Today in Science History -
That portion of the electromagnetic spectrum
which falls between 1000 megahertz and 100,000 megahertz is referred to as the
region. Before discussing the principles and applications of microwave frequencies,
the meaning of the term microwave as it is used in this module must be established.
On the surface, the definition of a microwave would appear to be simple because,
in electronics, the prefix "micro" normally means a millionth part of a unit. Micro
also means small, which is a relative term, and it is used in that sense in this
module. Microwave is a term loosely applied to identify electromagnetic waves above
1000 megahertz in frequency because of the short physical wavelengths of these frequencies.
Short wavelength energy offers distinct advantages in many applications...
"These eyes in the sky fly above drones
and below satellites. Alphabet's enthusiasm for balloons deflated earlier this year,
when it announced that its high-altitude Internet company, Loon, could not become
commercially viable. But while the stratosphere might not be a great place to put
a cellphone tower, it could be the sweet spot for cameras, argue a host of high-tech
startups. The market for Earth-observation services from satellites is expected
to top US $4B by 2025, as orbiting cameras, radars, and other devices monitor crops,
assess infrastructure, and detect greenhouse gas emissions. Low altitude observations
from drones could be worth.
Balloons in the stratosphere, 20 kilometers above Earth (and 10 km above most
jets), split the difference..."
By adding several shunt resistors in the
meter case, with a switch to select the desired resistor, the ammeter will be capable
of measuring several different maximum current readings or ranges. Most meter movements
in use today have sensitivities of from 5 microamperes to 1 milliampere. Figure
1-22 shows the circuit of meter switched to higher ranges, the shunt an
that uses a meter movement with a sensitivity of 100 microamperes and shunt resistors.
This ammeter has five ranges (100 microamperes; 1, 10, and 100 milliamperes; 1 ampere)
selected by a switch. With the switch in the 100 microampere position, all the current
being measured will go through the meter movement. None of the current will go through
any of the shunt resistors...
As with just about every other type of hobby
anymore, creativity and mechanical aptitude is not much of a necessity if you have
money to spend. There is such a plethora of options available for every conceivable
need to satisfy whatever degree of complexity you want your hobby to entail. The
back third of every edition of the ARRL's QST magazine is loaded with advertisements
offering antennas, radios, towers, test equipment, guy wires, insulators, cables,
connectors, soldering stations, semiconductors, tubes, nuts and bolts. It is a wonderful
world we live in if your desire is to engage in the operational aspect of a hobby
rather than the building and experimenting aspects. It was not always so. Half a
century ago the average hobbyist needed to scrounge for
components that could be "repurposed" for use as needed. Sure, there were many
sources for common components then, but even if they were available, hobbyists either
could not afford them...
RF Cascade Workbook 2018 is the next phase in the evolution
of RF Cafe's long-running series, RF Cascade Workbook. Chances are you
have never used a spreadsheet quite like this (click here for screen capture). 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...
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.
Radio Theme Crossword Puzzle for July 25th has many words and clues related
to RF, microwave, and mm-wave engineering, optics, mathematics, chemistry, physics,
and other technical subjects. As always, this crossword contains no names of politicians,
mountain ranges, exotic foods or plants, movie stars, or anything of the sort unless
it/he/she is related to this puzzle's technology theme (e.g., Reginald Denny or
the Tunguska event in Siberia). The technically inclined cruciverbalists amongst
us will appreciate the effort. Enjoy --- This one is going to take a while!
Navy Electricity and Electronics Training
Series (NEETS). A rectifier is a device that changes alternating current to a form
of direct current. The way in which this is done will be covered later in this training
By connecting a rectifier to a d'Arsonval meter movement, an alternating current
measuring device is created. When ac is converted to pulsating dc, the d'Arsonval
movement will react to the average value of the pulsating dc (which is the average
value of one-half of the sine wave). Another characteristic of using a rectifier
concerns the fact that the d'Arsonval meter movement is capable of indicating current
in only one direction. If the d'Arsonval meter movement were used to indicate alternating
current without a rectifier...
PCBONLINE supplies complex rigid and flex-rigid
boards (PCBs)，and one-stop production with maximum flexibility ranging from
prototype sample to mass production. Rigid-flex, HDI, multilayer, IC-loadboard,
LCP 5G optical module, ceramic, MCPCB. Materials include Rogers, Taconic, Arlon,
Isola, Bergquist, Kapton, Panasonic, and more. After more than 15 years of continuous
efforts, PCBONLINE constantly updates our equipment, improves our technology, and
serves you with the highest quality. Cost and delivery quotations online without
the need for multiple phone call and/or e-mails.
Joseph Ryerson (see 1976 award), of the Griffiss
AFB Air Development Laboratory was thinking in 1958 when this Radio-Electronics
article appeared about a method for exploiting
gravitational waves for communication purposes long before they were finally
detected for the first time in 2015. Even today, however, we are nowhere near being
able to control gravity waves. In fact, an Earth-based system is unlikely to ever
be developed due to the extraordinarily long wavelength of various kinds of gravity
waves with periods measured in minutes, hours, days, hours, weeks, and longer. Space-based
sun-orbiting interferometer satellite pairs (LISA) are in the planning stage to
more accurately measure gravity wave. I wonder if Mr. Ryerson was/is around
to witness the gravitational wave detection? Another major topic was the DIANA Moon
Radar project where the Army Signal Corps offered to send QSL cards...
Wayyyy.... back in 1992, RF Design
magazine (Gray Breed was editor at the time) ran a
Those were the days when most engineers and hobbyists wrote software in either Basic
or Fortran. I happened to use Turbo Pascal, by Borland. At the time, I was working
as an RF engineer for Comsat, in Germantown, Maryland. Having done a lot of frequency
conversion designs in my previous work at General Electric, and even more there
at Comsat, I had already written a crude program to calculate mixer spurious products,
so this challenge gave me the excuse I needed to refine the user interface and add
some creature comfort features like loadable mixer spur files and detection of spectral
inversion if present. Although I did not win the grand prize, I did win the runner-up
prize. The prizes included having the following article published in the November
1992 edition of the magazine, a couple experimenter kits of surface mount inductors
and resistors, a T-shirt, and a couple other items. Of course, the greatest prize
as far was I was concerned was having an article published in a major magazine...
"Researchers at Skoltech of Russia, MIT and
Nanyang Technological University of Singapore have created a neural network that
semiconductor crystals in a controlled fashion to achieve superior properties
for electronics. This enables a new direction of development of next-generation
chips and solar cells by exploiting a controllable deformation that may change the
properties of a material on the fly. Materials at the nanoscale can withstand major
deformation. In what's called the strained state, they can exhibit remarkable optical,
thermal, electronic, and other properties due to a change in interatomic distances..."
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. 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...
Withwave manufactures an extensive line of
metrology quality coaxial test cable assemblies, connectors (wave-, end-, vertical-launch,
board edge, panel mount), calibration kits (SOLT), a
4-port vector network analyzer (VNA) calibrator, between- and in-series connector
adaptors, attenuators, terminations, DC blocks, torque wrenches, test probes &
probe positioner. Special test fixtures for calibration and multicoax cable assemblies.
Frequency ranges from DC through 110 GHz. Please contact Withwave today to
see how they can help your project succeed.
According to this story in a 1945 issue of
Radio News magazine, Raytheon certainly had an ambitious plan with its
"Sky-top" network of microwave relay stations from border to border and coast
to coast. No orbiting satellites existed at the time, so purely terrestrial methods
were necessary. The basic idea was to build facilities at the peaks of the highest
mountains in the U.S. to enable high bandwidth, reliable, high quality broadcasting
of all known forms of services - television, facsimile, aircraft and nautical navigation,
telephone, emergency, et al. The funding and logistical investment would be enormous,
particularly with getting access roads, materials and electricity to all the remote
sites. Automation was to mitigate the difficulties involved in manning stations
fulltime, but there would be the need for periodic maintenance and repair. Plans
included tests for frequencies into K−band (26 GHz), which was really stretching
the limits of technology at a time when a few tens of MHz were challenging for most
"'The current reshoring of manufacturing,
especially in the packaging industry, has benefitted North American companies, and
we think this is going to continue,' says Paul Harencak, Vice President of Business
Development & Technical Services for LPS Industries. Reshoring accelerated during
the pandemic. The closure of whole cities in China disrupted manufacturing, as did
the rise in companies making products in America as inventories dwindled and shipping
slowed. Lesson learned: Made in the USA is the best way to ensure a reliable supply
chain. 'The current reshoring of manufacturing, especially in the packaging industry,
has benefitted North American companies, and we think this is going to continue
both in the short and longer term,' said Paul Harencak, Vice President of Business
Development & Technical Services for LPS Industries. Harencak told PlasticsToday
that through his plastics converting career, the one thing he’s learned about China
is that it's a 'tenuous supplier.' In addition to getting the product made correctly
and dealing with intellectual..."
Module 3 of the Navy Electricity and Electronics
Training Series (NEETS) series of lessons is entitled, "Introduction
to Circuit Protection, Control, and Measurement." Learning objectives include
why in-circuit meters are used, advantages of out-of-circuit meters, the way in
which a compass reacts to a conducting wire including the compass reaction to increasing
and decreasing dc and ac high and low frequencies, how a d'Arsonval meter movement
reacts to DC current, the purpose of a rectifier as used in AC meters, the meaning
of the term "damping" as it applies to meter movements and describe two methods
by which damping is accomplished, the electrical quantity measured by an ammeter...
This interesting - but not surprising - tidbit
appeared on the IEEE website. "A public SDR network triangulates the island as the
source of mystery signals. As anti-government protests spilled onto the streets
in Cuba on July 11, something strange was happening on the airwaves. Amateur radio
operators in the U.S. found that suddenly parts of the popular
40-meter band were being swamped with grating signals. Florida operators reported
the signals were loudest there, enough to make communication with hams in Cuba impossible.
Other operators in South America, Africa, and Europe also reported hearing the signal,
and triangulation software that anyone with a web browser can try placed the source
of the signals as emanating from Cuba..." Coming to a country near you?
acoustical tiles are not exactly the stuff of RF engineering, their properties
and their effects on sound waves are analogous to RF absorbers and their effects
on electromagnetic waves. Reflections that cause multipath reception of signals
that contain the same information but are out of phase and unequal in amplitude
to the primary (direct) path seldom combine to enhance the overall signal-to-noise
ratio, so placing absorbent material in the surrounding environment is necessary
to improve signal quality. This article from a 1959 issue of Popular Electronics
goes through the process of outfitting an area with acoustical tiles and gives some
empirical test data from before and after...