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 Welcome to the
RFCafe
Isolators & Circulators Quiz, a technical overview focused on non-reciprocal
microwave components. These specialized devices are the primary tools used to
protect sensitive signal sources from reflected power and to route signal flow
in multi-stage RF systems. Whether you are isolating a high-power transmitter
from a high-VSWR antenna, developing duplexers, or optimizing the signal
isolation between cascaded amplifiers in a precision measurement setup, a solid
grasp of circulator and isolator physics is essential. This assessment addresses
the fundamental properties of ferrite-based non-reciprocal hardware, including
insertion loss, port-to-port isolation, power...
 How far do you commute each day for
the privilege of doing your part to push back the frontiers of technical ignorance
and to boldly go where no engineer - or technician - has gone before. Do you
know what the cost equates for you each year? This handy-dandy infographic
lays out some
gruesome
numbers. Those with a weak stomach probably should pass on viewing this
one. Here's a hint at what you will see: See that big $795 in the thumbnail
image? That's the average cost per year for commuting -- per mile! Yessiree,
if you live just 10 miles from work, you're losing nearly $8,000 per year,
depending on you automobile type, on gas, tires, maintenance, devaluation,
and loss of your personal time (which is valuable, after all). Back in the
early 1990s I drove about 45 miles each way...
 Joe Cahak, owner of Sunshine Design Engineering
Services in Ramona, California, has written a white paper entitled, "Measuring
Semiconductor Device Input Parameters with Vector Analysis." This article covers
a recent test experience that utilized some thinking about the test fixture, the
bias requirements and the device mounting and special calibration offsets needed
to de-embed the test fixture response from the device response within the test fixture.
The device also had to have bias on several ports simultaneously. We had to establish
a "reference plane" within the fixture, from which we can use the Vector Network
Analyzer's Port Extension or Phase Offset to dial out the distance from our 1 port
calibration reference plane to the point of short reference within the fixture.
With this phase offset compensation we can then measure...
 Author Howard Wright takes the opportunity
here to distill the
concept of modulation down to its basic operation while dispensing
with the garbled mix of "graphs, formulas, charts, vectors, diagrams, and Greek
letters which often enter into various discussions of modulation". Wright describes
how to the uninitiated radio dial spinner, the culmination of events occurring behind
the scenes in an AM reception is akin to knowing "that, to be reproduced, the picture
[in a magazine] was broken down into its primary colors, if all we had to go by
was the original print and the magazine?" That is a very apt comparison...
 Alliance Test Equipment sells
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and calibration. Prices discounted up to 80% off list price. Agilent/HP, Tektronix,
Anritsu, Fluke, R&S and other major brands. A global organization with ability
to source hard to find equipment through our network of suppliers. Alliance Test
will purchase your excess test equipment in large or small lots. Blog posts offer
advice on application and use of a wide range of test equipment. Please visit Allied
Test Equipment today to see how they can help your project.
 Benjamin Franklin is famous for his kite-flying
experiment whereby he "discovered" not electricity (as many people believe), but
that
lightning is a form of electricity (most people thought it was
a jet of gas). A lesser known fact about Mr. Franklin is that he invented the
lightning rod after realizing the electrical nature of lightning. His understanding
of electric fields facilitated an implementation whereby hefty iron cabling interconnected
a tall, pointed rod installed at the tallest point on a building and a spike driven
into the ground. Lightning typically strikes the object that is the shortest distance
(in terms of electrical field strength) from it because the discharge can begin
at the lowest voltage. The presence of the grounded lightning rod above the highest
point on a structure effectively brings that point all the way down to ground level...
 These "Radio Term Illustrated" comics from vintage Radio-Craft
magazines are some of my favorite tech-themed comics. Most were drawn by Frank Beaven
in response to suggestions / requests by magazine readers. The one here from page
80 entitled "Crystal Gazing" was done by Franklin Folger. If you didn't know
that it appeared in a 1947 edition, you might assume it depicts a Steam Punk themed
LCD computer monitor mounted atop a Morse code straight key, but of course it is
not. At the time, cathode ray tubes (CRTs) were the only form of video display,
and while small like the one in the drawing (and round, unlike the drawing), they
were far from flat. Little did the artist suspect that his "Crystal Gazing" idea
meant to imply a type of mystic's medium for seeing...
 The big graphic with Figures 1 through 17
reminds me of the kinds of study sheets I used to make when cramming for exams in
my college circuits courses. Did I ever tell you about the wise guy instructor I
had for my first Circuits class at the University of Vermont? Anyway, this article
provides an introductory level treatment of using
negative feedback in amplifier circuits. Lots of illustration
and formulas are included. Frequencies are at baseband, so you won't learn any
secrets for high frequency amplifier stabilization, but then even RF and microwave
circuits eventually need to convert down to baseband at some point for sampling
or for use as audio or video...
 Prior to seeing this new tidbit in a 1976
issue of QST magazine, I had no idea that the wife of Peanuts comic strip
creator Charles Schulz was an airplane pilot - and that is with having been a huge
Peanuts fan for decades. Other than one of Snoopy's alter egos being that of
a World War I flying ace, there is no other theme of airplanes in the strip,
although according to this article, there was a 1975 Sunday comic strip with Peppermint
Patty and Marcie flying atop Snoopy's doghouse, from California to Michigan.
The Straits Area Radio Club (W8GQN) provided communications for the Powder
Puff Derby, aka the Women's Air Derby, race in which Mrs. Jean Clyde Schulz
took part in 1970, 1971, and 1975. It was a very long course - more than 2,000 miles
as the crow flies...
 Way...... back in 1992, RF Design
magazine ran a software contest. Those were the days when most engineers and hobbyists
wrote software in either Basic or Fortran. I happened to use Turbo Pascal, by Borland.
At the time, I was working as an RF engineer for Comsat, in Germantown, MD. Having
done a lot of frequency conversion designs in my previous work at General Electric,
and even more there at Comsat, I had already written a crude program to calculate
mixer
spurious products, so this challenge gave me the excuse I needed to refine the
user interface and add some creature comfort features like...
 Amateur radio operators - and all electromagnetic
spectrum users for that matter - have always lamented
crowded
bands and interference (QRM and QRN). That goes for licensed and unlicensed
bands. In 1976 when this editorial was printed in the ARRL's QST magazine,
spectrum occupation within allocated bands was defined by commonplace analog AM
and FM methods. Co-existence was generally not possible for operation within a common
frequency range. Spread spectrum modulation / demodulation changed all that beginning
in the 1990s, but prior to then such schemes were largely the exclusive domain of
military communications, as were many other spectrum-saving methods which are commonplace
today. A big part of the reason is the significant advances in digital processing
hardware and software, along with declassification of some of the algorithms that
eventually found their way into cellphone, WiFi, and other commercial applications.
Given that many of the professional engineers...
 As with many areas of electronics communications,
much of both the initial and continued research in
atmospheric scattering of electromagnetic signals was/is done
by amateur radio operators. The phenomenon is routinely used for accomplishing long
distance communications (DX, in Ham terms) by exploiting the reflection property
of ionized layers when radio signals impinge at a certain angle. The portion of
the signal that returns to the transmitter location, when monitored, can provide
information to the sender about the height, distance, and frequency range of the
reflecting atmospheric layer. Some of the first indications of backscattering were
noticed by radar operators who would receive echo returns from "phantom" targets
that were really atmospheric reflections...
 For many years I have been scanning and
posting Radio Service Data Sheets like this one featuring the
Admiral "Aeroscope" 161-5L, 162-5L, and 163-5L Midget Set models which appeared
in a 1939 issue of Radio-Craft magazine. There are still many people who restore
and service these vintage radios, and often it can be difficult or impossible to
find schematics and/or tuning information. Some websites offer to sell this information,
but often what is shown here is enough to get an old radio working again since most
times both schematics and alignment steps are included. I keep a running list of
all data sheets to facilitate a search...
 I'm probably one of the few people remaining
who fairly regularly recite the World War II (WWII) era slogan of "Use
it up. Wear it out. Make it do, or Do without." One of the primary killers of
economies has been inflation, whatever the cause - usually deficit spending by government
and/or printing of fiat money. Wartime typically produces high inflation levels
due to the need to produce the equipment necessary to wage a battle. Supply and
demand are another cause of inflation. If the demand is greater than the supply,
prices go up because owners want to maximize profits. If the need for skilled labor
is greater than what is available, workers demand higher pay, and the price goes
up. During WWII, as the chart to the upper left shows, inflation rates were sky
high, and the government propagandists called on the citizens to "do their part"
to keep prices under control by not creating a higher demand then the supply chain
could accommodate...
 SF Circuits' specialty is in the complex,
advanced technology of PCB
fabrication and assembly, producing high quality multi-layered PCBs from elaborate
layouts. With them, you receive unparalleled technical expertise at competitive
prices as well as the most progressive solutions available. Their customers request
PCB production that is outside the capabilities of normal circuit board providers.
Please take a moment to visit San Francisco Circuits today. "Printed Circuit Fabrication &
Assembly with No Limit on Technology or Quantity."
 Welcome to the
RF Cafe Antenna Theory
Quiz, a specialized assessment designed to test your knowledge of the radiating
structures that define the success of any RF communications system. From fundamental
dipole operation and feedpoint impedance to the critical nuances of gain, polarization,
and pattern formation, a deep understanding of antenna physics is essential for
any serious radio enthusiast or professional engineer. This quiz challenges you
on key concepts, including the characteristics of Yagi-Uda arrays, the significance
of front-to-back ratios, the dynamics of ground planes, and the practical challenges
of matching networks. By evaluating your grasp of these essential antenna principles...
 Each autumn I used to anxiously await the
appearance of the newest edition of
The Old
Farmer's Almanac on the store shelf, and such was the case with this 1981
issue. It is not that I was/am an avid farmer, just that I enjoy reading the anecdotes,
tales, and interesting historical tidbits included amongst the pages along with
tables of high and low tides, moon and sun rising and setting times, astronomical
events, and weather patterns expected for the year that lay ahead. Most of all,
I liked working the puzzles and riddles. Over the years the difficulty levels gradually
got lower and lower (aka dumbed down), to the point where for the last decade or
so I have not even bothered buying the OFA. Now it is full of numbnut stuff...
 This is a great
electronics-themed comic from a February 1972 issue of Popular
Electronics. It encompasses the essence of the stereotypical salesman ruse,
especially in that era when people were sure that electronics repair services were
out to rip them off by selling unneeded services and replacement parts. Aspiring
TV technicians who couldn't grasp the technology moved on to working as mechanics
in a garage, poking tiny holes in brake lines to scare owners into paying for complete
braking system rebuilds. I usually like to post multiple comics on each page, but
at the moment only this one is available...
 As with your school and college days where
once there was no longer any reason to memorize physical constants, conversion formulas,
and names of people, places, and things, much of the noggin's gray matter was
repurposed to remember topics of more immediate need. You can always look up what
you have forgotten. While studying for your Ham radio or FCC license, being able
to be able to quickly convert between wavelength and frequency is essential. Recalling
on demand
frequency-wavelength pairs is a real time saver on a timed exam.
Even being able to perform the conversion on a calculator during the test takes
up valuable time that could be better used on other tasks. This handy-dandy chart
for converting...
 IMS 2026 (IEEE MTT-S International Microwave
Symposium) is the world's premier RF and microwave conference, bringing together
thousands of industry professionals from around the globe to explore the latest
technologies, tools, and technical developments. IMS2026 will feature the RFIC Symposium,
the new RFSA and RFTT Symposia, and conclude with the ARFTG Microwave Measurement
Conference. everything RF
website's medai team is providing full coverage of the event. Stop by Booth 24048
to meet the crew.
 In
1961, the United States Navy commemorated the fiftieth anniversary of the A-1 Triad,
the service's first aircraft. This milestone honored
Glenn Hammond Curtiss, the father of naval aviation, who designed the versatile
machine capable of operating on land, water, and air. Born in Hammondsport, New
York, in 1878, Curtiss possessed an innate obsession with speed and mechanical ingenuity.
Before revolutionizing aviation, he dominated motorcycle racing, famously earning
the title of the fastest man on Earth. His transition to flight led to landmark
achievements, including winning the Gordon Bennett trophy in France and executing
the first successful U.S. intercity flight...
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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.
 The middle
of the last century was a time ripe with
opportunities for people with a penchant for innovation, experimentation, designing,
and building high technology products. Aviation, aerospace, land and sea transportation,
medicine, manufacturing, chemistry, physics, astronomy, communications, electronics,
mechanics, nuclear technology, remote exploration of space and the sea, and many
other realms were pushing forward the frontiers of knowledge (or pushing back the
frontiers of ignorance, depending on your viewpoint) at an incredible rate. Both
trade and hobby magazines often featured articles encouraging participation as technicians
and engineers in a field related to hobby interests (Ham radio, model airplanes,
boats, and cars, etc.). Air Trails magazine ran many such pieces, including
this 1954 example...
 For the sake of avid cruciverbalists amongst
us, each week I create a new crossword puzzle that has a theme related to engineering,
mathematics, chemistry, physics, and other technical words. As with all RF Cafe
crossword puzzles, this November 15th
Electronics Engineering crossword puzzle 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).
The technically inclined cruciverbalists amongst us will appreciate the effort.
, movie star unless he/she was involved in a technical endeavor (e.g., Hedy Lamarr)...
 That Hugo Gernsback was a profound and prolific
visionary is obvious by anybody's estimation. Throughout the early and middle 20th
century, the man both predicted and participated in as many technical creations
as any of his contemporaries. Being a publisher of both science fiction and science
fact books and magazines, Gernsback wrote of fantastic inventions ranging from weapons
to medical equipment to space travel (and the vehicles that would shuttle mankind
about in his quests). Just as Arthur C. Clarke's talents extended beyond
sci-fi adventures to include devising a scheme for geosynchronous orbit satellite
communications, Hugo Gernsback designed and sold many electronics experimenters'
kits, instruments, components, and even proposed a method for determining the rotational
period of
cloud-covered Venus. Because of Venus' perpetual atmospheric shroud of sulfuric
acid which is impenetrable by visible light, radar is needed to map the planet's
surface and determine when a full rotation has occurred...
 I have no idea why this "LSI Gives Semiconductors
a 'Trip'" quiz from Popular Electronics magazine is titled what it is.
LSI stands for "Large Scale Integration" and is generally applied to integrated
circuits, not discrete components. The quiz's creator has come up with 17 questions,
only the first of which has anything to do with LSI circuits. The other 16 are on
topics like capacitor plate spacing, magnetorestrictive material, and coaxial cable.
I realize that LSI attempts to minimize the number of external components necessary
by absorbing them into the IC, but I'm just not sure what that has to do with whether
a submarine can communicate via SHF while submerged.
 Radar speed guns have been the bane of drivers
- and the bounty of police department coffers - since the 1940s. The technology
that helped the Allied Forces win World War II was exploited immediately thereafter
by law enforcement in an effort to make the highways a safer place. Rather than
relying on a police officer's learned estimation of a car or truck's speed, a certified
radar unit was used by a trained operator. Prior to the advent of speed radar, a
common method for determining a motorist's speed was to measure the time taken to
travel between two points whose distance apart was known. The information was admissible
in court, but was more vulnerable to a crafty prosecutor's interrogation. Radar
removed that variable, although there probably have been cases where the accuracy
of the radar unit was challenged in terms of electronics performance, false signal
returns, adjustment for slant ranges, etc. The cover photo of this 1947 issues of
Radio-Craft magazine shows a constable...
 The following
technology-themed "Cryptoquip" appeared
in the Erie, PA, newspaper on December 26, 2019. It is from King Features Syndicate
and is likely covered by copyright. I attempted to find a webpage for it that I
can link to, but with no success. King Features Syndicate publishes a huge number
of my favorite comic strips. With a Cryptoquip, you try to decode a message by substituting
letters for the ones presented. It is usually pretty easy after you have done a
few. A clue is always provided for one letter. In this case it is F = P, so you
substitute the letter P everywhere you see the letter F. The message is usually
a form of pun (aka quip)...
 Somehow I missed the "Royal Engineer" part
of the engineering experience. In the first video, our hero Wally is evidently used
to it, though. "The Knack"
has become a classic amongst Dilbert fans, many of whom identify with his special
gift. The last video is sort of a take-off of the 1993 Michael Douglas movie "Falling
Down." Warning: Watching these clips from the Dilbert television show that ran from
January 25, 1999 through July 25, 2000, may cause you to spend hours of valuable
time viewing all the other clips that are available. RF Cafe cannot be held responsible
for lost productivity...
 Optical illusions have always been a big
attention-getter. Many companies have employed their intrigue to promote their products
and/or services. This
optical illusion was used by Littelfuse (not Littlefuse), a company founded
in 1927 and still in business today, to draw attention to a full-page advertisement
in a 1953 issue of Radio-Electronics magazine. More interesting than the illusions,
though is the information presented is about how their proprietary glass-encased
fuse design will always burn out in the center of the link, where it is visibly
obvious. It might seem trivial, but having tested fuses that appeared to be good
but tested bad, that is a great feature. Modern plastic-encased fuses with spade
terminals like those found in automobiles have a similar feature that makes visual
inspection very easy and unmistakable. In another Littelfuse ad, they educate the
reader about how a fuse's amperage rating is not the amperage level at which it
will blow...
 A few days ago, I was perusing an April 1973
edition of Popular Mechanics magazine, when I ran across the following
full-page ad with a
U.S. Air
Force enlistment aptitude test. Take the test, and if you get the same answers
as the geniuses that created the ad, you're a shoe-in for a great career in the
USAF! Uncle Sam wants you, bay-bee. I did the first two tests and got what they
got for answers. Then I took the third test - the one with the little folded house
- and was shocked at what I found. You take the three tests, and see if you think
something is amiss with the last one. Look way down at the bottom of the page for
my conclusion...
 The early 1950s was a time when people worldwide
were making a shift from radio to television as the primary form of in-home entertainment.
There was an aura of awe associated with TV with its ability to send recorded movies
and live shows over the air without any physical connection (although it can be
argued that an electromagnetic wave is "physical," since it is part of the study
of physics). Of course often times the feeling of awe was replaced by a feeling
of rage when the blasted thing went on the fritz. Then, the television repairman
became the objet d'awe (I just made up that phrase, a la objet d'art). Two of these
three
tech-themed comics are typical of the era. The other is timeless and could be
a modern comic if something other than vacuum tube equipment was shown in the scene.
Enjoy!
 Here is an advertisement for
Delco
Radio that I scanned from page 77 of my copy of the June 1944 QST magazine.
"What's Magic About Electrons?," is the question asked. Answer: "The magic about
electrons is man's ingenuity in putting them to work. The magic about electrons
is their promise of service in marvelous ways only hinted at in the last few years.
Now harnessed for war, the science of electrons will later work to enrich the peace.
Working in close cooperation with Army and Navy engineers, Delco Radio has applied
its knowledge and skill in putting electronics actively and effectively into the
fight for Victory. In Delco's laboratories, principles are explored and exploited;
in Delco's engineering departments, designs are evolved to apply these principles;
and on Delco's production line, complete equipment is manufactured with the speed
and skill that only a large manufacturer of precision radio instruments can bring
to such work..."
 General Electric's
19T8 vacuum tube was more than just a high frequency diode-triode component
for use in the upper radio and television circuits. It also included a dual-diode
element which was physically associated with the cathode of the triode side of the
tube. It is meant to be used in combination AM / FM receivers operating up to 100 MHz.
Its 18.9 V heater voltage is higher than the much more common 6.3 V and
12.6 V levels (note integer multiples of 6.3, including 25.2V sometimes used).From
the limited information I could find about the 19T8, it was not as widely used as
the 6T8...
 This
Famous Engineers & Scientists crossword puzzle took a long time to make
because of all the names that I managed to squeeze into the matrix. The way this
one works is the person's first initial and completely spelled-out last name, indicated
by (FI+LN) in the clue, is used as the answer. For instance, filter transfer function
developer Stephen Butterworth would be written as SBUTTERWORTH. There are at least
sixteen names here There are at least sixteen names here with which you should be
familiar. Good luck!
 If this article had appeared in the New
York Times in the year 2020, its author, Glenn Ellsworth, would have been labeled
a 'Depression
Denier!' Don't be confused by the word 'denier,' which most often prior to about
1999 was used to refer to a type of silver coin or a measure of fineness of silk
cloth. Today, it is seen most often as describing one who would deny something.
'Denyer' is the alternate spelling used by some authors to avoid confusion, and
since the level of spelling knowledge is so low, most people never notice. But,
I digress. The reason I bring up the point is because this article was published
in 1933, little more than three years after the Stock Market Crash of October 29,
1929 (aka 'Black Tuesday')...
 Over-the-Horizon (OTH) radio signal transmission
was a relatively new phenomenon when this advertisement by Bell Telephone Laboratories
appeared in a 1955 issue of Radio & Television News magazine. It was a big year
for OTH. The discovery and exploitation of it was originally the domain of Ham radio
operators who were allocated the believed-to-be useless spectrum that supports it.
However, once the government realized the important ramifications of OTH communications
(radar, voice, video), military research organizations quickly initiated efforts
to exploit it for national defense and security purposes, then classified much of
the science. In this same year as this advertisement an article by Bell Labs about
OTH technology entitled, "'Over the Horizon'" Transmission" appeared in Popular
Electronics magazine... |
