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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.
 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 the EV market grows, so does demand for
robust magnetic field sensors within these vehicles. Stray magnetic fields may diminish
the accuracy of these sensors, though, which is where active stray-field compensation
comes to the rescue." So begins Frederik Berstecher in his article entitled,
Overcome Stray Magnetic Fields with Active Stray-Field Compensation, posted
on the Electronic Design website. Continuing, "The electric-vehicle market
continues on a serious upswing: Allied Market Research forecasts show it will reach
$802.81B by 2027, up from $162.34B in 2019 [can they
really estimate to 5 significant digits? - KRB]. Such growth also pushes
the need for additional magnetic field sensors within these vehicles for position
detection. The sensors are robust enough to withstand a variety of harsh environmental
conditions, temperatures, vibrations..."
 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
 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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