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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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."
For the last few months, a clip from the Charlie Chaplain movie
"'The Circus," filmed in 1928, has been somewhat viral within the techie world because it includes a
short segment where there appears to be a strolling woman talking on a cellphone. Of course, that cannot
be what she is doing, cant it? It sure does appear like she's talking on a phone. Only a very few explanations
are possible. 1: She is a space alien amongst the human population. 2: She is merely an early adopter
of oblivion-like behavior. 3: (and this is the most likely) She is part of a vast government conspiracy
that has had advanced technology for decades and unintentionally walked into a movie shoot, thereby
exposing the devious scheme. I will be filing a Freedom of Information Act request later today.
US Navy engineers at the SPAWAR System Center Pacific has developed a technology that uses the magnetic induction properties of sodium chloride (salt) in sea water to create a VHF antenna. Sea water is pumped from the ocean into a stream and the width and length of the stream determine the frequency capabilities. An 80-foot-high stream could transmit and receive from 2 to 400 MHz with a relatively small footprint. The Sea Water Antenna is capable of transmitting and receiving VHF signals and has been tested at a receiving range of over 30 miles. The antennae needs of a typical Navy vessel with 80 metallic antennas could theoretically be replaced with only 10 Sea Water Antennas of varying heights and streams to cover the same frequencies.
Graphene and its biggest celebrity, the carbon nanotube, has been a huge headliner ever since a couple Nobel-winning lab rats discovered they could create copious amounts of graphene by peeling apart a couple pieces of Scotch tape. Prior to that, obtaining the single atomic layer of graphene had been quite difficult. Carbon nanotubes, stronger than steel and lighter than aluminum, are the new wonder product being used in electronics, mechanics, and medicine. Toxicologists, however, are concerned that they might also be the next asbestos since their similarity to asbestos in shape makes it difficult for the lungs to remove once inhaled. Fortunately, we know to study the potential dangers of nanotechnology during its development phase... not as a crisis response to devastatingly widespread deployment.
evidently wasn't enough to disgrace the world's most advanced smartphones to handfuls of powder in a
household blender. Now we have someone barbequing
them on a grill to see which will function longest when exposed to a flame. Although it could be argued
that the temperature distribution is not controlled, and that the flames appear to be skewed somewhat
to the left from a slight breeze, overall it probably is a fair indicator of survivability. An iPhone
4, an Android G2 and an HTC Surround vie for the title of most likely to give its owner one final phone
call from the afterlife if he/she winds up in... that hot place. Which won? You'll have to watch the
Space: The Final Frontier... but it's not just for rocket scientists anymore. With increasing frequency, amateurs are managing to launch platforms bearing payloads of cameras, GPS units, altimeters, thermometers, radios, cellphones, along with various and sundry other gizmos into the lower atmosphere where the earth's curvature and the blackness of space is readily apparent. This flight by father and son team Luke and Max Geissbuhler was launched from a field in New York an amazingly simple craft. It was a resounding success with an ascent to 100,000', then a parachute descent into a tree just 25 miles away. The camera rolled up until just the last 2 minutes. Here is an idea for some budding entrepreneur: Create a line of amateur space exploration kits with varying degrees of complexity. My guess is that it would catch on like the model rocketry craze of the 1960 space race era! You can cut me in on the profits for supplying the idea.
Did you know that for a while back in the 2005-2008 timeframe, Dilbert creator Scott Adams lost the ability to draw legibly and to speak intelligibly? It began with a tremor in a finger on his right hand and eventually took even his ability to speak. Spasmodic Dysphonia was diagnosed as the culprit. He switched to drawing Dilbert with his left hand until the tremor migrated there, too. Because of the unsteady hands, Adams had to adapt to drawing on a digitizing tablet rather than with a pencil. He selected the Cintiq 21UX from Wacom Technology, using Photoshop software. This video shows the master at work. Mercifully, a combination of surgery and therapy has mostly restored his abilities.
Here is a really cool demo showing the distribution of microwaves
inside a kitchen microwave oven. Experimenter Zeke Kossover drilled an array of holes in an acrylic
panel, into which he inserted neon bulbs. Per Zeke, "Microwaves are invisible, so you can't see them
inside microwave oven, but their presence can be detected with neon lamps. The changing electromagnetic
field from the microwaves will make charged particles move, and so the electrons in the metal legs will
move creating current. This current makes the lamps glow." You can see how the field changes as the
panel rotates, and also how the presence of a substance that absorbs the energy affects the pattern.
Here are some highlights from the Inaugural (2010) U.S. Science and Engineering Festival. High tech industry leaders like Lockheed Martin CEO Ray Johnson and Ernó Rubik['s cube] are there to promote an effort to get America's kids interested in science, math, and engineering. Einstein reincarnate even makes a pitch. Entrepreneur Larry Bock states that in building his businesses, he couldn't find enough qualified American workers to fill positions and had to look overseas. Warning flags have been up for two decades, so no one is surprised. Now, with the help of our massive export of technology knowledge and equipment, China and India are dominating the field. Scan through the Engineering News archives from RF Cafe and see how almost daily there are stories of companies transferring technology overseas. We have dug our own grave for the sake of short-term profit and a fear of being called protectionists.
At 1,730 ft (527 m) to the tip of the highest antenna, the Sears tower is the tallest building in the U.S. If the navigation warning light burns out there, you take the elevator up to about 1,500 ft., then climb the remaining couple hundred feet up the tower and replace the bulb - piece of cake, right? It's usually not that easy. The two guys in this video filmed their climb to the very top of this free-standing, 1,786-foot tower in order to replace its bulb. They latch in safety hooks during rest stop, but climb freely in-between; stops become more frequent near the top. You have to be in pretty good physical condition to do this work - which in this case is akin to crawling uphill on your hands and knees for ½ km. According to the narration, the visible horizon is 55 miles away at the top.
York City's David Brooks, owner of "Just Bulbs," had his shop featured in the November 2010 edition
of IEEE Spectrum. Mr. Brooks is a recovering lawyer who gave up the vice many years ago to
assume command of his family's business. Brooks' father started by peddling light bulbs during WWII
when maintaining bulbs in the Empire State Building. This video was made to accompany the original article,
"Last Hurrah for Banned Bulbs," which is on the IEEE Xplore website. Almost every imaginable kind of
bulb is available - about 45,000 different types crammed into a 1,000 sq. ft. shop. It is your #1 shopping
spot for bulbs in vintage equipment like projectors or appliances. Expect to pay a couple hundred dollars
for really hard to find bulbs. Just Bulbs has plenty of those incandescent bulbs that Thomas Edison
plotted to destroy the earth with, but it also stocks all manner of modern technology like fluorescent
and LED bulbs. I would not want to pay his electric bill.
America has lost world's lead in, among other topics, supercomputers, optical telescopes, particle accelerators, and manned space flight, to mention just a few newsmakers of the last many months. One area in which we still dominate is sensor system technology, as demonstrated here in this video from Northrop Grumman. Shown in the animation are the amazing capabilities of the AN/APG-81 AESA radar for the F-35 (I love the wheel coming off the truck). The level of situational awareness is phenomenal, and illustrates how the state of the art has advanced to where human pilots cannot fully exploit the ability of automated systems. Few people can assimilate and process such a large amount of real-time data as presented by a computer. The Air Force is already planning for pilotless fighter aircraft in the near future - consider what the UAV squadrons are already accomplishing in reconnaissance and strike roles. Of course, since politicians continue to write laws that permit the sale or free transfer of our technology - military or otherwise - any lead is in constant peril.
Wireless energy transfer is a big deal these days. This video from Intel labs shows an Intel engineer demonstrating his setup for transferring energy from a primary coil to a secondary coil located a couple feet away. The fundamentals aren't rocket science; this is basically a loosely coupled transformer that relies on mutual coupling of magnetic fields to move power from one place to the other. The trick is making the system highly efficient with small coil sizes. Consider the challenge of merely transferring low power data via near field communications (NFC) with coils the size of a cell phone cover. Texas Instruments and other companies are rushing to provide development platforms for contactless charging systems that are expected to eventually replace the wall wart world of chargers.