Sometime around 1980, while stationed at
Robins AFB, Georgia, I finally succumbed to the peer pressure of other more sophisticated
audiophiles in the barracks and bought a "real" stereo. Unlike my roommate who had
a full compliment of rack-mounted gear, my meager enlisted military pay only allowed
for a mid-grade instrument. The solution was a
Sansui TA−300 Integrated Tuner Amplifier. It put out a whopping 30 watts per
channel, but unlike my existing radio (a Readers Digest 800−XR), those 30 watts
were nearly distortion free when driving good speakers. Having only the pathetic
5 W speakers that came with the 800-XR, I designed a set of speakers rated
for 60 W, and built the enclosures myself in the base woodshop. Unfortunately,
in preparation for a household move about 20 years ago, I sold the Sansui and the
In case you forgot to put it on your calendar,
today, May 20th, is World Metrology Day. To commemorate the occasion, this is the
day that the official definition of the kilogram is being changed from a physical
cylinder of metal to the equivalent mass (recall Einstein's E=mc2) derived
from a photon energy-to-frequency ratio measured to its most precise value. Per
the new definition, the magnitude of a kilogram would be "set by fixing the numerical
value of the Planck constant to be equal to exactly 6.626 069… × 10–34
when it is expressed in the SI unit s–1 m2 kg (J s) ..."
This is a nice short article covering the
calculation of inductances for coils wound on cores and wire sizes. It appeared
in a 1932 issue of Short Wave Craft, but of course inductance has not changed
since then so it is still relevant. The author recognized that standard formulas,
although concise and accurate, are sometimes difficult to work with when calculations
for a large number of values is needed for a particular circuit design. To address
the situation, he presents a handy nomograph, chart, and a table of typical values.
He also introduces a rarely seen term "Nagaoka's correction factor*" for skin effect.
A smartphone app, a spreadsheet, or a desktop computer program would be used today
to calculate inductance ...
"The Indian Institute of Science claims the
first enhancement-mode (e-mode) operation of aluminum gallium nitride / gallium
nitride (AlGaN/GaN) high-electron-mobility transistors
(HEMTs) using p-type aluminum titanium oxide (AlTiO) gate insulation. The metal-oxide-semiconductor
(MOS) gate stack combined the high-k dielectric properties of TiO2 (k greater than
60) with the p-type properties supplied by Al2O3 doping (k ~9). The Al2O3 substitutes
the 2Als on Ti sites and the 3Os have a deficit of one vacancy that is doubly positively
charged. The charged O vacancy can release two holes, which can subsequently be
reabsorbed by uncharged O vacancies ..."
5G is providing plenty of challenges for filter
designers. The issue is probably no so much achieving narrow bandwidths with extremely
sharp rejection regions as implementation in available media. Peter Matthews, of
Knowles Precision Devices, as an article entitled, "Approaching the 5G mmWave Filter Challenge,"
on the Microwaves & RF website that discusses some of the issues. "In the
world of LTE, developers are very familiar with the available filtering technologies
that work, namely surface acoustic wave (SAW) and bulk acoustic wave (BAW) filters.
These filters cover a range of frequencies up to 6 GHz, come in small sizes and
offer good performance-to-cost trade-offs ..."
Since 2003, Bittele Electronics has consistently
provided low-volume, electronic contract manufacturing (ECM) and turnkey PCB assembly
services. It specializes in board level turnkey
for design engineers needing low volume or prototype multi-layer printed circuit
boards. Free Passive Components: Bittele
Electronics is taking one further step in its commitment of offering the best service
to clients of its PCB assembly business. Bittele is now offering common passive
components to its clients FREE of Charge
This week's crossword puzzle will keep you
busy for a while. Since 2000, I have been creating
custom engineering- and science-themed crossword puzzles for the brain-exercising
benefit and pleasure of RF Cafe visitors who are fellow cruciverbalists. The jury
is out on whether or not this type of mental challenge helps keep your gray matter
from atrophying in old age, but it certainly helps maintain your vocabulary and
cognitive skills at all ages. A database of thousands of words has been built up
over the years and contains only clues and terms associated with engineering, science,
physical, astronomy, mathematics, chemistry, etc. You will never find a word taxing
your knowledge of a numbnut soap opera star or the name of some obscure ...
Innovative Power Products (IPP) has over
30 years of experience designing & manufacturing RF & microwave passive
components. Their high power, broadband couplers, combiners, resistors, baluns, terminations and attenuators
are fabricated using the latest materials and design tools available, resulting
in unrivaled product performance. Applications in military, medical, industrial
and commercial markets. Take a couple minutes to visit their website and see how
IPP can help you today ...
RF Systems is a global leader in power amplifier solutions. Empower RF Systems
is an established and technologically superior supplier of high power solid state
RF & microwave amplifiers. Our offerings include modules, intelligent rack-mount
amplifiers, and multi-function RF Power Amplifier solutions to 6 GHz in broadband
and band specific designs. Output power combinations range from tens of watts to
multi-kilowatts. Unprecedented size, weight and power reduction of our amplifiers
is superior to anything in the market at similar frequencies and power levels
Rohde & Schwarz introduces their "This
Changes Everything" promotion which allows customers to purchase its oscilloscopes,
spectrum analyzers, power supplies and power analyzers each fully equipped with
the maximum bandwidth, channels, inputs, memory interfaces and signal generation
for one affordable, unrivaled price. The promotion runs May 20 through December
31, 2019. Customers who might need to budget for future upgrades based on design
needs can maximize their investment up front, making purchasing easier and less
expensive. Save up to $10,000 on full-solution instruments ...
"Characterizing Circuit Materials at mmWave Frequencies
Unless you are an airplane pilot or ship's captain, a Ham radio operator engaged
in long-distance (DX) operation, over-the-horizon radar operator, or a cartographer
involved with determining point-to-point straight line paths across the face of
the Earth, then you have probably never heard of
azimuthal equidistant projection (AEP). In a
nut shell, it has to do with the fact that other than at the poles, establishing
a bearing between two widely separated points on the Earth's surface is not a simple
matter of placing a compass on the familiar type of flattened
projection map. Curvature of the surface skews the apparent direction, so pointing
an antenna from Erie, PA, to London, England using a Mercator projection map would
suggest a bearing of about 80°, but would actually point to The AEP map
is only valid for the location at which it is generated. Create yours on the
Azimuthal-Equidistant Map generator website ...
Air Force says a ground-based laser downed multiple test missiles over New Mexico.
A successful ground test has moved the U.S. military one big step closer to putting
anti-missile lasers on its aircraft. A ground-based laser shot down 'several' missiles
in flight during an April 23 test at the White Sands Missile Range in New Mexico,
Air Force officials said. Run by the Air Force Research Laboratory, or AFRL, the
test was part of the
Self-Protect High Energy Laser Demonstrator,
or SHiELD, a program intended to protect aircraft from incoming missiles. AFRL officials
said security reasons prevented them from saying how many missiles were downed in
the test. The laser that the Air Force lab used for the test was ground-based ..."
"SpaceX CEO Elon Musk tweeted out a picture
of 60 of SpaceX's secret
Starlink satellites packed into a Falcon rocket,
ready to be launched this week in the first major test deployment of SpaceX's satellite-based
internet intrastructure. Starlink Satellites Ready for Launch On Twitter this week,
Elon Musk showed off 60 of SpaceX's new Starlink satellites being packed onto a
Falcon rocket in advance of this week's mission to test the deployment of the satellites
into low Earth orbit. In a series of tweets, Elon Musk showed off the satellites
along with a similar picture of SpaceX's Starman just prior to its launch into space
last year ..."
"The U.S. Air Force has deployed 20 missiles
which can zap enemy electronics with powerful pulses rendering weapons virtually
useless. They can be launched into enemy airspace at low altitude and emit blasts
of high-power microwave energy that immediately disable any devices targeted. The
Counter-Electronics High Power Microwave Advanced
Missile Project (CHAMP) is the brainchild of Boeing's Phantom Works lab. They
have not been operation until now and could be used to frazzle the military defences
of Iran and North Korea, reports DailyMail.com. News of the state-of-the-art weapons
- which are carried into battle by B-2 stealth bomber ..."
"As far as we know, Earth's
magnetic north has always wandered, but it has
recently gained new momentum and is making a dash towards Siberia at a pace not
seen before. While this has some practical implications, scientists believe that
this sprint is being caused by tussling magnetic blobs deep below our feet. Unlike
our geographic North Pole, which is in a fixed location, magnetic north wanders.
This has been known since it was first measured in 1831, and subsequently mapped
drifting slowly from the Canadian Arctic towards Siberia. One of the practical consequences
of this is that the World Magnetic Model has to be updated periodically with the
pole's current location. The model is vital for many navigational ..."
"Semiconductors, which are the basic building
blocks of transistors, microprocessors, lasers, and LEDs, have driven advances in
computing, memory, communications, and lighting technologies since the mid-20th
century. Recently discovered two-dimensional materials, which feature many superlative
properties, have the potential to advance these technologies, but creating
2D devices with both good electrical contacts
and stable performance has proved challenging. Researchers at Columbia Engineering
report that they have demonstrated a nearly ideal transistor made from a two-dimensional
(2D) material stack with only a two-atom-thick semiconducting layer ...
Any Star Trek fan would immediately recognize
this as Mr. Scott's "transparent aluminum." "In materials science,
achromatic optical components can be designed with high transparency and low dispersion.
Materials scientists have shown that although metals are highly opaque, densely
packed arrays of metallic nanoparticles with more than 75% metal by volume can become
more transparent to infrared radiation than dielectrics such as germanium. Such
arrays can form effective dielectrics that are virtually dispersion-free across
ultra-broadband ranges of wavelengths to engineer a variety of next-generation metamaterial-based
optical devices ..."
Landing System Made to Enter Spoofing
"Just what the airplane
passenger who is always skittish does not want to hear: Radio navigation on planes
for landing purposes is not secure; signals can be hacked. In a video demonstration
of the attack by researchers, 'Wireless Attacks on Aircraft Landing Systems,'
spoofing starts automatically as soon the aircraft enters 'the spoofing zone. The
attacker signal is in real-time generated accounting for the maneuvers of the aircraft.'
What does the spoof actually do, to trick the pilot? Dan Goodin in Ars Technica
said the researchers can spoof airport signals in a way that causes a pilot's navigation
instruments to falsely indicate ..."
"Fiber optic gyroscopes, which measure the
rotation and orientation of airplanes and other moving objects, are inherently limited
in their precision when using ordinary classical light. In a new study, physicists
have experimentally demonstrated for the first time that using
entangled photons overcomes this classical limit,
called the shot-noise limit, and achieves a level of precision that would not be
possible with classical light. The physicists, led by Matthias Fink and Rupert Ursin
at the Austrian Academy of Sciences and the Vienna Center for Quantum Science and
Technology, have published a paper on the entanglement-enhanced fiber-optic gyroscope ..."
Some things just don't look right. This is
one of them. "Experts at BAE Systems will demonstrate a new
dual-band towed decoy to help U.S. Navy F/A-18E/F
jet fighter-bomber pilots avoid modern sophisticated enemy radar-guided anti-aircraft
missiles. The DBD towed decoy project, launched last June, seeks to meet an urgent
Navy need to protect crews of area-penetrating attack jets like the F/A-18E/F from
enemy radar-guided missiles that operate on two separate frequencies, such as X-band
and S-band. Dual-band radar is particularly difficult to jam, and poses a serious
threat to U.S. aircraft that must operate in contested airspace. A towed decoy trails
behind the aircraft ..."
"Tired of trying to tap icons on small smartwatch
screens? Some day you could just swipe right through the air above them thanks to
miniaturized radar technology and its accompanying
gesture recognition technology in development at imec, the Belgium-based R&D
center. Imec's radar chips operate at around 145 GHz, well above the bands used
for car radar. That high up in the electromagnetic spectrum, the chip can take advantage
of a full 10 gigahertz of bandwidth, which leads to millimeter-scale resolution,
its inventors say. 'Gestures allow a lot of capabilities where screens are becoming
too small for fine movements,' says Kathleen Philips, program director for IoT at