1996 - 2016
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 ...
All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.
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The inventions and products featured on these pages were chosen either for their uniqueness in the RF engineering realm, or are simply awesome (or ridiculous) enough to warrant an appearance.
All Featured Product Archive Pages:
you have been an RF Cafe visitor for a while, you know that I am fond of vintage electronics magazines and hardware
(vintage electrical engineers and technicians are pretty cool, too). I am a firm believer that a knowledge of
relevant history is essential to a well-rounded experience in your chosen field. Reading about the trials and
tribulations of our forebears is both instructional and motivational. Fellow engineer
Bob Davis, himself a restorer
of old radios, sent me this link to the Antique Radio
Archive website. On it you will find many documents scanned to PDF files for manuals, schematics, and how-to
articles. An example is the Meissner "'How to Build' Instruction Manual for Beginners, Advanced Students, Instructors,
Servicemen, Hobbyists & Experimenters." It contains, "A wealth of information on basic theory, design, constructions
on AM circuits, FM circuits, phono pickups, audio amplifiers, speakers, ... construction of power supplies,
transmitters..., and scores od circuit diagrams covering varied applications." It's good stuff.
Some things cannot be improved upon, and this report on a rear view mirror with an integrated multimedia picture-in-mirror feature is one of them. Per the Vice website, "The Bluetooth Rearview Mirror Kit includes a host of potential driver distractions, including a GPS system with built in screen, hands free speakerphone, front and rear camera displays, video playback and of course touchscreen games. Best of all, it has a built in DVR that records the picture from the cameras. That way when you smash into the car ahead while trying reach level 9 on Super Mario as you cruise down the Interstate, the cops will have plenty of evidence." The kit fits over your existing mirror and includes a wireless rear view camera SD card, and new mirror surface w/LCD display. Cost is around $200. GizMag has more detail, but less wit.
Generating truly random numbers from a digital source is no trivial matter. Pseudo random numbers are simple enough to generate, but even with a fairly sophisticated seed key, today's powerful computers and extremely smart programmers are able to break all but the most advanced codes. Analog circuits are capable of producing genuinely random seeds, but they consume more power than can be spared in general-purpose processors for personal computers - the largest application base for digital security. One famous solution to the problem was the use of a lava lamp whose globulation was monitored by a CCD that generated a new random number on demand. The LavaRnd website was created to provide random seeds of up to 817 digits to users, but obviously that is not a blanket solution. An article in the September 2011 edition of IEEE's Spectrum reported on a new semiconductor process developed by Intel that is statistically even more random than LavaRnd, and sips only tiny amounts of current. The explanation is fascinating.
KM5KG RF Network Designer appeared in the New Products feature of the January 2012 QST magazine. Network
in this case refers primarily to R, L, C, and transformer circuits in most of the familiar configurations like
diplexers, bridged-Tee combiners, hybrid-pi combiners, L combiners, audio and RF attenuators, series and shunt
power dividers, and broadband impedance matching. It also has component designers for coils, transformers, solenoids,
transmission lines, and antennas. Extensive parameters are calculated for network components including complex
impedance, power dissipation, voltage across and current through, including phase. RF Network Designer is a
veritable cornucopia of calculated values. Both Amateur and Pro versions are available. There is no installation
program that makes sure all the necessary system files are present, so if you download the demo and it gives
you a notice about a system file missing, go to the website's
homepage and download that file from there.
Some things are obvious to even the casual observer, especially if you have seen The Matrix. Clearly, the über smart scientists and engineers who work at CRIM Lab, Scuola Superiore Sant’Anna, in Pisa, Italy must have had Mr. Smith's bug from The Matrix in mind when they developed this 12-legged, wireless human intestine explorer. Then again, it could equally likely have been inspired from torture implements employed during the The Inquisition era, intimately familiar to inhabitants of that geographical region. Imagine being told you need to swallow this thing so that doctors can wirelessly guide the beast through your intestines. The pill-sized electromechanical wonder (I'm being nice) settles naturally to the bottom of the stomach and enters the duodenum - the transition between the stomach and small intestines - whereupon the attending physician signals for extension <more>
Christmas is coming, so now is a good time to be thinking about what kind of gift to get your favorite engineer, scientist, hobbyist, or generic nerd. Fortunately, a catalog from the 3B Scientific company arrived in my mailbox that provides just the source needed. A lot of these I've never seen before, like a refrigerator magnet of Schrödinger's Cat and Pavlov's Dog. How about a T-Shirt that says, "If you're not part of the solution... you're part of the precipitate," or maybe shower curtain with the Periodic Table printed on it? (I'll spare you the trite insinuations about the chemistry that can happen in a shower). A nice selection of Sterling Engines are available for your desktop. I like this baby shirt with "Baby Genius" spelled out in chemical symbols. On the more serious - but not too serious - side, you can buy historic experiment sets, demonstrators for electricity and magnetism, optics, heat and thermodynamics, or waves and sound. If you are simply averse to fun, 3B Scientific will also sell you practical stuff as well.
apparently indefatigable Gary Breed, former editor of RF Design and current founder/editor of High
Frequency Electronics, has just launched a new publication:
RF Technology International. Subscribers to HFE received
the premier edition within the last week or so. Is there really a need for a new publication that caters to
the RF/microwave world? Gary believes there is. Per his opening editorial, "The mission of this new multi-media
publication is simple - Collect, sort, select and present information that is valuable to engineers who work
in RF, microwave and high speed technology." Chief amongst the goals is to provide a historical perspective
to new developments; that is, "We Build the Future on a Foundation Established by Earlier Generations." With
as rapidly as technology progresses and the pressure to invent and produce increases, there is precious little
time to reflect on how we got to where we are today. Some people don't think that is important as long as innovations
keep flowing. I do. Some of the most intriguing articles I read - and I read lot - contain references to the
people and events that led to the breakthrough technology being reported. The historical, indeed the personal,
perspective turns an otherwise dry presentation of words and numbers into a enjoyable story. I look forward
to seeing how Gary and his staff deliver on this promise.
I can imagine that by next Christmas, some incarnation of this prototype "Eye Ball" will be available at Toys R Us. If so, lots of parents and wives of soldiers will also probably be mailing them to their deployed loved ones for field use while on patrols in far-off lands. Per the Technology Review website review: "If you toss this foam-covered ball skyward, an accelerometer inside determines when it has reached its maximum height. At that moment, 36 cameras are triggered simultaneously, creating a mosaic that can be downloaded and viewed on a computer as one spherical panoramic image. The ball was created by researchers at the Technische Universität Berlin after one of them, Jonas Pfeil, labored to create panoramas while on vacation in Tonga." The interface is USB now, but a wireless version is likely.
This one will require a bit of work on your part or on the part of a friend with knitting skills. Laptop Compubody Sock is the brainchild of geek product designer Becky Stern. It serves a dual purpose by providing shelter from the cold while also affording privacy from wandering eyes while working on your laptop computer in public places. The might be a bit of a safety issue due to limited visibility of the situation surrounding you while "under the hood," but maybe the knitting is done loosely enough to permit to allow the wearer to see out while blocking the view in. Complete, illustrated instructions are provided. She also has a knitted keyboard glove that fits over your hands and keyboard to keep warm; of course, you will need to be a good typist (that leaves me out). For ready-made gifts, Becky offers emission spectrum scarves, an ASCII text art heart pendant (made from <3 characters), and even a necktie with resistor color codes (coming soon). Evidently, she makes all the stuff herself - truly Made in America.
is an accessory to add to your James Bond collection. These silver cufflinks double - no triple- as a 2 GB flash
drive and as a Wi-Fi hot spot. USB flash drive cufflinks have been around for awhile and are plentiful on
Amazon, but the Wi-Fi feature of this product is unique. I could not find any performance specifications
for them, but there is a funny review on the website link (click the picture and scroll down). If you have a
$250 to spare, you can buy a set and let me know how they work.
The maker of this wireless urinal game console probably would have named it the "Wee" (ref wii) if not for certain lawsuit from a major corporation. It is wireless only in the sense that infrared (really high frequency electromagnetic waves) sensors detect the "joystick" position. No, this article was not posted on April 1st. Debuting in London bars, the unquenchable need to present potential customers with an endless barrage of advertisements has led to the development of a ridiculous venue for occupying otherwise idle time - 55 minutes on average according some taxpayer-funded study. The console sports a 12" LCD display and is driven by Windows 7 on an Intel Atom processor. Now, rather than just whistling or reading hastily scribbled bits of prose on the wall, the patron can skillfully guide penguin skiers through a slalom course. I have an idea for an ad on the console: waterproof goulashes to slip over your shoes prior to entering the bathroom... to guard against aggressive gamers.
Brent Locher, of the fourier-series.com website, has produced quite a few nice Flash-driven RF and electronics tutorials over the last couple years. Interactive controls allow the user to change system parameters and see how the output responds. The newest tutorials deal with thermal noise and noise figure. Thermal Noise on a Transistor, for instance, demonstrates how bandwidth and termination resistance affects noise power. Adding Correlated and Uncorrelated Noise shows visually and numerically how to calculate the quantity and how to tell whether noise is correlated or not. Are you not quite sure how noise power affects noise figure in a cascaded system? Check this tutorial on noise factor and noise figure calculations. Oh, did I mention that audio tracks are included to narrate about each process?