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 ...
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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."
- make that two - final tributes to the Applemeister, and then let the world move on to the next iconic
genius. Here are clips from Comedy Central's Jon Stewart and Stephen Colbert on the night after news
of Steve Jobs' death (succumbed to pancreatic cancer). As you might expect, there was a mix of humor
and serious gratitude. Both hosts have done numerous skits over the years where they make fun of Apple
products, their users, and Jobs, while also begging on-air for early samples of the next big thing.
I'm a firm believer in the notion that nobody is irreplaceable, at least on an all-of-humankind scale.
Isaac Newton, Henry Ford, Thomas Edison, and Galileo Galilei contributed mightily, but each was followed
by another. It's time to let the venerable Mr. Jobs rest in peace. Every person leaves his mark on the
people around him, and the rare few leave a mark on the world. Who will be the next tech wonder? It
isn't likely to be this <more>
In the news recently
was restoration to operational condition a Tunny code-breaking machine from the World War II era. It
is part of the collection of calculating machines on display at the UK's
National Museum of Computing, located in the renowned
Blechley Park complex. Tunnys were used
to decipher messages generated on the Lorenz SZ42 enciphering machines and sent from Hitler to his generals. Work was
at a fever pitch in the days running up to the
D-Day invasion. Keep in mind that the computers did not crack the code, they were for rapid deciphering
of the volumes of messages sent daily. Restoration work on Tunny was performed by a team led by computer
conservationists John Pether and John Whetter. "As far as I know there were no original circuit diagrams
left. All we had was a few circuit elements drawn up from memory by engineers who worked on the original,"
per Mr. Pether. One of the original electrical designers, Sid Broadhurst, reportedly left an envelope
"55 year old Maurice Johnston lives in Boston, by way of Cleveland. He has a Masters Degree in Plasma Physics from Dartmouth College, and a masters in Electrical Engineering and acoustics from Purdue University. He's worked over 10 years at Lockheed Aerospace & Aerodyne Research Corp. Maurice has taught in Science and physics, and took care of both his parents in their time of need." Maurice has also been out of work for many months and is currently living on the streets of Boston. He moved there on the promise of a job which, upon arrival, he discovered it had been given to someone else. Despite having had a huge amount of media coverage - including Time, and many other online publications (including, now, RFCafe.com) - there is no indication that Maurice is employed yet. Maurice is suffering from the same horrible economy that is similarly affecting many people. He is an extremely likeable person judging from the interview, so why, after all this coverage, is the good man still on the <more>
8/16/2011"Should Math Be Taught in Schools?" That was the question posed
to a group of Miss USA contestants featured in this video. The responses offered will surprise you...
or maybe not. Every year at beauty pageants, at least one answer to the pool of questions will elicit
a rambling, nonsensical, usually politically correct reply where you find yourself embarrassed for the
poor lass (disclaimer: I never watch them). In these days of instant
video postings, if you screw up, the whole world will know within hours. Probably the most memorable
example of late was the during the 2007 Miss Teen USA
contest where the question, "Recent polls have shown at 1/5 of Americans can't locate the U.S. on a
world map. Why do you think this is?" Miss South Carolina's answer: "I... personally believe that U.S.
Americans are unable to do so, because, um, some people out there in our nation don't have maps and,
If you have never watched
the Red Green show on PBS, you don't know what you've missed. It is a veritable treasure trove of How-To
and Do-It-Yourself instructional videos. Possum Lodge's grand pooh-bah, the Doctor of Duct Tape
(aka duck tape for the ignorant), Red Green has produced
a seemingly endless collection of useful project shorts that cover just about every topic. The featured
video has a Possum Lodge expert answer a viewer's question about Boolean Logic in his new car's fuel
injection system. You can't get this kind of education at some fancy university. Another one shown is
a prime example of how a bit of redneck ingenuity allows the dedicated tinkerer to easily and cheaply
convert manually operated car windows to electric power. As Red aptly asks, "Ever notice how winding
your window down by hand makes you look lower-middle-class?" I won't spoil the surprise by telling you
how he does it. <more>
There are a few realms remaining
where America's lead has not been surrendered to the world; among them are military and aerospace systems.
The technological prowess applied to these tactical and strategic systems are the most advanced anywhere.
Yes, there are areas where other countries have the lead, but despite the best efforts of some of our
scumbag politicians, overall our advantage is unquestionable. It has never been so that if you are nice
to everybody, then everybody will be nice to you. Any country or bloc that lets down its guard will
eventually be attacked and dominated by an aggressor. Sorry, it's just the way it is on Planet Earth.
That said, I am glad to see promotions (call it propaganda if you like) for systems like Northrop Grumman's
AN/AAQ-37 Distributed Aperture System (DAS) for airborne platforms like the F-35 Joint Strike Fighter.
It assimilates data from a wide array of sensors spread across the aircraft structure to generate a
We have been treated to videos of superconductor levitation for
many years, so watching a super-cooled object float above a magnet is nothing new. The novel factor
in this demonstration is an effect called quantum flux tube formation (Trekkies
must love that term) where the properties of the superconductor are such that rather than completely
repelling the magnetic filed, which is the norm for superconductors, portals are created through the
material where flux line clusters actually retain the puck. In the other demos, you see a small puck
levitating over a large magnet. Here, it is the opposite. Rather than being constrained by the magnetic
wrapping around the perimeter of the puck and pretty much locking it in place, this structure allows
the supercooled puck to move around within the field. It can run along a track impeded only by air
about time for another episode of "Will It Blend?" Überblender maker Blendtec has created an Internet
sensation with their series of "Will It Blend?" videos, where the white-lab-coat-wearing engineer Tom
demonstrates the brute power of his company's blenders by reducing household items to a small pile of
dust and chips. Last year sometime I posted a video of the iPhone 4 being blended, and now we get to
see whether an iPad 2 will meet a similar fate. Whereas in the past, a simple video of the DTB (device
to blend) being dropped into the blender and being decimated sufficed for entertainment, now Blendtec
is making more of a full-scale production. In this video, a faux Steve Jobs does the introduction and
takes pleasure in admonishing Tom that the iPad can never be blended simply because it will not fit
into the glass blender thingy. Will the iPad 2 blend? You'll have watch to find out.
The news is replete with references
to carbon nanotubes, and deservingly so since they are in the process of revolutionizing many technologies
and allowing the creation of new ones. If you do not really have an understanding of just what carbon
nanotubes are, this excerpt form the TV show Nova does a good job of introducing them. Carbon
nanotubes are rolled-up sheets of graphene, which is a one-atom-thick layer of carbon atoms. To date,
carbon nanotubes have been used to create the world's smallest
radio, transistors, frequency
superconductors, and much
As you can see from the dates on some of the articles, carbon nanotubes have been around for over a
decade. The reason for a seemingly overnight interest in them is the discovery in 2004 by two
scientists of an amazingly low-tech method for creating graphene on a large scale. All it took was
some pencil 'lead' and a piece of Scotch tape. If you want to see more on nanotubes, there are plenty
of other videos listed on the page linked to with the thumbnail.
Well, somebody has finally done
it - a 3D Smith Chart applet that plots the entire reflection coefficient and impedance planes. Specifically,
Andrei Muller (who contacted me) and cohorts done it. "The 3D Smith
chart demo version has 3 planes: normalized impedance plane, reflection plane and 3D Smith chart. One
may draw the impedance and get the image of it on the reflection coefficient's plane or on the 3D Smith
chart. On the 3D Smith chart one can rotate it and play with the constant r,x, and abs(z) circles. The
3D Smith chart includes both extended reflection and impedance planes." It will take a bit of experimentation
to figure out exactly what is going on in 3D after years of using the standard 2D version we are all
familiar with. Andrei says that for now, there is no plan to extend the functionality beyond plotting
of S-parameters, but he and his co-developers are open to working with someone that is interested in
integrating the concept into a commercial application. It is copyrighted so permission is required.
June 2011 IEEE Microwave and Wireless Components Letters:
When it comes to Star Wars hysteria, there is no concept of what
is a reasonable limit to the extent to which someone will go to develop yet another novel application
of some feature of the epic film series. I'm glad to suffer their eccentric, yet entertaining, endeavors.
This video demonstrates how just about anything can be made into a musical instrument. The film maker
used two vintage floppy disk drives to perform a virtuoso performance of the Imperial March music from
Star Wars. If you are old enough to have used those floppy drives, you well remember the electromechanical
clacking and humming sounds emanating from the bowels of the device. If you worked in an open office
area (the pre-cubicle days), you can attest to how that sound violated laws of physics by travelling
extraordinary distances to reach your ear. Anyway, grab the light saber from the back of the desk drawer
and enjoy the ingenuity of the video.
If you recall back when 3D printers
first started making the news, they were rather crude, cobbled-together machines that laid down successive
layers of plastic polymer material by a nozzle driven in the x,y, and z axes. Then, the structure was
cured with radiant heat or microwaves. New generation 3D printers are capable of much more intricate
form factors that include integrated, moving parts. Resolution is fine enough that round surfaces can
be fabricated. This video shows an adjustable wrench being made. Its sliding jaw half and worm gear
are "printed in one step while the main body is being made - pretty slick. You might be surprised to
see what the finished part looks like before being removed from the machine. Having such a capability
greatly increases the likelihood of first-time success with manufacturing prototypes. These printers
are to mechanical engineers what we electrical types have in the way of printed circuit board etching
machines that use a high-speed milling bit to cut controlled impedance microstrip substrates.