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 A popular meme on chat websites these days
is the posting of some items or scenes indicative of times many moons ago, with
a comment something like, "If you know what this is, you are probably wearing reading
glasses." I recently saw one with a picture of an old cube type flash bulbs that
went on Kodak Instamatic cameras. In fact, I still have my Kodak Instamatic 40
camera and a couple of unused flashcubes. Those flashcubes were expensive for a
guy who never had much pocket cash; maybe that's why I have so few pictures from
back in the day. Anyway, I mention all that because some of the topics of these
electronics-themed comics from a 1962 issue of Electronics Illustrated
magazine would be likely candidates for the meme...
 A new word has been added to my personal lexicon:
"sphenoidal." Author John Kraus used it to describe the wedge shape
of a corner reflector. The Oxford Dictionary defines "sphenoid" thusly: "A compound
bone that forms the base of the cranium, behind the eye and below the front part
of the brain. It has two pairs of broad lateral 'wings' and a number of other projections,
and contains two air-filled sinuses." This "square corner" configuration - essentially
a "V" shape, is shown to exhibit up to 10 dB of gain while being relatively (compared
to a parabolic reflector) insensitive to physical size and driven radiator placement
across a wide band when made sufficiently large. No radiation pattern was...
 As you might know, particularly if you are
a frequent RF Cafe visitor, amateur radio operators (Hams)
were prohibited from broadcasting during the entirety of World War II,
(see
War
Comes) ostensibly as a security measure. The concern was that people
might unintentionally (or intentionally) convey information on troop positions and
family names, domestic factory locations and activities, and the general state of
the nation in regards to attitude and finance. Unlike today, that type of data was
not easily gathered even by a dedicated deployment of internal spies. In the early
1940s, the majority of amateur radio activity was carried out in the form of Morse
code, and operators were understandably concerned...
 Here is a fascinating story from a 1946
issue of the ARRL's QST magazine of the ordeal one Catholic priest
experienced while serving in the Philippines during the Japanese occupation in World
War II. Father Visintainer exploited his personal interest in
radio communications
to help keep local residents apprised of the war's progress and talk to the outside
world. Japanese troops confiscated all the existing shortwave radios and converted
them to their own frequencies. Some were re-converted by daring servicemen and then
hidden. Batteries were recharged using covert water wheel powered generators located
in the woods. Drama hit a peak one day when an attempt to formulate a make-shift
battery electrolyte resulted in an explosion that brought Japanese running to the
church lab...
 For decades, the engineering community has
viewed space as the ultimate frontier (Captain Kirk declared it) - a clean, vacuum-sealed
environment that offered a solution to the terrestrial limitations of bandwidth,
range, and latency. Nations and industries have long championed the
democratization of global communications, seeing Direct-to-Device (D2D) connectivity
as the next logical step in our technological evolution. But as we move from the
era of rare satellite backhaul to the age of the "mega-constellation," the engineering
paradigm has shifted. We are no longer just looking at the sky; we are beginning
to occupy it with such density that we risk creating a perpetual "noise floor" for
the rest of humanity. This article examines the thermodynamics, the mechanics of
orbital mesh nodes, and the sheer volume of material required to shift our compute
infrastructure into the heavens...
 Just the other day I saw a greeting card
with a sailboat on the front with the words "Anchors Away," on it. It was not meant
to be a pun on "anchors aweigh;" the card writer didn't know any better. This
episode of "Carl & Jerry" has our teenage Ham radio operators and electronics
hobbyists running a newly built model tugboat powered by a steam engine and navigated
via a radio control system. As is always the case, no activity of the pair goes
without drama of some sort. Author John T. Frye used his writings to present
technical topics within the storyline, both in the "Carl & Jerry" series here
in Popular Electronics magazine and his earlier "Mac's Radio Service Shop"
series that appeared...
 For the sake of all the avid cruciverbalists
amongst us, this
technical-term-themed
crossword puzzle 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)...
 Sam Benzacar, of Anatech Electronics, an
RF and microwave filter company, has published his May 2026 Newsletter that, along
with timely news items, features his short op-ed titled "The
Math of LEO No Longer Adds Up." Sam runs the numbers on Low-Earth-Orbit satellites,
and assesses future plans. "SpaceX now operates more than 10,000 Starlink satellites,
roughly two-thirds of everything in orbit. The next-largest operator, OneWeb, has
fewer than 700." They roam the nighttime sky, with small dots of light tracking
across our already light-polluted skies. The ITU coordination process now confronts
filings for more than a million LEO spacecraft, with half a million projected to
be in orbit by 2040. Now that Internet coverage and even Direct-to-Device (D2D)
networks...
 Meteor scatter communications is an excellent
example of where hobbyists - in this case amateur radio operators - have contributed
mightily to technology. It could be argued that a big part of the reason for such
occasions is that many people involved in science type hobbies are employed professionally
in a similar capacity, and their extracurricular activities are a natural extension
of what pays for the pastimes. It seems amazing to me that
meteor
scatter as a means of achieving upper atmosphere reflections of radio signals
went undiscovered until 1953, but evidently that is the case. Meteor scatter is
a very popular form of amateur radio challenge...
 "Make the most of your time at
Dayton Hamvention® with the free ARRL Events phone app. Hamvention is the world's
largest annual gathering of radio amateurs, and will be held May 15-17 in Xenia,
Ohio. There is a lot to do and see. Use the ARRL Events app to make sure you don't
miss a beat and plan out your visit now. The ARRL events app is produced by ARRL
The National Association® for Amateur Radio in partnership with Dayton Hamvention.
The app includes Hamvention's full program, so you can browse and schedule forums,
preview the extensive list of exhibitors, and find affiliated events. During the
event, attendees can use..."
 Here's a topic that never goes out of style.
Without bothering to worry about source and load impedances, this brief tutorial
on the fundamentals of
power supply filter design using series inductors and parallel
capacitor combinations. The author offers a rule-of-thumb type formula for guessing
at a good inductor value based on peak-to-average expected current. This is by no
means a comprehensive primer on power supply filter design and is directed more
toward someone new to the concept...
 Werbel's new
WMC-0.5-2-6dB-S, 6 dB directional coupler provides precision attenuation
where it matters most. It covers 500 MHz to 2 GHz with broadband flat coupling response,
high directivity, and excellent return loss performance. The device covers the upper
portion of the UHF band as well as L band in a single unit measuring just 3.60 x
0.60 x 0.38 inches. Minimized reflections increase accuracy of the measurement.
Mainline insertion loss of 1.2 dB (typical) includes coupling factor. The 6 dB coupling
ratio gives an approximate 75/25% splitting ratio and may be used as such to distribute
signals unequally where required, often to make up for asymmetrical losses elsewhere
in a system...
 Connecting a diode backwards across a solenoid
coil to shunt potentially damaging current and/or voltages when the supply is turned
off is a common trick for saving connected circuitry. Depending on the magnitude
of the magnetic field and how quickly the field collapses, some really high voltages
can be produced. In fact, the ignition coil and point (now
solid state) system in exploits exactly that principle to turn the 12 volts
from your car battery into 20-40 kV for firing the spark plugs. Engineers that
designed this early
cyclotron
had limited options for what to use given the state of the art in the early 1940s,
and chose to keep the generator permanently connected to the coil (no switch) so
that if the controller failed, the coil's energy...
 In the opening scene of "Gladiators," Quintus
remarks to Maximus (Russell Crowe), "A people should
know when they've been conquered." Such truth is applicable to society today regarding
ubiquitous surveillance. Less than two decades ago the media was
filled with stories of outrage over the discovery of some new form of monitoring
and reporting system having been installed on highways, in shopping malls, along
sidewalks, even bathrooms. Since the 9/11 terrorist attacks, anything goes with
government snooping. Count the numbers of freedoms you have lost and the inconveniences
suffered because of those 19 men with no identifiable common cause
(wouldn't want to profile). This story from 1956 shows
how long stealth installation...
 I wonder why today's editions of the ARRL's
QST magazine does not have a column dedicated to the "YL" (Young Lady,
or female in general) contingent of the amateur radio realm? Ham radio, as most
-if not all - historically male-dominated hobbies has fairly significant outreach
efforts to try attracting women into activities. My Model Aviation magazine
has a monthly column written by a lady whose enthusiasm for model airplanes equals
that of most males - and she's funny to boot! - but it is not dedicated to female
modelers. If there is a girl or woman present at a competition, she is almost guaranteed
to receive coverage...
 The December 1947 issue of Radio News
and the February 1954 issue of Radio & Television News published these
electronics-themed comics. Humor evolves over time, which is apparent when you
look over these and many of the other comics from these vintage electronics magazines.
The AVC comic is the best, IMHO. For those of you not around in the olden days of
vacuum tubes, tapping on a tube would often make it work properly again, either
because of a dirty contact in the socket or crud that had accumulated on the screen
grid. I give this batch a score of about 7 out of 10, but you might think otherwise.
There is a growing list of other comics at the bottom of the page. Enjoy...
 How RF circuits work have long been referred
to as "black magic,... even sometimes by people who fully understand
the theory behind the craft. To me the ways in which a transmission line - be it
coaxial cable, microstrip, or waveguide - can be manipulated and controlled with
various combinations of lengths and terminations is what most qualifies as "magic."
Sure, I know the equations and understand (mostly) what's happening with incident
and reflected waves, etc., and how the impedance and admittance circles of a Smith
chart graphically trace out what's happening, but you have to admit there's something
wonderfully mystical about it all...
 I remember hearing a long time ago about
"The Thing"
- a passive bugging device discovered within a wooden Great Seal gifted to the U.S.
Embassy in Moscow. This 1962 Electronics Illustrated magazine feature explores
the ingenious, battery-less Soviet listening device. Far from a conventional electronic
bug, this passive device utilized a specialized resonant cavity and a diaphragm
that modulated an external 1600 MHz radio beam, essentially acting as an echo-based
microphone that was incredibly difficult to detect. While the article highlights
the device's diabolical simplicity and sensitivity, it contains no mention of the
U-2 incident or Gary Powers; notably, historical records clarify that Ambassador
Lodge displayed the device in 1960 to expose Soviet espionage...
 Based on beleaguered wife Sylvia Kohler's
mention of GE's Electronics Park in this story (surely a fable... or not), she and
unintentional antagonist, superheterodyne hubby (aka "Happy Boy," but we know him
as Popular Electronics cartoonist
Carl Kohler) probably lived in the Syracuse, NY, area. Electronics
Park existed during the hey days of General Electric when the sprawling campus ,
just north of I-90, designed and manufactured a plethora of both household and military
electronics products. GE's Electronics Laboratory ("E-Labs") was the company's pride
and joy. Today, a tiny portion of Electronics Park is still occupied by Lockheed
Martin, who bought that GE division in the 1990s, and the rest belongs the city.
But I digress... enjoy the story (her reason for referring to hubby as a Superheterodyne
is highlighted)...
 Multielement quad antennas are as popular
today as they were in 1967 when this article appeared in the ARRL's QST
magazine. That is not to say they are common. This particular design is for the
10-, 15-, and 20-meters bands, all three
of which are still in use today. If you build a multielement quad as shown here,
you might want to find a substitute for the bamboo frame members; aluminum tubing
is pretty cheap, but if you use metal, you'll need to use insulators at the connection
points. Formulas are provided for determining element lengths and director and reflector...
 There is something about these proposed
shorthand circuit symbols that reminds me of the IEEE digital
logic symbols using the distinctive shape (the traditional format) versus the newer
rectangular shape format. The set is quite extensive when all the different flavors
of combinatorial blocks - flip-flops, timers, counters, shift registers, encoders,
decoders, etc. - are included. My personal preference, you might guess, is the original
format with distinctive shapes. Although I do not do a lot of digital work, it is
easier for me to follow the signal flow and mentally perform the logic operations
with the distinctive shapes. But I digress. This article from a 1947 issue of
QST magazine introduces...
|
 • Europe's
Electronics Sector Picks up Speed
• Top
5 Companies Granted U.S. Patents in 2025 (one American)
• Shape-Shifting
Semiconductors Activated by Light
• UK Teachers Say
AI Eroding Critical Thinking
• FCC
Approves Charter's $34.5B Acquisition of Cox
 The
RF Cafe Homepage Archive
is a comprehensive collection of every item appearing daily on this website since
2008 - and many from earlier years. Many thousands of pages of unique content have
been added since then.
 Here is a nice quiz on calculating total
equivalent capacitance for circuits containing various combination of series,
parallel, and series-parallel connections. To help in calculation, all of the individual
capacitor values are the same. Many of them you can probably solve in your head,
especially if you mentally rearrange the circuit into a more readily recognizable
configuration. For instance, circuit #1 can be redrawn having two parallel branches
across the source. One branch has just a single capacitor while the other has two
parallel capacitors in series with one capacitor. The equation is then C + (2C2/3C) = C + 2/3C = 5/3C. For C =
6 pF, Ctotal =
5/3*6 pF = 10 pF...
 This is another Radio Service Data Sheet
that appeared in the March 1936 edition of Radio-Craft magazine. I post
this schematic and functional description of the
Crosley Model 555 (A.F.M.) 5-Tube 2-Band Superhet radio manufacturers' publications
for the benefit of hobbyists and archivists who might be searching for such information
either in a effort to restore a radio to working condition, or to collect archival
information. As mentioned previously, manufacturers usually did not provide this
data to anyone other than an authorized service shop, so making it available via
the magazine was a huge benefit to repair shops and do-it-yourselfers. Unfortunately,
not very much textual content was included with the schematic. It was part of a
group of seven different models (see table of contents), and not much more than
the schematic was provided for each...
 This custom RF Cafe
electronics-themed crossword puzzle for April 30th contains words and clues
which pertain exclusively to the subjects of electronics, science, physics, mechanics,
engineering, power distribution, astronomy, chemistry, etc. Every other row has
words beginning with "R" and "F." If you do see names of people or places, they
are intimately related to the aforementioned areas of study. As always, you will
find no references to numbnut movie stars or fashion designers. Need more crossword
RF Cafe puzzles? A list at the bottom of the page links to hundreds of them dating
back to the year 2000. Enjoy.
 With more than 1000
custom-built stencils, this has got to be the most comprehensive set of
Visio Stencils
available for RF, analog, and digital system and schematic drawings! Every stencil
symbol has been built to fit proportionally on the included A-, B-, and C-size drawing
page templates (or use your own page if preferred). Components are provided for
system block diagrams, conceptual drawings, schematics, test equipment, racks, and
more. Page templates are provided with a preset scale (changeable) for a good presentation
that can incorporate all provided symbols...
 As mentioned in this 1961 Radio-Electronics
magazine article, fuel cells have been around for a long time. Francis T. Bacon
(not the 17th century philosopher Francis Bacon) built his first fuel cell sometime
in the 1940s. He designed the fuel cells for the Apollo 11 and other spacecraft.
President John Kennedy's famous moon speech was delivered a month after this article,
and predated the moon landing by more than eight years. Most critical technology
experiences an evolutionary period spanning decades from inception to practical
application. That time is being reduced with the advent of computers and larger
numbers of people working on the problems. Just as fuel cells have become ubiquitous
in electrical power generation processes, so, too, will other technologies that
were once considered to be pie-in-the-sky bits of science fiction - like nuclear
fusion reactors (aka tokamaks). Researchers are now very near the breakeven point
necessary to enable self-sustaining, controlled reactions...
 Evidently - and understandably so - a lot
of people in the electronics realm have a problem grasping the concept of a decibel
as it pertains to voltage, current, power, et al. This 1960 Electronics World
magazine "The
Decibel Without Pain" article takes a stab at making it all clear. As the c1991
Teen Talk Barbie famously said, and in some cases like in this YouTube video still
says, "Math class is tough." Believe it or not, that created quite a stir amongst
feminists who, BTW, would have had no problem with Ken saying the same thing. The
fact is, for many - probably most - people math class is tough. It was for me when
I was in elementary school and junior high school. I nearly failed 9th grade algebra
because for the life of me I could not get the hang of factoring polynomials. Being
given the option of enrolling the the electrical vocational program for high school
(grades 10 through 12) was my salvation. I loved working with electrical and electronic
things, so being able to spend my days in prison (aka school) learning about residential,
commercial...
 RF Cafe website visitor David Burger (VK2CZ /
K3HZ) sent me a great Excel spreadsheet titled, "Evaluating
Compliance with FCC Guidelines for Human Exposure to Radiofrequency Electromagnetic Fields."
As amateur radio operators learn when studying to earn a license, you are required to
perform a calculation to verify that the transmitted effective power radiating from your
antenna does not exceed a specified maximum value in areas where humans have access.
David's spreadsheet takes system parameter inputs and calculates, along with various
other values, the minimum required separation distance for both controlled and uncontrolled
human access. If your antenna is mounted up higher than the limit distance, then no action
is required to keep people away. Otherwise, you must either erect physical barriers or
reduce power output to comply with the maximum RF exposure limit...
 One of the first things you learn in school
when studying transistors is the
three classes of amplifier circuits: Class A, where the conduction angle
is a full 360°; Class B, where the conduction angle is 180°; and Class C,
where the conduction angle is less than 180°. There is a fourth hybrid Class AB,
which conducts more than 180° but less than 360°. Class A is generally considered
the simplest configuration to produce a linear operation, where the output signal
is exactly the same multiple in voltage as the input signal. For example if the
gain of the amplifier is 100, then a 0.01 V input produces a 1 V output,
a 0.1 V input produces a 10 V output, and a 1 V input produces a
100 V output. Perfect linearity produces no distortion in the output, with
no spectral components not present in the input. Why wouldn't you want to use a
Class A amplifier all the time, you might ask? The answer is that it is the
least efficient configuration. In order to conduct through a full 360°, a DC bias
is required to place the output halfway between the maximum peak-to-peak output
voltage so that the transistor is never turned fully on or fully off...
 Radio-Electronics magazine ran regular
column entitled "The Radio Month" with industry, government, and academic news briefs.
This 1951 issue included, amongst other tidbits, a report on TV pioneers Hugo Gernsback,
publisher of Radio-Electronics, and Isidor Goldberg, president of Pilot
Radio Corporation, having been presented scrolls by student members of the Institute
of Radio Engineers and the American Institute of Electrical Engineers at New York
University in recognition of their contributions to the development of television.
Pilot Radio manufactured kits for electronics hobbyists. In other news, the FCC
discovered its first instance of an
illegal television broadcast. It never takes long for the criminally insane
to corrupt a good thing; however, in this case it was a Sylvania Electric Products
test site operating without a license. Evidently they had adopted the philosophy
of "It's easier to beg forgiveness than to ask for permission...
 Germanium was "the" semiconductor of
choice in 1959 even though advances were being made with silicon. Most of the newer semiconductor
devices were being fabricated with germanium as the central transducer element. Temperature
sensors, strain gauges, "sensistor" variable resistance units, Hall effect sensors and
gyrators and circulators, torsional (twist) transducers, displacement sensors, and even
neutron detectors were done in germanium. Even though silicon is referenced as being
applicable to all the devices, it was not until the 1960s that silicon began to dominate
semiconductor fabrication. This paper titled ,"From Germanium to Silicon, A History of
Change in the Technology of the Semiconductors...
 Plastic is one of those materials that seems
like it has been around since the dawn of time - like metal. There was an Iron Age
in the 1,000 BC timeframe (depends on location), but the Plastic Age - not
that there officially was one - did not begin in the commercial world until World
War II. If you note in older photos and films, there was not much, if any,
in the way of objects made of
plastic before the 1940s. In fact, the formulation and production of some types
of plastic like Plexiglas and polycarbonates was considered a matter of national
security for a while both for Allied and Axis powers. Bomber and fighter aircraft
windshields were made of the material. After the war, use of plastics for industrial
and consumer products exploded due to the much easier manufacturing of product enclosures,
knobs, and parts with complex shapes. Lighter weight, lower cost, easy application
of color, and in some cases greater robustness made plastic very popular with consumers.
Plastic does have its drawbacks compared to the wood, metal, and phenolic materials
previously used for radios, TVs, and phonographs, and Barney experienced one of
them...
 Radio-Craft magazine ran a series
of feature articles on "Men Who Made Radio." The January 1930 edition honored Canadian
engineer
Reginald A. Fessenden, who is credited for making the first
wireless voice transmission. Mr. Fessended worked with both Thomas Edison and
George Westinghouse, eventually inventing the rectifying electrolytic detector,
which was the successor of the coherer and the precursor of the crystal and the
tube detectors. His interest in communications extended beyond radio to include
sonic devices like sonar, a field in which he also gained significant renown...
 There is a good reason why Harold Glenn called
this an "Elementary Radio Quiz." It appeared in a 1947 issue of Radio-Craft
magazine. If you have been in the analog and RF electronics field for more than
a couple years and don't score 100%, it has to be due to a misreading of accidental
selecting of the wrong answer. I know what you're thinking - "The fool must have
screwed up and missed at least one and is making excuses." Not this time - although
I don't deny it could have happened. Anyway, it might be a fun quiz to pass out
in the break room or maybe present it to a Ph.D. candidate during an interview ;-)
"Bonne chance!," as Corporal Louis LeBeau might say...
 Power, energy, force, and work are all
physical entities whose definitions are often incorrectly interchanged. As with
most cases in physics, knowing the unit associated with each entity is a way to
remember what it represents. For instance, force is fundamentally understood as
a mass being acted upon by an acceleration - whether it be gravity or motion. Its
SI units are kg·m/s2 (newton, with dimensions of mass x length / time2).
Energy is a force in motion (or its potential by virtue of relative position) with
units of force x mass (joule, with dimensions of mass x length2 / time2),
and an electrical unit of watt·seconds (power x time). Work is force through a distance,
with dimensions of mass x length2 / time2, which is the same...
 For twenty years now, I have been creating
weekly crossword puzzles for the education and enjoyment of the technically minded
visitor like you. This Physics Theme Crossword Puzzle for May 30th has many words
and clues related to RF, microwave, and mm-wave engineering, optics, mathematics,
chemistry, physics, and other technical subjects. 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., Reginald Denny or the Tunguska event in Siberia). The technically inclined
cruciverbalists amongst us will appreciate the effort. Enjoy! |
