A momentous development that changed the
field of radio communications warranted merely a half-page announcement in 1935
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...
RF Cafe's raison d'être is and always has
been to provide useful, quality content for engineers, technicians, engineering
managers, students, and hobbyists. Part of that mission is offering to post applicable
job openings. HR department employees
and/or managers of hiring companies are welcome to submit opportunities for posting
at no charge (of course a gratuity will be graciously accepted). 3rd party recruiters
and temp agencies are not included so as to assure a high quality of listings. Please
read through the easy procedure to benefit from RF Cafe's high quality visitors...
Precision ruggedized VNA cables from ConductRF
offer RF engineers great alternatives to costly OEM cables that are now past their
best days, and now you can reach out to Digi-Key for a quick and easy replacement.
We have standards for applications at 18 GHz, 27 GHz, 40 GHz, 50 GHz &
70 GHz. Our torque resistant connector heads and phase stable constructions
ensure great performance for many tests to come. ConductRF VNA series provides customers
with reliable ruggedized solutions for lab and production vector network analyzer
testing. We Know, Results Count...
"Engineers from the ESA and Sweden's Royal
Institute of Technology (KTH), have designed a novel
'water drop' antenna lens for directing radio wave signals.
In the same way that optical lenses focus light, waveguide lenses serve to direct
electromagnetic radio wave energy in a given direction. This can be used to minimize
energy loss when sending out a radar or a communication signal. Traditional waveguide
lenses have complex electrically-sensitive dielectric material to restrict electromagnetic
signals as desired. But once the top plate of this water drop waveguide lens has
been added on, it comes down purely to its curved shape for directing signals through
it. The inventors of this new lens design, which received an ESA Technical Improvement
award in February 2017, likes to call it..."
Keysight Technologies' Matt Ozalas and Thomas
Winslow will present a free webinar entitled, "Designing
for Stability in High Frequency Circuits," on January 29th at 1:00 pm ET. "High-frequency
circuit designers often struggle with stability. Learn techniques to identify and
solve stability problems in the design phase before they become headaches in the
lab. Classical techniques will be discussed, and a new technique will be introduced
using a bidirectional impedance probe in PathWave Advanced Design System (ADS) called
the 'Winslow Probe.' Techniques to identify and solve stability problems in the
design phase Basic design examples to compare various stability techniques Realistic
examples of a successful high frequency power amplifier design..."
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."
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
This assortment of custom-designed themes
by RF Cafe includes T-Shirts, Mouse Pads, Clocks, Tote Bags, Coffee Mugs and Steins,
Purses, Sweatshirts, and Baseball Caps. Choose from amazingly clever "We Are the World's Matchmakers"
Smith chart design or the "Engineer's Troubleshooting Flow Chart." My "Matchmaker's"
design has been ripped off by other people and used on their products, so please
be sure to purchase only official RF Cafe gear. My markup is only a paltry 50¢ per
item - Cafe Press gets the rest of your purchase price. These would make excellent
gifts for husbands, wives, kids, significant others, and for handing out at company
events or as rewards for excellent service. It's a great way to help support RF
Mr. Mark Misfud, chairman of the
Asia Pacific Electromagnetic Compatibility Symposium
2020 (APEMC 2020) wrote asking to have the event announced. It will be held May
19-22 at the Hilton Hotel, in Sydney, Australia. Per the website, "Modern Society
is increasingly becoming more connected and the technology that is enabling this
to happen is operating in a complex and hostile electromagnetic environment. As
such knowledge and practical experience in EMC design, mitigation and testing is
increasingly in demand. Developing technology such as 5G and autonomous vehicles
present exciting possibilities but also provide challenges to those in the field
due to the dynamic nature of the electromagnetic environment that the technology
operates in. For the uninitiated EMC is black magic but those in the industry know
it is application of common sense principles based on established electromagnetic
theory and implementation of good design..."
"2-D semiconductors could have very useful
applications, particularly as channel materials for low-power transistors. These
materials display very high mobility at extreme thicknesses, which makes them particularly
promising alternatives to silicon in the fabrication of electronics. Despite their
advantages, implementing these materials in transistors has so far proved to be
challenging. In fact,
2-D semiconductors are of a dangling-bond-free nature; thus, it is notoriously
difficult to deposit ultrathin high-κ gate dielectrics (i.e., substances with dielectric
properties or insulators) on the materials via atomic layer deposition (ALD), often
resulting in discontinuous films..."
Mya Rae Nelson has
an excellent article in the current issue of Fine Woodworking magazine
Science Behind Epoxies." I was surprised to read that epoxy has only been around
since the 1940s, so when
I first used it in the early 1970s, it was only a three decade old technology. As
with cellphones, now that we have epoxy, how did we ever get along without it? Ms. Nelson
uses layman terms to describe the molecular makeup of both the epoxy resin and the
hardener, and describes how the bonds between the resin atoms are broken then reestablished
with the insertion of hardener atoms into the matrix. If you attended classes for
and understood the basics of chemistry, that will help with understanding the technical
side of epoxy curing and strength, but even without the nerd knowledge you will
still gain a better understanding of how this indispensible modeler's brew works.
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. Please visit Allied
Test Equipment today to see how they can help your project.
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
Anatech Electronics (AEI) manufactures and supplies
RF and microwave filters
for military and commercial communication systems, providing standard LP, HP, BP,
BS, notch, diplexer, and custom RF filters, and RF products. Standard RF filter
and cable assembly products are published in our website database for ease of procurement.
Custom RF filters designs are used when a standard cannot be found, or the requirements
dictate a custom approach for your military and commercial communications needs.
Sam Benzacar's monthly newsletters address contemporary wireless subjects. Please
visit Anatech today to see how they can help your project succeed.
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...
"Researchers at Imec have demonstrated what
they believe to be the first functional GaAs-based heterojunction bipolar transistor
(HBT) devices on 300 mm Si, and CMOS-compatible GaN-based devices on 200 mm
Si for mm-wave applications, showing
cut off frequencies in the 40/50 GHz region. In wireless communication,
with 5G as the next generation, there is a push towards higher operating frequencies,
moving from the congested sub-6GHz bands towards mm-wave bands (and beyond). The
introduction of these mm-wave bands has a significant impact on the overall 5G network
infrastructure and the mobile devices. For mobile services and Fixed Wireless Access
(FWA), this translates into increasingly complex front-end modules..."
Copper Mountain Technologies (CMT) has produced
a series of videos to help users of its diverse line of vector network analyzers
(VNAs) get the most out of their extensive capabilities. Proprietary features in
both hardware and software supplies VNAs designed by CMT with capabilities far beyond
similar equipment by other companies. This video entitled, "Automatic
Calibration Module Confidence Check," is one of a series of videos that can
be found on the Copper Mountain Technologies website. "How many times have you completed
a series of measurements to find them tainted by a bad cable...
RF Cascade Workbook 2018 is the next phase in the evolution
of RF Cafe's long-running series, RF Cascade Workbook. It is a full-featured
RF system cascade parameter and frequency planner that includes filters and mixers
for a mere $45. Built in MS Excel, using RF Cascade Workbook 2018
is a cinch and the format is entirely customizable. It is significantly easier and
faster than using a multi-thousand dollar simulator when a high level system analysis
is all that is needed. An intro video takes you through the main features...
At VidaRF, the phrase 'Providing Simple
Solutions for Complex Connections' is more than just a slogan – it's a mindset,
a mission, and a driving force behind everything we do. Their pledge is to design
and distribute high performance, cost effective
RF Microwave products
to fit each customer's unique applications. Please visit VidaRF today to see how
their lines of attenuators & terminations, directional couplers, power dividers,
coaxial connectors, and circulator & isolators can be of use to your project.
"When the standard just will not do, VidaRF has the solution for you!"
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
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...
RF Cafe typically receives 8,000-15,000
website visits each weekday and about half that on weekends.
RF Cafe is a favorite of engineers, technicians, hobbyists, and students all
over the world. With more than 7,000 pages in the Google search index,
RF Cafe returns in favorable
positions on many types of key searches, both for text and images. New content
is added on a daily basis, which keeps the major search engines interested enough
to spider it multiple times each day. Items added on the homepage often can be found
in a Google search within a few hours of being posted. I also re-broadcast homepage
items on LinkedIn, Facebook, and Twitter. If you need your company news to be seen,
RF Cafe is the place to be. Banner advertising begins at $175/month...
Nova Microwave is a leader in technically differentiated
electronic and radio frequency Ferrite Circulators and Isolators that connect, protect and control
critical commercial and military wireless telecommunications systems. Our staff
is dedicated to research and development of standard and custom design quality Ferrite
Circulators and Isolators from 380 MHz to 26.5 GHz. Available in single
or multi-junction topographies, the Nova Microwave product line of is specifically
designed for use in varied environmental and temperature extremes.
"In sailing, rock climbing, construction,
and any activity requiring the securing of ropes, certain knots are known to be
stronger than others. Any seasoned sailor knows, for instance, that one type of
knot will secure a sheet to a headsail, while another is better for hitching a boat
to a piling. But what exactly makes
one knot more
stable than another has not been well-understood, until now. MIT mathematicians
and engineers have developed a mathematical model that predicts how stable a knot
is, based on several key properties, including the number of crossings involved
and the direction in which the rope segments twist as the knot is pulled tight.
'These subtle differences between knots critically determine whether a knot is strong
or not,' says Jörn Dunkel, associate professor of mathematics at MIT..."
Sam wrote from his One SDR website to request
I post a note about the resources he is providing on
Software Defined Radios. It is in its start-up
phase and already has many articles introducing the concepts of SDR. Topics include
low noise amplifiers, filters, bias tees, and how to shop for equipment. Says Sam,
"I hope to demystify RF technology and make it more accessible to the growing community
of SDR enthusiasts." The amateur radio community is adopting SDR in a major way
in order to make existence in the crowded electromagnetic environment more successful.
RF Superstore launched in 2017, marking
the return of Murray Pasternack, founder of Pasternack Enterprises, to the RF and
microwave Industry. Pasternack fundamentally changed the way RF components were
sold. Partner Jason Wright manages day-to-day operations, while working closely
with Mr. Pasternack to develop RF Superstore into a world class RF and
supplier. RF coaxial connectors & adapters, coaxial cable & cable assemblies,
surge protectors, attenuators. Items added daily. Free shipping on orders over $99.
We're leading the way again!
If you are a radio guy (or gal) who likes
international sleuthing, mystery, and intrigue, then you will probably want to read
an article entitled, "Decoding
Numbers Stations," from the November 2019 issue of the ARRL's QST magazine.
Author Allison McLellan,
who is interested in communications history but apparently not a Ham herself, writes,
"Scanning through the bands on AM, you stumble upon something odd. It might be the
last few notes of a folk song, a sound clip from an old cartoon, or phrases in a
different language. A voice cuts through the static, methodically calling out, 'Mike,
India, Whiskey, One, Four...' But this isn't a fellow ham announcing their call
sign. These are numbers stations, an eerie subset of radio stations that has intrigued
hams and non-hams alike for decades. Numbers stations are shortwave AM radio stations
that transmit messages via voice or Morse code, believed to be coded in one-time
pad (OTP) cryptography. In OTPs, the message is comprised of strings of numbers..."
I'm guessing most RF Cafe visitors who are
more than 50 years old are familiar with, and even have seen, the
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...
This excerpt from SpaceWeather.com reads
like the plot from an episode of Star Trek: "Earth may have crossed through a fold
in the heliospheric current sheet, described as 'a giant, wavy membrane of electrical
current rippling through the solar system'." It comes from a story on the ARRL news
webpage entitled, "Norway
Experiences Unexpected Ground Current 'Shockwave'." On January 6, "unexpected
electrical currents were detected in the soil of northern Norway starting at around
1930 UTC. 'It seemed to be some kind of shockwave,' said Rob Stammes, who monitors
ground currents at the Polarlightcenter geophysical observatory in Lofoten. 'My
instruments detected a sudden, strong variation in both ground currents and our
local magnetic field. It really was a surprise'..."
The American Radio Relay League (ARRL) includes
a free online sample article from their monthly QST magazine - definitely
a good policy to help sell the publication (and membership in the ARRL). The February
2020 edition offers "An
SWR-Shifting 'T'," written by Mr. Bill Conwell, K2PO. It includes some
useful Smith chart techniques. "Any feed-line mismatch can be brought to a 1:1 SWR
with a single shunt capacitor, provided its value and the location where it bridges
the coaxial center and shield conductors is chosen correctly. This is because there
are two locations at every half-wave along a mismatched feed line where the impedance
is exactly 50 Ω in parallel with a reactive component. By extending or shortening
the coax so that one of these locations is at the transmitter-end of the coax, a
counter-reactive shunt component can be applied using a coaxial T connector..."
Particle Accelerator in a Silicon
"Researchers in the U.S. are designing a
silicon chip that can accelerate electrons to over 94% of the speed of light.
The team at Stanford University and the SLAC particle accelerator, backed by the
Gordon and Betty Moore Foundation set up by one of the founders of Intel, and the
European Union's Horizon 2020 Research and Innovation Programme, used infrared lasers
and a nanoscale silicon channel to build the accelerator. The infrared pulses are
synchrnised to boost the energy of the electrons. Details of the prototype accelerator-on-a-chip
were published in today's issue of Science. The key is the design and fabrication
techniques can be scaled up to deliver particle beams..."
Reactel has become one of the industry leaders in the design and manufacture
of RF and microwave filters,
diplexers, and sub-assemblies. They offer the generally known tubular, LC, cavity,
and waveguide designs, as well as state of the art high performance suspended substrate
models. Through a continuous process of research and development, they have established
a full line of filters of filters of all types - lowpass, highpass, bandpass, bandstop,
diplexer, and more. Established in 1979. Please contact Reactel today to see how
they might help your project.
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