Today in Science History -
In this Radio & Television
News magazine article, author Jack Gallagher derives a formula for the number
of turns of wire to wind on a form of given dimensions for a parallel
network. He argues that although commonly used formulas like that of Wheeler provide
the number of turns needed to achieve a desired value of inductance, it does not
predict the size of cross-sectional shape of a coil form that results in an optimal
configuration. His work applies to audio frequency divider networks like those used
for speakers to steer specific frequency ranges to a woofer, midrange, and tweeter
trio; hence the need for "constant resistance" (e.g., for standard 8 Ω
or 16 Ω speakers). By the way, in case you are not familiar with the annotation
in older electronics articles, "mhy" is microhenries, and "s.c.c." is...
was neither particle nor wave, but a bit of both - a wavicle." - Ian Stewart, in
Pursuit of the Unknown: 17 Equations That Changed the World," 2012, regarding
the dual nature of light as covered in the chapter on
for wave functions. BTW, the real term used is "wave–particle duality,"
which is a quantum mechanical principle stating that all matter–energy has both
a wave and a particle nature. The wave behavior of light is exhibited in its ability
to be diffracted at a sharp edge. It is the particle nature which accounts for the
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...
"A database of
drone radar cross sections has been made public to help those developing countermeasures.
'We measured drone radar cross sections at multiple 26-40 GHz mm−wave frequencies
to better understand how drones can be detected, and to investigate the difference
between drone models and materials in terms of scattering radio signals,' said researcher
Vasilii Semkin of VTT Technical Research Centre of Finland. 'We believe that our
results will be a starting point for a future uniform drone database. Therefore,
all results are publicly available along with our research paper..."
Ok, the real title on the Interesting Engineering
website is, "11
Ways Engineers Are Helping out to Fight Against the Pandemic." Individuals and
companies (comprised of individuals) are responding to the COVID-19 crisis in an
utterly amazing manner. Except for grandstanding politicians and agenda-driven,
hateful media types, many of our fellow Earthlings are working tirelessly to provide
a way out of this present surreal crisis, and in the process are developing new
knowledge and technology that will benefit us during "the next big thing."
Others do what they can do by honoring precautionary rules of sanitation and
separation. Admittedly, the exercising of extreme governmental powers worries me
a bit as limits of citizens' willingness to comply are tested. One American
politician famously recommended, "You never let a serious crisis go to waste.
And what I mean by that it's an opportunity to do things you think you could not
do before." Here is the original 1974 "Everybody Was Kung Fu
Fighting" song (I was in 10th grade). Be careful.
In an effort to promote entry of women and
girls into the amateur radio hobby, Short Wave Craft magazine ran a few
Best "YL" Photos. Amazingly - and maybe there are still instances of it today
- many (if not most) of the YLs featured had built their own equipment. In 1935,
most people built their own equipment, so that is not too surprising. The winner
for this month was a 16-year-old young lady (i.e., "YL") who in fact built her rig.
Another winner was an 83-year-old grandma who was born before Marconi, Maxwell,
and Hertz did their best work! The third winner was a girl who earned her Ham license
at age 6, which back in the day required sending and receiving 5 words per minute
(WPM) in Morse code. BTW, according to the Bureau of Labor Statistics' (BLS) Inflation
Calculator says $5 in 1935 is the equivalent of $94.41 in 2020 money...
Anatech Electronics (AEI) manufactures and supplies
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Custom RF filters designs are used when a standard cannot be found, or the requirements
dictate a custom approach for your military and commercial communications needs.
Sam Benzacar's monthly newsletters address contemporary wireless subjects. Please
visit Anatech today to see how they can help your project succeed.
Multiple path transmission, diffraction around
obstacles, absorption by foliage, and reflection from moving objects have always
been challenges to the wireless system designer and/or user. Whether it concerns
communications between a WiFi router and a notebook computer, a cellphone and a
tower, an FM radio with a broadcast station, or deep space probe with an earth station,
all of the aforementioned mechanisms must be dealt with to some degree. Although
in a different way, even
transmissions within a waveguide or coaxial cable deal with those same issues
- reflections and the resulting standing waves have the same effect as multipath
in terms of vectorially additive versions of the same original signal. Signal degradation
issues can usually be overcome when all components are performing within specifications,
by having knowledge of potential causes, and then assessing the situation at hand.
Of course an insufficient signal power from the transmitter, too-high Friis-determined
atmospheric path loss...
ConductRF LSA series of Low Loss, Performance
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for most applications. Here we offer customers a solution for 0.086" diameter cable
that facilitates greater flexibility and handling or, 0.141" diameter that exploits
the same great performance but with almost half the loss. Connector options include
SMA, Type-N, TNC & SMP that provide excellent VSWR between DC and 18 GHz,
also solutions for MCX & SMB are available in a wide array of configurations.
These assemblies are built using our own double shielded, FEP jacketed cable, that
was developed specifically for performance solutions. With shielding effectiveness
exceeding 90 dB through 18 GHz, these cables minimize the threat of cross-talk
effect. ConductRF guarantees its performance through 100% factory test prior to
shipping. Additional options are also available...
Triad RF Systems' Steve Barthelmes, Patrick
Sherlock, and Ken Andrew published a Technical Brief article entitled, "Methods
to Increase Channel Capacity in RF Data Links," in Microwave Product Digest.
"As can be seen, increasing the robustness of RF links is a tricky business, however,
there are multiple weapons in one's toolkit to increase capacity and combat RFI.
MIMO is a radio technology that is taking hold worldwide. This wireless technology
increases the channel capacity of the system while improving the reliability of
the link. High gain antennas and tracking technologies can be employed, however,
the mobile aspects of many RF links (UxV systems) do not always allow for the size,
complexity, and sensitivity trade-offs that come along with them. BDAs can be employed,
in conjunction with these other technologies, or alone, to increase the link margin
of systems that are underperforming..."
Do you know how engineering whipping boy
Dilbert came to be called
by that name? Per Scott Adams, while working at Pacific Bell he ran an informal
name-the-comic-strip-engineer contest from his cubicle. A guy named Mike Goodwin
suggested Dilbert. "I ended the contest immediately and declared Mike the winner,"
says Adams. It sounded perfect. Years after the comic strip had become syndicated,
Mike commented that he believes the name idea might have come from seeing his father's
old WWII aviator comics with "Dilbert the Pilot." DtP was a screw-up, invented by
Navy artist Robert Osborn, whose purpose in life was to illustrate the wrong way
of doing things so that real pilots wouldn't make the same mistakes. The name was
funny then, as it is funny now. BTW, Dilbert is a variant of Delbert meaning nobly
famous. During the War, "dilbert" became a synonym for "blunder" for Navy pilots.
The Navy even produced an aviator safety film titled, "Don't Kill Your Friends,"
featuring Dilbert the Pilot...
"Verizon, along with Samsung Electronics
Americas, Motorola Mobility, and Qualcomm Technologies, have teamed up to demonstrate
5G peak speeds of
4.2 Gbps on a live 5G network. Using carrier aggregation, a technology that
combines multiple channels of spectrum to provide greater efficiency for data sessions
transmitting over the wireless network, the four companies combined eight separate
channels of mmWave spectrum to achieve the multi-gigabit speeds on Motorola's upcoming
flagship smartphone. Adam Koeppe, Senior Vice President of Technology Planning at
Verizon commented that they are continuing to expand the 5G Ultra Wideband network,
built to enable unique and transformational experiences for their customers. They
continue to innovate and introduce advanced technologies on their 5G network that
will help them reach 'never seen before' mobile capabilities..."
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Those of us who have been around for six
or more decades have lived through two evolutions of video display types - raster
cathode ray tubes (CRTs) and digitally pixelated light-emitting diode (LED)
and liquid crystal (LCD) displays. Unlike with the latter display types that improved
in color depth, picture resolution and display size, the former had effectively
a fixed resolution of horizontal lines (525 vertical steps - only 484 visible, actually,
due to blanking). That meant for CRTs, designers needed to find ways to make images
appear in-focus while also looking continuous on larger screens. Doing so involved
cleverly adjusting the size and spacing of fluorescent color dots on the picture
tube face while also using special metal masks between the electron gun and the
tube. A lot of research that included panels of people rendering opinions...
Watched These Movies and TV Shows as a Kid. The Design News website
likes to run these "You Know You're an Engineer If..." things, and usually they're
pretty good. This one, of course, has me waxing nostalgic. "Here are some of classic
engineering and robot movies and TV shows from the 1950s and 1960s. Every kid who
grew up to be an engineer loved robots. The love of science fiction and robots seems
to follow closely on the heels of the fascination with dinosaurs. Some of these
movies were scary for a kid, like the deadly robot in The Day the Earth Stood Still.
Others were lovable, like Robbie the Robot in Forbidden Planet. Some were terrifying
in a more realistic way, such as HAL in 2001 a Space Odyssey..."
Each year the Foundational Questions Institute
(FQXi) holds an essay contest inviting writers to submit missives addressing the
question chosen by the FQXi board as being particularly thought-provoking. In their
words, "FQXi catalyzes, supports, and disseminates research on questions at the
foundations of physics and cosmology, particularly new frontiers and innovative
ideas integral to a deep understanding of reality, but unlikely to be supported
by conventional funding sources." The 2011 question was "Is Reality Digital
or Analog?" Scientific American magazine, being one of three partners,
published the runner-up entry in the December 2012 issue: University of Cambridge
professor of theoretical physics professor David Tong's paper argues that the world
is in fact fundamentally analog. Professor Tong actually tied for second place,
but for some reason SciAm does not tell us whether the other second place paper
supported an analog or digital viewpoint...
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 (of course a gratuity will be graciously accepted). 3rd party recruiters
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"Provider of integrated solutions for transportation
and defense C4ISR, Cubic Corporation has announced that their Cubic Mission Solutions
(CMS) business division has been selected as one of the awardees to compete under
the U.S. Army for
Global Tactical Advanced Communication Systems (GTACS II) Indefinite Delivery/Indefinite
Quantity (IDIQ) contract vehicle. The contract has a ceiling of $5.1 billion, with
a five-year base, one five-year option period and a Firm Fixed Price, Cost Plus
Fixed Fee and Cost No Fee contract, in support of the Program Executive Office Command,
Control and Communications-Tactical (PEO C3T), and Project Manager Tactical Network
(PM Tactical Network)..."
As with many relatively new technologies,
exuberance over radio peaked quickly once the benefits of communications over
long distances without the need for wires was realized by the public. After a couple
decades a lot of "authorities" began pontificating about how all the useful applications
of radio waves had been discovered and that any new innovation would be merely incremental
improvements in existing technology. Novel circuits for minimizing static over the
radio or maybe building more powerful transmitters for longer range were the only
concepts within reach of their limited imaginations. Similar phenomena occurred
for those who thought airplanes would always have two (or more) wings and that automobiles
would never be faster than a train. This 1935 issue of Short Wave Craft
magazine reported on the beginnings of investigations into the use of radio waves