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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.
Electronic Design
| High Frequency Electronics | Microwave Journal | Microwaves &
RF | Microwave Product Digest |
Test & Measurement World
 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
 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
 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
 "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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