Thank you for visiting 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 Wireless System Designer RF Stencils for Visio Shapes for Word Search RF Cafe Sitemap Advertising Facebook RF Cafe Forums RF Cafe Homepage Thank you for visiting RF Cafe!

Two Peak Curve on S22 When Measure Return Loss - RF Cafe Forums

The original RF Cafe Forums were shut down in late 2012 due to maintenance issues. Original posts:

Amateur Radio | Antennas | Circuits & Components | Systems | Test & Measurement

Post subject: Two peak curve on S22 when measure return loss Posted: Sun Apr 23, 2006 10:33 pm

Joined: Sun Apr 09, 2006 8:48 pm
Posts: 2
Location: Penang
Good day everybody,

currently, i doing PA evaluation board measurement. i just wanna to know why on the return loss of S22 have 2 peak curve occur? is it because there have 2 resonane circuit on the board? if yes, where is that 2 resonance circuit forming on the board?

(on output of this board's circuit diagram, there have 2 capacitor placed in parallel.(one is act as DC bolck and another one is short to ground.). And so have some capacitive decoupling circuit)



Post subject: Posted: Tue Jun 13, 2006 10:50 pm


Joined: Tue Mar 15, 2005 11:43 pm
Posts: 65
Location: Singapore
Hi :

I am not very sure about your question. But I assumed that it's kinda valley on yout S22 measurement. First, the S22 will go much lower at your operating frequency which means it has the best return loss in the operating frequency.

Regarding 2nd valleys appearance, I guess it most likely the resonance frequency appears. It can be caused by the capacitive coupling somewhere in the circuit. I am not very sure about this either. Please feel free to correct me if I'm wrong.



Post subject: Posted: Wed Jun 14, 2006 12:18 am


Joined: Tue Apr 11, 2006 8:13 pm
Posts: 34
Is your PA enclosed in a metal housing? Could there be cavity modes?

Posted  11/12/2012

RF Cafe Software

   Wireless System Designer - RF Cafe
Wireless System Designer

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

About RF Cafe

Kirt Blattenberger - RF Cafe WebmasterCopyright
1996 - 2022
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 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:

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