HF Dipole Antennas for Amateur Radio, just released a few
days ago is a collection of 20 HF dipole antenna designs published in QST,
ARRL's membership journal, between 2000 and 2017. It includes innovative antenna
projects for single-band and multiband antennas, as well as antennas for
portable applications. Some of the featured antennas are: "An Easy-to-Make
Three-Band Dipole for ARRL Field Day," "A Field-Portable Multi-Band Rotatable
Dipole Antenna," "A Small, Portable Dipole for Field Use A Portable Twin-Lead
20-Meter Dipole," "The NJQRP Squirt Multiband Antennas," "A Shortened 60 Meter
Dipole That Also Covers 15 Meters," "A Compact Multiband Dipole," "A Folded
Skeleton Sleeve Dipole for 40 and 20 Meters ..."
Short wave radio was a boon to both professional
and amateur radio operators because of its ability to be received over longer distances
using significantly lower transmitter power. The problem was (and still is) that
short wave bands typically suffer from atmospheric ionization effects that vary
depending on time of day, local weather, solar activity, pollution, and other phenomena.
Long wave's advantage was that although it required higher power and longer antennas,
it was (and is) extremely reliable. For other than the most critical applications,
idiosyncrasies of short wave communications were accepted as the price of more convenient
and lower cost operation. Widespread adoption of short wave communications brought
extensive studies and characterization of atmospheric influences in particular frequency
bands. Discovery of distinct 'F' layers (regions) in the ionosphere and their effects
on radio transmission has allowed ...
Whitepapers, pamphlets, books, magazines,
and chapter examples listed here are a small sample of a lot of new items that are
offered for FREE through
TradePub. The publishers make them available to qualifying people as a promotional
campaign for their full line of offerings. Whitepaper topics include careers, manufacturing,
and engineering, while magazine titles include
Microwave Engineering Europe,
Electronic Design, and
Microwave Product Digest. Note: I earn a few pennies (literally)
when you download one of these or the many other pubs available, so please help
Sam Benzacar, of RF and microwave filter
company Anatech Electronics, has written as part of his February newsletter this
piece titled, "'Mysterious'
Cuban U.S. Embassy Weapon: It Wasn't Crickets." Sam keeps abreast of all the
latest news in the wireless world, which is not unexpected given his company's long-time
involvement in helping others make their products play well together in an increasingly
crowded electromagnetic spectrum - both licensed and unlicensed. Beginning in late
2016, news reports told how many U.S. and Canadian embassy staffers and their families
told of hearing strange sounds in their heads and experiencing nausea and headaches.
I read many of them. Of course no conclusive evidence as to the source has ever
been discovered since officials of the western hemisphere's only Communist nation
(Cuba) allows ...
QuinStar Technology designs and manufactures
for communication, scientific, and test applications along with providing microelectronic
assembly, rapid prototyping, and mass customization. Amplifiers, Oscillators, Switches,
Attenuators, Circulators, Isolators, Filters, Waveguide, Antennas, Phase Shifters,
Transceivers, Mixers, Detectors. QuinStar specializes in cryogenic
amplifiers, circulators, and isolators. Please visit QuinStar today to see how they
can help your project ...
Webinar presentations have become a huge part
of ongoing training for engineers and managers - both by attending and conducting
them. Your opportunity for becoming well-known in the industry can be greatly enhanced
with an effective, attention-grabbing production as the star of a webinar (of course
a bad performance can sink you just as easily). Register for your free OnDemand
webcast now titled, "How to Become a Superstar Webinar Presenter." The last thing
you want to hear is that your presenter was dull and people weren't engaged. A bored
audience means low viewing time, low content retention, and, sometimes, total brand
rejection. Don't let that happen to you! In this on-demand webinar, you'll learn
how to find great webinar talent and best practices to make your existing presenters
more engaging and presentations more fun ...
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 the barrier a bit. An engineer I worked with once had the uncanny ability
to comprehend time domain waveforms in the frequency domain, and vice versa, when
viewing an o-scope or spectrum analyzer display. Sure, simple things like sine waves
or square waves can be recognized by most people who have been in the field for
a couple years, but this guy's ability ...
vertical launch 1.85 mm connectors are specially designed for solderless
vertical PCB launch on test & measurement board. These connectors have excellent
electrical transition performance up to 67 GHz as well as reduce installation
time by eliminating soldering. It is the best solution available for easy use in
test & measurement boards, high speed digital test boards. We solve your performance
and cost problems ...
This chapter from the 1949 edition of the
U.S. Navy's Electrician's Mate 3 course (NAVPERS 10548) requires an
important clarification. Current flow in this article is defined as going from negative
to positive, which is
opposite of today's convention. Per the text: "Modern experiments have
shown that a current of electricity is really a flow of electrons, and the direction
of flow is from negative to positive." Beginning sometime in the 1960s, concurrent
with the great amount of research being done in semiconductor electronics, the convention
of positive-to-negative current flow was adopted, defined as the direction of positive
charge carriers (holes). The negative-to-positive convention is defined based on
the direction of negative charge carrier (electron) flow. I personally never understood
the crisis that retaining the electron flow convention would have caused, but higher
authorities decreed it to be done. We have gone from + to − current flow ...
A new application note titled "Network
Synthesis Wizard Automates Interactive Matching-Circuit Design" features the
network synthesis wizard in NI AWR software that automates interactive matching-circuit
design, thus reducing design time. Network synthesis is helpful at the earliest
stages of a design to help determine reasonable performance targets based on device
performance limits, device sizing (decisions on active device periphery), part selection
for discrete packaged transistors and other early design decisions. Available as
a free download now ...
BBTLine offers a unique patented
combiner / splitter design that
allows for more compact devices while maintaining low insertion loss, excellent
return loss and excellent amplitude/phase balance. These are not standard Wilkinson-style
RF splitters. 2-, 4-, and 8-way, broadband 0.5 - 6 GHz, low loss (0.7 dB @ 6 GHz),
excellent amplitude / θ balance (±0.1 dB, ±1°), surface mount & connectorized.
Please visit BBTLine today to see how they can help your project ...
If you want to know what was really going
on at some point in the past, there is usually nothing more reliable than reading
a print story or advertisement from the era. That way you're getting the news "straight
from the horse's mouth," so to speak, rather than being interpreted or filtered
by some unassociated source. This report on "The
Transistor in Industry" was written in 1956 by Mr. Frank Durat, a product
manager at Raytheon, at a time when transistors were first making inroads for replacing
the venerable vacuum tube (valve) which had launched and propelled the electronics
industry since 1908 when Lee de Forest introduced the triode Audion amplifier. Germanium
and silicon were the semiconductor base crystals du jour, and achieving the requisite
purity was a primary concern for advancing the state of the art for higher frequencies,
power handling, and circuit density (for integrated circuits) ...
Guerrilla RF, a leading provider of high performance
MMICs, today introduces GRF2073-W, a new addition to the company's growing list
AEC-Q100 automotive-qualified amplifiers. This ultra-low noise amplifier is
targeted at high-volume applications, with first-stage satellite radio LNAs and
GPS modules being prime examples. It is offered in an industry-standard, ultra-small
2.0 x 2.0 mm DFN-8 package thus sharing a common pin out with other infrastructure-class
devices from Guerrilla RF. "Guerrilla RF is proud to offer this new amplifier for
automotive applications which addresses an industry need for a cost-effective, first-stage
LNA delivering outstanding RF performance with low power ...
You've probably heard the old saying regarding
"getting it into gear," when attempting to motivate a company, person, or group
of people who are stuck in an intractable rut to start moving in a new direction.
A couple years ago I ran across a drawing similar to the one shown here. It was
on a technical venue where whoever used it should have recognized that as shown,
the meshed gears would never move due to a rotation direction conflict (see my arrows).
I posted a screen shot of it here on RF Cafe. The scheme as depicted is antithetical
to the concept of motion. In fact, it is the very epitome of being locked in place
with no hope of moving (other than slop between the cogs). Sadly - and I hate to
even draw attention to it - the image shown appeared in the March 2019 issue of
QST magazine. I know for a fact those guys are way, way
smarter than I am, so how it slipped past the editors is a mystery. BTW, the other
entity eventually corrected its mistake by "unmeshing" the three gears. ...
San Francisco Components (SFC) has updated
printed circuit board (PCB) turnkey assembly capabilities. Full turnkey PCB
assembly through SFC reduces the customer's responsibility to source components
(and the surrounding issues), manage the bill of materials (BOM), inventory, and
logistics associated that can be encountered when working with a PCB assembly partner.
SFC's turnkey and partial turnkey or consigned assembly options are designed to
meet the individual needs of their customers, depending on how much of the assembly
process they want to manage versus outsource. SFC's turnkey PCB specialists can
help guide customers through the benefits of each approach and ultimately deliver
the optimal product and service ...
"Designed for use in closed HF RFID systems,
PragmatIC's PR1101 and PR1102 flexible integrated circuits (FlexICs) are the first products in the company’s ConnectIC family.
Developed using PragmatIC's unique platform of patented technologies, ConnectICs
deliver connectivity solutions at the lowest cost point in the market, claims the
manufacturer, delivering an ultra-thin and flexible solution that can be embedded
into a wide range of substrates, including paper and plastic. The devices reduce
the complexity of inlays by using single layer antennas, delivering a further step
down in cost to brand owners and retailers. These ConnectICs are extremely attractive ..."
KR Electronics designs and manufactures high
quality filters for both the commercial and military markets. KR Electronics' line
of filters includes lowpass,
highpass, bandpass, bandstop and individually synthesized filters for special applications
- both commercial and military. State of the art computer synthesis, analysis and
test methods are used to meet the most challenging specifications. All common connector
types and package form factors are available. Please visit their website today to
see how they might be of assistance ...
Just about everyone who has worked in the
radar field for a long time is familiar with the name of
Dr. Robert M. Page. He was the first to come up with the concept of
monopulse radar, and he invented the familiar Plan Position Indicator (PPI) radar
display and the RF duplexer which allows one antenna to be connected to both the
transmitter and the receiver. Amazingly, I recently received an e-mail from Dr. Page's
son, John Page. An interest in his father's career combined with insight that only
growing up under the loving care of Dr. Page can provide has afforded him some
unique tidbits of information that many (most, per John) historical accountings
omit. Rather than me summarizing his letter, you will want to read it yourself as
presented below. World War II aficionados will particularly appreciate the
information. John pays homage to his father's co-workers ...
VidaRF, a manufacturer of high performance
RF and microwave high performance isolators, circulators, power dividers, couplers,
and other passive components, is proud to introduce the
VDC-05180-XX line of Directional Couplers with SMA connector, operating from
0.5 to 18 GHz. It is available with coupling value of 10 dB, 20 dB
and 30 dB and can handle up to 50 watts of RF power. VidaRF's product
line includes drop-in, coaxial, and waveguide configurations for many items. Custom
designs available ...
I don't know about the rest of the country,
but this Monday morning in Erie, Pennsylvania, is cold and snowy. That means people
going to work had to shovel their driveways, maybe brush snow and ice off their
windows, and brave hazardous conditions on the streets on the way to the office.
Moods are understandably less than jovial and nerves might be shot. For those of
you who identify with this scenario, these
electronics-themed comics from a couple vintage Radio & Television News
magazines might help assuage your anxieties. The same goes for those who are in
Southern California and managed to arrive safely from a commute on the notoriously
unfriendly highways there. As with many of these old comics, you have to be privy
to the mindset of the day to fully appreciate the topic. TV repair was big business
and people were fascinated with the boob tube innovation rapidly consuming the attention
of domestic dwellers ...
"A team of researchers at the University
of Chicago has developed a circuit platform for the exploration of quantum matter
made of strongly interacting
microwave photons. In their paper published in the journal Nature,
the group outlines their platform and how it might be used. As part of the effort
to create a useful quantum computer, scientists have been investigating superconducting
circuits, which are controllable, have long coherence times and have strong interactions
- characteristics required when studying quantum materials with microwave photons.
The researchers note also that photon losses in such circuits ..."
Innovative Power Products (IPP) has over
30 years of experience designing & manufacturing RF & microwave passive
components. Their high power, broadband couplers, combiners, resistors, baluns, terminations and attenuators
are fabricated using the latest materials and design tools available, resulting
in unrivaled product performance. Applications in military, medical, industrial
and commercial markets. Take a couple minutes to visit their website and see how
IPP can help you today ...
Beginning in 2000, I have created hundreds
of custom 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 start like Hedy Lamarr or a geographical
location like Tunguska, Russia, for reasons which, if you don't already know, might
surprise you ...
"A team of researchers from Germany and Argentina
have devised an ultra-thin planar Hall effect (PHE) sensor capable of detecting
faint magnetic fields even when flexed or wrapped around a wire.
In a paper titled “Highly compliant planar Hall effect sensor with sub 200 nT sensitivity”
published in Nature’s npj Flexible Electronics journal, the researchers describe
a very simple fabrication process, whereby asymmetrical Permalloy (Py) Hall crosses
just 20nm thick are patterned on 6µm-thick PET foils before being magnetized through
multiple magnetic field sweeps (between ±3 mT) ..."
"Lasers are widely used in household appliances,
medicine, industry, telecommunications and more. Several years ago, scientists introduced
nanolasers. Their design is similar to that of the conventional
semiconductor lasers based on heterostructures in common use for several decades.
The difference is that the cavities of nanolasers are exceedingly small, on the
order of the wavelength of the light they emit. Since they mostly generate visible
and infrared light, the size is on the order of one millionth of a meter. Nanolasers
have unique properties remarkably different from those of macroscopic lasers. However,
it is almost impossible to determine at what current the output radiation of the
nanolaser becomes coherent ..."
electromagnetic pulse (EMP) emitted by a nuclear weapon exploded
high above the United States could disable the electronic circuits of many devices
vital to military defense and modern living. These could include complicated weapon
systems as well as phones, laptops, credit cards and car computers. Also in trouble
might be home appliances, gas station pumps and bank accounts. Fortunately, military
equipment is designed to be immune to various levels of EMP, and the validity of
its designs - and some civilian designs as well - have been tested and improved
by a 'friendly' EMP generator installed in a recently renovated facility at Sandia
National Laboratories ..."
"Meta surfaces can be designed to steer sound
or electromagnetic waves in arbitrary directions, or act as beam splitters, according
a team from Aalto University in Finland and Duke University North Carolina.
'Existing solutions for controlling reflection of waves have low efficiency or difficult
implementation,' said Aalto researcher Dr Ana Díaz-Rubio. 'We solved both of those
problems. Not only did we figure out a way to design high efficient meta-surfaces,
we can also adapt the design for different functionalities. These meta-surfaces
are a versatile platform for arbitrary control of reflection.' The surfaces have
been dubbed meta-mirrors, and the key to creating them is applying new physics ..."
"Researchers at MIT have developed a
sub-terahertz-radiation receiving system that could help steer
driverless cars when traditional methods fail. Currently, autonomous vehicles traditionally,
use light-based image sensors that often struggle to see through blinding conditions,
such as fog. Sub-terahertz wavelengths, which are between microwave and infrared
radiation on the electromagnetic spectrum, can be detected through fog and dust
clouds with ease, whereas the infrared-based Lidar imaging systems used in autonomous
vehicles struggle. To detect objects, a sub-terahertz imaging system sends an initial
signal through a transmitter; a receiver then measures the absorption and reflection
of the rebounding ..."
"A crash plan to scale up
solar thermal power generation struggles amidst overly-ambitious
timing and market uncertainty. In the final days of 2018 a 100-megawatt solar thermal
generating station capable of running around-the-clock, 365-days-a-year connected
to the Northwest China regional power grid. It was a race against time to commission
the plant in temperatures as low as −20C - and one that plant designer and
builder Beijing Shouhang Resources Saving Co could not afford to lose. 'We must
finish on time. Otherwise we may face a heavy financial problem,' says Chen Han,
Shouhang's director for international markets ..."
"Scientists from the University at Buffalo
in New York are looking into a common but mysterious phenomena -
static electricity. Experts believe that this form of electricity
could be one day utilized to power all sorts of electronic devices, provided we
find out exactly how it works and functions. And a new study may shed some light
on this strange occurrence. Researchers believe that the actual cause of static
electricity is due to small structural changes at the surface of materials. These
changes arise when certain materials come into contact with each other, and friction
occurs. Scientists believe this revelation could help in the design and creation
of longer-lasting, sustainable power sources for many small electronic devices ..."
"An international team of researchers led
out of Macquarie University has demonstrated a new approach for converting ordinary
laser light into genuine
quantum light. Their approach uses nanometer-thick films made
of gallium arsenide, which is a semiconductor material widely used in solar cells.
They sandwich the thin films between two mirrors to manipulate the incoming photons.
The photons interact with electron-hole pairs in the semiconductor, forming new
chimeric particles called polaritons that carry properties from both the photons
and the electron-hole pairs. The polaritons decay after a few picoseconds, and the
photons they release exhibit distinct quantum signatures. The teams' research was
published overnight in the journal Nature Materials. While these quantum signatures
are weak at the moment, the work ..."