Custom Search
More than 12,000 searchable pages indexed.

Your RF Cafe
Progenitor & Webmaster

Click here to read about RF CafeView the YouTube RF Cafe Intro VideoKirt Blattenberger ... single-handedly redefining what an engineering website should be.

Carpe Diem!
(Seize the Day!)

5th MOB:
My USAF radar shop

Airplanes and Rockets:
My personal hobby website

Equine Kingdom:
My daughter Sally's horse riding website

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

Job Board

About RF Cafe™


Microwave Noise - 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.

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