 Wednesday the 21st
 Having worked on S-band and X-band radar
as a maintenance technician for a four-year hitch in the U.S. Air Force, articles
like this one from a 1961 issue of Popular Electronics magazine always
piques my interest. A lot of ground is covered here regarding some history on documented
cases of unintentional
human exposure to microwaves and laboratory experiments on animals exposed to
microwave radiation. Author Ken Gilmore points out the difference between ionizing
radiation from nuclear actions and reaction, and non-ionizing radiation from microwave
generators. In today's political environment, facilities in Ukraine, China (Wuhan
in particular), etc., would need to be secretly paid to do the animal experiments
described herein. Some pretty incredible scenarios are described where radar technicians
would stand in front of radiating antennas to keep themselves warm in cold climates,
and one guy would stick his hand into an antenna horn to check whether the transmitter
was on by noting if his hand got warm (probably causing a wickedly high VSWR on
the output amplifier)...
 From Microwaves & RF magazine:
"This article covers the basics of attenuator ICs, including the various types,
design configurations, and key specifications you'll need to know when specifying
them. The attenuator is a control component, the main function of which is to reduce
the strength of the signal passing through it. This type of component is generally
used to balance signal levels in the signal chain, to extend the dynamic range of
a system; provide impedance matching; and implement various calibration techniques
in the end application design. From the key functional perspective, attenuators
can be classified as fixed attenuators with an unchanging level of attenuation and
variable attenuators with an adjustable level of attenuation. Depending on the form
of attenuation control supported by variable attenuators, they can in turn be further
classified as
voltage variable attenuators (VVAs), featuring analog control, and digital step
attenuators (DSAs) that are controlled digitally..."
 X-ray inspection capability is a vital tool
not just in medicine but in industry. During my tenure with a major cellphone power
amplifier company as an RF Applications Engineer, I relied heavily on x-ray imaging
for many of the teardown reports that I wrote on competitors' products. It included
everything from determining metal layers in integrated circuits to deducing multi-layer
ceramic PCB routing lines and distributed components to just getting a quick look
inside a shielded enclosure without needing to disassemble it. A skilled x-ray technician
can make a huge difference in the quality of information that can be gleaned from
the images since angle, power level, and focusing takes a deft touch. My first experience
with using x-rays for inspection was while doing automated test system design for
production base station equipment companies. Very stringent PIM (passive intermodulation)
specifications were required for high power filters in order to minimize 3rd and
higher level intermods. The N-type connectors ended up being the Achilles' heel
of the switching filter matrix, and we had ordered a large quantity from one highly
qualified manufacturer...
 Printed circuit boards (PCBs) can have a
major impact on electrical systems so the materials used when creating them should
be carefully considered. San Francisco Circuits has put together a "PCB
Material Reference Guide" to assist with making these decisions. Some of the
key PCB characteristics to consider include the dielectric constant, dissipation
factor, thermal conductivity, and coefficient of thermal expansion. Each is explained
in detail along with some commonly available materials by the manufacturer that
can be used when constructing PCBs. A comparison chart is also included so that
readers can then quickly compare the characteristics of each material and determine
what would be best for their PCB’s specific application. This reference guide has
been carefully created by the experts at San Francisco Circuits to help readers
determine the best material to use when constructing PCBs based on their specific
applications...
 Here is a
vacuum tube chart everybody needs. Well, not really, but surely somebody out
there in the RF Cafe audience will find it useful. By "audience" I mean most likely
a hobbyist who is restoring or repairing a vintage tube-type radio, television,
piece of test equipment, etc., and has never even heard of RF Cafe, but finds exactly
what he/she needs as the result of a Google (Bing, Yahoo, whatever) search. If it
seems like you can find information on just about anything you need on the Internet
these days, it is at last partly because of efforts like mine that uses a lot of
personal time and some personal funds to establish and perpetuate the reality. Others
of you contribute in different ways; this is mine. A helpful way to make it worthwhile
is to visit websites of companies that advertise on RF Cafe. A lot of great products
and services are offered, and it doesn't cost you a penny to investigate...
RF Cascade Workbook 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...
 Lotus Communication Systems began in 2009,
setting up CNC machine shop and RF/microwave assembling and testing lab in Middlesex
Country, Massachusetts. Lotus is committed to highest quality and innovative products.
Each RF/microwave module meets
exceedingly high standards of quality, performance and excellent value, and are
100% MADE IN USA. Lotus' RF/microwave products cover frequency band up to 67 GHz.
Lotus also offers an COTS shield enclosures for RF/microwave prototyping and production.
All products are custom designed. We will find a solution and save your time and
cost. Lotus has multiple 4 axis CNC machines and LPKF circuit plotters.
Tuesday the 20th
 John T. Frye's "Carl & Jerry" technodramas
are always both eventful and instructive in the realm of electronics and physics,
but Mr. Frye really outdoes himself with this "A Low Blow" episode from the
March 1961 issue of Popular Electronics magazine. The gist of the story
is how they boys construct and use an
"infrasonic" microphone to detect low audio frequency sounds. Information provided
by the National Bureau of Standards (NBS, now the National Institute of Standards
and Technology - NIST) served as the basis for designing and implementing a measurement
system that ultimately resulted in a situation which provided the title "A Low Blow."
You might be surprised to learn that low frequency sound waves are subject to atmospheric
properties similar to radio waves, which can produce areal skipping and hopping
phenomena where reception is possible only in certain regions between the source
and the receiver. This is a very interesting read...
 MoneyWatch (CBS) recently published their
survey of
America's 50 most expensive colleges. It included both liberal arts and engineering
schools. I expected the usual suspects like Ivy League and top engineering institutions
like Harvard and Rensselaer Polytechnic Institute
(RPI), respectively, to head the list, but was surprised
to find that neither was included - shocking to say the least. Stanford, at #50,
was at the bottom, costing a mere $74,570 per annum (for "privileged" students who
foot their entire bill). At #23, Cornell runs $76,258. #18 Yale will set you (or
your parents) back $76,645 per year. Calling yourself a Duke (#18) Blue Devil carries
a $77,029/year price tag. Harvey Mudd, always at the top of all sorts of lists,
is #3 at $79,539 per year. Believe it or not, the most expensive college in America
is University of Chicago. Every year you survive without getting shot costs you
a hefty $81,531. There you go.
 If you have never paid much attention to
the state of the art in telescopes, then you might believe they consist of either
the $99 Tasco jobs in Walmart's toy department or the 200" Hale atop Mount Palomar,
with not much in−between. You might also think that objects which emit or reflect
light in the visible spectrum are the only things studied. You might not know that
telescopes have been built to detect frequencies ranging from HF all the way up
into cosmic rays. Newer telescopes search for gravity waves and even neutrino and
"dark matter" pseudo particles. You might not know that there is a broad selection
of optical telescopes for amateur and research grade telescopes and that the line
between amateur and research grade telescopes grows less distinct every year. Even
radio telescope equipment is beginning to hit the market. This article gives a nice
intro to the subject of radio telescopy; the basics haven't changed...
 It has been my belief for a long time that
the vast majority of
print magazine advertisements are never seen by potential customers because
very few of those potential customers ever bother to pick up a print magazine. More
than a decade ago (around 2007) when I was spending my last days working in a corporate
environment, I do not ever recall seeing anyone reading a trade magazine, be it
Microwave Journal, Microwaves & RF, Electronic
Design, EE|Times, or any of the others. In fact, most of the magazines
I saw were deposited in the mail room recycle or trash bin before they ever made
it to an engineer's, technician's, or manager's desk. That is not to say or imply
the magazines are not excellent - they are, indeed - but even back then most people
were getting their needed information online. Being able to show a print version
circulation number to advertisers does not in any way correlate directly to the
number of potential customers who will ever see their advertisements...
 Clutch head screws were one of the original
"security" or "tamper-proof" type fasteners.
United Screw and Bolt Corporation undoubtedly hoped their patented design would
become the new standard in screw heads and drivers. Clutch head screws are still
available today, but many do not include the round shape in the middle of the "bowtie"
shape. Fortunately for Mr. Henry Phillips, his eponymous screw head design, first
introduced a decade earlier than when this advertisement appeared in Radio News
magazine, won out in the battle to replace the straight slot screw type. Any kind
of screw head that captures the driver to prevent it from slipping off the head
and stabbing into and/or scratching the work piece is a welcome improvement...
 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 Cafe. Thanks...
 Since 1996, ISOTEC has designed, developed
and manufactured an extensive line of RF/microwave connectors, between-series adapters, RF components
and filters for wireless service providers including non-magnetic connectors for
quantum computing and MRI equipments etc. ISOTEC's product line includes low-PIM
RF connectors components such as power dividers and directional couplers. Off-the-shelf
and customized products up to 40 GHz and our low-PIM products can meet -160 dBc
with 2 tones and 20 W test. Quick prototyping, advanced in-house testing and
high-performance. Designs that are cost effective practical and repeatable.
Monday the 19th
 Mica capacitors of the leaded, dipped type
were used quite a bit in the military electronics assemblies I used to build in
the early and middle 1980's while working at Westinghouse Electric Corporation's
Oceanic Division in Annapolis, Maryland. They had the characteristic medium brown
color and were shiny. According to Arco Electronics author E. M. Rothenstein, mica
is one of a very few natural materials directly adaptable for use as a capacitor
dielectric. "Mica, being a natural mineral and adapted to use without physical or
chemical alteration, is completely inert both dimensionally and electrically. As
a dielectric, it will not exhibit aging or deterioration nor subtle variants in
electrical properties." In 1965 when this article appeared in Electronics World
magazine, mica capacitor tolerances were in the realm of ±0.25%, which is amazingly
good, and were useable over the full -55 to +150°C MIL-SPEC range. Values from 1 pF
through 1 μF were available. Most likely modern processes have found a way
to improve on the natural characteristics. In fact, this 2022 Cornell-Dubilier datasheet
for their line of surface mount mica capacitors suggests (IMHO) they are the world's
most perfect capacitor...
 "Atomically thin materials such as graphene
have drawn attention for how electrons can race in them at exceptionally quick speeds,
leading to visions of advanced new electronics. Now scientists find that similar
behavior can exist within two-dimensional sheets, known as domain walls, that are
embedded within unusual crystalline materials. Moreover, unlike other atomically
thin sheets, domain walls can easily be created, moved, and destroyed, which may
lead the way for novel circuits that can instantly transform or be
repaired on command. In the
new study, researchers investigated crystalline lithium niobate ferroelectric film
just 500 nanometers thick. Electric charges within materials separate into positive
and negative poles, and ferroelectrics are materials in which these electric dipoles
are generally oriented in the same direction. The electric dipoles in ferroelectrics
are clustered in regions known as domains. These are separated by two-dimensional
layers..."
 What better way is there to resuscitate
a challenging work day than to kick back and enjoy these
electronics-themed comics from a vintage edition of Radio & Television
News magazine? Seeing a comic panel in any modern technical magazine these
days is rare, if for no other reason than a fear amongst publishers (and their lawyers)
that somebody, somewhere might be offended. You have my invitation to create a good-humored
cartoon about me or RF Cafe anytime you wish, and I promise not to sue you. I'll
even post it here on the website if you like. BTW, these comics make great fodder
for the front page of your technical presentations - a good way to soften the edge
going into a meeting, especially if you are not good at delivering jokes...
 This rather extensive article from a 1947
issue of QST magazine describes the method used by author Philip Erhorn
to experimentally (i.e. empirically) determine
optimum spacing for the parasitic elements of his antenna. Unless you have electromagnetic
field simulation software available for designing antennas, the procedure typically
involves beginning with published formulas for element length and spacing, then
resorting to a cut-and-test method of finding a combination that works best for
your installation and goals. Almost certainly no two Hams end up with identical
configurations because differences in terrain, physical obstacles, antenna height,
soil conductivity, test methods and available equipment, and ability to interpret
results affect outcomes. Even with software like "EZNEC" (free as of January 2022)
and more sophisticated professional programs like NI/AWR's "Analyst" and Keysight
Technologies' "Momentum," significant variations can occur one an antenna is deployed
in an operational environment...
 It was a lot of work, but I finally finished
a version of the "RF & Electronics Schematic & Block Diagram Symbols" that
works well with Microsoft Office™ programs Word™, Excel™, and Power Point™.
This is an equivalent of the extensive set of amplifier, mixer, filter, switch,
connector, waveguide, digital, analog, antenna, and other commonly used symbols
for system block diagrams and schematics created for Visio™. Each of the 1,000 or
so symbols was exported individually from Visio in the EMF file format, then imported
into Word on a Drawing Canvas. The EMF format allows an image to be scaled up or
down without becoming pixelated, so all the shapes can be resized in a document
and still look good. The imported symbols can also be UnGrouped into their original
constituent parts for editing. Check them out!
 TotalTemp Technologies has more than 40 years
of combined experience providing thermal platforms.
Thermal Platforms
are available to provide temperatures between −100°C and +200°C for cryogenic cooling,
recirculating circulating coolers, temperature chambers and temperature controllers,
thermal range safety controllers, space simulation chambers, hybrid benchtop chambers,
custom systems and platforms. Manual and automated configurations for laboratory
and production environments. Please contact TotalTemp Technologies today to learn
how they can help your project.
Sunday the 18th
 This September 18th custom made crossword
puzzle has an
Amateur Radio (aka Ham Radio) theme, compliments of RF Cafe. Clues specifically
related to the Ham Radio theme are marked with an asterisk (*). All RF Cafe
crossword puzzles are custom made by me, Kirt Blattenberger, and have only words
and clues related to RF, microwave, and mm-wave engineering, optics, mathematics,
chemistry, physics, and other technical subjects. As always, this crossword puzzle
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!
RF Cascade Workbook 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...
 Innovative Power Products (IPP) has over
35 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 are serviced around the world. Products listed on website
link to detailed mechanical drawings that contain electrical specifications as well
as performance data. Please take a couple minutes to visit their website and see
how IPP can help you today.
Friday the 16th
 My, how times have changed. In 1960 when
this article entitled "Showdown
for the FCC?" appeared in Popular Electronics magazine, the Federal
Communications Commission was being criticized for its failure to properly regulate,
monitor, and police broadcasters who were granted licenses to occupy commercial
airwaves. The FCC faces similar issues today covering a much wider assortment of
spectrum bands, but this particular piece was triggered by a "whistleblower" (a
popular term in today's news) who discovered outcome rigging by the producers of
CBS's "Dotto" television quiz show in 1958. The public, feeling violated by the
Columbia Broadcasting System, used it as a springboard for protesting the FCC's
general lack of ignoring other responsibilities like preventing dishonest and/or
misleading and/or "offensive" advertisement. To demonstrate how far decency standards
have fallen in half a century, one of the products deemed not proper for airing
during family programming time was Preparation H...
 Anatech Electronics offers the industry's
largest portfolio of high-performance standard and customized
RF and microwave filters and filter-related products for military, commercial,
aerospace and defense, and industrial applications up to 40 GHz. Three new
filter models have been introduced - a 2450 MHz cavity bandpass filter with
N-type connectors, an 18 GHz stripline highpass filter with SMA connectors,
and a 6790 MHz waveguide bandstop filter. Custom RF power filter and directional
couplers designs can be designed and produced with required connector types when
a standard cannot be found, or the requirements are such that a custom approach
is necessary...
 Lots of Hams still use this tried-and-true
"Tune
Your Antenna with a String" system for tuning antennas for efficient operation
on a variety of bands. There are plenty of multi-band designs that rely on traps
to reactively isolate portions of the antenna that properly resonate at the desired
frequency, but there is usually a price to be paid in VSWR. Poor VSWR; i.e., higher
mismatch loss, can be overcome with higher transmitter output power, but the real
sacrifice for poor matching is loss of receiving range. The utter simplicity of
using an insulated cord to vary the physical length of the antenna element(s) for
tuning is hard to beat. The scheme presented in the October 1949 issue of Radio &
Television News magazine could be impractical on a setup where access to the antenna
mount is difficult, but my guess is most people can make good use of it...
 "BAE Systems plans to launch its first
multi-sensor satellite cluster into low Earth orbit in 2024 to deliver high-quality
information and intelligence in real-time from space to military customers. Known
as Azalea, the group of satellites will use a range of sensors to collect visual,
radar and radio frequency (RF) data, which will be analyzed by onboard machine learning
on edge processors to deliver the resulting intelligence securely, anywhere in the
world while still in orbit. Following the acquisition of In-Space Missions last
year, BAE Systems is one of a small number of British companies with the capability
to design, build, launch and operate satellites. The expertise brought by In-Space
Missions complements the Company's existing advanced technologies and will become
an integral part of its multi-domain capability..."
 My flight simulator software (MS Flight
Sim 2002) and computer it runs on (HP i7 notebook) are each more powerful than the
software and computer that ran the
Douglas DC-8 pilot training simulator featured in this 1958 article in Popular
Electronics magazine. Two racks of 1000+ vacuum tubes did the figurative
electronic heavy lifting while massive DC motors did the literal physical cockpit
heavy lifting. The computer needed to handle as many as 40 variables at one time,
including 6 differential equations of motion. 100 servomotors, 540 amplifiers and
2,200 gears drove the instrument panel gauges, dials, and movie projector mechanisms.
The instrument panel description conjures images of the inside of a modern office-grade
copying machine with its very dense conglomeration of gears and axels...
/jobs.htm" target="_top">
 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 /jobs.htm"
target="_top">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...
 Since 2003, Bittele Electronics has consistently
provided low-volume, electronic contract manufacturing (ECM) and turnkey PCB assembly
services. It specializes in board level turnkey
PCB assembly
for design engineers needing low volume or prototype multi-layer printed circuit
boards. Free Passive Components: Bittele
Electronics is taking one further step in its commitment of offering the best service
to clients of its PCB assembly business. Bittele is now offering common passive
components to its clients FREE of Charge.
Thursday the 15th
 Things were moving fast in the electronics
development realm in the 1960s. Many relatively new technologies were undergoing
rapid development due to a number of factors - high numbers of engineering and science
students graduating from college, a huge demand by the commercial and consumer sectors
for creature comfort products, the Cold War requirement for advanced weapons systems,
and the advent of increasingly powerful computers for aiding the design process.
Electronics World magazine ran a monthly column entitled "Recent
Developments in Electronics" which reported on those activities. This July 1967
issue included the Early Bird communications satellite for supporting commercial
telephone traffic and international television programming, a portable battlefield
radar system, a radar transponder built with solid state devices rather than vacuum
tubes, and the OSCAR III satellite designed and built by radio amateurs to
enable Hams...
 Radio was a powerful propaganda tool and
strategic communications means toward the end of World War I, and certainly
in the lead-up to and during the course of World War II. Many governments,
including the United States and most European countries,
forbade the broadcasting of signals by anything other than an entity licensed
for commercial and/or military purposes. Amateur radio broadcasts were prohibited,
although at least here in the U.S. possession of a receiver for listening was still
allowed. Some of the regions controlled by Nazis did not even permit receivers -
mainly because the government did not want citizens listening to anything that could
be considered propaganda. Jamming of broadcast signals from "Allied" countries was
routinely practiced by Hitler's and Mussolini's tight-fisted controllers. Many
citizens were imprisoned or executed...
 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.
 With newcomers entering the field of RF
and microwaves all the time, an introduction to and familiarity with
scattering parameters (aka s−parameters) is a continuing issue needing to be
addressed. Fortunately, there are plenty of knowledgeable people ready and willing
to write tutorials for that purpose - in this case Anton Patyuchenko, in Microwaves & RF
magazine. He begins: "Development of RF applications relies heavily on S−parameters
to describe integral structures and constituent RF components at different frequencies
and for different power levels of a signal. Scattering parameters (S−parameters),
which describe the fundamental characteristics of RF networks, come in many flavors,
including small signal, large signal, pulsed, cold, and mixed mode. They quantify
how RF energy propagates through a system and thus contain information about its
fundamental characteristics. Using S−parameters, we can represent even the most
complex RF device as a simple N−port network..."
 Take a break from the workaday doldrums and
enjoy a few vintage
Ham-themed
comics. Artist Phil Glidersleeve (aka "Gil"), W1CJD, created hundreds - if not
thousands - of such comics for QST and other technical magazines during
his multi-decade career. These appeared in the June 1940 issue. Most of these particular
comics accompanied monthly columns and have a theme related to something within
the text. However, I did not feel like processing all the text of those columns
since it is not necessary to enjoy the humor depicted in the comics...
 New Scheme rotates
all Banners in all locations on the page! RF Cafe typically receives 8,000-15,000
website visits each weekday.
RF Cafe is a favorite
of engineers, technicians, hobbyists, and students all over the world. With more
than 12,000 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.
 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.
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