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    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 typing up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

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IEEE MTT-S Buys Rights to Smith Chart
Kirt's Cogitations™ #268

New 2015 IEEE MTT-S Logo Using Smith Chart - RF Cafe

New header graphic for mtt.org website incorporates the Smith chart (although not being used yet at the time of this writing).

Image of the Smith chart from U.S. Department of Commerce documents for trademark 73/750111 - RF CafeSomehow, even with trolling daily for technical headlines, I managed to miss (until recently) that back in April of this year, IEEE's Microwave Theory and Techniques Society (MTT-S) acquired the copyright to Phillip Smith's legendary eponymous graphing format: the Smith Chart. Per a column by 2015 IEEE president Tim Lee in the Xplore publication:

Tim Lee

IEEE's 2015 president.

"In 2015, the MTT-S had the opportunity to meet with Mrs. Anita Smith and her family and propose a way to preserve the legacy of her husband and their father. The MTT-S offered to buy the rights from the Smith family of the Smith trademark belonging to Analog Instruments, along with the copyright. In return, the MTT-S would make the Smith chart available to students, practitioners, and indeed people all over the world involved in microwave technology. We would not be buying the rights to re-author Smith's books or to print and distribute the charts, which is still the business of the Analog Instruments."

Interestingly, Mr. Lee mentions the widespread use of the Smith chart in magazines, books, company logos and artwork, personal products, and software both with and without appropriate attribution and/or permission. Most people probably assume that just as they are free to reproduce the ubiquitous x-y rectangular coordinate graph developed by Rene Descartes (i.e., Cartesian coordinates), that use of the Smith chart display for plotting impedances and admittances is permitted as well. I try to remember to include attribution when using the Smith Chart. A Google search turns up no instances of any copyright infringement lawsuits on behalf of the Smith family. Can you imagine the amount of money that could be collected if such a lawsuit were successfully prosecuted?

According to the above quotation, MTT-S will not attempt to prevent the Smith Chart's continued use, which should come as a huge relief to the microwave and RF community. We all owe a huge debt of gratitude to the family of Phillip Smith and equally important to the IEEE for its gracious stewardship of our treasured Smith Chart.

Consider this my formal, "Thank-you!" to both parties.

3D Smith Chart - RF CafeNote: Dr. Andrei Muller has extend the 2-dimensional Smith chart into a 3rd dimension. See his extensive work on the 3D Smith Chart website.

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Posted December 29, 2015

RF Cafe University"Factoids," "Kirt's Cogitations," and "Tech Topics Smorgasbord" are all manifestations of my rantings on various subjects relevant (usually) to the overall RF Cafe theme. All may be accessed on these pages:

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