Anatech Electronics (RF Filters) - RF Cafe
Windfreak Technologies
 

About RF Cafe

Kirt Blattenberger - RF Cafe Webmaster

Copyright: 1996 - 2024
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 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:

AirplanesAndRockets.com

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 App Notes Calculators Education Engineering magazine articles Engineering software Engineering smorgasbord RF Cafe Archives RF Cascade Workbook 2018 RF Symbols for Visio - Word Advertising RF Cafe Homepage Thank you for visiting RF Cafe!
Innovative Power Products Couplers

Microstip/CPW question - RF Cafe Forums

RF Cafe Forums closed its virtual doors in 2012 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. If the folks at phpBB would release a version with integrated sign-in from the major social media platforms, I would resurrect the RF Cafe Forums, but until then it is probably not worth the effort. 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.

-- Amateur Radio
-- Anecdotes, Gripes & Humor
-- Antennas
-- CAE, CAD, & Software
-- Circuits & Components
-- Employment & Interviews
-- Miscellany
-- Swap Shop
-- Systems
-- Test & Measurement
-- Webmaster

boon
Post subject: Microstip/CPW question Posted: Thu Apr 13, 2006 7:21 pm

Captain

Joined: Tue Feb 21, 2006 5:19 pm
Posts: 17
hi

which one is less lossy: microstrips or CPW's given both are on the same substrate and the conductor metal is at the same distance away from the substrate? some discussion will be nice. thanks


Top

kpainter
Post subject: Posted: Thu Apr 13, 2006 10:56 pm

Colonel


Joined: Wed Aug 20, 2003 11:47 am
Posts: 47
Location: Santa Barbara, CA
IMHO and experience, the CPW is the less lossy of the two. This has more to do with the fact that the fields tend to be more contained than with Microstrip which go to infinity on the air side. The losses are due to radiation. Dielectric losses should be the same. Because the radiation is reduced, coupling between lines is also reduced. If you are worried about spurs, CPW is the way to go - that is unless you can do stripline.

Microstrip kinda sucks, otherwise folks wouldn't make antennas out of a similar structure.


Top

boon
Post subject: Posted: Mon Apr 17, 2006 6:17 pm

Captain

Joined: Tue Feb 21, 2006 5:19 pm
Posts: 17
thanks kpainter....but the field coupling to substrate is a major issue in on-chip transmission lines and wouldn't microstrip be better because the substrate is shielded by a ground plane whereas in CPW the conductor plane and ground plane are all on the same plane.

boon


Top

kpainter
Post subject: Posted: Tue Apr 18, 2006 1:25 am

Colonel


Joined: Wed Aug 20, 2003 11:47 am
Posts: 47
Location: Santa Barbara, CA
Hi Boon,
I assumed you were talking about grounded CPW. In this case, there is a ground below the substrate just like microstrip. It turns out, according to AWR's Txline program, that the calculated loss is approximately the same for grounded CPW and microstrip when the gap on the CPWG is the same as the transmission line width. Otherwise, the loss of CPWG is higher - which makes sense. I am saying that in my experience, the actual loss of microstrip is somewhat higher due to radiation. But then, I don't recall what gap I was using but I think it was equal to the line width.

In both structures, the primary propagation path is in the substrate, not in the air - otherwise Er would 1. I don't know how you could build the ungrounded version of CPW in a IC??

Then again, your results may vary.


Posted  11/12/2012
Werbel Microwave - RF Cafe
Axiom Test Equipment - RF Cafe
 

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

These Are Available for Free