Today in Science History -
Part VI of the
multi-month series of articles
on antenna principles which appeared in Radio-Craft magazine covers directive
arrays with metal-screen reflectors. Metal-screen, wire, and mesh reflectors are
discussed as reflector surfaces for broadside array, the collinear array, and
billboard array collections of dipole elements. An interesting statement by
author Jordan McQuay is, "It is more practical and efficient to use a reflector screen
[as opposed to reflector dipole elements], particularly if there are a large
number of dipoles. Such a non-resonant reflector is easier arid cheaper to
construct, and provides a better broad-band response than a resonant reflector."
I don't know enough about antenna deign to determine whether with modern methods
of simulation and construction, if that still holds...
Reading trade journals is always given as
one of the main ways cited by engineers on career surveys for continuing
education. Engineering whitepapers, pamphlets, books, magazines, and chapter
examples listed here are a small sample of a lot of new items that are offered
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 yourself.
The Design News website
published their list of engineering schools with alumni that earn the
highest salaries. As usual, all the familiar names appear, but with some
shuffling of positions. For a reason I still do not understand - and I'm not
knocking it - Harvey Mudd College leads the pack with an entry level salary of
$90,700 and a mid-career salary and $161,800. Stanford was #2 and MIT #3. For
reasons I do understand, military academies consistently rank highly (USNA #4,
USMMA #10, USCGA #19). Says, the article: "As part of Engineering Week, we're
2020 report from PayScale (2019 report) shows which schools are turning out the
highest paid grads with a bachelor's or graduate degree. Two years ago we posted
the results of PayScale's study that only included grads with bachelor’s
degrees. The difference in the lists is surprising. PayScale defines engineering
schools as those public or private institutions that grant more than 50 percent
of their undergraduate degrees in math, sciences, computer science, engineering,
or engineering technology majors..."
Use of a
load line chart is a fast way of selecting the bias (operating) point and
operational range for nonlinear devices. Notice that I didn't specifically say
for transistors because this particular article deals with load lines for vacuum
tubes. Almost nobody has any need for tube load line charts anymore, but the
skill needed to interpret load lines for transistors is fundamentally the same
as for tubes. Substitute Vce (collector-to-emitter voltage) for Plate Volts and
Ic (collector current) for Plate Milliamperes and you have equivalence.
Popular Electronics magazine ran this "After Class" tutorial series
covering a broad variety of topics for many years. There is a short quiz at the
now, the cousin of the
Capacitor --- the
"In what is claimed to be a world first, physicists have developed a so-called spin
capacitor that could herald new electronics that require less power and generate
less heat. The advance by scientists at Leeds University generates and holds the
spin state of electrons for a number of hours compared to previous efforts that
held the spin state for a fraction of a second. Their results are published in Science
Advances. A conventional capacitor holds energy in the form of electric charge and
the development from Leeds does this also whilst storing the spin state of a group
of electrons. According to the university, this could lead to a storage device measuring
one square inch that could store 100 terabytes of data..."
me start by saying this is NOT the COVID-19 form of coronavirus. It is patent
to a UK research entity. A CNIPA (China
National Intelligence Property Administration) website search does not show any
coronavirus patents - maybe the
of Virology application is still pending. A search on the USPTO website for
(ttl) turns up 75 results. I'm not sure which makes me more uncomfortable - a communist
country's patent office that shows no coronavirus patents or a representative republic
country's patent office that shows scores of them, with 5 having
China (cn) as the assignee country (acn).
MPDevice (MPD) has become a trustworthy
and reliable company in the global RF market as a manufacturer of
passive RF Devices. Included
are attenuators and terminations, coaxial connectors, adapters, and cable assemblies,
DC blocks, surge arrestors, power combiner / dividers, and directional couplers.
The Korean Telecommunication market is now entering into the era of hyperconnected
society. With continuous enhancement in R&D capabilities and quality control,
MPD will continue in an effort to become the No. 1 technologically innovative
company with a focus on the emerging 5G marketplace.
Famous quotation books are full of statements
made by people - many of them "experts" - throughout history which have proven to
be hilariously wrong, and unfortunately some have been tragically wrong. Thomas
Watson, president of IBM, in 1943 famously predicted on digital computers, "I think
there is a world market for maybe five computers." In 1946, 20th Century Fox's Darryl
Zanuck declared, "Television won't be able to hold on to any market it captures
after the first six months. People will soon get tired of staring at a plywood box
every night." Virtually on the eve of the PC revolution (1977), DEC founder Ken
Olsen, "There is no reason anyone would want a computer in their home." British
Prime Minister Neville Chamberlain assured his countrymen regarding Adolph Hitler's
assurance of nonaggression, "I have returned from Germany with peace for our time".
In 1947 when Radio-Craft magazine founder and editor wrote this article
telling of the many in-the-know types who were predicting a
grave future for commercial broadcast radio once television became a common
fixture in households...
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 13,000 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. If you need your company news to be seen, RF Cafe is the place
to be. Advertising begins at $40/month.
When it comes to low loss transmission media,
it's hard to beat waveguide and open wire. Open wire can exhibit less a couple tenths
of a decibel per hundred feet at low frequencies, but it is very susceptible to
perturbations from nearby objects, wind and moisture. Waveguide exhibits a few tenths
of a decibel per 100 feet at very high frequencies, but it is expensive and difficult
to work with. In the middle is coaxial cable, which for a good quality product of
appropriate size, you can get very low attenuation. As with most things, you get
what you pay for in coax cable. I once used really expensive Andrew (now Commscope)
Heliax coax cable on an S-band radar (2.8 GHz) system that had only a little
more than 1 dB/100 ft, which was necessary from a receiver noise figure
requirement rather than for transmitter power efficiency. This article from
QST covers some of the basics of low loss cable...
International Commission on Non-Ionizing Radiation Protection (ICNIRP) has released
new guidelines for the protection of humans exposed to radio frequency electromagnetic
fields. The guidelines cover the upcoming 5G technologies, as well as AM and DAB
radio, WiFi, Bluetooth, and the currently used 3G/4G mobile phones. ICNIRP Chairman,
Dr. Eric van Rongen, said the new electromagnetic field guidelines have taken seven
years to develop and are more appropriate than the 1998 guidelines for the higher
frequencies that will be used for 5G in the future. He added that they know parts
of the community are concerned about the safety of 5G and they hope the updated
guidelines will help put people at ease. The guidelines have been developed after
a thorough review of all relevant scientific literature, scientific workshops..."
Mr. Asem Elshimi has an article entitled
Sense of Antenna Design and Matching Networks" on the EDN website. He introduces
the basics of EM radiation and ideal antenna formats, then discusses acceptable
compromises based on the application. "When it comes to actual antennas in the real
world, much of our knowledge is empirical. We know very broadly theories that explain
how a point charge radiates (Maxwell’s equations), the need for matching (microwave
theory), and how dipole antennas drawn on paper radiate the way they do, but these
laws are nearly useless in solving the real-world problem of antenna design. By
sharing my intuition on how wireless electronics work on a physical level, I hope
to be useful in shaping a broad understanding of antenna design and matching networks
and underscore the value of best practices and hard-earned wisdom..."
(note Fig. 1
drawings appear to be mine)
"EE suspects telephone mast engulfed by
fire in Birmingham was an arson attack as celebrities claim Covid-19 caused by new
network ('ØG' video).
Ofcom has warned broadcasters to refrain from spreading rumors that
5G is linked to coronavirus. Telecoms engineers are facing verbal and physical
threats during the lockdown, as baseless conspiracy theories linking coronavirus
to the rollout of 5G technology spread by celebrities such as Amanda Holden prompt
members of the public to abuse those maintaining vital mobile phone and broadband
networks. Facebook has removed one anti-5G group in which users were being encouraged
to supply footage of them destroying mobile phone equipment, with some contributors..."
Exodus Advanced Communications is a multinational
RF communication equipment and engineering service company serving both commercial
and government entities and their affiliates worldwide. Power amplifiers ranging
from 10 kHz to 51 GHz with various output power levels and noise figure
ranges, we fully support custom designs and manufacturing requirements for both
small and large volume levels. decades of combined experience in the RF field for
numerous applications including military jamming, communications, radar, EMI/EMC
and various commercial projects with all designing and manufacturing of our HPA,
MPA, and LNA products in-house.
Whenever I post any of these Radio Data Sheets
from vintage electronics magazines, I attempt to find photos of actual units. Drawings
are good, but actually seeing a for-real example is the best option. This
Admiral Model 6RT44-7B1 phonograph appears on the Radio Attic's Archive website.
As mentioned previously, electronics service shops relied heavily on these Radio
Data Sheets that were printed in monthly magazines like Radio-Craft, Radio News,
and Radio & Television News. The alternative was purchasing service documentation
from the manufacturer (often only available to factory-authorized shops), from Sam's
Photofacts, or some other third-party supplier. Of course experience and intuitiveness
could substitute for documentation, but as many episodes of John T. Frye's
series of "Mac's Radio Service Shop" illustrates, quirky variations in circuits...
"A new type of graphene amplifier could offer
researchers a unique way to access the electromagnetic spectrum. Engineers from
Loughborough University have designed an optical transistor out of graphene and
a high-temperature superconductor that can
amplify terahertz frequencies, and could unlock a whole new field of potential
technologies. Terahertz waves (THz) have long fascinated scientists, but unfortunately,
their use has been limited by their weak signals. Without an added boost of power,
the wavelengths have been too weak for researchers to harness their potential power
- until now, that is. The amplifier is deceptively simple, made up of two layers
of graphene and the superconductor..."
"There's a tricky question asked at Google
and Amazon interviews that is bound to stump you. However, worry not as YouTuber
Zach Star is here with the solution in this fun video. The question goes like this:
let's say you have a stick that you will randomly cut in three pieces.
What are the odds that the three pieces created can form a triangle? If the
three pieces are about equal in size, you can make a triangle. If, however, you
have two much smaller pieces, you can not. It should also be known that for a triangle
to be made, the two shortest lengths combined need to be bigger than the third.
How does that relate to our question? Well, you have to watch the video for that..."
Z-Communications, Inc., announces a new
RoHS compliant VCO (Voltage-Controlled Oscillator) model
The SMV0912B-LF operates from 865 to 960 MHz within a tuning voltage range
of 0 to 2.5 Vdc. This low cost VCO features very clean spectral purity performance
of -100 dBc/Hz @10 kHz offset and covers the frequency range with an average
sensitivity of 80 MHz/V. The SMV0912B-LF is designed to deliver 3±3 dBm
of output power into a 50 ohms load while operating over the industrial temperature
range of -40 to 85°C. This high performance VCO is further enhanced by saving precious
energy. It consumes a mere 6 mA of current while operating off a 3.0 Vdc
supply. The SMV0912B-LF features a typical 2nd harmonic suppression of -10 dBc...
Question: According to the legend on this
graphic, how many confirmed cases of coronavirus do the gray-colored areas have
(answer below)? Look at this "Countries
with Confirmed Cases of Coronavirus" map used in an MSN.com news story. According
to graphic creator Tara, it was provided by the World Health Organization. This
is an example of why the news media should not be unquestioningly believed when
presenting data. Its reporters are for the most part very scientifically and mathematically
ignorant (and some are plain stupid). They do not know how to assimilate and present
numerical information, while pompously demanding that everyone listen to the scientists.
Answer: Exactly 100. Do you understand why?