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.
My Hobby Website:
This collection of video and a few audio files represents files that have been featured on the RF Cafe homepage. Every week or so a new file is added that should be of interest to RF Cafe visitors.
Please send me an e-mail if you have a good subject. Note: "Videos for Engineers" formerly went by the name "Cool Videos."
The next time you are sitting
in city traffic and get an eerie feeling when a large panel van goes driving stealthily by, relax. It
probably is not a terrorist with a load of ammonium nitrate fertilizer, but it might just be a
Z Backscatter Van™ (ZBV) spraying you with x-rays.
OK, don't relax. AS&E has developed a dynamic x-ray backscatter imaging system that uses a non-descript
commercial van as its mobile platform. Typical radiation dosage information is not offered, but the
good news is it supposedly will not cause cellular damage (even though it can see through heavy-walled
steel shipping containers). The system's "drive-by" capability allows operators to conduct X-ray imaging
of vehicles... <more>
Star Wars (SDI) derivative technology has paid off again. Per Raytheon's press release, "Raytheon Company and a U.S. Navy team used a combined-beam fiber laser to shoot down four unmanned aerial vehicles in flight during an over-the-water engagement. The UAV targets were engaged and destroyed using the Navy's Laser Weapon System guided by Raytheon's Phalanx Close-in Weapon System sensor suite. LaWS is made up of six industrial-use lasers that simultaneously focus on the target. " Awesome, n'est-ce pas?
This gives a whole new meaning to "branch circuits." Kaitrees craftsman Kevin forms his trees from bundles of aluminum wire that begin at about 6 feet in length. The trunk is the thickest part of the bundle, which is twisted tightly to keep everything together. No solder or glue is used. Roots, branches, and leaves are fashioned from individual wires. Ends are trimmed as necessary. His videos give info on cunstruction. Kevin currently has 7 different models available for purchase. They would make great props for company lobbies or conference rooms.
6/29/2010IEEE TV has a video reporting on a 270 MW geothermal power generation facility on the grounds of the Naval Air Weapons Station in China Lake, CA. The unground heat generated by the friction of tectonic plates in relative motion manifests itself on the surface with hot springs and bubbling mud pits. It is the perfect opportunity for tapping energy. Per the narrator, enough electricity is generated to not only power the facility, but also to sell power back to the grid. It is one of the largest of such facilities in the U.S. Unlike wind turbines and massive solar cell arrays, geothermal and hydro generation are are very efficient, low maintenance, are and non-polluting.
The world's first telephone book - and only known surviving copy - from the New Haven, CT, telephone exchange, was recently auctioned off by Christie's for a mere $170,500. Along with the names and phone numbers of 391 subscribers were commercial advertisements in the back ala our modern Yellow Pages, and even instructions for how to properly use the newfangled devices. "Pick up the receiver. Say 'Hello." Say 'That is all,' when you are finished." Albert W. Adams appears to be the first name listed. There were no phone numbers, because operators patched through all calls (and no doubt listened in on many of them - like NSA does today).
Regenerative braking has been around for a long time. It converts the kinetic energy of a moving vehicle into electrical energy that is stored in an onboard battery. The concept makes sense for vehicles that are primarily powered by electric motors driving the wheels, because for most motors, the only difference between being a motor and being a generator is the direction in which the energy is being delivered (into or out of the motor). Large city busses outfitted with regenerative braking have been a dismal failure in efficiency, but for primarily electric cars, there is a real advantage. This video is from Popular Science's Theodore Gray, whose Gray Matter column each month usually has a very interesting demonstration fitting for a HS science lab.
There has been a
lot of research into remotely powering aerial vehicles via high power lasers. DARPA and NASA fund numerous
projects, and sponsor contests to encourage participation. System efficiency greatly limits range and
vehicle size/weight, since not only does beam power drop off rapidly with distance, but the photocells
or RF antennas only capture a small percentage of the impinging signal. At a recent trade show,
LaserMotive, winner of NASA's
Power Beaming Challenge last year ($900k prize!), had a demonstration of a laser-powered
model helicopter being powered entirely by an 810 nm laser. They demonstrated capability of 1 km during
the competition. We still have a long way to go, but progress is being made. Futurists envision powering
the Space Elevator and even free-flying
rockets with remote laser power.
Somehow I missed this part of the engineering experience. Our hero Wally is evidently used to it, though. Warning: Watching this short clip from the Dilbert television show that ran from January 25, 1999 through July 25, 2000, may cause you to spend hours of valuable time viewing all the other clips that are available. RF Cafe cannot be held responsible for lost productivity.
Japanese artist Isao Hashimmoto created this video that shows all of the world's nuclear detonations from 1945 to 1998. "This piece of work is a bird's eye view of the history by scaling down a month length of time into one second... The blinking light, sound and the numbers on the world map show when, where and how many experiments each country have conducted." At 1 sec/mo, things are slow-moving at first, then by 1955 the fireworks really get going. The first blip is in the Nevada desert at the Trinity test site in July of 1945. The USSR entered the nuclear club in May 1949, followed by the UK in August 1952. By the end, 7 countries were players, but since then N. Korea joined. Soon, thanks to moronic politicians, Iran will also have detonated a nuke.
7/13/2010A lot of effort has been expended working girls into the realm of the techie / geek / nerd (remember the Nerd Girls video?) - a label assiduously avoided by many boys... until they get rich from being one. The saga continues. "Hello friends, don't you want to meet a nice girl?" That is the opening line in this music video produced by Team Unicorn, whose mantra is Geek Girls: Like unicorns, we're not supposed to exist. Sadly, I am not familiar with any of the players in the video, but reportedly it is full of cameo appearances of movie stars and techie world moguls. Warning: There's nothing too radical in here, but use discretion if playing in your cubicle.
Massachusetts Institute of Technology led the way in providing free access to the content of course material via their MIT Open CourseWare initiative. Although credit is not awarded for the courses, they are a great way to refresh your knowledge or to learn subject matter anew. Lots of professors have gained popularity through these videos. To wit: Dr. Walter Lewin's lectures on Electricity & Magnetism, which are replete with demonstrations using animate (student) and inanimate objects as part of the show. He covers all the classical topics like charges and fields, solenoids and dipoles, Poynting vectors, oscillating charges, and radiation pressure. Digressions into talks on levitating bullet trains and the aurora borealis keep things interesting. Enjoy.
Watch the CNN reporter guy demonstrate how easily his iPhone 4 loses a signal. Problem is, he really has to work at it to get the signal to drop off. On top of that, he does not seem to consider that holding that big metal video camera pressed right up to the phone face might be affecting the signal quality. I doubt that Apple antenna engineers modeled that scenario. Yeah, there really does appear to be a problem with the antenna, but I find it amusing when the know-it-all TV people unknowingly expose the ignoramuses that most of them really are.