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Today in Science History -
 This
Engineering Theme Crossword Puzzle for February 28th contains only words
and clues related to engineering, mathematics, chemistry, physics, and other
technical words. As always, this crossword 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., Hedy
Lamarr or the Bikini Atoll). The technically inclined cruciverbalists amongst
us will appreciate the effort. Enjoy!
 "Two's company, but three's a crowd
- unless you're trying to make graphene superconduct at higher temperatures.
That is the finding of researchers at Harvard University in the U.S., who
discovered that the superconducting state in three stacked and twisted layers
of graphene is more robust to temperature increase than the equivalent state
in two-layer graphene. The researchers also found evidence that superconductivity
in the trilayer system comes from strong interactions between electrons, rather
than weak ones as in most conventional superconductors - corroborating a result
reported a few days earlier by a separate team at the Massachusetts Institute
of Technology (MIT). A sheet of graphene consists of a simple repetition of
carbon atoms arranged in a two-dimensional hexagonal lattice..."
 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...
 "Princeton University has found a way
to determine the direction to an object in three dimensions using only
on-chip THz antennas with ~2°accuracy. It exploits frequency-dispersive
leaky-wave antennas - end-fed strips, 1.7mm long, with transverse slots spaced
at 43 μm intervals. The crucial property of these, is that injecting
a frequency between 360 and 400 GHz into one end results in fan of energy
leaving the antenna at right angles to its long axis (see diagram). The higher
the frequency, the further tilted away from the feed end is the fan: 360 GHz
leaves at right angles and 400 GHz tilts the fan at 40° to the normal,
so scanning from 360 to 400 GHz sweeps the fan from 0° (normal) to +40°..."
 "My husband wants a selenimum rectalfire,
a silicode capasitator, and a 16 bome appleflyer." That is the caption of
one of the "Hobnobbing
with Harbaugh," comics that appeared in the June 1962 edition of Popular
Electronics magazine. Dave Harbaugh's "Hobnobbing with Harbaugh"
was a monthly feature for a couple years that dealt with stereotypical (pun
intended) behavior of technophiles and their often unwilling, often unwitting
wives, girlfriends, kids, parents, workmates, and neighbors.
 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!
 Exodus Advanced Communications has
introduced a broadband amplifier, model
AMP1074−9, which covers 1.0 to 18.0 GHz and produces >10 Watts
minimum power (15 W nominal). The AMP1074−9 has a minimum gain of 40
dB with -20 dBc harmonics. The unit is a compact Linear Class A/AB design
for optimum reliability & ruggedness for all applications. Nominal dimensions
of 140W x 160L x 27H mm with SMA female connectors. Features: Class AB
GaN design, instantaneous ultra-wide bandwidth, broadband coverage of C, X
and Ku Bands...
 Triad RF Systems designs and manufactures
RF power amplifiers and systems.
Triad RF Systems comprises three partners (hence 'Triad')
with over 40 years of accumulated knowledge of what is required to design,
manufacture, market, sell and service RF/Microwave amplifiers and amplifier
systems. PA, LNA, bi-directional, and frequency translating amplifiers are
available, in formats including tower mount, benchtop, rack mount, and chassis
mount. "We view Triad more as a technology partner than a vendor for our line-of-sight
communications product line." Please check to see how they can help your project.
 This
Electronic Puzzle Square, compliments of Lt. C.K. Johnson, appeared in
the January 1945 issue of Radio-Craft magazine. It consists of electronics-related
numerical questions whose answers, if correct, create a 4x4 matrix whose columns,
rows, and long diagonals all add up to 45. Non-integer answers need to be
rounded according to standard rules (do not just truncate). In case you left
your slide rule at the office, a link is provided to assist with Q2. The biggest
head scratcher question is Q4, since it requires the conversion from polar
to rectangular coordinates, but hey, you're an engineer (or a crack technician).
Having Euclid on-hand for Q5 might be helpful. A link is provided to a copper
wire parameter table for Q9. Have fun.
 Withwave's W701 Series are complete
line of high performance flexible microwave cable assemblies. Specially,
Flexible Armored W701 Series have low density PTFE structure to achieve
velocity propagation of 76% and good phase and amplitude stability performance.
They have excellent RF performance up to 26.5 GHz, and DC to 40 GHz with SMA
and 2.92 mm connectors, respectively. Features: center conductor: silver plated
copper, insulator: low density PTFE, outer conductor 1: silver plated copper
foil, outer conductor 2: silver plated copper wire, jacket: FEP...
 When doing some research for creating
a new quiz on inventors
and their inventions, I decided to look for people according to their
countries. I almost always do image searches since doing so does a good job
of filtering out pages that merely mention the topic of interest. My first
Google search was "american inventors." I expected to see the familiar faces
of Thomas Edison, Henry Ford, George Westinghouse, Marie Curie, Alexander
Graham Bell, George Washington Carver, Edwin Armstrong, Hedy Lamarr, Benjamin
Franklin, Robert Goddard, Albert Einstein, the Wright Brothers, Samuel Morse,
William Shockley, etc. Those are the names that first come to my mind, and
admittedly the list is dominated by White men. Imagine my surprise when the
Google search results belied my perception. Take a look at the first few pages
of results to see what I mean. Next, I moved on to an image search for "canadian
inventors..."
 "A team of researchers from Duke University,
in partnership with Facebook's Connectivity Lab, have announced a major advancement
towards the dream of ditching the fiber in fiber optics. Visible and infrared
light can carry more data than radio waves, but has always been confined to
a hard-wired, fiber-optic cable. While working to create a
free-space optical communication system for high-speed wireless internet,
the researchers showed that speed and efficiency properties previously demonstrated
on tiny, single-unit plasmonic antennas can also be achieved on larger, centimeter-scale
devices. The research appeared online in the journal Optica. In 2016, researchers
from Internet.org's Connectivity Lab..."
 Anatech Electronics offers the industry's
largest portfolio of high-performance standard and customized
RF and microwave filters and filter-related products for military, commercial,
aerospace and defense, and industrial applications up to 40 GHz. Two
new filters have been introduced: a 10.01 GHz cavity bandpass filter
with a 320 MHz bandwidth and 1 dB of insertion loss, and an LTE
Band 8 uplink / Band 3 downlink multiband duplexer filter with <50 dB isolation
between bands and 1 dB insertion loss. Custom RF power directional coupler
designs can be designed and produced when a standard cannot be found, or the
requirements are such that a custom approach is necessary...
 Audio crossover networks have the same
fundamental mission as RF multiplexer filters in radio systems, which is to
separate and steer specific bands of frequencies into two or more signal paths.
While simple in concept, implementation in hardware can be a major challenge
depending on requirements for channel separation, feedthrough, phase and group
delay, amplitude equalization, distortion, and other factors. This article
discusses some of the decisions used by crossover network designers when considering
where to make band breaks, while leaving actual circuit design rules to other
authors. I built a set of custom speakers many moons ago and went through
the frustrating process of deciding where to place the breaks and which speakers
to use...
 Yes, this is another article that will
probably appeal to a small percentage of RF Cafe visitors, but please countenance
my indulgence in things aeronautical as well as things electrical. The early
1930s was a time when both airplanes and electronics were a wonder and a mystery
to most of the public worldwide. Of course today both are still a mystery
to the public but the wonder is gone - it's merely taken for granted. Many
idiosyncrasies of
airborne electronic communications were encountered for the first time,
like the need for proper grounding and static electricity dissipation. Ruggedization
of chassis assemblies in terms of mechanical vibration and shock as well as
for temperature extremes was a real challenge to engineers, technicians, and
pilots...
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