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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
used / refurbished test
equipment and offers short- and long-term rentals. They also offer repair, maintenance
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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Loading history...
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 is the second of a two-part series
discussing the
propagation of shortwaves, the first part having appeared in the December 1931
/ January 1932 edition of Short Wave Craft. Keep in mind that at the time
of the writing, no instrumented sounding rockets had been sent into the upper atmosphere
for empirical measurements, so the author's conjectures being inaccurate are forgivable.
Mr. Meyer's supposition that there are "cosmically-located network of conductive
lines" that influence seasonal propagation as the earth moves through them during
its revolution around the sun is actually not an unreasonable theory for its era.
It certainly is no more outlandish than a modern-day celebrated astrophysical genius
proposing a series of vibrating 'strings' in an 11-dimensional universe...
 I'm guessing most RF Cafe visitors who are
more than 50 years old are familiar with, and even have seen, the
Sams
Photofacts packages of documentation for consumer electronics appliances that
include televisions, radios, phonographs, clock-radios, tape recorders/player, amplifiers,
etc. Most electronics service shops couldn't have existed with them since many manufacturers
did not distribute technical and service data to anyone who was not a certified,
sanctioned dealer. Howard Sams, the company's founder, did the equivalent for electronics
of what Chilton did for cars and trucks. They basically reverse engineered models
bought off a showroom floor. This advertisement from a 1958 issue of Radio &
TV News magazine features the man himself, Howard Sams, so now you'll recognize
him if you pass him on the street...
 As with my hundreds of previous
engineering and science-themed crossword puzzles, this one for January 19, 2020,
contains only clues and terms associated with engineering, science, physical, astronomy,
mathematics, chemistry, etc., which I have built up over nearly two decades. Many
new words and company names have been added that had not even been created when
I started in the year 2002. You will never find a word taxing your knowledge of
a numbnut soap opera star or the name of some obscure village in the Andes mountains.
You might, however, encounter the name of a movie star like Hedy Lamarr or a geographical
location like Tunguska, Russia, for reasons which, if you don't already know, might
surprise you.
 A couple years ago a house two streets away
had an estate sale after the elderly gentleman who owned it passed on. There was
a lot of old
amateur radio gear for sale, and most of it had been bought early in the morning,
right after the beginning of the sale according to the man's daughter who was on-hand.
The newspaper notice mentioned the Ham equipment. In the back yard was a nice 40-foot
crank-up tower that was a bit weather-worn, but otherwise appeared to be in good
condition. She said that was the first item sold. I didn't ask how much she got
for it. The house was to be sold, and they were glad to have the tower gone before
listing it on the market. I have wondered in the past when seeing a "For Sale" sign
in the lawn of a house with one or more radio towers in the yard how much they would
impact the sale price. Some Hams would plan to take...
 Anyone who pays attention in a present-day
high school physics class would read this article from 1944 and immediately appreciate
the advances that have been made in atomic theory during the ensuing 75 years. With
modern knowledge, it is hard to believe that even in 1944 someone would seriously
suggest that theorized
sub-electronic particles (building blocks of electrons) might be responsible
for supporting the propagation of electromagnetic energy. We still consider the
electron to be an elementary particle (although now not so the proton and neutron),
but at this point we are aware of many elementary particles other than the electron
(some of which make up protons and neutrons). There are six types of quarks, the
gluon, the photon, three types of bosons, and five other types of leptons other
than the electron - for a total of 17. The author's characterizing of the electron
as having a "flitting and jerking" "enormous" positional presence...
 Here be another brain teaser from quizmaster
Robert P. Balin. The "Amplifier
Quiz" is one of sixty or so I have posted thus far from vintage issues of
Popular Electronics magazine. Having been created in 1964, the circuit
schematics use vacuum tubes, but don't let that inhibit you from taking the test.
Enhancement mode field effect transistors (FETs) are an apt analogy to tubes for
determining function, so I added symbols for FETs next to the vacuum tube symbols
to help you visualize the equivalence. I usually do a respectable job on these quizzes,
but have to admit to only getting 4 out of 6 this time (67%), and one of those was
just a lucky, semi-educated guess. Shameful.
 Interestingly, the February 1958 article
in Radio & TV News magazine entitled "Report
on the Soviet Earth Satellite" never mentions the craft's name - "Sputnik 1,"
or "Простейший Спутник-1," which in English is "Elementary Satellite 1." Sputnik 1
was, in case your history is a bit fuzzy, the world's first successful artificial
communications satellite. Launched by the Union of Soviet Socialist Republics (USSR)
on October 4, 1957, Sputnik 1 remained operational for about three weeks in
low Earth orbit (284 miles average), during which time radio receiving stations
across the globe anxious tuned in hoping to hear the 20.005 MHz and 40.002 MHz
pulses that alternately repeated continuously in an alternating manner - the first
FSK (frequency-shift keying) from space. Ruskie engineers made the signal frequencies
and periods as stable as possible in order to enable careful frequency and timing...
 Advertisements for this
Scotch 200 magnetic tape product appeared many time in electronics magazines
during the big stereo era that ran from the 1950s through to the 1980s. High Fidelity
(Hi-Fi) was a big deal as major improvements in receivers, tape decks, phonographs,
amplifiers, and speakers were being made. I decided to highlight this one in particular
for a couple reasons. First is that when I was in the USAF stationed at Robins AFB,
GA (1979-1982), one of the roommates I had in the barracks had a father whom, at
least per his claim, invented reflective tape for 3M. The guy was a true Lennon
fanatic, and even wore faux Lennon glasses when off duty. He didn't look the part.
When Mark David Chapman shot and killed Lennon on December 8, 1980, his entire raison
d'être came to an end. I'm surprised he didn't go for psychiatric counseling. Second,
did you know (or care) that "3M" stands for...
 Each month Radio & TV News magazine
contained a section entitled, "What's New in Radio," which reported on some of the
latest happenings in the fields of commercial, military, space, transportation,
broadcast, and all other forms of wireless communications. This 1958 issue show
the world's first volume production airborne digital computer, designed by Hughes
Aircraft Company, installed in the nose of a U.S. Air Force F-102A Delta Dagger
fighter jet (built by Convair). The 456th Fighter Interceptor Squadron website has
a lot of information about the
Hughes MA-1 Digitair computer and its integration with airborne radar to create
a flight control system that could guide aircraft to a target for ordinance (bombs,
missiles) deployment. Other topics included a wideband oscilloscope from Electronic
Industries (EIC) that handled a whopping 5 MHz...
 For a given semiconductor compound, the maximum
operational speed of a transistor is governed pretty much by its gate thickness.
Capacitance and impurities along with lithography precision and accuracy are the
culprits. Shrinking gate sizes and growing crystals with greater purity has driven
operational speeds upward significantly over the years. An equivalent set of issues
plagued vacuum tube development a century ago. The physical spacing of grid elements
wrt each other as well as to the cathode and plate placed an
upper limit on amplification bandwidth. As always, judicious study of the underlying
causes led to the development of new designs that, along with improved manufacturing
techniques, overcame existing barriers and, also as always, exposed yet a new set
of limiting criteria for conquering...
 Upon seeing this advertisement by Bell Laboratories
for their "Twistor"
form of magnetic memory data storage in a 1958 issue of Radio News magazine,
my thought was that it was just another flash in the pan, so to speak, in the history
of breakthrough, paradigm-changing inventions. It was a variation of the non-volatile
magnetic core memory that used sections of ferromagnetic wire twisted around copper
wire in such a way that electrical currents directed to particular intersections
in an x-y grid would cause a magnetic orientation to be set (store a bit) and a
set or read and sense wires permitted detection of the stored magnetic field to
be determined (read a bit). The Twistor was hailed as a much more manufacturable
form of the magnetic core memory, which required production workers with small hands
and finger to manually thread...
 News headlines are filled with stories about
how certain segments of the society are routinely excluded from participation in
activities which have been historically 'dominated' by adult white males. Not only
have 'outsiders' been prevented from engagement, but, you would likely conclude
based on the invective words that drip from the pens and/or mouths of those reporting,
tireless campaigns have been mounted to see to it that exclusiveness continues.
I will agree that there have been instances of preferential treatment by some groups
and people, but I also know many attempts have been made over the decades to attract
other than white males into all kinds of activities normally associated with white
males. In fact, it is not a stretch to say many specialty groups go out of their
way to make a big deal out of non-typical persons interested in joining. Here is
one of many examples that appeared in a 1935 (yes, 1935) edition of Short Wave Craft
where the editor, Hugo Gernsback,
encouraged women and girls to get involved in amateur radio...
 As with my hundreds of previous
engineering and science-themed crossword puzzles, this one for January 26, 2020,
contains only clues and terms associated with engineering, science, physical, astronomy,
mathematics, chemistry, etc., which I have built up over nearly two decades. Many
new words and company names have been added that had not even been created when
I started in the year 2002. You will never find a word taxing your knowledge of
a numbnut soap opera star or the name of some obscure village in the Andes mountains.
You might, however, encounter the name of a movie star like Hedy Lamarr or a geographical
location like Tunguska, Russia, for reasons which, if you don't already know, might
surprise you...
 British engineer John Sargrove was to the
production of radios what Henry Ford was to automobiles. At the time this "Robot
Makes Radios" article appeared in a 1947 issue of Radio-Craft magazine, Sargrove
had recently put his
Electronic Circuit Making Equipment (ECME) fully automated assembly line into
operation. Applying knowledge from two decades of developing methods of crating
inductors, capacitors, resistors, and interconnecting conductors using controlled
deposition of various materials on flat substrates, he was able to build 2-tube
AC/DC radios at a rate of up to three per minute, with only two ECME operators -
one at the input and one at the output. The only manual assembly required was the
installation of a potentiometer-switch, a transformer, speaker...
 QST reader George P. Orphan, KG4DXJ,
wrote in the February 2020 issue's "Letters from Our Members" column about an episode
of the old "Hazel" television show entitled, "Stop Rockin'
Our Reception," where interference on the Baxters' TV set was blamed on the
"shortwave set" operated by a teenager, Bruce, who had recently moved in down the
street. George Baxter, the household's impulsive lawyer father, was convinced enough
that Bruce, a friend of his son, Harold, was responsible that he paid a visit to
the boy's house and spoke to his father about it. Bruce politely informs Mr. B
that unless his television was was manufactured before 1950, it was unlikely that
his operations on the 10-meter band would be causing the interference, but it fell
on deaf ears. Shortly thereafter, a power company investigator was seen walking
around the front yard with a box bearing a loop antenna on the top of it. At the
request of Bruce's father... |
