RF Cafe Software
About RF Cafe
1996 - 2022
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 Internet was still largely an unknown entity at the time and not much was available in the form of WYSIWYG ...
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These images have been chosen for their uniqueness. Subject matter ranges from historic events, to really cool phenomena in science and engineering, to relevant place, to ingenious contraptions, to interesting products (which now has its own dedicated Featured Product category).
Cool Pic Archive Pages
Berkeley researchers constructed this map of potential wireless data rates that has or will be freed up as "White
Space" as the result of the digital transition of analog TV. It shows the variation in personal bandwidth that might
be available across the country in a scenario in which every 2,000 people use one white-spaces transmission tower
in their area. The redder the area, the high the bandwidth, while the bluer areas indicate that users would experience
slower speeds. All relevant data and code to replicate the results will soon be published by the authors.
If you are as old as I am, you probably remember your high school - and even college - teacher telling you that we will never be able to actually image an individual atom or even molecule. We were taught the Bohr model in my Jr. high (before being called middle schools). Atomic force microscopes had not been invented at the time, which is what was used to obtain this image of a pentacene (C22H14) structure. Pentacene is a flatish molecule made of five linearly fused benzene rings (penta = five, acenes = polycyclic aromatic hydrocarbons with fused benzene rings). It is a p-type organic semiconductor that has been used to make field effect transistors (OFETs).
This quilt, made by HAD (Historical Astronomy Division, of the American Astronomical Society) past chair Sara Schechner, is a copy of a well-known photograph of the 26-inch Alvan Clark telescope as first set up at the original USNO site in Foggy Bottom, c.1873. Simon Newcomb is at the eyepiece. Details of the quilt (size, length of time to make, where displayed, etc.) are hard to come by. If you know Sara, please have her contact me.
strikes in Chicago are nothing new, but this June 2010 photo showing simultaneous instances of electrostatic discharge
(ESD) on both the Willis Tower (1,451') and the Trump Tower (1,389') is indeed rare. It was a wicked storm, with
tornado warnings as winds gusted to up to 80mph. If you are thinking one of those towers looks like the Sears Tower,
you are correct; it was renamed in 2009 when London-based broker Willis Group Holdings leased a portion of the building
and obtained the naming rights (at least it's not the BP Tower). The Trump Tower was set to be the world's tallest
building, but was shortened after the September 11 attacks by Muslim terrorists to make it a less valuable target.
Thank your politicians (and yourself if you vote for them) for the demise of America.
There is apparently no limit to the creativity of people. I am envious of those who are able to see art forms in objects that are totally unrelated to the end product, and especially ones that use a collection of objects with a common theme. This collection of people-themed art figures is amazing. Using resistors, capacitors, transistors, ICs, and inductors, the artist has created a gallery of very clever and entertaining scenarios. A few of my favorites are shown here; you can go to Lenny & Meriel's Flickr page to view the rest of their "Sparebots."
In a world where moral deviance, underachievement, and and overall lameness are regularly rewarded, the wire-bundling-challenged now have an opportunity to claim their due recognition. ZVOX Audio is holding an "UglyTV" contest. The person submitting a photo of the nastiest snarl of interconnects wins "a Z-Base 550 surround sound system with one cabinet, a one-page owner's manual, and one connecting wire!" If your competitive juices are flowing already, calm down; the contest ended on April 30.
is just one of the featured "20 Homemade Things That Shouldn't Be Home-Made." Whether meant to be a supercapacitor
replacement for a cellphone battery, or the owner was just too cheap to buy a new battery, it just doesn't feel
right. Some are undoubtedly intended to be jokes, but others, well, unfortunately not so much. There really are
a lot of Red Greens in the world,
and somehow at least one tends to live near all of us. I guarantee you can find many instances of the ad hoc "circuit
breakers" shown in the bottom photo.
Twins separated at birth? Probably not based on the years between them. For a few years, I have been collecting images of electronics industry personalities who remind me of famous people of science and engineering. The latest one is Peter Claydon, co-founder of picoChip, who, at least in the accompanying photo, reminds me a lot of Nikola Tesla. Put some glasses on Mr. Tesla, turn him face-on, and you've got Mr. Claydon. Maybe worm holes do exist.
There are a number of Museum of Unworkable Devices type websites on the Internet, but this one has many good links to follow. A lot of duplication exists on the various sites, but there are so many examples that you can spend hours reading about them. A lot of thought goes into developing the ideas that would work as planned if not for that friction demon. Many involve perpetual motion devices, but you will also find illusions such as the famous "Waterfall," by M.C. Asher. If you have time to spare or like to surf on your smartphone while occupying a stall, look up the patents that were actually awarded to a few of these devices.
and nano scale imaging has become an avant-garde art form, and is popularized and exemplified by people like Dr.
Albert Folch (Folch Lab). As
we all learned in undergrad physics class, thin films, which by definition are a small fraction in thickness of
the wavelength of light impinging upon them, can generate some really colorful patterns. A macro scale example is
the rainbow of color on a thin film of oil or gasoline on water on a sunny day (unlike
the thick film in the Gulf of Mexico). Phenoms who study such phenomena can determine the thickness profile
based on the color distribution.
XRD, and other near-atomic-level imaging
is opening new realms every day. The social artsy-fartsy crown think it is "pretty." Nerds like us just think it's
RF Cafe visitor Bob Davis sent me this link to the xkcd (it's just a word with no phonetic pronunciation) website, "A webcomic of romance, sarcasm, math, and language." This spoof schematic would make a good opening slide for your next circuit design presentation. If you don't like this one, you can spend an hour or so scanning through the hundreds of similar items on the site. Webmaster Randall Munroe is an admitted physicist. That explains a lot ;-)
Washington, D.C., circa 1919. "Chesapeake & Potomac Telephone Co. central office wiring." This Harris & Ewing glass negative provides a behind the scenes look at communications technology 75 years after the first telegraph message was tapped out in 1844 by Samuel Morse. It is only 43 years after Alexander G. Bell (1847 - 1922) received his Improvement in Telegraphy (aka telephone) patent in 1875. The resolution is so good that you can see the twists in the twisted pairs.