 2003 and was quite well-attended for many years. By 2010, Facebook and Twitter were overwhelmingly dominating online personal interaction, and RF Cafe Forums activity dropped off precipitously. Regardless, there are still lots of great posts in the archive that ware worth looking at. Below are the old forum threads, including responses to the original posts.

-- Amateur Radio

-- Anecdotes, Gripes, & Humor

-- Antennas

-- CAE, CAD, & Software

-- Circuits & Components

-- Employment & Interviews

-- Miscellany

-- Swap Shop

-- Systems

-- Test & Measurement

-- Webmaster

 Post subject: Microwave Noise
Posted: Wed Mar 18, 2009 11:21 am 

Joined: Wed Mar 18, 2009 11:07 am

Posts: 2


I am a junior RF planner and just need some guidance in a thought that a have. In a split configuration microwave setup you have your ODU up on the mast and your IDU down in a protected housing right. Now if I want to calculate the thermal noise I use

Nt = kTB

(k = Boltzmann, T = temperature in kelvin and B spectrum bandwidth)

My problem, as the receiver sits in the IDU should I use the IF bandwidth in the feeder as my spectrum bandwidth or should I use the channel bandwidth that is received by my antenna? Maybe I should use a combination of both?

I figure you can't just use the IF bandwidth as some thermal noise would have already been added to the system by the amplification of the antenna and ODU.

Does anybody have some thoughts on this?


 Post subject: Re: Microwave Noise
Posted: Thu Mar 19, 2009 6:14 am 
User avatar

Joined: Fri Feb 17, 2006 12:07 pm

Posts: 304

Location: London UK

Hi avalon

A better approach is to convert all significant elements into equivalent noise temperature, then add them up.

There are some excellent sources on the net to guide you through the process. See for example http://www.satsig.net/noise.htm

Also agilent have an Application Note on the subject number 57-1 which can probably be downloaded from [url]hp.woodshot.com[/url]


At bottom, life is all about

Sucking in and blowing out.

 Post subject: Re: Microwave Noise
Posted: Sun Mar 29, 2009 2:37 pm 

Joined: Wed Mar 18, 2009 11:07 am

Posts: 2

hi nubbage

thanks for the info, it answers alot of my questions...

Posted  11/12/2012

Copper Mountain Technologies (VNA) - RF Cafe
RF Cafe Sponsors
PCB Directory (Manufacturers)
Innovative Power Products Passive RF Products - RF Cafe

Please Support RF Cafe by purchasing my  ridiculously low−priced products, all of which I created.

These Are Available for Free