RF Cafe Software

RF Cascade Workbook 2005 - RF Cafe
RF Cascade Workbook

Calculator Workbook
RF Workbench
Smith Chartâ„¢ for Visio
Smith Chartâ„¢ for Excel
RF & EE Symbols Word
RF Stencils for Visio

About RF Cafe

Kirt Blattenberger - RF Cafe WebmasterCopyright
1996 - 2016
Webmaster:
Kirt Blattenberger,
 BSEE - KB3UON

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 Internet was still largely an unknown entity at the time and not much was available in the form of WYSIWYG ...

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:
 AirplanesAndRockets.com

Try Using SEARCH
to Find What You Need. 
There are 1,000s of Pages Indexed on RF Cafe !

Electronics World Cover,TOC,and list of posted Popular Electronics articles QST Radio & TV News Radio-Craft Radio-Electronics Short Wave Craft Wireless World About RF Cafe RF Cafe Homepage RF Cafe in Morse Code Google Search of RF Cafe website Sitemap Electronics Equations Mathematics Equations Equations physics Manufacturers & distributors Engineer Jobs Twitter LinkedIn Crosswords Engineering Humor Kirt's Cogitations Engineering Event Calendar RF Engineering Quizzes AN/MPN-14 Radar 5CCG Notable Quotes App Notes Calculators Education Magazines Software,T-Shirts,Coffee Mugs Articles - submitted by RF Cafe visitors Simulators Technical Writings RF Cafe Archives Test Notes RF Cascade Workbook RF Stencils for Visio Shapes for Word Thank you for visiting RF Cafe!

Atmospheric Absorption / Attenuation

Electromagnetic waves are absorbed in the atmosphere according to wavelength. Two compounds are responsible for the majority of signal absorption: oxygen (O2) and water vapor (H2O).

The first peak occurs at 22 GHz due to water, and the second at 63 GHz due to oxygen. The actual amount of water vapor and oxygen in the atmosphere normally declines with an increase in altitude because of the decrease in pressure, so these graphs apply from sea level to around 1 km altitude.

Total attenuation through the atmosphere at any frequency through unobstructed atmosphere is the sum of free space path loss, attenuation caused by oxygen absorption and attenuation caused by water vapor absorption. Rain attenuation, when present adds an additional element. For a chart of sunlight power density in the visible light and infrared / ultraviolet region of the electromagnetic spectrum, click here.

So, AttenTotal = AttenFreeSpacePathLoss + AttenOxygen + AttenWaterVapor + AttenRain

Atmospheric absorption or electromagnetic energy vs. frequency - RF Cafe

Atmospheric Attenuation Chart

This chart was generated from frequency / attenuation data points picked off of a published graph that were entered into Excel and plotted.

Recommendation ITU-R P.676-9, Attenuation by Atmospheric Gases, P Series, Radiowave Propagation - RF CafeHere is the official document by the International Telecommunications Union that contains very detailed data.

Recommendation ITU-R P.676-9
(02/2012)
Attenuation by atmospheric gases
P Series Radiowave propagation