In the beginning, man created monophonic
(mono) radios and phonographs that had sound with no
spatial separation (left and right) in the source(s) and featured a single speaker.
As such, except for being sure to not locate your radio or phono behind the sofa,
sound perception at any point the room was fairly consistent - except maybe for
volume level. Still, there was ample opportunity for the time of arrival due
to multipath effects to distort the sound. Up until the 1950s or so, most homes
had hardwood floors (with a few rugs) and rock-hard plaster walls to reflect sound
waves, and rooms were relatively sparsely populated with furniture and wall hangings
(look at photos in vintage magazines for proof), all of which provided means for
distorted sound at a distance. And man said, "Let there be stereophonic (stereo)
sound," which ...
Part 3 of Kenneth Wyatt's "Design PCBs for EMI" series focuses on Partitioning
and Routing. Part 1 covered "How Signals Move" and Part 2 dealt with Basic
Layer Stack-up. "Besides proper layer stack-up, the next most important consideration
when laying out the circuitry on your board is partitioning of circuit functions,
such as digital, analog, power conversion, RF, and things like motor control or
other high-power circuits. Before we get to circuit layout, we must first understand
and visualize how return currents flow and how the electromagnetic fields are distributed
under high-speed circuit traces. At low frequencies - below about 50 kHz -
return currents tend to follow the path of lowest resistance. They tend to travel
along the shortest distance between source and load, as simulated by the green area
in Figure 1 ..."
In the continuing saga of
Carl and Jerry, our two young electronics hobbyists visit a college radio station
where the manager gives a tour while explaining the technical aspects of the equipment.
RF bridges, hybrid junctions, oscillator coils and plate-tank pi-networks, cue amplifiers,
limiter amplifiers, patch board, power supplies, and a lot of other terms that cause
RF Cafe visitors to salivate are woven into the story. Carl and Jerry are surprised
to learn that the transmitter output power is high enough that dormitory residents
can pick up the signal with "only a pair of earphones clipped across a 1N34 diode"
as well as with a standard AM radio. In fact, that's the whole point of the story
because the broadcast is not over the air, but via the campus' AC electrical system
- hence, "wired wireless." ...
Advanced Test Equipment Rentals (ATEC) is
looking for multiple
Calibration Technicians who will apply knowledge of measurement science, mathematics,
physics, and electronics to troubleshoot and calibrate inspection, measurement,
environmental and a wide variety of equipment such as AC/DC, RF Frequency, EMC,
RF/Microwave, ESD Guns, Temperature Chambers, Power Supplies, Transit Generators,
High Voltage, Flow, Pressure, etc. ...
"Softbank's HAPSMobile this week announced
it's investing $125M in Alphabet's Loon business, as the two companies form a long-term
strategy partnership to advance high-altitude connectivity. Both companies are exploring
ways to deliver internet services to remote areas using high altitude vehicles.
HAPSMobile, which includes the acronym for
high-altitude platform station (HAPS), began
in 2017 as a joint venture between Softbank and Aerovironment, a U.S.-based aerospace
company. The venture has developed a solar-powered drone, called Hawk 30, which
travels up to 20 km above Earth's surface for stratospheric telecommunications delivery ..."
Transient Specialists specializes in
equipment rentals and carries a complete line of ESD guns, surge immunity test
equipment, and EFT generators. Rentals available for military (Mil-Std 461), automotive
(ISO 7637), and commercial (IEC 61000-4) EMC testing. Flexible terms, accredited
calibrations and technical support on EMC testing equipment offered. Equipment consists
of top EMC Test System manufacturers, including Teseq, Thermo Keytek, EM Test and
EMC Partner ...
Last Fall I posted part 2 of this
Radio-Electronics article first because I did not yet have the May issue that
contained part 1. So, if you read "JFET's - Put Last Month's Theory to Work"
and have been waiting with bated breath for part 1, you may breathe easily
again; here it is. Author Thomas Haskett enthusiastically introduces readers to
junction field effect transistors (JFET) as a more natural replacement
than the bipolar junction transistor BJT) for vacuum tubes because of JFET (and
other varieties of the FET) operational parameters being much more those of tubes
than a BJT. Regarding his conversion, Haskett refers to himself as a "die-hard 'fire-bottle'"
man - a term with which I am not familiar. My assumption is that "fire-bottle" is
a slang name for vacuum tubes because of how hot they get, and they glow orange
like a fire in a glass bottle ...
When I first saw this line drawing in
High Frequency Electronics magazine' article entitled, "Delivering the World's First Digital Radar on Chip," my first
thought of was an
Escher drawing like Relativity. Per the authors, "Uhnder, a
stealth startup company based in Austin, Texas, has developed the world's first
automotive digital radar on chip (RoC). The company, co-founded by Manju Hegde and
Curtis Davis in 2015, has been working furiously to transform the automotive industry
by delivering a new generation of radar chips capable of achieving unprecedented
levels of performance in the new mmWave automotive radar band of 76 GHz to
81 GHz. Sensors based on Uhnder's digitally coded modulation (DCM) technology
easily exceed current requirements for Advanced Driver Assistance Systems ..."
At the end of the last century (the 20th),
aside from the impending total collapse of the world's electrical infrastructure
due to Y2K computer date issues, technovisionaries (a word I just made up) predicted
the near-term demise of local over-the-air (OTA) broadcasting of both commercial
radio and television. Cable and satellite was going to supplant it all. For a short
while things seemed to be going that way, particularly as both forms of media (radio
and TV) began being available via smartphones. The FCC (Federal Communications Commission)
was so sure OTA television was dead that it wanted to reallocate unused spectrum
(white space) for other uses. It also mandated a conversion of all TV broadcasting
to be done in digital form. The plan forced either trashing of existing television
sets and purchase of new models or the purchase of analog-to-digital conversion
boxes. The compliant public folded like a cheap suit ...
QuinStar Technology, a California-based microwave
and millimeter-wave engineering company, is exhibiting June 4 - 6 at the International
Microwave Symposium. The IMS will convene at the Boston Convention and Exhibition
Center. We'll unveil some new products and prototypes. In addition, QuinStar is
offering the opportunity to schedule a one-on-one appointment with our Product Sales
Specialist. We understand that the requirements change rapidly in the emerging technologies
that rely on millimeter-wave components. To that end, QuinStar is continually working
to meet your requirements. To discuss your project and requirements or just learn
firsthand what's new at QuinStar ...
"Japanese scientists have developed a technique
to transform a
copper-based substance into a material that mimics
properties of precious and pricey metals, such as gold and silver. The new medium,
made of copper nanoparticles (very small copper-based structures) has promising
applications in the production of electronic devices that would otherwise depend
on expensive gold and silver counterparts. It is also suitable in the fabrication
of electronic components using printing technologies that are recognized as environmentally
friendly production methods. The study was published ..."
Microwave is a leader in technically differentiated electronic and radio frequency
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. Please visit Nova Microwave today ...
Even though this article was written more
than 50 years ago, the fundamentals of
protecting relays against interference from either internally generated or externally
generated noise haven't changed. Sometimes a datasheet will recommend protection
and noise suppression techniques, and when that is that case, the manufacturer's
advice should be followed (unless you have a really good reason to deviate, possibly
voiding a warranty). When you find yourself on your own with the design, whether
a new creation or modifying an existing circuit, use this article and the very comprehensive
table of application examples ...
In March of 1958 when this article appeared
in Popular Electronics, learning of semiconductor devices other than
transistors was usually new to experienced professionals as
well as to hobbyists. Vacuum tubes still dominated electronic products in the day.
Companies like General Electric, Sylvania, and RCA were the pioneers for development
of Zener diodes, photodiodes, SCRs, thyristors, etc. Relatively simple compounds
like selenium, germanium, silicon, and lead and cadmium sulphides were used. The
exotic witch's brew of elements in modern semiconductors - particularly those used
to photovoltaics - were likely not even envisioned in 1958. This article discusses
some of "new" devices using simple compounds ...
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 ...
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 ...
"What's needed for us to move towards the
future of drones? According to experts, the next step must be towards ensuring that
future drones are connected via cellular networks and there is collaboration between
the aviation and telecom industries in order to secure public trust in drones. The
Global Unmanned Traffic Management Association (GUTMA) on
Connected Skies, a major conference on drones
and UTM, aims to work on this prospect, and for the first time ever will bring the
aviation and telecoms industry together under one roof. The event will consider
key technical concepts, aerial LTE coverage, 5G in aviation deployment road mapping
and much more. GSMA, the trade body ..."
PCB Directory is the largest directory
of Printed Circuit Board (PCB) Manufacturers, Assembly houses, and Design Services
on the Internet. We have listed the leading printed circuit board manufacturers
around the world and made them searchable by their capabilities - Number of laminates
used, Board thicknesses supported, Number of layers supported, Types of substrates
(e.g., material, flexible, rigid), Geographical location, and more ...
Anatech Electronics, an RF and microwave filter
company, has introduced a new line of suspended stripline and waveguide type RF
filters. Also, Sam Benzacar wrote as part of his April newsletter an article entitled
Brings EM Radiation Front and Center," which discusses the physiological implications
of cellphone and WiFi radiation on humans. As with so many things, politics and
money (intimately entwined) drive the issue with little concern for the truth. On
a lighter note, the topics of FCC spectrum auctions, Google Fiber disappearance
in some locations, and rural broadband delivery schemes are covered ...
Mrs. Helen McKee knew exactly what she was
signing up for when she agreed to marry Mr. McKee. After all, she met and got familiar
with the guy over the air during some rag chewing sessions. This story is a humorous
(and true) account of what life can be like for the
spouses of enthusiastic
Ham radio operators. We all hope for such an understanding 'significant other.'
Melanie has certainly endured and supported a lot of my pastime endeavors over the
past 32 years. It's a short read, so take a break and put a smile on your face ...
Windfreak Technologies designs, manufactures,
tests and sells high value USB powered and controlled radio frequency products such
as RF signal generators, RF synthesizers, RF power detectors, mixers, up / downconverters.
Since the conception of WFT, we have introduced products that have been purchased
by a wide range of customers, from hobbyists to education facilities to government
agencies. Worldwide customers include Europe, Australia, and Asia. Please contact
Windfreak today to learn how they might help you with your current project
Dan Birch has a useful article on the
High Frequency Electronics website entitled, "Understanding Low Loss Coaxial Cables and Their Applications."
It is a concise intro to the cables we typically use for distributing RF signals
including impedance, shielding, dielectric types, loss, etc. "Coaxial assemblies
form the wired backbone necessary to accomplish wireless systems. They are therefore
utilized in a broad range of environments and circumstances. The military-style
RG coaxial cables have been the go-to standard when first understanding what cables
to leverage in a particular installation. However, there are times where these cables
will not suffice and a low loss alternative is necessary. This article attempts
to cover the general construction of a low loss cable. Thanks to Joe B. for the
"A novel PIN diode concept is said to achieve
10 to 50 times better isolation than a typical PIN diode. The RF PIN diode as we
know it today was invented by J. Nishizawa in 1950. Now, almost 70 years later,
a new PIN diode concept -
shielded-anode PIN diode (SAPIN) - has emerged.
This new PIN diode offers 10 to 50 times better 'OFF' isolation thanks to the introduction
of a simple electrostatic shield. An 'OFF' isolation greater than 40 dB at 2 GHz
and 0 Vdc is achieved from a single series device. The theory of operation will
be presented here along with measurements on fabricated silicon (Si) SAPIN didoes.
A PIN diode is built with a wide undoped intrinsic ..."
Empower RF Systems is a global leader in
power amplifier solutions. Empower RF Systems is an established and technologically
superior supplier of high power solid state RF & microwave amplifiers. Our offerings
include modules, intelligent rack-mount amplifiers, and multi-function RF Power
Amplifier solutions to 6 GHz in broadband and band specific designs. Output
power combinations range from tens of watts to multi-kilowatts. Unprecedented size,
weight and power reduction of our amplifiers is superior to anything in the market
at similar frequencies and power levels
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 ...
In another installment in their "Algorithms
to Antenna" series in Microwaves & RF magazine, Rick Gentile
and Honglei Chen discuss micro-Doppler effects. "Micro-Doppler effects are a result of motion
with respect to platform motion. This post investigates these effects, using pedestrian
identification and helicopter-blade-speed estimation as examples. We have described
radar modeling in past blogs. Now, we want to dig a little deeper in terms of modeling
objects and targets that a radar may see in its field of view. The most common technique
is to define targets using radar cross-section (RCS) profiles that may vary with
aspect angle ...
John Booher, of TotalTemp Technologies, has
published a new Blog topic titled, "Cascade Temperature Algorithm Demonstrates Thermal
Testing Goals Reached Faster with the Potential of Differential." Per John's
post: "Having a specific requirement to test a product to a given temperature profile,
how does one show that the actual temperature requirements are being achieved? Many
times, there are parts of a device to be tested that have different heat capacities
and also possible active load heat sources. A single point temperature control algorithm
can have trouble effectively dealing with these variables. Additionally, while it
may be tempting to say that a temperature setpoint has been achieved ..."
This article from the May 1967 edition of
Electronics World shows you just how long the
Frequency Electronics company has been around! In fact, here is an excerpt from
their website: "Frequency Electronics, Inc. was founded in 1962 and is now a well-established
public company in Long Island, New York, and trades on the NASDAQ Stock Exchange
under the symbol FEIM." Mr. Irwin Math, the project engineer at Frequency electronics
who wrote the article, has surely retired by now. The discussion on short- and long-term
stability is as relevant today as it was 45 years ago. Interestingly, the term "phase
noise" is nowhere to be found. Neither is "digital," which might explain the absence
of the former ...
"A CubeSat containing the first commercial
microwave radiometer and
3D-printed antenna for space has launched from the US. Dubbed
IOD-1 GEMS, the miniaturised weather observing and forecasting technology is the
first of the Satellite Applications Catapult's In-Orbit Demonstration (IOD) Programme,
which is funded by Innovate UK. It is also the first satellite in Orbital Micro
Systems' (OMS) Global Environmental Monitoring System (GEMS) constellation. 'Through
the support and collaboration with Satellite Applications Catapult and other IOD
team members, OMS is now positioned to be a market leader in gathering and delivering
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.
Sam Benzacar's monthly newsletters address contemporary wireless subjects. Please
visit Anatech today to see how they can help your project succeed ...
Since 2000, I have been creating custom
science and technology-themed crossword puzzles for the brain-exercising benefit
and pleasure of RF Cafe visitors who are fellow cruciverbalists. The jury is out
on whether or not this type of mental challenge helps keep your gray matter from
atrophying in old age, but it certainly helps maintain your vocabulary and cognitive
skills at all ages. A database of thousands of words has been built up over the
years and contains only clues and terms associated with engineering, science, physical,
astronomy, mathematics, chemistry, etc. 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 ...