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 Engineering smorgasbord RF Cafe Archives RF Cascade Workbook 2018 RF Symbols for Visio - Word Advertising RF Cafe Forums Magazine USAF Radr Shop Sponsor RF Cafe RF Electronics Symbols for Visio RF Electronics Symbols for Office Word RF Electronics Stencils for Visio Thank you for visiting RF Cafe!
Triad RF Systems Amplifiers - RF Cafe
Windfreak Technologies Frequency Synthesizers - RF Cafe

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:


quasi optical microwave management - 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. 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

 Post subject: quasi optical microwave management
Posted: Thu Dec 15, 2005 6:55 am 
Hello all,

As this forum seems to be chock full o' people who know a thing or two or three about microwaves, I figure I'd ask the following questions. Please keep in mind that I'm a laser jock by trade and my practical microwave experience is limited to nuking tv dinners for the most part.


I am working on an inhouse project to build a microwave based Chemical Vapor Deposition system. Basically all that is being done is to use microwave ebergy to dissasociate reactant gas at sub atmospheric pressure to coat a substrate with the thin film of your dreams. I have modeled my efforts thusfar after the work done on microwave based diamond cvd as there is alot of effort put into that field. the first reactors used for this kind of work were called NIRIM systems, after the japaneese agency that developed the reactor design - basically a piece of fused sillica stabbed through a waveguide. This doesnt work well for a number of reasons and cant reach high power density.

The next generation systems basically used an antenna to couple microwave radiation into a cavity, part of witch was under reduced pressure. some of the more novel designs used tricks such as elliptical cavities with an antenna at one foci and the product deposition area at the other to increase power density and remove the plasma from the cavity walls (a major source of contamination).

Essentially all of this work has been done using 2450 or 915 microwaves.

To use the words of my favorite tv cheif - i'd like to kick things up a notch or two. I happen to have in my hot little hands a 20kw source at 18 gig - previously I had been playing with a 100kw source at 915, but since i care about power density and not power I think the shorter wavelength will ahve more pros than cons. What i would like to do is take the output of my klystron to a horn or dish and then refocus the the enegy with an off axis parabolic reflector to a point where as much of that 20kw is concentrated into a region ideally no more than a few cm in diameter... A smallish stainless steel reaction vessel will be located at this focal point and ideally the paraolic reflector will be as 'fast' as possible to keep the e field gradient near the focus as steep as possible to avoid the problem of plasma comming into contact with the chamber walls or pressure window.

now... cosidering my desire for optimum efficency in energy transport from the tube to my product, my desire for highest power density possible, the need to keep plasma away from the chamber walls and the philosophy that this is applied research funded on a small busines budget so therefore must be as cheap as relitivly possible - would anyone care to comment on anything that they see that jumps out that I might be ignoring, not thinking of, alternate suggestions, ect??

Lastly, I am boardering on paranoid when it comes to saftey with 2450 and 915 - i know the military has done some non lethal areal denial weapons testing with mm wave sources - 95 gig iirc - what kind of hazards are present with roughly 18 gig? Will it cook ya just the same as the lower frequency stuff?

Many thanks in advance.

If you would prefer to contact me via email please do so at bobthewoundermoose@hotmail.com

Posted  11/12/2012

Berkeley Nucleonics Phase Noise Testing Seminar - RF Cafe
RF Cafe Sponsors
Lotus Communication Systems Modular RF Component Building Blocks - RF Cafe
everythingRF RF & Microwave Parts Database - RF Cafe

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

These Are Available for Free