|
 Welcome to the
RF Attenuator Quiz, a technical
resource specifically designed for engineers and radio hobbyists who demand precision
in their signal chain analysis. Whether you are troubleshooting high-frequency systems,
optimizing cascaded RF stages for improved impedance matching, or developing custom
measurement tools like RF Cascade Workbook, a thorough understanding of passive
attenuation is essential for maintaining signal integrity. This assessment challenges
your knowledge across ten critical areas, including power handling limits, thermal
derating, noise figure degradation, and the strategic use of attenuators to enhance
system IP3...
 If anything qualifies for meeting the criteria
of the old adage that says "Necessity is the mother of invention," it is
coaxial transmission cable. Wireless communications during World
War II was the necessity that drove the rapid development and continuous improvement
of coax. Other than materials technology for wire, dielectric, protective jacket,
etc., the basics of coax cable have not changed. It was during the war that polyethylene
was developed and adopted as a dielectric material much superior to previously used
copolene. Understanding of how electromagnetic fields propagate within and, under
non-ideal conditions - on the outside of the cable has increased significantly...
 If you are just starting out in the realm
of electronics or maybe just need a little freshening up of your
basic math skills, this rather extensive article from a 1942 issue
of QST magazine is just what you need. Author Dawkins Espy does a really
nice job of laying out the basics of algebraic operations, Ohm's law, trigonometry,
and logarithms. Examples are provided for each category. In this day of calculators
doing all the hard work of calculating logs, antilogs, and trig functions, it does
even seasoned veterans at electronics calculations a bit of good to do a quick read-through
to knock off cobwebs in the gray matter. How long has it been since you have seen
tables of sine, cosine, and tangent values and/or tables of logarithms? Not long
enough, you say?
 Astronomers consider all elements heavier
than helium to be metals. That definition obviously does not jive with the standard
chemical definition of a metal as an element that readily conducts electricity,
but a concept called "metallicity"
argues that from a star (and therefore the universe) formation perspective, extremely
high temperatures and pressures in first generation stars (like our sun) preclude
the identification of distinct elements other than hydrogen and helium. Heavier
elements, such as lithium (#3 on the periodic chart and a major component in LiIon
batteries, is classified as a metal in chemistry) are overwhelmingly created after
a massive enough hydrogen star collapses and begins fusing H and He into heavier
elements. The relative abundance of hydrogen in the universe is deemed to be about
92%, and helium is 7.1%, so together they comprise about 99% of all elements...
 Amplifier Solutions Corporation (ASC) is
a manufacturer of amplifiers for commercial & military markets. ASC designs
and manufactures hybrid, surface mount flange, open carrier and connectorized amplifiers
for low, medium and high power applications using Gallium Nitride (GaN), Gallium
Arsenide (GaAs) and Silicon (Si) transistor technologies. ASC's thick film designs
operate in the frequency range of 300 kHz to 6 GHz. ASC offers thin film
designs that operate up to 20 GHz. ASC is located in an 8,000 sq.ft. facility
in the town of Telford, PA. We offer excellent customer support and take pride in
the ability to quickly react to evolving system design requirements.
 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...
 Transcat | Axiom Rental Equipment allows
you to
rent or buy test equipment,
repair test equipment,
or sell or trade
test equipment. They are committed to providing superior customer service and high
quality electronic test equipment. Transcat | Axiom offers customers several practical,
efficient, and cost effective solutions for their projects' TE needs and is committed
to providing superior customer service and high quality electronic test equipment.
For anyone seeking a way to offload surplus or obsolete equipment, they offer a
trade-in program or they will buy the equipment from you. Some vintage items are
available fully calibrated. Please check out Transcat | Axiom Rental Equipment today
- and don't miss the blog articles!
 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...
|
 • Low Power
360 Gbps Laser Wi-Fi
• 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
 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.
 This week's custom RF Cafe crossword puzzle
contains some words particular to amateur radio, along with other tech-themed words
and clues. Each week for two decades I have created a new
technology-themed
crossword puzzle using only words (1,000s of them) from my custom-created lexicon
related to engineering, science, mathematics, chemistry, physics, astronomy, etc.
You will never find among the words names of politicians, mountain ranges, exotic
foods or plants, movie stars, or anything of the sort. You might, however, find
someone or something in the otherwise excluded list directly related to this puzzle's
technology theme, such as Hedy Lamarr or the Bikini Atoll, respectively. Avid cruciverbalists
amongst us: the gauntlet has been thrown down...
 Stanford R. Ovshinsky is a name with which
most people are probably not familiar, even though some of his 400+ patented inventions
can be found in many products. The most notable is the nickel-metal hydride (NiMH)
battery. He also delved deep into phase change memory and amorphous semiconductors.
What caught my attention in this 1969 Radio-Electronics magazine article
was the claim that use of an ovonic switch matrix in conjunction with red, green
and blue (RGB) phosphor light sources could produce the world's first large screen,
flat panel video display that would not require scanning electron beams or rear
projection. History shows that the idea never came to market, probably due to a
combination of technical, financial, and manufacturability issues. Ovonics (a portmanteau
of "Ovshinsky" and "electronics") is still used in aspects of the alternative energy
industry...
 Learn-at-Home correspondence courses for
a career in electronics maintenance and repair was a big deal throughout most of
the last century. Similar training was offered by many other trades, such as automobile
/ aircraft engine repair, plumbing, HVAC, electrical wiring / control / motors,
small appliance repair, watch / clock repair, etc. Many moons ago (c.1985) I took
an electronics course from
National Radio Institute. It included a few pieces of test equipment which required
building and aligning, including a digital multimeter, signal generator, and a 10 MHz
bandwidth oscilloscope. I still have many of the electronic components - lights,
inductors, switches, transistors, ICs, diodes, capacitors, solderless breadboard,
terminal strips - that came with it for experimentation. This particular course
in the December 1954 issue of Radio News magazine offered instruction in
television repair...
 This second in a series of
International Geophysical Year (IGY) articles that appeared in Radio-Electronics
magazine in 1958. The author covers basics of satellite configuration, launching,
and tracking based on knowledge of the era. Keep in mind, though, that the U.S.
had not actually launched its first satellite at the time. In fact, the two satellite
models shown possess antennas suggesting active radio circuits within, but Echo,
our first passive earth-orbiting satellite, was just a metallized plastic sphere
that reflected radio signals back to Earth. The Russian Sputnik, by comparison,
did have electronic circuitry onboard for transmitting but not receiving a signal.
SCORE, launched in December of 1958, was America's first transponder satellite...
 It wasn't all that long ago that deadlines
for magazine printing cycles were measured in months - unlike today where electronics
on-demand printing has cut lead times to weeks and even days. Accordingly, this
National Schools advertisement pitching "after the war" training in electronics
servicing that appeared in the September 1945 edition of Radio-Craft magazine
was likely designed and submitted two or three months ahead of the publication month
(e.g., in June or July). How could they be so sure that their scarce advertising
dollars wouldn't be wasted? Simple. By that time, the entire country seemed to have
a sense that World War II would come to an end soon since Hitler's, Mussolini's,
Tojo's, and other Axis Powers' forces were under severe stress and suffering profound
defeats in every theater. Surrender was deemed imminent. It was as if word had leaked
earlier in the year that Little Boy and Fat Man were under construction and about
to deliver the debilitating and psychologically devastating blow that would finally
end the saga. It turns out they were correct...
 It was a lot of work, but I finally finished
a version of the "RF &
Electronics Schematic & Block Diagram Symbols"" that works well with Microsoft
Office™ programs Word™, Excel™, and Power Point™. This is an equivalent of the extensive
set of amplifier, mixer, filter, switch, connector, waveguide, digital, analog,
antenna, and other commonly used symbols for system block diagrams and schematics
created for Visio™. Each of the 1,000+ symbols was exported individually from Visio
in the EMF file format, then imported into Word on a Drawing Canvas. The EMF format
allows an image to be scaled up or down without becoming pixelated, so all the shapes
can be resized in a document and still look good. The imported symbols can also
be UnGrouped into their original constituent parts for editing...
 Here for your enjoyment at the end of another
week are three more vintage
electronics-themed comics - this time from a 1966 issue of Popular Electronics
magazine. The "quarter-inch Mylar" referenced in the title is recorder tape used in the
very popular machines of the day. Not only were serious" music aficionados huge proponents
of the medium, but so were the many recreational users. There was a sort of mystique
involved with being able to record and instantly play back even normal conversations
- sort of like with videos these days, except there is no mystique anymore because most
users couldn't care less about the technology which enables their proclivities...
 Before there was the annual
International Microwave Symposium (IMS) trade show, the Institute of Electrical
and Electronics Engineers' (IEEE) Microwave Theory and Techniques Society (MTT-S)
hosted the show, which was widely known as the MTT-S show. Before that, the event
went by a variety of names, including "Intercon," (International Convention and
Exposition) as reported in this 1972 issue of Popular Electronics magazine.
For the first few decades since its inception in the 1950s, New York City was the
venue, often in a hotel. As with tides and solar cycles, enthusiasm and attendance
waned and ebbed over the years. 1972 was one of the low years. Per the story, about
half the number of people were there compared to two years prior. I could not locate
a chart of attendance numbers over the years, nor the numbers to generate my own
chart...
 While working on vacuum tube based USAF
air traffic control radar and radio systems, and having seen many tube television
and radio sets I never recall seeing one of these
form-fitting metal shields like this one appearing in a 1935 issue of Radio-Craft
magazine. All the ones I've seen are simple cylinders that slide over the tube and
either twist into a receiving rim slot like a bayonet type lock or they have spring
metal fingers that grab the glass envelope. One kind of scary feature of this shield
is that there is a tab with a hole in it to go around a grounded pin on the tube,
requiring that the installer pay close attention to how it goes on. Putting it on
the wrong pin could cause serious problems like shorting out part of the circuit
if the shield also happens to contact a nearby ground, or it could inadvertently
broadcast (or pick up) a signal, or likely put a hazardous voltage on the shield.
As you might guess, utilizing a metal shield around a tube for anything other than
a low frequency application like an audio amplifier or poser supply requires circuit
design that takes into account the capacitive effects of the large, usually grounded,
metal plates...
 This
crossword puzzle from a 1958 issue of Popular Electronics magazine
is a little trickier than some because it uses abbreviations rather than full words.
Not everyone uses the same abbreviation, so some answers are a bit more subjective.
For instance, many people abbreviate the word 'transformer' as 'xfmr,' while others
use 'trans' or 'trr' (I use xfmr). Where you really have to be careful, though,
is with evolutional changes in terminology as is the case for frequency units, where
'cps' was most often used in 1958 rather than today's 'Hz." Enjoy.
 Mixing a little fun with learning has always
been a good motivation for students. I have written in the past about a particular
electronic circuits professor I had that liked to play practical jokes during lessons
and exams. Including gag options on a multiple choice test is a great way to inject
a bit of tension-easing levity while at the same time eliminating one or more opportunities
to guess at a wrong answer (although no relief for the truly clueless). I sometimes
do that on the RF Cafe Quizzes that I generate. Radio-Craft printed a large
bunch of such quiz questions under the title "Radio
WittiQuiz," where the questions and answers were provided by readers. Here
is one from October 1938...
 Maybe it comes from having crossed the half-century
Rubicon, but with increasing frequency I find myself seeking out vintage magazines
to learn how the world used to be. I am a realist who has no misconceptions about
how idyllic things used to be and that today is utter debauchery, but it is apparent
from a lot of the publications that we surely have changed significantly in the
last 50+ years - better in some ways, worse in others. For many years I have been
purchasing of WWII era
QST magazines off eBay. As I have been doing for a while on my Airplanes and
Rockets website, I am going to begin scanning and posting vintage electronics magazine
advertisements and articles. A lot of the information is timeless in its application,
especially since vacuum tubes are still in widespread use in the Amateur Radio realm.
Of course electronics...
 Every hobby magazine worth the paper its
printed on has a "tricks
of the trade" type column. Popular Electronics started out its very
first issue in October 1954 with a column that went by exactly that name. It contained
a very extensive assortment of tips and tricks (aka "kinks"). The images are rather
small, but you can get what the inventor had in mind. It's good stuff to know, even
in 67 years later in 2022 because just about everything here is applicable in today's
electronic projects...
 One aspect of advertising on the RF Cafe
website I have not covered is using
Google AdSense.
The reason is that I never took the time to explore how - or even whether it is
possible - to target a specific website for displaying your banner ads. A couple
display opportunities have always been provided for Google Ads to display, but the
vast majority of advertising on RF Cafe is done via private advertisers. That is,
companies deal with me directly and I handle inserting their banner ads into the
html page code that randomly selects and displays them. My advertising scheme is
what the industry refers to as a "Tenancy Campaign," whereby a flat price per month
is paid regardless of number of impressions or clicks. It is the simplest format
and has seemed to work well for many companies. With nearly 4 million pageviews
per year for RFCafe.com, the average impression rate per banner ad is about 225,000k per
year (in eight locations on each page, with >17k pages)...
 In 1967, when this parody was published in
Popular Electronics, the Iron Curtain of Communist Russia and the Union of Soviet
Socialist Republic (USSR) was still firmly in place. Constructing faux
Russian-sounding words was common at the time. All a comedian needed to do to have
their audiences rolling in the aisles was to append "ski," "ovitch" or "skov" to the
end of any word, or add lots of "z"s and "k"s in the middle of words. Tim Conway and
Harvey Korman did many hilarious skits on the 1970s' Carol Burnett show where they feigned
speaking in German, Japanese, and Russian tongues. Nowadays... |
