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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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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.
 If you had a father, brother, uncle, grandfather,
husband, or neighbor who was an electronics service technician in the days of yore,
he might have been mentioned in this 1958 issue of Radio & TV News magazine
highlighting General Electric's
Service Technicians' All-American Award Winners. Rather than rewarding the independent
businessmen for their technical prowess, the company assigned awards based on community
services performed, thereby reflecting positively on both GE and the electronics
service business as a whole. Each winner received a $500 check, which in 2020 money
is the equivalent to about $4,500 in today's economy. The closest thing we have
to the radio and television serviceman today is maybe the guys who install broadband
cable and satellite dishes. Their level technical knowledge is not required to be
anywhere near as deep...
 If you do a Google search on the
Talos Defense Unit at White Sands Proving Grounds, you have to look really hard
to find any mention of Radio Corporation of America (RCA) having had any part of
the program. Bendix Corporation built the Talos missile. According to the sparse
documentation on the development of the AN/FPS-16 monopulse radar, it was the brainchild
of the U.S. Naval Research Laboratory and built by RCA in Moorestown, NJ. This 1958
Radio & TV News magazine article claims the FPS-16 was developed with
a lot of input from Applied Physics Laboratory (APL) of Johns Hopkins University,
but the Wikipedia webpage makes no mention of it. The FPS-16 had the highest spatial
resolution of its time at 0.15° and 4.5 meters. It operated at 5400-5900 MHz...
 Here is yet another example of where the
basics in electronics never changes. There are always new people entering into the
realm, so even if the subject has been covered countless times already, there is
always a need to print it again. Remember that at one time you were a newbie and
appreciated seeing beginners' concepts explained. The old-timers of the day probably
complained about being tired of seeing the simple stuff re-hashed over and over.
Most standard
potentiometers (pots) are linear in operation, that is, the resistance between
the moveable wiper contact and the overall resistance between the two ends is directly
proportional to the percentage of travel along the length of the resistive element
(printed or wirewound). One of more popular specialty pots is the logarithmically
tapered type that is used in audio circuits...
 World Radio Laboratories (WRL) was a major
manufacturer of amateur radio equipment in the middle of the last century. They
were famous for high power transmitters like the Globe King models, which looked
exactly like the big, black, rack-based units seen in older movies with Ham radio
cameos. It took a couple chassis filled with big glowing vacuum tubes to pump out
a kilowatt of power. Today's semiconductor-based transmitters do the job in a small
fraction of the volume, with higher quality and higher reliability and with usually
no periodic maintenance required. The savings in your electric bill is substantial.
WRL provided a great service to the amateur radio community that constituted its
customer base by encouraging anyone passing through Council Bluffs, Iowa...
 You have probably seen
Fahnestock clips, but did you know that's what they were called? Me neither,
until I first saw the name of them on a page in a MicroMark catalog a while back.
When I ran across this advertisement in a 1947 issue of Radio News magazine, it
seemed like a good opportunity pass the revelation on. Model train enthusiasts must
not use Fahnestock clips as much anymore for wiring their layouts since there are
more modern quick-change type terminal connections available. MicroMark does not
sell them anymore, but you can still get some from Newark Electronics and other
online sellers. Maybe the ones sitting in my parts drawer will one day be worth
big $$$ to collectors (just kidding).
 Author Edward Tilton discusses here the tradeoff
between
bandwidth and sensitivity in receivers, given that broadband noise power follows
bandwidth in a 10 log BW fashion. Pulling in the most distant stations requires
very low noise in able to get the SNR as high as possible, which requires the minimum
bandwidth possible. Prior to highly stable local oscillators, operating successfully
in a narrow bandwidth for voice (phone), and particularly for CW (Morse code), dictated
the use of a fixed frequency crystal to keep from having to constantly re-tune the
station. Nowadays, of course, what used to be considered a metrology grade oscillator
can be bought for tens of dollars...
 This article on the design and use of
antennas for television and FM radio was printed in a 1948 issue of Radio-Craft
magazine. Equations and charts are provided for calculating element lengths for
half-wave antennas, including directors and reflectors. Many types of antennas -
dipole, stacked dipole, folded dipole, conical, adjustable "V," cross-element -
are discussed regarding siting issues (location and height above the ground), and
radiation patterns. It is a pretty good primer for someone new to antennas, and
makes a great supplement to the data furnished in study guides for obtaining a Ham
radio license...
 Prior to the Rural Electrification Act of
1936, the year this Radio Service Data Sheet appeared in Radio-Craft magazine,
commercial electric service was limited primarily to urban and suburban areas. Vast
expanses of rural farmland were without electric service and had to rely on individual
wind and, where possible, hydro power
generators for DC power. The output voltage was of course direct current since
it could be stored for later use. Even through the early 1940s many farms and rural
households had only the convenience of DC power by virtue of banks of lead-acid
batteries. Sears, Roebuck &Co. sold wind-driven electricity generators for farm
use to charge batteries in place rather than having to load them onto a wagon and
truck them into town for charging. Many farms already had windmills erected to mechanically
drive grist mills, saws...
 As with my hundreds of previous
engineering and science-themed crossword puzzles, this one for January 12, 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 momentous development that changed the
field of radio communications warranted merely a half-page announcement in 1935
when
frequency modulation inventor Edwin Armstrong had his article published in Radio-Craft
magazine. It indisputably changed the world while causing poor Mr. Armstrong
much grief while defending his right to the invention. Spread spectrum modulation
/ demodulation would be the next big communications advance that began with the
frequency hopping (FHSS) scheme dreamed up by Hollywood actress Hedy Lamarr and
pianist Antheil George during World War II. Direct sequence spread spectrum
(DSSS) followed in the digital age, and since then I do not know of any fundamentally
new communications technology in that time...
 One of the photos in this 1958 Radio &
TV News magazine article on the
Jodrell Bank radio telescope shows what appears to be the largest multi-conductor
cable connector I have ever seen. It looks like a early Photoshopping of a DB-9
connector with a heavy metal back shell. The cable bundle is three to four inches
in diameter. Rather than use slip rings to transfer the control, data, and power
signals from the base to the steerable 250-foot diameter parabolic dish of the Jodrell
Bank radio telescope (now called the Lovell telescope), a single massive cable does
the job. The science of radio astronomy was barely three decades old at the time
it was built. It was in 1931 that Karl Jansky first determined that radio signals
were coming from our Milky Way galaxy. He eventually ended up working for Bell Labs
in Homdel, New Jersey, where he built a radio telescope to investigate background
noise in the 10-20 meter wavelength band, where Bell planned to use its microwave
relay system...
 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...
 One day in late spring of 1973 I found myself
walking around the gymnasium of Annapolis Junior High School (AJHS) trying to decide
which courses I would prefer upon beginning tenth grade the following fall. It was
one of the final days of ninth grade, which had been by far my least happy year
in school. Living in Mayo, Maryland, I and my fellow neighborhood ninth graders
should have attended Southern Senior High School (SSHS) in Harwood, Maryland, where
our predecessors had gone for ninth grade, but overcrowding caused the Anne Arundel
School Board wizards to decide that for at least that year, we would remain at AJHS
for another term. Historically, kids from my area went to AJHS only for seventh
and eighth grades and then switched to SSHS. Annapolis, being the capital city of
Maryland, was significantly more urban than the rural areas to which SSHS type people
were accustomed. The clientele was much more aggressive in the big city. Sure, we
had our "red neck greaser" rowdies in the southern part of the county, but at least
their parents would whip them if they got caught getting into trouble...
 Imagine reading an article from a 1958 magazine
that references the schematic for a specific radio manufactured in Germany, and
then being able to download a copy of it for free on the Internet. Such is the case
with this Mac's Radio Service Shop story entitled, "Was Ist Los?" Mac is describing
to his sidekick Barney the difficulty in troubleshooting and repairing a
Metz Transformatoren: Babyphon 56 that a serviceman had purchased while
stationed overseas. The diagram is of course in German, which requires Mac to pull
out a language translation dictionary. The problem was that many words unique to
technical jargon were not in it. Additionally, units of measure for the capacitors
and inductors were not like U.S. units. Mac noted that many capacitor values were
labeled with units of "u," "n," and "p," for "micro," nano," and "pico." He mentions
the "micro" prefix for the letter "u," but never calls the "n" and "p" by the now-standard
terms...
 As with my hundreds of previous
engineering and science-themed crossword puzzles, this first one
of the new decade, January 5, 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... |
