|
 The
bridged-T filter is a quick-and-dirty construct used to notch out a specific
frequency that is interfering with a desirable frequency or band of frequencies.
It is a resonant LC (inductor-capacitor) circuit consisting of a single inductor
"bridging" a pair of series capacitors having a resistor to ground between them,
or, if preferred, a capacitor bridging one or two inductors. A convenient
nomogram (aka nomograph) is provided by the author in this 1964
Radio-Electronics magazine article for quickly selecting values, which was
a very popular design aid in the pre-calculator era. A slide rule could be used
to calculate a range of values when only a single variable was in play, but
juggling more than one variable (component value) was greatly aided by a
multivariable nomograph. Truth is nomographs can still...
 Television, in 1955, was still a relatively
new phenomenon to many - maybe even most - people. According to multiple sources,
the portion of American households with a TV set went from under 20% in 1950 to
nearly 90% ten years later in 1960. That was a meteoric rise, particularly considering
the expense of even a minimal TV. The technology was not even available commercially
when most people were born, so the rush to join in on the craze was akin to the
mass adoption of cellphones in the 1990s. "Carl &
Jerry" creator John Frye used his pair of electronics-savvy teenagers to help
make the "magic" behind recreating a moving picture on a CRT miles away from where
it was created. Water flowing through a garden hose has often been employed as an
analogy for current flowing through a wire to explain electricity to laymen and
beginning students of the craft. Here, it is not water flowing through the hose
but water leaving the hose and flowing through the air that serves to represent
an electron stream travelling from the electron gun to the phosphor-coated glass
front of a CRT. Frame rates, scan lines, deflection coils, and other relevant terms
are i
 "The
RF front-end (RFFE) industry, valued at $21 billion, is expanding beyond its
traditional focus on mobile and infrastructure to drive innovation in the automotive
sector. Each segment within the industry presents unique dynamics and growth opportunities.
After a difficult 2022, the smartphone market is showing signs of recovery, with
expected year-over-year growth of 4%, projected to reach 1.2 billion units by 2024.
The mobile RFFE market is predicted to hit US$18 billion by the end of 2024, though
it may face stagnation due to market saturation and pricing pressures. This
market is expected to expand, with the 2027 launch of RedCap..."
 I'm having a hard time writing this with
my eyes rolled back in my head. The last time I experienced this level of overwhelmedness
was probably the third or fourth week of my feedback and control class at UVM. Even
though
electricity and magnetism shares many complimentary and parallel concepts, for
some reason thinking in terms of magnetics when describing amplifiers, mixers, modulators,
etc., has always caused brain freeze. Maybe it has to do with an ingrained bias
due to my earliest dealings with circuits being from a technician background before
earning an engineering degree. The equations of electric fields and magnetic fields
are very similar so that helps lower...
 Temwell is a manufacturer of
5G wireless communications filters for aerospace, satellite communication, AIoT,
5G networking, IoV, drone, mining transmission, IoT, medical, military, laboratory,
transportation, energy, broadcasting (CATV), and etc. An RF helical bandpass specialist
since 1994, we have posted >5,000 completed spec sheets online for all kinds
of RF filters including helical, cavity, LC, and SMD. Standard highpass, lowpass,
bandpass, and bandstop, as well as duplexer/diplexer, multiplexer. Also RF combiners,
splitters, power dividers, attenuators, circulators, couplers, PA, LNA, and obsolete
coil & inductor solutions.
 Here we are with another set of three "What's
Your EQ?" circuit challenges, these from the February 1962 issue of Radio-Electronics
magazine. As usual, those challenges provided by Jack Darr are the purview of television
servicemen of the era. The photo shown of the problematic CRT display looks like
a chest x-ray or maybe hieroglyphics in the dark corner of a cave, but evidently
the artifacts are readily identifiable to an initiated few. The Forbidden Current
Path circuit answer is not what I thought it would be. I maintain that whether my
answer or the designer's answer is correct depends on the physical...
 "A new
world record
in wireless transmission, promising faster and more reliable wireless communications,
has been set by researchers from UCL. The team successfully sent data over the air
at a speed of 938 Gb/s over a record frequency range of 5–150 GHz. This speed
is up to 9,380 times faster than the best average 5G download speed in the UK, which
is currently 100 Mb/s or over. The total bandwidth of 145 GHz is more
than five times higher than the previous wireless transmission world record. Typically,
wireless networks transmit information using radio waves over a narrow range of
frequencies..."
 Sputnik refers to the first series of satellites
launched by the Soviet Union. The word "Sputnik" means "satellite" in Russian. The
launch of Sputnik 1 on October 4, 1957, marked a monumental moment in human history,
heralding the dawn of the Space Age and sparking a fierce technological competition
known as the Space Race between the United States and the Soviet Union. This satellite,
the world's first artificial one, orbited Earth at an altitude of roughly 215 to
939 kilometers and broadcast a radio signal that astonished the world, particularly
in the United States, where it spurred rapid advancements in aerospace and scientific
research. The successful launch of Sputnik was an achievement that was years in
the making, involving a combination of visionary planning, political motives, and
intensive engineering by some of the Soviet Union's top scientists.
Blog: Air Quality
Measurements with Particle Counters
 Transcat | Axiom Test Equipment, an electronic
test equipment rental and sales company has published a new blog post entitled "Provide
Essential Air Quality Measurements with These Particle Counters" that covers
how particle counters can provide essential measurement capabilities that can help
avoid contamination and support high manufacturing yields. These measurement tools
can detect and measure microscopic particles suspended in air that can contaminate
the most carefully planned manufacturing lines. Air particle counters can be designed
for various...
 In 1958, most people were not accustomed
to seeing the now-familiar maps plotting
sinusoidal
courses of satellites across the face of the earth. It had only been in October
of the previous year that any object other than the moon was in orbit around our
home planet - that was U.S.S.R.'s Sputnik. Just as people of all ages and all backgrounds
enthusiastically joined in the newfangled phenomenon of aeroplanes after the Wright
Brothers flew their fragile craft at Kitty Hawk, electronics communications and
scientists worldwide hopped aboard the satellite train. This article from a 1958
issue of Radio & TV News magazine provided insight into the construction
and flight characteristics...
 LadyBug Technologies was founded in 2004
by two microwave engineers with a passion for quality microwave test instrumentation.
Our employees offer many years experience in the design and manufacture of the worlds
best vector network analyzers, spectrum analyzers, power meters and associated components.
The management team has additional experience in optical power testing, military
radar and a variety of programming environments including LabVIEW, VEE and other
languages often used in programmatic systems. Extensive experience in a broad spectrum
of demanding measurement applications. You can be assured that our Power Sensors
are designed, built, tested and calibrated without compromise.
 What were some of the
top issues of the radio and television industry half a century ago? In a lot
of respects, the same things that concern it today. A ready supply of service technicians
was a concern that was taken seriously by the Electronics Industry Association (EIA).
While there are not many local repair shops for electronics products nowadays, there
is still a huge demand to techs who are willing and able to do the hard work of
keeping the world's communication infrastructure operational - climbing towers,
repairing cell equipment. Now, as then, good pay, job security, benefits, and respect
for the job being done were at the top of...
 In a parallel to the traditional test setup
of signal generation and signal acquisition, RIGOL Technologies announced today
the latest additions to its portfolio of
performance measurement equipment with the introduction of the DG5000 Pro Series
Generators and DHO/MHO5000 Series Oscilloscopes. The DHO/MHO5000 Series bring next-level
performance to RIGOL's respected line of high-resolution oscilloscopes, while the
DG5000 Pro generators do the same for the company's capable Pro Series arbitrary
waveform generators...
 When selecting articles for posting here
on RF Cafe, I like to include ones that are directed toward newcomers to the field
of electronics as well as for seasoned veterans. This piece from a 1958 issue of
Radio & TV News magazine entitled "Basic Electronic Counting," is a
prime example in that it introduces the concept of binary numbers. We've all been
there at some point in our careers. A big difference between now and when this article
appeared is that in 1958, almost nobody was familiar to binary numbers, and fuggetabout
[sic] octal and hexadecimal. Only those relatively few people designing and working
with multimillion dollar, vacuum tube-based digital computers installed in universities,
megacorporations, and government research facilities had ever dealt with digital
numbers. The earliest example of powers of two I remember was back in junior high
school. It had to do with a
 "Every invention begins with a problem -
and the creative act of seeing a problem where others might just see unchangeable
reality. For one 5-year-old, the problem was simple: She liked to have her tummy
rubbed as she fell asleep. But her mom, exhausted from working two jobs, often fell
asleep herself while putting her daughter to bed. 'So [the girl] invented a teddy
bear that would rub her belly for her,' explains Stephanie Couch, executive director
of the Lemelson MIT Program. Its mission is to nurture the
next generation of inventors
and entrepreneurs. Anyone can learn to be an inventor, Couch says, given the right
resources and encouragement. 'Invention doesn't come from some innate genius, it's
not something that only really..."
 Mechanical filters of the type described
in this 1969 Electronics World magazine article are yet another example
of the genius of some people. They are actually a form of electromechanical device
in that the applied electrical signals are first converted into mechanical signals,
followed by resonant mechanical elements that discriminate according to frequency,
and finally a conversion back to an electrical signal is made. It is fundamentally
the same principal as a crystal, SAW, or BAW filter, albeit each with distinctly
different methods and topologies. Mr. Donovan Southworth, of Collins Radio, presents
the basics of mechanical filters in this brief write-up...
LadyBug Technologies was founded in 2004
by two microwave engineers with a passion for quality microwave test instrumentation.
Our employees offer many years experience in the design and manufacture of the worlds
best vector network analyzers, spectrum analyzers, power meters and associated components.
The management team has additional experience in optical power testing, military
radar and a variety of programming environments including LabVIEW, VEE and other
languages often used in programmatic systems. Extensive experience in a broad spectrum
of demanding measurement applications. You can be assured that our Power Sensors
are designed, built, tested and calibrated without compromise.
 Attempts at making an
electronically printed facsimile (fax) of an original document at a location
distant from the source have been around for quite a while. As mentioned by
Radio-Electronics magazine editor Hugo Gernsback in this article, Samuel Morse
had a crude working device for printing messages on paper even before his eponymously
named code of dots and dashes became famous in 1837. A couple decades earlier, a
fellow named John Redman Coxe, of Philadelphia, Pennsylvania, devised a method of
electronically printing images and text on paper using a conductive solution and
a direct current pile (aka battery). Dr. Coxe, a physician, is not a well-known
figure in the electronics world, but in his day...
 "Researchers have discovered how the 'edge
of chaos' can help electronic chips overcome signal losses, making chips simpler
and more efficient. By using a metallic wire on a semi-stable material, this method
allows for long metal lines to act like superconductors and amplify signals, potentially
transforming chip design by eliminating the need for transistor amplifiers and reducing
power usage. A stubbed toe immediately sends pain signals to the brain through several
meters of axons, which are composed of highly resistive fleshy material. These axons
operate using a principle known as the 'edge of chaos,' or semi-stability, enabling
the swift and precise transmission of information..."
 The January 1969 issue of Electronics
World magazine published an extensive list of
Japanese company trade names and their addresses. Many of them went out of business
or were bought by other corporations long ago, as occurs in all countries. "Aiwa"
is listed twice, but that might have been a legitimate duplication due to separate
locations (BTW, I owned an Aiwa stereo at one time). My first "real" cassette tape
deck was made by TEAC (founded in 1953 as the Tokyo Electro Acoustic Company) and
my first "real" stereo receiver was made by Sansui. I remember the line in "Back
to the Future 3" where Doc Brown, having time-travelled from 1955, makes a
disparaging remark about a circuit in the DeLorean failing because of it being labeled
"Made in Japan." Marty counters...
• ARRL Defends
902-928 MHz Amateur Radio Band
• FCC's
Auto Safety Spectrum Rules
• $5M in U.S.
Chips Act Money to Metrology Projects
• U.S. State Department Approves
Surveillance Radar System Sale to Romania
•
5G Americas ITU IMT-2030 Vision for 6G White Paper
 John Redman Coxe was a prominent American
physician, scientist, and innovator born on September 20, 1773, in Philadelphia.
Coxe's intellect and curiosity drove him toward an illustrious career in both medicine
and early scientific exploration, which included experimentation in electrochemistry.
He graduated with a degree in medicine in 1794, setting the course for his lifelong
journey into medicine and early scientific innovation. Coxe broadened his approach
to medicine and science, inspiring him to explore the convergence of scientific
methods and practical applications. John Redman Coxe is most remembered not only
for his contributions to medicine but also for his interest in experimental physics,
particularly in the field of electrochemistry...
 TotalTemp Technologies has more than 40
years of combined experience providing thermal platforms.
Thermal Platforms are
available to provide temperatures between -100°C and +200°C for cryogenic cooling,
recirculating & circulating coolers, temperature chambers and temperature controllers,
thermal range safety controllers, space simulation chambers, hybrid benchtop chambers,
custom systems and platforms. Manual and automated configurations for laboratory
and production environments. Please contact TotalTemp Technologies today to learn
how they can help your project.
 When I saw this 1966 Radio-Electronics
magazine article entitled, "Vibration
and Shock - Nature's Wrecking Crew," for some reason the first thing I thought
of was "The Wrecking Crew," that anonymously played the music for a huge number
of popular singers - mostly those without prominent bands of their own during the
1960s and 1970s rock-and-roll era. ...but I digress. My introduction to the potential
deleterious effects of vibration on electronics was in the 1970s, with airborne
receivers and servos in my radio controlled model airplanes. Even though they were
transistorized, vibration from glow fuel engines could wreak havoc with potentiometers
in servos and solder joints everywhere, including battery packs. I remember seeing
the control surfaces jitter...
 You don't see jobs advertisements like this
anymore. Here is an ad that appeared in the the July 1944 edition of QST
(the American Radio Relay League's, ARRL's, monthly magazine), placed by Raytheon
Manufacturing Company (now just Raytheon Company), looking for
vacuum tube design, test, and processing engineers. Licensed amateur radio operators
were in high demand during the war years because of their knowledge and enthusiasm
for electronics and wireless communications. I hope you didn't come to this page
hoping to really find a tube designer job available. Of course, there are still
vacuum tubes being designed for TWTs and magnetrons, but those are few and far between...
 The "carborundum"
signal detector, an innovative device developed by engineer General H. H. C. Dunwoody
in the early 20th century, represents a significant advancement in radio technology,
particularly in the context of crystal detectors used for receiving radio signals.
This device utilized the unique properties of silicon carbide, also known as carborundum,
which was synthesized in the late 19th century by Edward Goodrich Acheson. The connection
between Dunwoody and the material lies in the application of carborundum as a semiconductor
in radio signal detection. The operational theory of the carborundum signal detector
is rooted in its ability to rectify alternating current (AC) signals. When radio
waves, which are essentially electromagnetic waves...
 "Researchers have created a cutting-edge
structure by placing a very thin layer of a special insulating material between
two magnetic layers. This new combination acts as a quantum anomalous Hall insulator,
significantly broadening its potential use in developing ultra-efficient electronics
and innovative solar technology. A Monash University-led research team has found
that a structure featuring an ultra-thin topological insulator, sandwiched between
two 2D ferromagnetic insulators, transforms into a large-bandgap quantum anomalous
Hall insulator. This heterostructure opens the door to ultra-low energy electronics
and even topological photovoltaics..."
|
 You have probably seen some pretty atrocious
coaxial cable connector installations. You might have even been responsible
for a few of them ;-( It could be tempting, at least for frequencies
in the lower megahertz range, to allow yourself to be a little sloppy with coaxial
cable preparation and connector attachment, but doing so can result in marginal
functionality if power levels are high or if power levels are extremely low. When
voltage levels are high, excessive air gaps between the inner and outer conductors
can result in arcs, and poor connections can generate intermodulation products high
enough to cause interference (possibly subjecting you to a violation citation from
the FCC). At very low power levels, distortions and lack of symmetry in the interface
between the cable and the connector...
 According to this full-page advertisement
in the June 1955 issue of Radio & Television News magazine, Bell Telephone
Laboratories was responsible for designing and fielding "waveguide pipe," aka flexible circular waveguides. According to
other historical sources, both George Southworth of Bell Telephone Laboratories
and Wilmer Barrow of the Massachusetts Institute of Technology (M.I.T.) independently
and simultaneously developed circular waveguide, but the early devices were rigid
pipe rather than being fabricated from tightly wrapped, insulated wire that permitted
it to be bent rather than requiring separate corner and offset pieces. Insertion
loss and VSWR is typically not as good as with rigid waveguide, but the ease of
installation in many situations justifies the poorer electrical performance. Bell
Telephone Laboratories was responsible ...
 Each week, for the sake of all avid cruciverbalists
amongst us, I create a new technology-themed crossword puzzle using only words from
my custom-created lexicon related to engineering, science, mathematics, chemistry,
physics, astronomy, etc. This week's puzzle contains a special holiday message (colored clues) to all RF Cafe
visitors. 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,
see someone or something in the exclusion list who or that is directly related to
this puzzle's theme, such as Hedy Lamarr or the Bikini Atoll, respectively...
 When I saw this
Hughes Research and Development Laboratories employment ad in a 1955 issue of
Radio & Television News, I wasn't sure how to take it. The text of the ad makes
no reference to the bar graph and the weird drawing. Note the
"bottle" is actually a slide rule. The graph can be interpreted to indicate
that the more education a person has, the less likely he is to have children. If
the typical age of the respondent is in the twenties, then that might reflect
how people still in school to earn a higher degree would not be having children.
It might also show that people with higher degrees focus more on their careers
than on having a family. If you extrapolate the graph backward, does it imply
people with an Associate's degree might average 1.5 children, those with just a
high school diploma have about 1.7 children, and high school dropouts average
maybe 2.0 kids? You have to also assume that most of the people with higher
degrees earned them prior to beginning work or else you would have to ask what
the Ph.D. with 0.9 kids did...
 With more than 1000
custom-built stencils, this has got to be the most comprehensive set of
Visio Stencils
available for RF, analog, and digital system and schematic drawings! Every stencil
symbol has been built to fit proportionally on the included A-, B-, and C-size drawing
page templates (or use your own page if preferred). Components are provided for
system block diagrams, conceptual drawings, schematics, test equipment, racks, and
more. Page templates are provided with a preset scale (changeable) for a good presentation
that can incorporate all provided symbols...
 You probably need to be a
Ham radio operator to fully appreciate the humor in some of these comics. The first
one, for instance, is a poke at a guy proudly pointing out his QSL cards from distant
(DX) stations "right near the city limits," "on the other side of town," etc., basically
what you can pull in with a home Citizens Band (CB) radio base station and a rooftop
antenna. In another, the "73" signoff code is from the Western Union telegraph standard meaning "Best regards." "88" means
"Love and kisses," hence the guy's unnerved response. The others don't really require
an insider viewpoint. Let me know if you need any more help ;-)...
With more than 1000
custom-built stencils, this has got to be the most comprehensive set of
Visio Stencils
available for RF, analog, and digital system and schematic drawings! Every stencil
symbol has been built to fit proportionally on the included A-, B-, and C-size drawing
page templates (or use your own page if preferred). Components are provided for
system block diagrams, conceptual drawings, schematics, test equipment, racks, and
more. Page templates are provided with a preset scale (changeable) for a good presentation
that can incorporate all provided symbols...
 Collins Radio Company (later on Rockwell Collins
and now Collins Aerospace) has been around since 1933. Like the vast majority of
U.S. companies during the World War II era, they - management and employees - took
great pride in doing their part for the war effort. Unlike today, when a relatively
few people actually know someone on active duty in the armed forces, workers were
very likely to have a brother, son, father, or husband in the service. Here is an
advertisement that I scanned out of my copy of the April 1945 QST
magazine. It mentions that many of the employees are amateur radio operators.
During the war, a call went out for surplus equipment from all sources,
including amateurs, so some sacrificed their personal equipment for the good...
 Major Eugene Skinner (a mere Captain when
the previous two parts were written) wrote many articles about radar and microwave
technology for Radio-Craft magazine. In 1945 he provided a three-part series
entitled "Microwaves." This third part focuses on
antennas and radiators, including waveguides and feedhorns. The discussion is
high level covering the basic operation of basic circuit elements, so it is excellent
fodder for people new to the field - hobbyists, students, technicians, and engineers.
The previous two parts are also available if you want to start at the beginning...
 Sunspot cycles repeat approximately every
11 years, so there had only been six solar maximums from the beginning of long distance
radio communications (Marconi in 1901) up until this article was published in 1957.
That year ('57) had the sun experiencing an extremely high number of sunspots (see
chart below), as had the previous few years, which caused communications to be profoundly
affected during the period. Under ideal conditions, high energy electrons typically
ejected from the sun (coronal mass ejection, CME) cause the Earth's ionosphere to
become an excellent reflector of RF energy at certain wavelengths, resulting in
phenomenal long distance contacts. Under the worst conditions, extreme levels of
"noise" are injected into radio signals, thereby severely degrading or even eliminating
communications. This story reports on a comprehensive study on the effect of such
activity on long distance communications...
 Home entertainment is as big of a deal (or bigger)
today as it was in the 1960's and 1970's when high fidelity personal sound gear was coming
into the mainstream. Capability and features were going up while the price was coming
down on really nice equipment. In order to achieve theater quality sound from your stereo
and/or large screen television, thought and planning is essential or you will end up
with a confusing mess of directed and reflected sounds. This article contains very valuable
information on room configuration and sound absorbing materials and strategies. A fairly
extensive table of common floor, wall, and ceiling sound absorption coefficients is provided,
as are charts of reverberation times of various venues and volumes...
 Centralab (Central
Radio Laboratories, aka CRL) was a major manufacturer of capacitors in the early
days of radio and television, and pioneered many of the ceramic compounds that eventually
replaced paper and mica as dielectrics. In fact, according to this 2-page advertisement
in a 1951 issue of Radio & Television News magazine, their researchers
mixed and tested more than 20,000 ceramic compounds while developing a line of capacitors
that met strict precision, stability, and durability tests. It is reminiscent of
Thomas Edison reportedly having tried a thousand or more filament types for his
incandescent light bulb before arriving on a suitable candidate. Centralab did not
invent ceramic capacitors, but they played an important role in their adoption.
As with many of the early electronics companies, Centralab no longer exists. It
was bought by Philips...
 After reading both this article and "The
Sarasota Mystery First Follow-Up" article in the April 1966 issue of Popular
Electronics, I'm convinced that the inventor Wallace Minto either did not understand
the phenomenon he describes, or he's out to punk the reader. If this initial article
had been printed in the April issue rather than March, it almost certainly would have
to have been a Fool's scam. Minto believes he has discovered a new form of electromagnetic
propagation that exploits molecular / atomic properties of water to transmit the signal
- without attenuation and without picking up noise. If it...
 It is hard to imagine a time when integrated circuit
(IC)
comparators were a big deal, but as recently as 1973 when this article appeared in
Popular Electronics, they were new to a designer's bag of tricks. Prior to an
IC solution, comparators needed to be constructed from opamps and a handful of peripheral
biasing components. As with other integrated circuits, not only does the overall price
go down, but so does circuit board real estate, cost, temperature variability, and electrical
parameter variance between devices. The first comparator circuit I remember designing
was a temperature sensor that went in an oven used for curing the potting...
 If you are a Ham radio operator - especially
a DX (long distance) operator, you have been required to study and learn about how
the various layers of the Earth's ionosphere can, under predictable conditions,
be an excellent reflector of certain radio wavelengths, thereby facilitating
over-the-horizon communications. Reading this article is like a flashback from
the license preparation manuals - particularly for the General license exam. There
is a lot of information here. When this article was published in a 1958 issue of
Radio & TV News magazine, the world was nearing the end of the International
Geophysical Year (IGY), which had as its goal learning as much as possible about
the properties of the upper atmosphere. The first earth-orbiting satellites were
being launched and manned space flight was only months away, so there was much interest
in learning ...
 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)...
 This March 15, 2020,
tech-themed crossword puzzle contains only clues and terms associated with engineering,
science, physical, astronomy, mathematics, chemistry, etc., which I have personally
built 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.
 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...
 The newest release of RF Cafe's spreadsheet
(Excel) based engineering and science calculator is now available -
Espresso Engineering Workbook™. Among other additions, it now has a Butterworth
Bandpass Calculator, and a Highpass Filter Calculator that does not just gain, but
also phase and group delay! Since 2002,
the original Calculator Workbook has been available as a free download.
Continuing the tradition, RF Cafe Espresso Engineering Workbook™ is
also provided at no cost,
compliments of my generous sponsors. The original calculators are included, but
with a vastly expanded and improved user interface. Error-trapped user input cells
help prevent entry of invalid values. An extensive use of Visual Basic for Applications
(VBA) functions now do most of the heavy lifting with calculations, and facilitates
a wide user-selectable choice of units for voltage, frequency, speed, temperature,
power, wavelength, weight, etc. In fact, a full page of units conversion calculators
is included. A particularly handy feature is the ability to specify the the number
of significant digits to display. Drop-down menus are provided for convenience...
 In 1945, when this article was published
in QST, radar was still in its infancy. Engineers were already aware of the need
to shape pulse waveforms from experience with CW keying and the need to mitigate
the effects of "chirping." A perfectly rectangular pulse in the time domain, as
we learned in our signals and systems courses, creates a sin (x)/x response in the
frequency domain. The Fourier transform shows that a perfectly square pulse in the
time domain is the summation of an infinite number of odd harmonics of the fundamental
(1st harmonic). The first few harmonics are audible to the CW copier as higher frequency
"chirps." To reduce the annoyance (and wasted transmitted energy), time constants
were added to the leading and trailing edges of the waveform to remove the higher
frequencies, while leaving the pulse shape sufficiently rectangular to achieve its
goal... |
