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Monday the 31st
Sunday the 30th
Friday the 28th
Thursday the 27th
Wednesday the 26th
Tuesday the 25th
Monday the 24th
Sunday the 23rd
 This January 23rd custom made
crossword puzzle has an Amateur Radio theme, compliments of RF Cafe. All
RF Cafe crossword puzzles are custom made by me, Kirt Blattenberger, and have
only words and clues related to RF, microwave, and mm-wave engineering, optics,
mathematics, chemistry, physics, and other technical subjects. As always, this crossword
puzzle contains no names of politicians, mountain ranges, exotic foods or plants,
movie stars, or anything of the sort unless it/he/she is related to this puzzle's
technology theme (e.g., Reginald Denny or the Tunguska event in Siberia). The technically
inclined cruciverbalists amongst us will appreciate the effort. Enjoy!
 There are not many technical realms where
Google engineers have not either entered or created. Wireless connectivity is key
to their continued dominance in the information domain, so they understandably have
a vested interest in the "white space"
spectrum debate. White space comprises portions of the electromagnetic spectrum
where bands are either unlicensed or where licensed bands are or will be up for
grabs. An example of the former is the 2.4 GHz Wi-Fi band, and an example of
the latter is some parts of the broadcast television band that is being vacated
in areas. Although this information is a few years old, it shows how Google was
working early−on with the Federal Communications Commission (FCC) to build a real-time
database of what they term "dynamic spectrum" in order to provide useful information
about available white space (now directs here) to both users and providers. A separate
database is available for fixed and mobile spectrum. Enter your location of interest
and the map zooms into that region. For instance, in my town (at the time) of Erie,
Pennsylvania (see marker on map below), as of January 2013 when this was first posted
there were 21 channels available...
 This assortment of custom-designed themes
by RF Cafe includes T-Shirts, Mouse Pads, Clocks, Tote Bags, Coffee Mugs and Steins,
Purses, Sweatshirts, and Baseball Caps. Choose from amazingly clever "We Are the World's Matchmakers"
Smith chart design or the "Engineer's Troubleshooting Flow Chart." My "Matchmaker's"
design has been ripped off by other people and used on their products, so please
be sure to purchase only official RF Cafe gear. My markup is only a paltry 50¢ per
item - Cafe Press gets the rest of your purchase price. These would make excellent
gifts for husbands, wives, kids, significant others, and for handing out at company
events or as rewards for excellent service. It's a great way to help support RF
Cafe. Thanks...
Reactel has become one of the industry leaders in the design and manufacture
of RF and microwave
filters, diplexers, and sub-assemblies. They offer the generally known tubular,
LC, cavity, and waveguide designs, as well as state of the art high performance
suspended substrate models. Through a continuous process of research and development,
they have established a full line of filters of filters of all types - lowpass,
highpass, bandpass, bandstop, diplexer, and more. Established in 1979. Please contact
Reactel today to see how they might help your project.
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 In response to my solicitation for information
on the origin of band letter
designations, a website visitor offered this: "I just looked at your web page
that gives the names of the various RF bands, and, in one place asked for any information
on origins of the names. I have some history on the band names that apply to UHF
and above. In the early days of radar (during WWII), the British and the U.S. researchers
at MIT chose, arbitrarily I believe, letter designations for radar frequencies.
The frequencies that were then possible to use for radio communication were just
called by their 'meter range' names: HF, VHF and UHF. The new frequencies that were
then only used for deployable radar sets, and for new technology looking for even
shorter wavelength radars, were given letter designations. So, in the 1940s and
1950s, radar sets were identified as being UHF, L-Band, S-Band, C-Band, X-Band and
K-Band. Later they added Ku-Band - presumably for 'K Upper,' but I do not know..."
 "What are these devices?" "How do they work?"
"What are their characteristics?" "How are they used?" Those are the kinds of questions
about
semiconductor diodes posed - and answered - in this article in a 1961 issue
of Popular Electronics. Author Jim Kyle runs through a short history of
he diode and then delves with more detail into physical construction, I-V curves,
power handling, junctions capacitance, resistance, etc. An interesting point mentioned
is that while a semiconductor diode will conduct some finite amount of current when
biased in the reverse direction (sometimes a desired characteristic), a vacuum tube
diode will not conduct at all when reverse biased - thereby making the tube a more
perfect rectifier...
 This "R/C
Triplex: Three Channels on One Channel" article that appeared in a 1956 issue
of Popular Electronics magazine was written by a fellow who was well known in the
aeromodeling world at the time - Claude McCullough. Claude won many titles in precision
scale for both control line (C/L) and radio control (R/C). As was the case with
many R/C modelers of the era, he did a lot of experimentation with transmitters,
receivers, and electromechanical devices used to move control surfaces. Rubber-band-powered
escapements dominated the field, but some servomechanisms were being developed to
provide a means for proportional control and/or a more powerful means of multiposition
control. As can be seen in the video I produced showing how a typical escapement
worked, the output drove the airplane's rudder to either neutral, full left, or
full right deflections, with no position in-between. To actuate the control, the
R/C pilot pushed a button on the transmitter the number of times required to affect
the desired control movement. That made for somewhat jerky flights, but it was a
very popular setup...
 This custom made
Antenna theme crossword puzzle for January 30th is provided compliments of RF Cafe
All RF Cafe crossword puzzles are custom made by me, Kirt Blattenberger, and
have only words and clues related to RF, microwave, and mm-wave engineering, optics,
mathematics, chemistry, physics, and other technical subjects. As always, this crossword
puzzle contains no names of politicians, mountain ranges, exotic foods or plants,
movie stars, or anything of the sort unless it/he/she is related to this puzzle's
technology theme (e.g., Reginald Denny or the Tunguska event in Siberia). The technically
inclined cruciverbalists amongst us will appreciate the effort. Enjoy!
 Some people like to demean engineers and
scientists for their propensity to want to conduct experiments and obtain measured,
empirical data rather than "winging it" and being satisfied with intuitive knowledge
or the contemporarily popular term "gut." If mankind had not adopted scientific
methods and ventured beyond the so−called cradle of civilization on the African
continent, we would all still be living in grass huts, hurling rocks at prey, and
foraging for berries.
Quantifying and categorizing all things in nature helps inventors create new
and improved implements that help make life better. Early on it was mostly individuals
like Archimedes, Euler, Newton, and Edison who built the pool of knowledge that
fed and evolved into corporations, governments, and universities doing the vast
majority of the work. Bell Laboratories is probably one of the most recognizable
names for a group of people that collectively produced an immense amount of data
and products...
 During my daily technical headlines search,
one of the websites I regularly visit is Radio Ink. As a lifelong fan of over-the-air
broadcast radio (and TV), it is interesting to see what trends are playing themselves
out.
OTA (over the air) broadcasting is struggling to survive in this modern world
of Podcasts and Internet streaming broadcasts; indeed, I do a lot of my radio listening
via the Internet because the local stations don't provide what I want. The Big Media
types are involved in a major lobbying effort to mandate FM radio receivers in all
cellphones, which of course is a prime example of corporate chieftains using their
financial might to pay off politicians for something that the rest of us will ultimately
have to foot the bill for. Radio's early days faced no such dilemma. People the
world over were excited about the advent of radio and eagerly awaited their favorite
broadcasts each day...
 The advent of FET-input
multimeters greatly reduced reading accuracy errors due to not taking into account
the impedance of devices being measured. A certain amount of familiarity with how
to interpret the indication on a meter movement on analog meters is still required
based on the multiplier switch position and scale selected, but for most users simply
reading the number beneath the pointer - or interpolating its position between two
numbers - is good enough. Mirrored scales take the some of guesswork out of that
by reducing parallax issues. Finally, digital multimeters (DMMs) hit the scene and
made slackers out of just about all of us when it comes to making voltage, current,
and resistance measurements. With few exceptions, only production test, research,
and metrology environments require pulling out the meter specifications to determine
precision and accuracy numbers...
 Hogarth is a comic character invented by
the
Echophone
Radio Company. Their bespectacled Army grunt was one of the first technology
nerd types who always managed to appear with pretty girls. His caricature evolved
quickly over the two or three year run of the advertisements in electronics magazine.
Most Echophone Radio ads I have seen either feature Hogarth and his woman/women
or Hogarth and a demanding sergeant. This full-page advertisement appeared in the
June 1945 edition of Radio−Craft magazine. Echophone radios can still be
found on eBay for fairly low prices - often less than the shipping cost...
 You probably read a while back of the San
Francisco's Bay Area Rapid Transit (BART - good acronym, as in Simpson) shutting
down cellphone service in order to thwart a rumored attempt to organize a flash
mob attack. 1st Amendment groups have sued BART over the action. Also in the news
has been the government's plan for being able to
shut down the
Internet in the event of a national emergency (defined as whatever they need
it to mean). We already know that Big Brother has the capability to universally
control both wired and wireless phone service. OnStar-equipped vehicles have been
shut down remotely by law enforcement. It all seems very Orwellian, but it began
before the publication of "1984" (in 1949). Did George just dream up the book's
theme of total government control and a lemming populace, or did it come from astute
observations of past behavior that was projected into the future? On December 8,
1941, the day after the Japanese attack on Pearl Harbor, the FCC issued a "Notice
to All Amateur Licensees" that began thusly: "All amateur licensees are hereby notified
that the Commission has ordered the immediate suspension of all amateur radio operation
in the continental United States...
 Varian is a company familiar to most people
involved in early development of radar and other higher power microwave systems.
While the name sounds like a moniker construed from a combination of technical terms,
it is actually the surname of engineer brothers Russell H. and Sigurd F.
Varian. They are credited with building the first practical reflex klystron tube,
and its variant the
rhumbatron, while at Stanford University. Velocity modulation, the subject of
this 1939 QST magazine article, changes the speed of a stream of electrons
flowing at a constant current rate, rather than modulating the current. It was a
big deal that eventually found application in CRT displays for adding another dimension
to information on monochrome presentations...
 Before a plethora of readily available and
affordable electronic and mechanical components of all sorts was at your fingertips
(on a keyboard), often times project builders and repairmen either did without,
substituted "close enough" parts, waited a long time for mail order, drove long
distances to a supply house, or did like
Carl and Jerry did in this May 1960 Popular Electronics magazine adventure
- they modified on-hand equipment to suit the need. Replacing the center conductor
of a length of RG-58 coaxial cable in order to change its capacitance (and impedance)
might seem like an extreme measure to take, but half a century go it was de rigueur
with hobbyist of all sorts. Magazines of the era nearly always had monthly hints,
kinks, tip, and suggestions features, enthusiastically provided by readers who had
already reaffirmed the old adage of necessity being the mother of invention. As
is author John Frye's normal practice...
 RF Superstore offers
a wide selection of popular
coaxial cable in bulk lengths at exceptional prices - order by the foot for
any custom length needed for your project. RF coaxial connectors are available
for terminations. RF Superstore also offers power couplers, attenuators,
terminations, DC blocks, surge protectors, waveguide, and more. The launch of RF
Superstore in 2017 marked the return of Murray Pasternack to the RF and
Microwave Industry. As founder and CEO of Pasternack Enterprises from 1972 to
1992, Mr. Pasternack fundamentally changed the way RF components were sold
throughout the industry. His signature catalog greatly simplified the ordering
process and became the industry standard for RF component sales. We're leading
the way again...
 David Goins, founder of and chief
engineer for Windfreak Technologies, has written a number of application notes
pertaining to the specification and testing of RF and microwave frequency signal
generators. Most of the articles include features and applications for Windfreak Technologies
products, but the concepts are universally applicable. His latest, "Testing RF Generators for
Reliability" is featured here. It begins: "We pride ourselves in designing,
building, and selling high value radio frequency products that are thoroughly
evaluated and tested. All of our products go through rigorous testing before
releasing to our customers. Our devices have proven to be very reliable. In rare
cases, we have had a product come back for repair caused by output amplifier
failures. In this post, we explain the testing process we go through to ensure
our high-quality products and the two reasons for output amplifier failures..."
 New Scheme rotates
all Banners in all locations on the page! RF Cafe typically receives 8,000-15,000
website visits each weekday.
RF Cafe is a favorite of
engineers, technicians, hobbyists, and students all over the world. With more than
12,000 pages in the Google search index, RF Cafe returns in favorable positions
on many types of key searches, both for text and images. New content is added on
a daily basis, which keeps the major search engines interested enough to spider
it multiple times each day. Items added on the homepage often can be found in a
Google search within a few hours of being posted. I also re-broadcast homepage items
on LinkedIn. If you need your company news to be seen, RF Cafe is the place
to be.
RF Cascade Workbook is the next phase in the evolution of
RF Cafe's long-running series, RF Cascade Workbook. Chances are you have
never used a spreadsheet quite like this (click here for screen capture). It is a full-featured RF system
cascade parameter and frequency planner that includes filters and mixers for a mere
$45. Built in MS Excel, using RF Cascade Workbook 2018 is a cinch
and the format is entirely customizable. It is significantly easier and faster than
using a multi-thousand dollar simulator when a high level system analysis is all
that is needed. An intro video takes you through the main features...
 With more than 1000
custom-built stencils, this has got to be the most comprehensive set of
Visio Stencils available for RF, analog, and digital system and schematic
drawings! Every stencil symbol has been built to fit proportionally on the included
A-, B-, and C-size drawing page templates (or use your own page if preferred). Components
are provided for system block diagrams, conceptual drawings, schematics, test equipment,
racks (EIA 19", ETSI 21"), and more. Test equipment and racks are built at a 1:1
scale so that measurements can be made directly using Visio built-in dimensioning
objects. Page templates are provided with a preset scale (changeable) for a good
presentation that can incorporate all provided symbols...
 It was a lot of work, but I finally finished
a version of the "RF & Electronics Schematic & Block Diagram Symbols" that
works well with Microsoft Office™ programs Word™, Excel™, and Power Point™.
This is an equivalent of the extensive set of amplifier, mixer, filter, switch,
connector, waveguide, digital, analog, antenna, and other commonly used symbols
for system block diagrams and schematics created for Visio™. Each of the 1,000 or
so symbols was exported individually from Visio in the EMF file format, then imported
into Word on a Drawing Canvas. The EMF format allows an image to be scaled up or
down without becoming pixelated, so all the shapes can be resized in a document
and still look good. The imported symbols can also be UnGrouped into their original
constituent parts for editing. Check them out!
 With more than 1000
custom-built symbols, this has got to be the most comprehensive set of
Visio Symbols available for RF, analog, and digital system and schematic drawings!
Every object has been built to fit proportionally on the provided A-, B- and C-size
drawing page templates (or can use your own). Symbols are provided for equipment
racks and test equipment, system block diagrams, conceptual drawings, and schematics.
Unlike previous versions, these are NOT Stencils, but instead are all contained
on tabbed pages within a single Visio document. That puts everything in front of
you in its full glory. Just copy and paste what you need on your drawing. The file
format is XML so everything plays nicely with Visio 2013 and later...
 RF
Cafe's raison d'être is and always has been to provide useful, quality content for
engineers, technicians, engineering managers, students, and hobbyists. Part of that
mission is offering to post applicable job openings. HR department employees and/or managers of hiring
companies are welcome to submit opportunities for posting at no charge. 3rd party
recruiters and temp agencies are not included so as to assure a high quality of
listings. Please read through the easy procedure to benefit from RF Cafe's high
quality visitors...
This assortment of custom-designed themes
by RF Cafe includes T-Shirts, Mouse Pads, Clocks, Tote Bags, Coffee Mugs and Steins,
Purses, Sweatshirts, and Baseball Caps. Choose from amazingly clever "We Are the World's Matchmakers"
Smith chart design or the "Engineer's Troubleshooting Flow Chart." My "Matchmaker's"
design has been ripped off by other people and used on their products, so please
be sure to purchase only official RF Cafe gear. My markup is only a paltry 50¢ per
item - Cafe Press gets the rest of your purchase price. These would make excellent
gifts for husbands, wives, kids, significant others, and for handing out at company
events or as rewards for excellent service. It's a great way to help support RF
Cafe. Thanks...
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 "When scientists discovered DNA and learned
how to control it, not only science but society was revolutionized. Today researchers
and the medical industry routinely create artificial DNA structures for many purposes,
including diagnosis and treatment of diseases. Now an international research team
reports to have created a
powerful supermolecule with the potential to further revolutionize science.
The work is published in Nature Communications. The researchers describe their supermolecule
as a marriage between DNA and peptides. DNA is one of the most important biomolecules,
and so are peptides; peptide structures are used, among other things, to create
artificial proteins and various nanostructures. 'If you combine these two, as we
have, you get a very powerful molecular tool..."
 "Thales has partnered with the climate and
aerospace research project Airbus Perlan Mission II, with plans to create the 'highest
ever Wi-Fi hotspot.' Airbus Perlan Mission II Through the partnership, Thales
will aim to fly its latest mobile satellite communications system, FlytLink, in
a zero-emission glider to more than twice the altitude of a commercial airline flight.
Based in Nevada, the Airbus Perlan Mission II team is planning for a possible return
to flight this year in the US and El Calafate, Argentina. The group has already
set aviation world altitude records in the Perlan 2 glider, which was designed,
built and deployed to fly to 90,000ft. Launched in 2015, the Perlan 2 achieved its
highest record-setting flight of above 76,000 in 2018. The organisation's mission
is to conduct climate, atmospheric and aeronautical research at extreme high altitudes.
Applications of its research include informing more accurate climate change models,
innovating zero-emission aviation and demonstrating feasibility of using energy-efficient
winged aircraft on Mars..."
 "Researchers in China have developed an
adaptive liquid
lens based on dibutyl adipate (DBA), a new electrically responsive fluid that
changes focal length when a voltage is applied. According to the team, the lens
is suitable for mobile phone cameras, endoscopes, eyeglasses and machine vision
applications because it is lightweight, compact and simple to fabricate. 'The human
eye can arbitrarily focus on objects at different distances at incredibly fast speeds,'
said research team leader Miao Xu from Hefei University of Technology. 'Inspired
by this functionality, we developed an eye-like adaptive liquid lens that can be
used to diverge or converge light by changing the shape of the DBA liquid.' In Optics
Letters, the researchers describe their new DBA-based adaptive liquid lens..."
 "A study of electron dynamics timed to millionths
of a billionth of a second reveals the damage radiation can do on a molecular level.
The first-of-its kind study used
ultrafast
X-ray laser pulses to disrupt the electrons in a molecule of nitrous oxide and
measure the resultant changes with unprecedented accuracy. The work, published today
in Science, was performed at the Linac Coherent Light Source (LCLS) at the Stanford
Linear Accelerator Centre (SLAC), Stanford, U.S. and was supported by a team of
five scientists from Imperial College London. Conventional X-rays used in imaging
and radiotherapy can cause damage to cells, but exactly how on a molecular level
is not known. Additionally, new high-intensity and short-pulse-duration X-ray lasers
are being proposed to image smaller molecules with greater precision, leading to
questions about potential damage this could cause to living tissue. For the first
time..."
 "Atoms bind together by sharing electrons.
The way this happens depends on the atom types but also on conditions such as temperature
and pressure. In two-dimensional (2D) materials, such as graphene, atoms join along
a plane to form structures just one atom thick, which leads to fascinating properties
determined by quantum mechanics. Researchers at the University of Vienna in collaboration
with the Universities of Tübingen, Antwerp and CY Cergy Paris, together with Danubia
NanoTech, have produced a new 2D material made of
copper and iodine atoms sandwiched between two graphene sheets. The design of
new materials allows for either improved efficiency of known applications or totally
new applications that were out of reach with the previously existing materials..."
 "The
Gouy-Chapman
theory describes what happens near an electrode when it is in contact with a
salt solution, but this description does not match reality. Researcher Kasinath
Ojha, assistant professor Katharina Doblhoff-Dier and professor Marc Koper present
a new version. 'The next generation of textbooks on electrochemistry is going to
look different.' When you look inside a fuel cell, one of the things you will see
is an electrode, often made of platinum. This piece of metal is in contact with
a salt solution, which contains positively and negatively charged particles called
ions. If you were to zoom in on the interface between the electrode and the salt
solution, you would perceive all kinds of interactions. At the surface of the electrode,
a shortage or abundance of electrons exists..."
 "A semiconducting material that performed
a
quantum "flip" from a conductor to an insulator above room temperature has been
developed at the University of Michigan. It potentially brings the world closer
to a new generation of quantum devices and ultra-efficient electronics. Observed
in two-dimensional layers of tantalum sulfide only a single atom thick, the exotic
electronic structure that supported this quantum flip was previously only stable
at ultra-cold temperatures of −100 degrees Fahrenheit. The new material remains
stable at up to 170 degrees Fahrenheit. 'We've opened up a new playground for the
future of electronic and quantum materials,' said Robert Hovden..."
 "National Yang Ming Chiao Tung University
in Taiwan has reported
increased transconductance (gm) and reduced OFF-current (IOFF) for indium gallium
arsenide (InGaAs) fin field-effect transistors (FinFETs) from remote nitrogen plasma
passivation of the gate insulation layers [Hua-Lun Ko et al, IEEE Transactions on
Electron Devices, published online 20 December 2021]. The devices were fabricated
from n+-InGaAs on heavily p-type indium phosphide (p+-InP). The source/drain regions
were doped with silicon implantation and activation annealing. The fins were etched
with plasma, followed by citric acid sidewall smoothing and fin-width shrinking.
The fins were oriented in the (010) crystal direction to give the highest aspect
ratio. The gate insulators consisted of 0.8nm aluminium nitride and 2.9nm hafnium
dioxide, both applied using atomic layer deposition..."
 "Potential future transistors that consume
far less energy than current devices may rely on exotic materials called 'topological
insulators,' in which electricity flows across only surfaces and edges, with virtually
no dissipation of energy. In research that may help pave the way for such electronic
topological transistors, scientists at Harvard have now invented and simulated the
first acoustic
topological transistors, which operate with sound waves instead of electrons.
Topology is the branch of mathematics that explores the nature of shapes independent
of deformation. For instance, an object shaped like a doughnut can be deformed into
the shape of a mug, so that the doughnut's hole becomes the hole in the cup's handle.
However, the object couldn't lose the hole without changing into a fundamentally
different shape. Employing insights from topology, researchers developed the first
electronic topological insulators in 2007..."
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