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 If you are like me, you spend a lot of time
reading articles from technical magazines. Sometimes I read the entire article,
but usually I just scan the text for highlights and look at the schematics,
block diagrams, and charts / graphs. Often, I want to go back and find an article
but cannot recall where I saw it. A Google search will usually eventually reveal
a hyperlink to the article, but a lot of times it takes a lot of digging. Since
my key interests are not necessarily the same as RF Cafe visitors, an attempt
will be made to catalog all of them. If there is a magazine not included here
that you would like me to include in the list, please send me an e-mail and
I will try to incorporate its articles, too.
Aerospace & Defense | EDN | Electronic Design |
High Frequency Electronics |
IEEE Spectrum | Microwave
Journal | Microwaves & RF |
Microwave Product Digest |
 Mssrs. G. Kiesel, P. Bowden, K. Cook,
M. Habib, J. Marsh, D. Reid, C. Phillips, and B. Baker of Georgia Tech Research
Institute have an interesting article on the Aerospace Defense website entitled,
"Practical
3D Printing of Antennas and RF Electronics." The earliest forms of 3D printing
involved depositing successive layers of a pasty substance on a substrate, with
a curing steps between layers. Next can using a melted polymer (plastic) filament
to lay down tiers without the need for intermittent curing. For many years processes
have been developed for 3D printing metallic structures. Many of these techniques
are being used in "additive manufacturing" schemes to produce marketable items,
including complex 3D shapes needed for medicine, automotive, and aerospace markets.
This article discusses 3D printing in the RF & microwave realm.
 Mr. Kishore Ramaiah has an interesting
article on the EDN website entitled, "Antenna-on-Package
Technology Simplifies Automotive In-Cabin Radar Sensor Design." 60 GHz
and 77 GHz have quarter wavelengths of 1.25 mm (0.0492") and 0.973 mm
(0.0383"), respectively, meaning efficient radiators (antennas) can be fabricated
directly on the IC substrate, thus saving some of the complexity and expense
of creating and matching an off-chip antenna. The story begins: "Millimeter-wave
(mmW) radar is one of the primary sensing modalities for automotive and industrial
applications because of its ability to detect objects from a few centimeters
to several hundred meters with high distance, angle, and velocity accuracy,
even in challenging environmental conditions. A typical radar sensor consists
of a radar chipset along with other electronic components such as the power-management
circuit, flash memory, and interface peripherals assembled on a PCB. Transmit
and receive antennas are also typically implemented on the PCB..."
 Kenneth Wyatt has a good article on the
EDN website entitled, "Quickly
Assess Relative Coax-Cable-Shielding Quality." It begins: "Testing most
products for radiated emissions usually requires all I/O and power cables to
be attached to the equipment under test (EUT) and spread out in accordance with
the specific product standard. In many cases, we test engineers simply grab
the nearest cables and hope for the best during the compliance test. Unfortunately,
poor-quality cables can lead to emissions failures due to poor shielding or
poor shield termination (via 'pigtails') to the connectors. In an earlier article,
I related the issue of HDMI cable radiation due to shield pigtails. I also graphically
demonstrate why cable shield pigtails lead to radiated emissions in the video.
In addition to the shield pigtail issue, coax cables..."
 EDN has published the results of their
2020 "Mind
of the Engineer" survey. It reflects changes in attitudes and workplace
preferences in this era of the Wuhan Virus (aka COVID-19). Many engineers -
and other workers - are discovering that they really like working remotely from
home. Of course some jobs require a physical presence at an office building,
but a lot of engineers are setting up labs in their homes where possible. "What's
on the design engineer's mind in 2020, the year pundits claim will change the
workplace forever with the option to work remotely during the COVID-19 pandemic?
The electronic design arena is already starting to witness the change, as corroborated
in the latest 'Mind of the Engineer' survey carried out by AspenCore, the parent
company of EDN. For instance, while most engineers prefer to conduct circuit
design and simulation at work, European designers are happy to do circuit design
and research remotely..."
 Over on the EDN website, Mssrs. L. Rizzatti,
R. Squiers, and M. Castren have a good article entitled, "Design and Verify
5G Systems." It begins with recalling some of the features of previous generations,
then, as the title implies, focuses on current 5G system definitions, expectations,
and requirements. "Starting in the 1980s, the mobile industry has been upgrading
the wireless technology at the rate of one new standard every decade. The first-generation
(1G) cell phones launched in the '80s, although they were not referred to as
1G at the time, were based on an analog technology that supported only voice
communication with poor quality. The second generation (2G) mobile phones introduced
in the '90s upgraded analog voice transmission to digital voice communication,
added support for short message service / multimedia messaging service (SMS/SMM)..."
 Kenneth Wyatt, a consulting engineer,
has a very useful article on the EDN website entitled, "Kit
for Testing Wireless and IoT Antennas," which features Copper Mountain Technologies'
IoTest Antenna Testing Kit. FCC certification can be an expensive process,
so if you are developing a wireless product, a setup like this could save you
a bundle by allowing you to do an initial level of measurement prior to submission
to a certification lab or consultant. Mr. Wyatt begins, "In recent years, many
of my clients have been developing products that incorporate wireless and cellular
communications into IoT products. I've also been partnering with a local CTIA-approved
wireless test lab, BluFlux in Louisville, Colorado, to help mitigate various
EMC issues. In working with BluFlux, the major issue seemed to be self-generated
EMI affecting the cellular LTE and GPS receiver sensitivity..."
 Everyone reading the is familiar with
the "bell curve," and most have been exposed to the mathematics of it. Standard
deviations, normal distribution, mean, median, variance, etc., are seen often
in technical writings. John Dunn has a good intro (or refresher) on the EDN
website entitled, "The
Mathematics of Gaussian Probability Distribution." It begins: "All sorts
of physical processes in this analog world exhibit some degree of randomness.
Think of noise, for example. Many noisy processes are described by Gaussian
probability distributions. We should take a look at the mathematics of that.
Consider the equation of the “bell curve” for a Gaussian probability distribution
by starting with a very simple equation..."
 If 5G began life as and still does to
many people remain a nebulous concept, then the definition of 6G is really up
for grabs. This article on the EDN website by Jessy Cavazos, entitled "Aspects
of 6G That Will Matter to Wireless Design Engineers," is one of the first
attempts I've seen to explain it. Here is her summation: "In addition to the
next-level evolution in automated driving and smart manufacturing, 6G will enable
innovative applications by combining sensing, imaging, and precise timing with
mobility and truly leveraging artificial intelligence (AI) and intelligent networks.
Further integrating communications technologies into society, 6G technology
will bring mixed reality experiences and telepresence to life, while playing
a pivotal role in achieving global sustainability, improving society, and increasing
productivity across industries."
 John Dunn has a good article on the
EDN website entitled, "Understand
the Damaging Effects of Phase Dispersion." He begins: "Amplitude modulation,
or AM, is probably the simplest method of getting a voice or some music onto
a radio signal and then sending that signal off to some far distant place. Because
of that simplicity, a study of AM signals is a convenient tool for showing a
damaging effect arising from phase dispersion. With AM radio, the audio signal
usually gets reproduced pretty nicely at the receiving end, but not always.
Sometimes a phrase like, 'You give us 22 minutes and we'll give you the news'
can come out sounding like 'Y'mph gvmmph ush tentee-two mnshunts...' and maybe
you would wonder why. Consider an AM signal source from which there is a carrier
that, just for the sake of example, we can amplitude modulate using either the
first or the second of two 'audio' signals..."
 Messrs. Krunal Maniar and Ryan Andrews
have published an article on the EDN website entitled, "Mitigate
Clock Intermodulation Effects in Characterization Setups." Intermods have
been an issue since the beginning of electronic - even before digital circuits.
It begins: "Mixed-signal PCBs present unique challenges in high-performance
applications, such as vibration analysis and other multi-channel data acquisition
systems. Nonlinear signal-chain elements introduce unwanted harmonic distortion,
increasing the magnitude of the input signal's harmonic content. Meanwhile,
multiple switching elements produce intermodulation artifacts that present themselves
as frequency spurs asynchronous to the signals of interest. The noise and distortion
degradation introduced by these nonidealities can significantly limit the overall
performance of applications aiming for high resolution at high bandwidth. In
this article, we'll explain how clocks and other switching elements produce
intermodulation artifacts..."
Oscilloscope Cursors Complement Other Measurement Tools Arthur Pini
Match Modular EMI AC Line Filters to Application's DC Supply Needs Gary
Bocock
Design PCBs for EMI, Part 4: More on Partitioning Kenneth Wyatt
 As a great appreciator of equipment teardown
reports, I always like reading through articles like Paul Rako's "The
Tektronix Function Generator Teardown" on the Design News website.
This is a Tektronix FG503 function generator of a 1970s vintage, contained in
a TM503 mainframe chassis along with a PG502 pulse generator, an RG501 ramp
generator. The entire assembly is very well p[reserved. One of the nice things
about photos of the older equipment it the presence of leaded discrete and IC
components, so it is easier to visualize what a circuit is doing, aided by a
schematic. Circuits from the pre-IC era are even easier to follow because every
item in the schematic is right in front of you - except the occasional use of
a "gimmick"
capacitor or inductor. Here is my
HP5212A Electronic Counter teardown if you're interested.
 Now that the wonder material graphene and
the wonder wireless communications scheme of 5G has had their respective heydays,
much attention is being given to quantum computing and quantum-tunnel transistors.
"Quantum," which already had its own heyday back in early last century, is in
vogue again - like wide ties, big-framed eyeglasses, and miniskirts. Lee Goldberg
has a piece entitled "Are
Quantum-Tunnel Transistors Real, and What Do They Mean for Power Tech?"
posted over on the Electronic Design website in case you are interested
in learning about the latest happenings in the field of quantum-tunnel transistors.
They actually have nothing to do with quantum computers, and get their name
due to tunneling effects (a la the familiar tunnel diode) that are exploited
in this new "Bizen" phenomena that is being touted as a replacement for CMOS
ICs. Time will tell how accurate the prediction is, as with the recently mentioned
Wamoscope.
 Wi-Fi 6 is a familiar term, but
it is not as well defined or understood as 5G - not that 5G is all that well
understood. Richard Edgar has a piece on the Electronic Design website
entitled, "2020's
Perfect Storm: Wi-Fi 6, BLE, and AI?," which helps unmuddy the waters a
bit for Wi-Fi 6. He begins, "The innovations of connectivity and AI are
about to shift into full gear as new advances - edge computing, Wi-Fi 6, and
Bluetooth Low Energy (BLE) v5.2, to name a few - arrive in full force. These
developments are quite significant. Wi-Fi 6 will improve robustness and performance,
while Bluetooth audio sharing will make it possible for multiple consumers to
personally enjoy the audio of a single device. In addition, edge computing will
give a significant boost to the Artificial Intelligence of Things (AIoT). This
is a win-win for those wishing to utilize these technologies, but not everyone
will feel like a winner in 2020. The year could bring hardship to AI hardware
startups that have risen up after years of long-term and highly intensive R&D.
In many ways, this process has led to incredible results, including complex..."
 Some hard core bikers consider an electric-powered
Harley to be sacrilegious. Can a Harley-Davidson that doesn't make the classic
"poTAYto - poTAYto - poTAYto" be considered a Harley? This article on the Electronic
Design website does a great job of summarizing all the technical features of
H-D's 2020
LiveWire all-electric motorcycle (first released in 2019). The number of
sensors and active feedback stabilization and control features is amazing. Its
anti-lock braking system features a Rear-Wheel Lift Mitigation system that "borrows
the C-ABS sensors and six-axis inertial measurement unit to manage rear-wheel
lift during heavy braking, while balancing deceleration and rider control."
Hopefully, the 553-pound (~same as
ICE version),
$30k bike doesn't rely too heavily on all the computer control to the point
that its ultimate stability is as dependent on microprocessor control that it
has become like the Boeing
737 MAX's
MCIS...
 Electronic Design's 2019 Salary &
Career Survey asked readers, among other topics, what their attitudes were regarding
continuing education. The main question in that sections was, "What are
some of the ways in which you continue your engineering education?" I could
not find the total number of respondents to the survey, but of those who did,
87% held a Bachelor's degree or higher. Among resources used to maintain currency
in their professions, 60% say they use printed engineering & technology
publications while 57% use similar websites. 60% use seminars and webcasts and
65% read whitepapers. 13% attend in-classroom instruction while 31% use online
courses. About 45% of employers reimburse costs for seminars and trade shows,
32% pay for college courses, and 23% cover nothing at all. Click the link above
for the full report, as well as to access the
Job Satisfaction section from last week.
At Last, Voltage-Tunable and Adjustable Thermal Conductivity Bill Schweber
How to Design an Optimal Electronic Load for High-Current, Low-Voltage Power
Supplies (Part 1) Dwight Larson
A Critical Short Pulse Frederik Dostal
What Actually Is a Hot Loop? Frederik Dostal
What's the Difference Between AC-DC and DC-DC Power Supplies? Paul Rako
Minimizing Power-Supply Voltage Drop on PCBs Bill Schweber
Stuck in the Middle: How to Choose Your Next Bandpass Filter James Price
Protection for the Power Supply and Its Load Bill Schweber
Demystifying Electronic Calibration Bob Zollo
Inductor Current Measurement in Switched Power Supplies Frederik Dostal
 Peter McNeil has an article on the High
Frequency Electronics website entitled, "Considerations
for Very-High-Frequency Connectors in Defense Systems." He begins, "Of the
hundreds of different environments in which microwave coaxial cables and connectors
are used, defense systems are probably the most demanding. They're handled by
people who don't realize they're not just 'wires,' but technically sophisticated,
precision components. After all, they're warfighters, not microwave engineers.
So, they're run over by heavy vehicles, used as a handy way to pull equipment
carts, and exposed to chemicals, fuels, saltwater, and many other hazards. Aging
and various environmental factors are major contributors to the failure of cables
and connectors, but it is arguable that most of the damage is done by the people
who use them. That's why, according to one assessment, about 75% of microwave
cable assemblies are replaced frequently..."
 Dr. Gary Giust has an article on the
High Frequency Electronics website entitled, "Solving
the Tough Timing Challenges of 5G Wireless Infrastructure." He begins: "Timing
is the heartbeat of any electronic system and 5G networks will be particularly
dependent on the accuracy, stability and reliability of their clock sources.
Traditional quartz timing devices used in 4G networks are faced with new challenges
to support higher bandwidths and narrower channels of coming 5G networks. MEMS
technology solves these problems, meeting all timing requirements while performing
significantly better than quartz solutions in the presence of dynamic environmental
stressors such as shock, vibration, and rapid temperature changes. In addition,
a 100% semiconductor supply chain inherently provides MEMS solutions with superior
quality and reliability compared to quartz, which is critical to supporting
the quality-of-service planned for 5G applications..."
 Just as in the Gulf War air superiority
was credited for minimizing damage to bodies and structures on the ground, so
will space superiority be essential to surviving global threats on the ground.
A strategically sufficient space system of communications and retaliatory weapons
will be key to maintaining peace (at least physically if not financially). Gen.
Steven Kwast, USAF, ret., has an opinion piece posted on the High Frequency
Electronics website entitled "The
Urgent Need for a U.S. Space Force," with useful professional insight. "The
following is adapted from a speech delivered on November 20, 2019, at Hillsdale
College's Allan P. Kirby, Jr. Center for Constitutional Studies and Citizenship
in Washington, D.C., as part of the AWC Family Foundation lecture series. In
June 2018, President Trump directed the Department of Defense to 'begin the
process necessary to establish a space force as the sixth branch of the armed
forces..."
Educational Requirements Must Keep Pace to Enable Technology Expansion
William Cave and Vladimir Gelnovatch
Antennas Evolve To Meet 5G Requirements Mark Miller
Broadband Design of a High Efficiency 200-W GaN HEMT Doherty Amplifier
 "The
Uncertain Future of Ham Radio." Now there's a loaded title for an article
on the IEEE Spectrum website. Written by Julianne Pepitone asserts,
"Software-defined radio and cheap hardware are shaking up a hobby long associated
with engineering." There are couple ways to look at the situation. One is that
the availability of pre-engineered and built equipment is harming the fundamentals
of the hobby by removing the requirement for a deeper understanding of the fundamentals.
Another is that the real world of engineering is going the same way as well.
Freeing up talent from the need to create and fabricate every minute aspect
of a project opens opportunity for other creativity and skills building. As
a documented lover of vintage equipment, I am willing to allow for modern approaches
for vastly improved technology and, coincidently, lower prices. Ditto for all
hobbies and activities.
 "A workflow that combines measurement-based
models with discrete part-value optimization can aid designers by automatically
adjusting a design's component values to optimal manufacturer part values."
So begins an article by Chris DeMartino entitled, "Accurate
Models and Discrete Part-Value Optimization Combine to Improve Workflows."
Chris was an editor for many years at Microwaves & RF magazine
where this appears, and is now at Modelithics. "Designing RF filters and other
high-frequency circuits with today's simulation software tools often involves
performing some form of optimization to achieve the desired performance. For
example, take the case of a lumped-element filter. Optimizing such a filter
involves adjusting the values of its lumped..."
 Microwaves & RF magazine
just posted the Employment portion of their "2019
Salary & Career Report." It might seem like last year's news and not
relevant, but the year has to be over in order to assimilate data from the entire
year, so it really is timely. Author James Morra wrote, "Most respondents said
that they feel confident about their prospects for employment. But many are
also troubled by the possible shortage of skilled engineers and its impact on
the broader industry, according to 750 respondents polled by Electronic Design
and Machine Design last year. Endeavor's Design Engineering and Sourcing group
rolled out the survey with questions on more than 40 separate topics, ranging
from salaries to job satisfaction..."
 As reported in this 1967 Electronics
World magazine piece, lasers were still the things of science fiction to most
people. Real-world applications seems to be far off in the future, but in fact,
work was underway setting the stage for today's blazingly fast communications
systems. The author here references to attaining 5 THz optical transmission
speeds through fiber and through the air. At the time, a laboratory filled with
bulky prototypes chassis and optical tables were required to get those results.
I can remember reading articles in the 1970s when laser power output was measured
in "Gillette
power," referring to the beam's ability to burn through a number of razor
blades (a big deal at the time). In 2020, devices that greatly surpass 5 THz
are available in consumer quality IC packages...
Algorithms to Antenna: Modeling Antennas Installed in the Presence of Large
Platforms Honglei Chen, Rick Gentile, Vishwanath Iyer, and Giorgia Zucchelli
 This article on the Microwaves & RF
website entitled, "Algorithms
to Antenna: Modeling Antennas Installed in the Presence of Large Platforms,"
deals with large conductive solid surfaces and meshes (e.g., towers and steel
beam buildings) in the near field. Even with today's powerful PC platforms,
solving the huge matrices involved in method of moments (MoM) simulations can
take a significant amount of time. That's not so bad once an accurate model
has been confirmed, but during the "guesstimate" stage running validation simulations
can suck up a lot of time. "To consider the effects of an electrically large
platform, a physical-optics (PO) solver helps provide you with a good result
without a large increase in simulation time." Sure, it's an infomercial for
Mathworks, but then a large portion of these magazine articles are, and they
are extremely valuable.
Algorithms to Antenna: Exploring Hybrid-Beamforming Architectures for 5G Systems
Honglei Chen, Rick Gentile, and Tim Reeves
Stuck in the Middle: How to Choose Your Next Bandpass Filter James Price
Algorithms to Antenna: Classifying Radar Micro-Doppler Signatures Honglei
Chen, Rick Gentile, Chaofeng Wang, and Sara James
What's the Difference Between RMS and Peak Watts? David M. Foster
 A common cause for systems not performing
as simulations predict is neglecting to account for an imperfect impedance match
between components in the chain. Murray Slovick, of JFW Industries, has an article
in Microwave Product Digest (MPD) entitled, "The
Value of Testing with Mismatch Terminations," which addresses the issue.
"Mismatch loads can be used to test amplifiers and help characterize their performance
under conditions that might occur in the field. To do so, a mismatch load (or
mismatch termination) is used to present a specified VSWR, rather than the usual
1:1 perfect 50 ohm load. There are many situations in which it becomes necessary
to match the impedance of a load to that of the source so as to maximize power
transfer. Having a mismatch between a source (an amplifier) and a load reduces
the delivered power and efficiency of the system; when a transmission line is
terminated with impedance that is not equal..."
 L-com has a useful article posted on
the Microwave Product Digest (MPD) website entitled, "Rules
of the Road for RF and Microwave Filters." No particular author is credited,
so it is likely a re-published company app note. The piece begins: "Interference
has been the bane of wireless communications since the earliest days of radio,
and scientists and engineers of every era no doubt found their challenges to
be the worst. Then, as now, RF and microwave filters are some of the foremost
contributors to keeping interference in check, and most of the attention to
filter design is focused on end-user devices that use tiny acoustic-wave filters.
However, the need for traditional connectorized filters has not abated because
in many applications there is no suitable substitute. So, it seems prudent to
review some basic rules about key performance specifications..."
Solid-State T/R Module Design and Modeling for Radar Applications Manjunatha
Reddy H. V. and Tabish Khan
The Role and Trending Requirements of RF Limiters in Multifunctional AESA Radar
Fairview Microwave
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