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 RF Cafe Archives RF Cascade Workbook 2018 RF Symbols for Visio - Word Advertising RF Cafe Forums Magazine Sponsor RF Cafe RF Electronics Symbols for Visio RF Electronics Symbols for Office Word RF Electronics Stencils for Visio Sponsor Links Saturday Evening Post NEETS EW Radar Handbook Microwave Museum About RF Cafe Aegis Power Systems Anritsu Alliance Test Equipment Amplifier Solutions Anatech Electronics Axiom Test Equipment Berkeley Nucleonics Bittele Centric RF Conduct RF Copper Mountain Technologies Empower RF everything RF Exodus Advanced Communications Innovative Power Products ISOTEC KR Filters Lotus Systems PCB Directory Rigol RF Superstore San Francisco Circuits Reactel RFCT TotalTemp Technologies Triad RF Systems Windfreak Technologies Withwave LadyBug Technologies Wireless Telecom Group Sponsorship Rates RF Cafe Software Resources Vintage Magazines Thank you for visiting RF Cafe!
RF Electronics Shapes, Stencils for Office, Visio by RF Cafe

rat-race coupler / 180 degree phase shifter - RF Cafe Forums

RF Cafe Forums closed its virtual doors in 2010 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.

NOTICE: The original RF Cafe Forum is available again for reading, and the new RF Cafe Blog is an active board.

-- Amateur Radio

-- Anecdotes, Gripes, & Humor

-- Antennas

-- CAE, CAD, & Software

-- Circuits & Components

-- Employment & Interviews

-- Miscellany

-- Swap Shop

-- Systems

-- Test & Measurement

-- Webmaster


Post subject: rat-race coupler / 180 degree phase shifter Posted: Wed Sep 07, 2005 7:45 am


I need to take a single ended signal at 8GHz and convert it to a balanced signal. i.e. two outputs are 180 degrees out of phase. This is in order to drive a PLL differentially.

I've simulated a microstrip rat-race coupler in order to achieve this. It seems to work ok.

Another option is to use a microstrip wilkinson power divider, then after the divider, have a meandering line on one leg which basically delays the signal to give the 180 degree phase shift necessary.

Any opinions on which is better? From my sims, the isolation with the wilkinson power divider is good, whereas the S11 is about -9dB - only ok. With the rat-race coupler, the isolation is poor, but the S11 is pretty good.

Any suggestions?




Post subject: Posted: Wed Sep 07, 2005 7:48 am

I guess the real question is - how important is isolation between the two lines? They're carrying the same signal, 180 degrees out of phase....



Post subject: Posted: Wed Sep 07, 2005 12:01 pm

I would say use the rat-race. No, actually use the Wilkinson.

ummm, rat-race.



Post subject: Wilkinson vs. rat-race for differential conversionPosted: Wed Sep 07, 2005 12:34 pm

If I "read between the lines" accurately, the single-ended signal is coming from a VCO.

The important factor here is going to be minimizing the effects of the following circuitry on the VCO (noise, detuning, pulling, etc). So either a very uniform S11 over the band of interest, or a very low S11, would be important.

If the S11 is very low, it can't vary very much and stay very low. That would tend to point to the rat-race coupler - IF the input impedance of the driven stage is constant. But, again, "reading between the lines", the driven stage might be a divider. Depending on its input structure, "digital" circuits (like dividers) don't always present a constant S11 themselves... which would tip the stage toward the Wilkinson. Enough? good question.

So the "devil is in the details" - as always.

Good Luck!



Post subject: reg: coupler 180 degPosted: Thu Sep 08, 2005 5:43 pm


Joined: Wed Jul 06, 2005 5:54 pm

Posts: 24

Location: Germantown,MD

hi there

if ur familiar with genesys then this tool provides a synthesis option for 180 coupler. mebbe u can optimise to get the required S11 and then mebbe introduce non-ideality into the circuit.

all the best

Posted  11/12/2012

Exodus Advanced Communications Best in Class RF Amplifier SSPAs
Berkeley Nucleonics Corporation - RF Cafe
withwave microwave devices - RF Cafe
ConductRF Phased Matched RF Cables - RF Cafe
Anatech Electronics (RF Filters) - RF Cafe

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

These Are Available for Free


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: