Homepage - RF Cafe
Webmaster: Kirt Blattenberger | KB3UON | Sitemap | ©1996-2014
Menu below is just a small sample of what is here!
Custom Search
More than 10,000 searchable pages indexed.
•−•  ••−•    −•−•  •−  ••−•  •
RF Cafe Morse Code >Hear It<

Electric Field strength to power conversion.. - 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: Electric Field strength to power conversion..
Posted: Tue Apr 12, 2005 8:01 am 

Joined: Fri Aug 27, 2004 11:25 am
Posts: 4
Location: Cape Town, R.S.A.
Hi All,

I was hoping someone could help me with a fundamental issue.

I have had some EMC problems (radiated) and am trying to analyse the results.
The test is done by monitoring the radiated signal with an antenna placed 1m from the DUT. The levels are then given in dBuV/m.
I understand that this is a measure of the Electric field strength, but my question is how to relate this to an absolute power measurement.
Is it a straight conversion from dBuV to dBm, assuming a 50 ohm system, and can the /m part of the unit be dropped because of the distance between DUT and antenna being 1m?
If this reasoning was followed, a +30dBuV/m translates to -77dBm/m, or -7dBm power level at source if a cable with 70dB isolation was used. (cable connected to known source of offending signal and terminated into 50 ohm)

Am I way off the mark, and if so can someone please shed some light?


 Post subject: Electric Field strength to power conversion..
Posted: Tue May 10, 2005 10:13 am 
To convert from dBuV to dBm in a 50 ohm system, just subtract 107 from the value in dBuV. As far as dropping the /m (per meter), you will need to obtain the antenna correction factor (which should have been supplied with the antenna) and subtract it from the value. Once you have this answer, it is no longer a field strength though. This is useful if you want to determine what level to inject (bypassing the antenna) when checking out your measurement system

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

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
Your RF Cafe Progenitor & Webmaster
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

Airplanes and Rockets: My personal hobby website

Equine Kingdom: My daughter Sally's horse riding website