These archive pages are provided in order to make it easier for you to find items
that you remember seeing on the RF Cafe homepage. Of course probably the easiest
way to find anything on the website is to use the "Search
RF Cafe" box at the top of every page.
About RF Cafe.
Oscilloscopes
are usually the first instrument of choice when scouring for agile or unknown analog
or digital signals. Modern oscilloscopes offer impressive functionality, but operating
these scopes can be a challenge. As a welcome contrast, the new R&S RTE digital
oscilloscopes from Rohde & Schwarz
provide generous measurement capabilities, minus the operating complexity. With
each sporting a common-sense operating scheme, efficient internal circuit architecture,
and flexible, high-resolution touchscreen...
Have you ever heard
of a "swinging choke?" I surely hadn't, so my probability of getting
Inductance Quiz question number 5 correct was 50% at best. I guessed
wrong - just my luck. As a result my score was 8/9 = 89%. Oh, the shame. Maybe you
will have a better time of it. Be careful with Q6 as well. Otherwise, if you understand
the fundamentals of inductor circuit analysis, you will have no problem.
Rentals May 2014 Newsletter
"Need It? Rent It!" That is what was embroidered
on the baseball cap my rental store owner father-in-law used to wear. Sometimes
it just just makes sense to avoid the cost of ownership.
Advanced Test Equipment Rentals just issued
their TEC Talk newsletter for May 2014. It includes hot topics in the tech news
world, highlights of new or special function test equipment they have available,
and some electronics industry news.
If you are looking
for a very thorough treatise on
transformers, from AC line frequency up through audio and RF frequencies,
but without a lot of formulas to distract you, then this article by Ken Gilmore
is it. He begins with the fundamentals of a current setting up a magnetic field,
talks about mutual coupling and induction, step-up- and step-down transformers,
autotransformers, iron and laminated core transformers, multi-tap voltage and impedance
matching transformers, and even touches on the mage-size transformers in electrical
distribution system substations. Transformers fundamentally work the same way today
as...
of Activities at IMS2014
AWR Corporation, the innovation leader
in high-frequency EDA software, offers a wide range of activities during IMS2014.
As a platinum sponsor with its parent company National Instruments, AWR will be
demonstrating its newly released V11 NI AWR Design Environment™ in Booth #633 on
June 3-5, 2014, presenting numerous MicroApps presentation, hosting a customer appreciation
event as well as sponsoring other IMS-related offerings.
Pulse modulation
comes in many forms, including pulse position modulation (PPM), pulse
width modulation (PWM), pulse frequency modulation (PFM),
pulse amplitude modulation (PAM), and pulse code modulation (PCM).
In addition to providing a nice introduction to the concept of pulse modulation,
author Herbert Kondo covers the basics of each type and then discusses their application
in various communications systems. The first time I recall encountering
pulse modulation was in the mid-1970s with radio control system
for model airplanes. Pulse position modulation was the scheme used in both AM...
Scale Model Complete
USAF radar tech Elbert
Cook has completed his scale model of the
MPN-13 GCA
(Ground Control Approach) mobile radar system that he worked on. It
has an incredible amount of detail, including the ASR (airport surveillance
radar) and PAR (precision approach radar) antennas, the VHF
and UHF radio antennas, navigation hazard light, and even the gin poles that stabilize
the trailers against wind forces. Elbert's modeling skills are impressive indeed!
Hopefully, this model will someday end up in a USAF museum - maybe at Wright-Patterson
AFB.
Now here is a profound
ode to one of the most noble of technician genres ever to tweak a receiver front
end or to change out a transmitter magnetron -
The Radar Man! Some of you know that I worked on airport surveillance
and precision approach radar in the USAF, so my bias is established. Hmmm... now
that I read the poem more carefully, I realize that it is not complimentary at all.
It must have been one of those jealous TACAN or satellite comms techs that wrote
it!
The
first commercial
color television broadcast occurred in 1954 during the Tournament
of Roses Parade. By the late 1950s, color television sets were becoming popular
in homes, but the price, at around $500, was too prohibitive for most people to
afford. In 2014 dollars that is equal to around $4,200, which would allow you to
hang a 70" Sharp 3D HDTV on the family room wall. This 1957 article reported that
there were only about five major manufacturers (more, actually) making
color TV sets, including RCA, Sylvania, Emerson, Westinghouse, Magnavox, Zenith,
and Philco. Most or all used a common 21" round CRT. Over the years many television
manufactures came and went...
for Their Ongoing Support
RFtronics develops
both turnkey and custom solutions for the RF telecom equipment designers and manufacturers.
Currently, our product line includes high power
couplers, splitters / combiners and
filters
between 1 MHz and 3 GHz. Local, ISO certified manufacturing with a 25
000 sq. ft. facility and more than 20 years experience in the RF/microwave design
and manufacture. This gives us the best of both worlds, the agility of a small company
and the production capabilities of a larger-sized, high-volume manufacture.
Signal
from a Helicopter
"A self-taught signals &
electronics hacker from Helsinki, Finland. Fond of mysteries, codes and ciphers,
and vintage tech. Absorptions
is a blog about my hobbies." That is the tag line for Ms.
Oona Räisänen's website. Thanks to QST's "Eclectic Technology"
column author Steve Ford for bringing this impressive story to the public. Oona's
article tells of her adventure in tracking down the source of a mysterious element
of an audio clip from a video of a news station helicopter following a police chase.
After multiple efforts, the embedded digital signal was decoded and then confirmed
to be accurate by the transmitting equipment manufacturer. It's a quick read, complete
with good graphics, that you'll enjoy.
(please support RF Cafe)
Printed
MIMO Antenna Engineering, by Mohammad Sharawi. Wireless communications has made
a huge leap during the past two decades. The multiple-input-multiple-output
(MIMO) technology was proposed in the 1990's as a viable solution that
can overcome the data rate limit experienced by single-input-single-output
(SISO) systems. This resource is focused on printed MIMO antenna system design.
Printed antennas are widely used in mobile and handheld terminals due to their conformity
with the device, low cost, good integration within the device elements and mechanical
parts, as well as ease of fabrication.
Southern
Fried Transformer
If you like good old fashion
3Ø, high voltage generator and transformer stories with
troubleshooting and analysis, then you won't want to miss this one. Having started
my career as an electrician with tech school and field experience, I am always drawn
to such topics even though I seldom have a chance to tinker with it anymore. The
comments section at the end already has quite a few posts, including responses from
the author. There's usually one obnoxious person who wants to demonstrate superiority
and call names, and there's one here, too. I give Mr. Hardy a lot of credit for
his ability to deal with an aspect of electrical engineering for which he was not
necessarily trained in depth.
Here is a short
tutorial on how to construct a
1/4-wave stub "trap," or filter to attenuate even-order harmonics
from transmission lines, be they antennas or sections of track running on a microwave
substrate. The article appeared in a 1960 edition of Popular Electronics.
"Far better an approximate
answer to the right question, which is often vague, than an exact answer to the
wrong question, which can always be made precise." -
John Wilder Tukey, statistician
and developer of the Fast Fourier Transform (FFT).
New Product Plans for 2014
Werbel Microwave is a designer and manufacturer
of RF and microwave passive components
that operate up to 18 GHz. Products and designs are for the commercial wireless
industry, featuring power dividers & combiners, directional and hybrid couplers,
bias Ts, and resistive dividers. An expansion is planned for business year 2014
that include high power directional couplers, weatherproofed enclosures, and miniature
drop-in packages. Typical turnaround time from concept to manufacture is within
four to six weeks after receipt of order.
John H. of Tucson, AZ!
John
H., of Tucson, AZ, is the April winner! He selected
Microwave and Millimeter-Wave Electronic Packaging, by Rick Sturdivant.
John was not only a purchaser of
RF Stencils for Visio, but he also pointed out an error on on
of the pages, so he was awarded his choice of a book. Two other people had been
notified on May 1 and again on May 3, but neither responded, so they lost the chance.
Graciously provided by Artech
House
Crossword for May 11, 2014
For the sake
of avid cruciverbalists, each week I create a new
crossword puzzle that has a theme related to engineering, mathematics,
chemistry, physics, and other technical words. You will never be asked the name
of a movie star unless he/she was involved in a technical endeavor (e.g., Hedy Lamar). This particular puzzle has lots of
abbreviations and acronyms.
the Crazies Anymore?
Hide me. My predicament
started out as a mere curiosity, but then over time the phenomenon seemed to occur
with greater and greater frequency. I tried to dismiss it as being a "coincidence"
that was only noticeable because I was subconsciously monitoring and listening for
it. After today, however, the time has clearly come to take action. The
disturbing
events are instances where I am reading or writing a particular word or phase
and at the exact same instant I hear that exact word or phrase spoken on the radio.
Now, I have to admit that I spend practically my entire waking life either reading
or writing, while simultaneously listening to a variety of talk and music radio
in the background. Melanie will attest to the alarmingly large number of times I
remark...
Helping Deliver RF Cafe
For over 20 years Z-Comm has employed the
latest in proven technology to achieve low phase noise, wide tuning ranges and higher
operating frequencies in our VCO and PLL modules. Our state-of-art, high speed SMT
manufacturing facility is located in
San
Diego, CA. Our solutions can be tailored to address any VCO or PLL need with the
highest performance available in today's demanding market. Z-Comm can also provide
custom solutions for customers with short deadlines.
Hobbyists
in the technical realm have in many ways contributed mightily to the advancement
of professional scientific knowledge and practice. This is partly because many hobbyists
are also career technologists, but the majority are tinkerers, experimenters and
otherwise participants who come from all walks of life geographically, economically,
professionally, and socially. Just as with university and corporate laboratories,
some of the discoveries are the result of structured, preconceived plans of action
and designs of experiments with certain goals in mind; many, however, are due to
serendipitous events that are recognized by their participants as being significant.
Such is the case of 'TV DX' as related in this story. TV DX is the use of...
for Their Continued Support!
Dow-Key Microwave is the world's largest
manufacturer of electro-mechanical RF switches in coaxial, waveguide, and rack
switching matrix formats. We are 
certified
and committed to providing unparalleled customer service, competitive pricing, on-time
delivery and products that are distinguished by quality and reliability. Dow-Key
offers the largest switch product line in the world with over 10,000 unique configurations.
Magazine Articles
OK, time again for weekly
links to RF and microwave magazine articles. I wish
HFE would make their PDF
format with bookmarks so I could link directly to an article page, but unfortunately
you have to view the online version and thumb through to the page.
•
Millimeter-Wave
Advances
Give
Science a Boost,
J-J DeLisle
• Möbius
Coupling Approach
Drops
SMD DRO Phase
Noise,
A.K. Poddar,
U.L. Rohde
• The
Quirks of Quarks,
R. Stephens
• Measure
an ADC's Offset
and Gain Error,
A. Chakravarty, S. Jain
• Multiband Doherty
Amplifiers for Wireless
Applications (p.30),
A. Grebennikov
• Jitter
and SSN, M. Dunn
• How Trends in Electronics
are Affecting Connectors
(p.22), B. Stanton
The proper care and feeding
of
vinyl records was - and still is - a big topic amongst audiophiles.
As with so many things, phonographs and platters have experienced a resurgence in
popularity in the last decade or so as the world gets nuttier and people crave for
a simpler, saner time - imagined or otherwise. I remember back in the barracks at
Robins AFB, GA, where there was always at least one guy who would have a very extensive
(pronounced "expensive") stereo setup complete with an equipment rack,
reel-to-reel tape player, dual cassette tape deck, super-sensitive AM/FM receiver
with a huge tuning knob on the front, a turntable with a precisely balanced and
weighted tone arm (with a stylus that cost two month's pay for an enlisted
man)...
Microwave for Their Support!
Established in 1987, Pulsar Microwave is a
supplier of high quality RF and microwave
passive components in the frequency range of DC to 85 GHz. Because of our large
library of designs, we are able to provide custom
products with little effort and in most cases with no additional price increase
above the standard catalog item. New products are introduced on an almost monthly
basis, the most recent of which are high power directional couplers and power dividers.
Coming shortly are high power switches and low power resistive power dividers.
A good technician,
knowing what sine-wave signals are simultaneously applied to the horizontal and
vertical inputs of an oscilloscope, can predict what the displayed
Lissajous pattern will be. In this quiz, the same signal is applied
to both amplifiers, but through combinations of impedances that cause differences
in the phase angle and amplitude of the actual AC voltages reaching the inputs.
All resistances and reactances have the same ohmic impedance at the applied frequency,
the gain of both amplifiers is equal, and positive-going voltage deflects the spot
upward, or to the right...
L-Band Planar Array Antennas
API Technologies' Transmit and Receive
L-Band Antenna Arrays
are designed for military and commercial markets and applications including point-to-point
communications, satellite communications, and RF transmitters and receivers. This
low profile, high gain, linearly polarized planar antenna array achieves wider bandwidth
than similar sized antennas. API utilizes an in-house proprietary mix of substrate
materials which allows wider than normal bandwidth for an antenna of this size and
frequency range.
Send a Man to Do a Meter's Job
I love these
kinds of stories. It has the perfect combination of situational humor, irony, and
a very important lesson about relying on subjective measurement versus objective
measurements. If you have a great tale to tell about one of your work or hobby experiences
that no respectable publisher will print, you're welcome to send it to me for consideration
in the RF Cafe "Out of Order" series.
Elementary Induction
While
a bit far-fetched, this
Carl & Jerry saga has the two amateur radio hobbyists cum
detectives applying their knowledge of standing waves and an invention called SNARE
(Signal Net for Actuating Radio-sensitive Explosives, by Irwin Ehlmann) to thwart
an assassination attempt on a visiting foreign dignitary. The choice by author
John T. Frye of a halo antenna on their mobile shortwave
rig was probably no coincidence given the guardian angel role it played in the adventure.
Adds Israel to the Tour
AWR Corporation
has extended its 2013 ADF tour well into 2014. The final venue stops being
added to this tour are located in Israel. Late addition dates and locations
include May 20th in Haifa and May 21st in Tel-Aviv. The agenda details as well as
registration are all online and available
now. AWR Design Forum is a free and open
event where designers of microwave and RF circuits and systems can network, share
useful information and resources pertinent to high-frequency design, and collaborate
on industry issues
in Electronics
"Unprecedented
openings for non-engineers result from industry growth and shortage of skilled men."
Thus goes the subtitle for a magazine article pitching the promises of a
career in electronics technology. It came at a time that predated
throw-away everything rather than attempting to repair stuff. It was before the
term 'personal device' (aka 'throw-away') had been coined. It was before
placards warning "No user serviceable parts inside" were routinely stuck on practically
every item purchasable in a department store. It was a time when people took stuff
apart to see how it works, and were actually able to figure it out because parts
were large enough to see and actually moved, and even printed circuit boards...
Meteor Bursts
Long distance
communications
(DX) thrives on ionized atmosphere. It causes boundary
layers at various altitudes that function as reflecting surfaces and thereby facilitate
the 'bouncing' of radio waves off the sky so that they bend around the curvature
of the Earth. Early sounding rocket experiments verified that indeed ionized layers
of atmosphere did exist as suspected based on theories of aurora activity during
periods that correlated with observed solar flare activity. Intense solar flare
periods are associated with large numbers of sun spots, since coronal mass ejections
(CMEs) are produced which supply enormous amounts of electrons traveling
at high speed earthward. CME matter of course shoots in all...
Please Support RF Cafe
Filter Synthesis
Using Genesys S/Filter (Artech
House) Hardcover, by Randy Rhea. S/Filter includes tools beyond direct
synthesis, including a wide variety of both exact and approximate equivalent network
transforms, methods for selecting the most desirable out of potentially thousands
of synthesized alternatives, and a transform history record that simplifies design
attempts requiring iteration. Very few software programs are based on direct synthesis,
and the additional features of S/Filter make it a uniquely effective tool for filter
design. This resource presents a practical guide to using Genesys software for microwave
and RF filter design and synthesis.
Advice for May 6, 2014
It's time for another
helping of job hunting
and career advice stories. There seems to be no limit to the amount of advice
available by helpful 'experts.' Many of these particular bits of guidance for your
life come from authors on LinkedIn, which typically does have good content. Considering,
however, the quality of helpful suggestions offered by your friends and acquaintances
in the real world, it would be wise to learn a little about the source before potentially
risking your future. With that bit of my own advice in mind...
—
Is Your Present Job Costing
You Your Retirement?
—
Why to Skip the Fancy
Resume Paper
—
Preparing for the Financial
Roller Coaster of
Entrepreneurship
—
Baby Steps That Lead to a
Successful Career Change
—
more...
of Their Long-Time Support
Innovative Power Products has more than 30
years of experience designing and manufacturing
RF passive components. Our couplers,
combiners, resistors, and terminations incorporate
the latest technology
in materials available, which equates to unrivaled product performance. Products
include 90° couplers (30 MHz to 4.2 GHz), directional couplers (20 MHz to 6 GHz),
combiners (20 MHz to 4 GHz), RF resistors and terminations (DC to 8.5 GHz, up to
800 W CW)
Rankings for 2014
Engineering
college rankings for 2014 have been out for a while now, so I'm a bit late reporting
the results. All the ranking entities have their own set of criteria and claim to
be objective, but unless there is a mutually agreed upon standard, let's face it,
they all have a component of subjectivity in the ordering. I'm not going to tackle
the validity of methods used, but instead will present the data. Note, however,
that it is worth doing a quick read through the stated methods since some are based
on institutional research and others rely solely on student surveys. Some rate only
schools whose highest degree offered is a Bachelor's, while others include graduate
and post graduate schools. Being that RF Cafe is viewed by a worldwide audience,
I have included...
for Continued Support!
Since it was established in 1979, Reactel
has become one of the industry leaders in the design and manufacture of RF and Microwave
filters, diplexers, and sub-assemblies. Through a continuous process of
research and development, we have established
a full line of filters of all types. We offer the generally known tubular, LC, cavity,
and waveguide designs, as well as state of the art high performance Suspended Substrate
models. We use the latest in CAD/CAM methods and equipment in all of our design
and manufacturing processes. We feature a modern, well-equipped machine shop...
The Load Line Story
If you are familiar
with Saunder Harris'
After Class stories for Popular Electronics, you know
they were written in the form of a story that describes a mentor mentoring a mentee
(yes, mentee is a real word). "The Load Line Story" presents a quick lesson on how to determine
the operational points of in this case a vacuum tube, but it applies equally well
to a transistor. If you have had a difficult time conceptualizing the usefulness
of I-V curves a load line, then this might be just what you need to get you going.
Sure, all the designers out there do this in their sleep, but remember that every
day there are new people getting into electronics and this is what they are looking
for to help get them on the path to where you are.
Drop-in Hybrid Coupler
Innovative Power Products introduces their Model
IPP-2247, a 150 watt 90 Degree Coupler in a Drop-In package style that operates
from 20 - 1000 MHz. The IPP-2247 will combine two signals up to 150 Watts CW of
total output power. This coupler has a remarkable amplitude balance of ±0.25
dB across the whole band. This design is a 3 port device with an internal Termination
capable of handling 50 watts. Insertion Loss is less than 0.90 dB, VSWR is less
than
Enrico Fermi
"There
are two possible outcomes: if the result confirms the hypothesis, then you have
made a measurement. If the result is contrary to the hypothesis, then you have made
a discovery." Enrico Fermi. Caveat: This quote is widely repeated on the Internet
and in printed material. I could not find an original source, but it sounds good
and he could easily have said it considering his other sourced quotes.
Differential Calculus
This
entry level introduction of
differential calculus as it applies to electronic circuit analysis
appeared way back in a 1932 edition of Radio News. It was written by none
other than Sir Isaac Newton himself (just kidding, of course). Author
J.E. Smith created an extensive series of lessons that began with simple component
and voltage supply descriptions and worked up through algebraic manipulations and
on finally to calculus. I remember not being the best math student in high school
(OK, one of the worst), but once I got an appreciation for the power
of mathematics for analyzing electronics, mechanics...
Puzzle or May 4, 2014
This week's
RF Engineering crossword puzzle, like all my crossword puzzles,
uses only words that I personally placed into a custom dictionary of words relating
to science, mathematics, engineering, chemistry, astronomy, electronics, and other
technical fields, plus you are likely to find a few company and engineering schol
names that your recognize as well. Contact me if you would like to have your company
or school name added to the dictionary terms.
"Are we killing the broadcasting
goose, layer of many golden eggs?"
Dr. Lee de Forest asked in his inaugural address, upon his election
to the presidency of the Institute of Radio Engineers. So went the opening editorial
in a 1930 edition of Radio News magazine. It was directed at the question of whether
excessive, "gratuitous" advertising was going to be so offensive to listeners that
they would turn off the set and go back to their former silent worlds. Remember
that many, if not most, households, and certainly not automobiles, even had radios
at the time. Building an audience was essential to nurturing the new phenomenon
of radio, and to saturate the listeners with commercials would surely doom...
1.0-1.1 GHz Reflective Switch
PMI Model No.
P2T-1G1R1G-25-R-TFF-40W
is a single pole, two throw, hermetically sealed, reflective switch designed to
operate over the 1.0 to 1.1 GHz frequency range. This model is designed to
handle 40 watts average input power and 4 kW peak having a 3usec pulse width
and 1% duty cycle. The switch offers fast switching speeds of 300 nsec maximum,
low insertion loss of 0.4 dB typically and high isolation of 37 dB typically
Class A Radio License
- Funny!
Not very
long ago I mentioned
Jean Shepherd (original asignee of W9QWN and later K2ORS
call signs) as being one of my favorite old-time radio broadcasters
(1960s-1970s). Jean was famous for recounting stories of his own life and
for reporting news of the time in a way that could hold you in rapt attention from
beginning to end. His humor, wit, and command of the English language was acknowledged
by his contemporaries. If you listen to enough of his broadcasts you will notice
the frequent mention of electronics and his experiences as a licensed amateur radio
operator beginning at a tender young age. Just recently I listened to him recount
his first day in high school when a SNAFU in the computer-generated (must
have been a UNIVAC) class schedule mistakenly had him reporting to the girls'
swimming pool...
Allowing Expert Testimony
This
article by Bob Ambrogi, of
IMS Expert Services, reports on the 10th U.S. Circuit Court of Appeals' addressing
the need for a more objective means for testing whether
expert testimony should be allowed
during
litigation. The action was taken as the result of an IP theft case whereby a software
engineer was accused of stealing code from his former company and using it to help
start a new competing company. Precedence is given a lot of weight when courts consider
testimony and in determining the rules of engagement before the bench. I am innately
dubious of simply regarding precedence as settled law because of how often decisions
are overturned on appeal. When precedence is used to sidestep the need to make a
courageous ruling...
My father
used to refer to the "sweet-voiced lady predicting the weather over and over again"
as my girlfriend because I would call the 'WEather-1212' phone number (936-1212)
so often. It really wasn't because I was infatuated with her voice, it's that I
was obsessed with
weather forecasting. Most of my free time as a kid and teenager
was spent building and flying model airplanes and rockets, and at eighteen years
of age I began taking full-size aeroplane flying lessons, so my world revolved around
a zone extending from terra firma up to about 5,000 feet AGL. This collection of
communications news items in a 1940 edition of National Radio News includes the
creation of that very recorded weather forecasting service. Now, I admit to having
a bit more of a problem explaining...