|
 Maxwell's inception of the theory of electromagnetic
radiation is compared here to if Christopher Columbus had conceptualized the existence
of America and mapped its features based solely on observations of how the known
oceans and land masses interacted. I have always been amazed at the ability of people
who formulate entirely new theories of science, finance, medicine, etc., and manage
to detail and support their ideas with hard data and mathematics. Einstein did so
with relativity, Dalton did so with atomic structure, Darwin did so with evolution,
Pasteur did so with germ theory; the list is long. There are lots of geniuses out
there, but a relative few change the world...
 "A research team affiliated with UNIST has
introduced a novel, high-performance, and thermally stable polymer-based non-volatile
analog switch. This next-generation device is as
thin and flexible as vinyl, yet capable of withstanding high temperatures. Professor
Myungsoo Kim and his team from the Department of Electrical Engineering at UNIST,
in collaboration with Professor Minju Kim from Dankook University, have developed
this robust, flexible radio-frequency (RF) switch. Such technology could enable
reliable 5G and 6G wireless communication in demanding environments -- such as wearable
devices and the Internet of Things (IoT)..."
 Werbel Microwave began as a consulting firm,
specializing in RF components design, with the ability to rapidly spin low volume
prototypes. Our
WM4PD-0.5-18-S is a wideband 4-way in-line power splitter covering 500 MHz
to 18 GHz with excellent return loss, low insertion loss, and high isolation
performance. The device covers several military radios letter octave bands in one
product, delivering much value to the program. Aluminum enclosure measures 6.25
x 2.98 x 0.50", includes four through-mounting holes, and has durable, stainless
steel SMA female connectors. One device covers the upper UHF band, as well as L,
S, C, X and Ku bands...
 This week's
Wireless Engineering crossword puzzle contains the usual collection
of only 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!
 Providing full solution service is our motto,
not just selling goods. RF &
Connector Technology has persistently pursued a management policy stressing
quality assurance system and technological advancement. From your very first contact,
you will be supported by competent RF specialists; all of them have several years
of field experience in this industry allowing them to suggest a fundamental solution
and troubleshooting approach. Coaxial RF connectors, cable assemblies, antennas,
terminations, attenuators, couplers, dividers, and more. Practically, we put priority
on process inspection at each step of workflow as well as during final inspection
in order to actualize "Zero Defects."
 "Essayons," that's the motto of the U.S.
Army Corps of Engineers. It means "Let us try," in French. In 1968, when this
G.I. Engineers editorial appeared in Electronics World magazine, it
noted that about 38,000 engineers, or roughly roughly 6% of the nation's total,
served in the U.S. Armed Forces, far more technically skilled than in World War
II or Korea. Despite surpluses in bachelor's-degree holders, advanced-degree shortages
persisted, with over 15 thousand master's and PhD positions unfilled - by fewer
than 8,500 qualified personnel, forcing underqualified assignments. Utilization
varied: Air Force effectively deployed 14,000 engineers in R&D and civil roles;
Navy specialist programs covered ship, ordnance, aeronautical, and Civil Engineer
Corps (Seabees)...
 Here is a handy-dandy baker's dozen worth
of "kinks," otherwise known as
tricks, shortcuts, or clever ideas, that could prove useful while
working in the lab at work or in your shop at home. One suggestion is to place a
sheet of tracing paper over your schematic while wiring a circuit and draw each
connection as it is completed, rather than mark up the original drawing. That was
definitely good for a time when making a spare copy of a magazine page or assembly
instruction from a kit was not as simple a matter as it is today...
 "Apple has published a patent application
describing a method to detect user gestures on wireless earbuds by measuring changes
in RF antenna impedance, potentially reducing the need for dedicated touch-sensing
hardware. The filing, titled 'Gesture
Detection Based on Antenna Impedance Measurements,' published on January 8,
2026 as US 20260010234, describes using antennas already present for wireless communication
as dual-purpose components that can also detect user input..."
 This week's
crossword puzzle has the theme of electronics and engineering
magazines and their editors. I have to plead guilty at not knowing who the editor-in-chief
(EiC) of many of the publications were. After so often reading the names of the
many authors and technical editors and contributing editors, etc., getting printed
every month, keeping track is difficult. You should recognize all the magazine names
since they are our industry's primary publications. Apologies to Microwaves &
RF magazine (Nancy K. Friedrich, EiC), and to High Frequency Electronics
(Scott Spencer, EiC), for not including them in the puzzle. The fact is, though,
that the more words I insert at the outset, the more difficult it is...
 Exodus Advanced Communications, is a multinational
RF communication equipment and engineering service company serving both commercial
and government entities and their affiliates worldwide. Exodus'
AMP20097 Pulse Amplifier is designed for Pulse/HIRF, EMC/EMI Mil-Std 461/464,
and radar applications. Providing superb pulse fidelity and up to 100 μsec
pulse widths to 10 kW peak power. Duty cycles to 10% with a minimum gain of
63 dB. Available monitoring parameters for forward and reflected power in watts
and dBm, VSWR, voltage, current, and temperature sensing for outstanding reliability
and ruggedness in a compact 7U chassis...
 If you have been searching for a do-it-yourself
VLF loop antenna that can be resonated from approximately 14 to
25 kHz, then look no more. This article from a 1963 edition of Electronics
World presents a relatively simple to build job that reportedly provides excellent
reception. At these frequencies a wavelength is measured in miles, which makes even
a simple dipole antenna impractical, so the multi-turn loop is the only alternative.
It is the same principle that allows the little ferrite-core antenna inside your
AM radio to work so well when the shortest wavelength in the commercial AM broadcast
band is nearly 600 feet...
 This 1968 Electronics World magazine
article nails the basics of
trade secrets law that still hold today: if you learn your boss's secret info
- like formulas, processes, or customer lists that give them a business edge - you
can't share it with a new job, even by accident, and your new employer can get sued
if they know about it and use it. No signed paper needed; courts protect "real"
secrets (not public stuff or your general skills) with court orders to stop use
or money damages. Good faith matters - act fair, don’t copy files or exact products,
and you have defenses like competing honestly. Big changes now: almost all states
follow uniform rules (UTSA) plus a 2016 federal...
 Here is a batch of
electronics-themed comics that appeared in the July 1948 edition of Radio
News magazine. The comic on page 122 would probably elicit cries of racism
or hate speech these days, even though there is nothing racist about it. Note how
prescient the comic on page 140 was. It shows how long futurists have ben contemplating
the technologies that have become or are becoming common place today - of course
many of them were promised to us by the end of the last century by the like of
Popular Mechanics, Mechanix Illustrated, et al...
 "A new type of circuit board which is almost
entirely biodegradable could help reduce the environmental harms of electronic waste,
its inventors say. Researchers from the University of Glasgow have developed a new
method of printing
zinc-based electronic circuits on environmentally friendly surfaces including
paper and bioplastics. Once the circuits are no longer needed, 99% of their materials
can be disposed of safely through ordinary soil composting or by dissolving in widely
available chemicals like vinegar..."
 If you think government bureaucracies meddling
in the affairs of private business is a relatively new phenomenon, think again.
Elected and unelected persons and agencies have since the inception of control over
the populace made it their business to dictate which pursuits of technology are
sanctioned and which are not. Often, the motivation lies in who within those bureaucracies
stands to benefit monetarily from the decision. In this story lamenting the painfully
and, in the author's opinion, unnecessarily long time experienced in bringing
commercial broadcast television to the marketplace - in 1935.
One of the primary stumbling blocks was the FCC preventing companies from televising
paid commercials during programs because, in the FCC's view, picture quality was
not good enough to serve advertisers' interests. In this story lamenting the painfully...
 Here in one short editorial article, Hugo
Gernsback outlines the application of
shortwaves in "the next war" to maintain wireless surveillance of the airspace
over towns and cities via what is essentially radar, to detonate explosive devices
by means of a powerful "special combination impulse," and long-distance wireless
communications via radios "so small that one man can easily carry it." This might
seem rather moot in today's world, but in 1935 it required a certain amount of knowledge
of wireless communications and a vision regarding its potential. In my readings
of a great many early- to mid-20th-century technical articles on electronics, aeronautics,
physics, etc., it is interesting to notice how authors of the pre-WWII era referred...
 Here is a layman's analysis of the Lorentz
force, a fundamental principle in electromagnetism governing the interaction of
charged particles with electric and magnetic fields. Named after Hendrik Lorentz,
the force law underpins numerous engineering systems from electric motors to particle
accelerators. The document details Lorentz's biography, the discovery context, precise
definition, mathematical derivation, equations, and both historical and contemporary
applications. Hendrik Antoon Lorentz (1853-1928) was a Dutch physicist whose contributions
to theoretical physics...
 In 1938, Bell Telephone Laboratories, Western
Electric Company, United Air Lines, and Boeing worked together to developed the
first practical
microwave radio altimeter for use in commercial aircraft. This
is not a radar unit in that the distance is not determined solely by emitting a
signal and measuring the time taken to the target (the ground in this case) and
back again. Rather, the radio altimeter relies on a heterodyned beat frequency generated
between a reference signal and that of the transmitted and received ground-directed
signal. Author Washburn does a nice job explaining the process, so I needn't add
to it. It is interesting to note the statement about the 500 MHz used being
the "highest frequency ever to be used for practical purposes...
 "A UCLA-led, multi-institution research
team has discovered a metallic material with the
highest thermal conductivity measured among metals, challenging long-standing
assumptions about the limits of heat transport in metallic materials. Published
in Science, the study was led by Yongjie Hu, a professor of mechanical
and aerospace engineering at the UCLA Samueli School of Engineering. The team reported
that metallic theta-phase tantalum nitride conducts heat nearly three times more
efficiently than copper or silver, the best conventional heat-conducting metals..."
 Modulating a light beam for secure communications
was not a new concept is 1939 when Gerald Mosteller invented his device, but doing
so with inexpensive equipment, using "outside-the-box" thinking, was new. Exploiting
the relatively recently discovered physical phenomenon of "skin effect," his system
used a specific range of frequencies to modulate the filament of a standard flashlight
type incandescent light bulb that could effect temperature changes - and therefore
intensity changes - rapidly and of significant amplitude to transmit information
in the audio frequency range. Mr. Mosteller's contraption evolved as the result
of a college thesis project. There does not exist a plethora of modern-day
modulated light communications systems using incandescent bulbs
as the source, so it is safe to assume insurmountable physical and/or financial
obstacles...
 In no way do I advocate going back to the
'old ways' for manufacturing electronic components, but I do admire and like to
give credit to the people who used to perform the tedious procedure of
building vacuum tubes, hand-wire chassis assemblies, circuit boards,
etc. The process required being able to sit or stand at the same work station and
perform the same range of operations day after day, often for years on end. Of course
at the time, automation processes were not what they are today and machinery needed
to be driven by mechanical means using motors, solenoids, and limit switches. That
made employing people more financially rewarding than using a machine. You can find
details on the algorithms and methodology for designing those contraptions in older
engineering handbooks. It is an amazing sight to to tour a WWII vintage battleship
and look at the hardware that...
 I learned (or, "leared," in MN Somali daycare
lingo) a new word today -
ergodic - from a 1968 issue of Electronics World magazine. Ergodicity is a concept
from mathematics and physics describing systems where the time average of a property
equals its average across all possible states (space average). In simpler terms,
a system is ergodic if, over time, it explores all possible states in a way that
reflects the overall statistical distribution of those states. In physics and dynamical
systems: An ergodic system eventually visits all parts of its phase space...
 Once again, electronics and overall tech
visionary Hugo Gernsback, editor at the time of Radio-Craft magazine, prognosticated
in the 1930s what was then a pipe dream but what is today commonplace -
remote control of multi-functioned apparati (sic) via secure wireless digital
communications. Adolph Hitler had risen to power a year earlier and was a precursor
to what would officially become World War II. By 1937, nations were thinking
about what kinds of technologies would be necessary should the little mustachioed
dictator decide to invade his neighbors' countries in an attempt to rule over the
Earth. That this was so is apparent in many magazine articles in the decade of the
1930s: The Saturday Evening Post, Life, Popular Mechanics, and
even Good Housekeeping...
 "An international team of astronomers has
developed a new way to extract
solar polar magnetic information from more than a century of historical observations,
improving prospects for predicting future solar cycle activity. The work combines
data from the Kodaikanal Solar Observatory in India with modern measurements to
reconstruct the behavior of the Sun's polar magnetic field over more than 100 years.
Researchers from Southwest Research Institute, the Aryabhatta Research Institute
of Observational Sciences and the Max Planck Institute used archival Calcium K (Ca
II K) images..."
 The use of
intermediate frequency (IF) coils
and interstage coupling transformers were a major feature of vacuum tube based receivers.
Both served the dual purpose of impedance matching and frequency selectivity. Resistive
losses in the relatively large passive components required careful attention to
matters that affect signal sensitivity, especially in the front end where losses
add significantly to the overall noise figure. This article appeared in an early
1930s edition of Radio-Craft magazine at a time when superheterodyne receivers
were just coming into popularity and were a new challenge for many designers...
|
 • EIB Backs
Europe's 1st Gallium Production Investment
• 2026 a
Pivotal Year for 6G Standardization
• New
60-Meter Frequencies for Hams
• EMC
Test Lab Market Expected to Double in 10 Years
• Sony
to Spin off TV Business
 The
RF Cafe Homepage Archive
is a comprehensive collection of every item appearing daily on this website since
2008 - and many from earlier years. Many thousands of pages of unique content have
been added since then.
 Hugo Gernsback, born in Luxembourg, made his
fame and fortune in America as a serial electronics magazine publisher, science
fiction author, inventor, and visionary. Radio Craft magazine, in which this editorial
was printed, began in 1929 on the heels of Radio News, which began in
1919 and ran through 1959. Hugo Gernsback had a huge influence on the direction
of communications electronics, and his opinions were widely sought. As has been
the case since governments first regulated services and manufacturing, there was
in the middle of the last century a debate over whether electronics servicemen
should be required ...
 Here is a brief but informative introduction
to the story behind French physicist
Andre Marie Ampere's discovery of the eponymously named law that governs the
relationships between current flow and a magnetic field. It appeared in a 1972 issue
of Popular Electronics magazine. As most RF Cafe visitors know, both a
steady state and time-varying current will generate a magnetic field, but only a
time-varying magnetic field can generate a current flow. In less than a week after
witnessing Hans Christian Ørsted's demonstration of a current-carrying wire influencing
a compass needle, Ampere discovered the Right-Hand Rule of current flow direction
based on the direction of the magnetic field...
 Most regular RF Cafe visitors will probably
not be too interested in this 1960 Popular Electronics magazine article,
but there are a lot of people who build and/or repair vintage radio gear and search
the Internet for helpful information. Having built a couple
crystal radio sets as a kid, I've always been amazed at how a few picowatts
of RF energy can be received, processed, and heard through an ear plug without the
need for external power from a battery. Speaking of crystal radios, I remember one
time while working as an electrician in Annapolis, Maryland, (prior to entering
electronics) I had a telephone handset for use in communicating with other electricians
in a building I was wiring, and it picked up the local AM radio station. A pair
of the old style handsets with carbon microphones would, with the help of a single
'D' cell in series, function as a very acceptable intercom system using two standard
electrical wires between them...
 Not many people are still using
analog meters for making voltage, current, resistance, and power measurements
these days; however, for those who are and even for those using digital readout
meters, there are valuable lessons to be learned from this article on factors that
can affect the accuracy of your measurements. Whenever you make a measurement with
any kind of instrument, the first step to take in minimizing the chances of inaccurate
readings is to be certain the instrument is in good working order and is known to
be reasonably accurate. If it is battery powered, know that low battery voltage
can cause erroneous readings in both analog and digital meters, so beware. If you
are making a measurement to verify a known entity and the reading is correct, then
there is little reason to suspect that anything is wrong with your meter. If a reading
is way off from what you expect to see, then verify the accuracy of your instrument
before going any further lest...
 For two decades, I have been creating custom
engineering- and science-themed crossword puzzles for the brain-exercising benefit
and pleasure of RF Cafe visitors who are fellow cruciverbalists. This December 1st
puzzle uses as part of its grid the common schematic symbol for a MOSFET dual gate,
n-channel, depletion mode transistor. A database of thousands of words is used which
I have 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 star like Hedy Lamarr or a geographical location like Tunguska,
Russia, for reasons which, if you don't already know, might surprise you...
 For the sake of all the avid cruciverbalists
amongst us, each week I create a new
technology-themed crossword puzzle using only words from my custom-created
list related to engineering, science, mathematics, chemistry, physics, astronomy,
etc. At least 10 clues with an asterisk (*) in this technology-themed
crossword puzzle are pulled from the past week's (7/30 - 8/3) "Tech Industry Headlines"
column on the RF Cafe homepage. You will never find among the words names of politicians,
mountain ranges, exotic foods or plants, movie stars, or anything of the sort. You
might, however, see someone or something in the exclusion list directly related
to this puzzle's theme, such as Hedy Lamar or the Bikini Atoll, respectively. Enjoy!...
 If you believe this 1969
Sylvania General Telephone & Electronics advertisement, you needed only
to stock their specially-designed 60 components to be able to replace every
other component made anywhere in the world. Even in 1969 when semiconductors
were becoming the majority active devices in electronics (replacing vacuum
tubes), the claim is a bit of a stretch. I have my doubts. The ad probably got
posted on a few engineering lab bulletin boards (the physical kind of yore, not
computer BB's) to elicit a few laughs. It reminds me a little of the episode of
M.A.S.H. where a war correspondent asked Captain Hawkeye Pierce what he brought
with him from home, and he responded that he only brought...
 If you read the physics and geographic news
of the day, most likely you have seen articles on the rapidly increasing
migration rate of the geomagnetic "north pole" over the past few decades. Magnetic
north has never exactly lined up with geometric north (as borne out in geological
samples of rocks), and neither has it ever been uniformly distributed across the
globe. Ancient explorers on terra firma and at sea knew that a magnetic compass
needle did not align with the same stars, moon, or sun position for every location,
after accounting for difference in longitude. That is because the earth's magnetic
field is very nonuniform in strength and does not follow straight lines from pole
to pole as they more generally do from outer space. A correction factor must be
applied to any magnetic north indication based...
 "The more things change, the more they remain
the same." That old saw has held true throughout the ages, but there seems to be
cycles within cycles that causes, to mix in a metaphor, the pendulum to swing back
and forth in greater and lesser peak amplitudes, and over long periods of time a
bias sets in that causes a perceivable change from the symmetric tick-tock-tick-tock-tick-tock,
to tick----tock-tick----tock-tick----tock-tick. Without an outside-of-the-system
input, the bias grows. If you have a "real" gravity-driven pendulum clock, you probably
know what I mean. Bringing the system back to symmetry requires adjusting the clockworks
movement or "righting" the physical orientation by rotating the clock on the wall
or shimming up one side on the shelf until the preferred tick-tock-tick-tock is
restored. Economic cycles are much the same, as alluded to in this World War II,
War Bonds promotion. There are long periods of overall ups and
overall downs, and in-between there are lesser rises and falls. Eventually, those
who learn to control the cycles tend to insert a bias into the works...
 A couple years ago a house two streets away
had an estate sale after the elderly gentleman who owned it passed on. There was
a lot of old
amateur radio gear for sale, and most of it had been bought early in the morning,
right after the beginning of the sale according to the man's daughter who was on-hand.
The newspaper notice mentioned the Ham equipment. In the back yard was a nice 40-foot
crank-up tower that was a bit weather-worn, but otherwise appeared to be in good
condition. She said that was the first item sold. I didn't ask how much she got
for it. The house was to be sold, and they were glad to have the tower gone before
listing it on the market. I have wondered in the past when seeing a "For Sale" sign
in the lawn of a house with one or more radio towers in the yard how much they would
impact the sale price. Some Hams would plan to take...
 The extreme level of complexity and
consolidation of circuit functions in today's functional integrated circuit (IC)
blocks makes it so that people with almost no instruction or experience in
circuit and system design can assemble and make work some pretty impressive
creations. The days of vacuum tubes and early discrete semiconductors required a
designer to know how to properly bias and interface various sections of circuits
and systems. Nowadays, with the ready availability of impedance-matched
amplifiers, filters, mixers, couplers, detectors, and other pre-packaged
components, even RF and microwave frequency systems are within the reach of
relative amateurs. Likewise, people interested in digital and microprocessor
circuits...
 Admittedly, the only thing I remember about
Gray Code (aka reflected binary) from college courses is that successive count
values change only one bit per increment, saving power in some digital circuits.
The power savings comes from the fact that, especially for CMOS circuits, current
only flows during the transition of a state change from "0" to "1" or from "1" to
"0." Shaft position encoders were and still are a primary application of Gray Code
switching. If the encoder output digital code is going to be used in a binary computation
system, then there is an advantage in generating a direct binary ("natural") count
that does not require a Gray-Code-to-Binary conversion circuit (or software routine).
When the Wayne-George Corporation introduced its paradigm-changing "Natural Code
Non-Ambiguous Optical Encoder" in 1964, those conversion circuits were probably
not simple, compact, inexpensive semiconductor IC's, but more likely vacuum tube
behemoths. Even if IC's were used, the conversion circuit would have been comprised
of quad packs of AND's, OR's, NAND's, and NOR's, not even a single application...
 If this 1960 Popular Electronics
magazine article was written today, the title would more likely be, "One
IC Pocket Radio," and rather than a couple dozen resistors, capacitors, and
inductors (and a transformer), and there might be one or two decoupling capacitors.
Everything else would be contained within the integrated circuit. There are plenty
of single-chip radio circuits available from distributors like Digi-Key, Newark
Electronics, etc. Oh, and how many of you even know what a phenolic board looks
like? Better yet, how many of you can identify the unique smell of one heating up
or burning due to component overheating? If you can't, then consider yourself lucky,
because that probably means you're 40-50 years younger than I am, and you have that
much longer to live then me...
 When
color televisions hit the stores in 1954, most households could not afford one.
For that matter, most households could not afford a black and white TV, either.
By 1959 when this article appeared in Popular Electronics magazine, TV
in general was still a novelty to most people. It is amusing to read about how much
more lifelike everything would appear when broadcast in "living color." Well, duh.
It's as if it never occurred to anyone that the images previously did not contain
color like the real world did. I was born in 1958, and remember that my family's
was last of all the households I knew of to own a color television set. We never
even had a console floor model, just small tabletop pieces of junk. It was a big
deal the day I, at about age 16, bought and installed a remote rotor for the rooftop
antenna so we could receive more than three stations. There was no cable TV service
in our neighborhood...
 This
electronics analogy quiz is a little easier than many of the others
published in Popular Electronics magazine because all of the electrical
and mechanical objects depicted here are very familiar. The concepts might seem
trivial to those of us who have been immersed in the science for decades, but I
for one can remember when first hearing these analogies how helpful they were.
Not only that, but I also recall during physics and mechanics courses in college
being amazed at the similarity of equations shared by electrical and mechanical
processes. Wikipedia has a huge page describing many of the most familiar
mechanical-electrical analogies...
 Most of us, long before being introduced
to the concept of power in electrical circuits, learn about it in terms of mechanical
power and/or sound power. It takes some doing to abandon the esoteric nature of
power and be trained to grasp the scientific and mathematical aspects of power in
all its forms. When the driving source is steady state or a pure sinewave, life
is relatively simple, but such is more often than not an exception to the system
being studied. Here is a nice, short treatise in a 1960 issue of Electronics
World magazine on the concept of sound power that will augment your earlier-learned
knowledge of
music power rating...
 This week's crossword puzzle for November
6th sports a
radar and radio theme. 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 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!
 I remember in one of my circuits classes
in college when the
gyrator was introduced, and I thought it was an ingenious invention. The gyrator
circuit, implemented with an opamp and a couple resistors and capacitors, changed
its measured impedance type from that of a capacitance to that of an inductance.
That is, its impedance represents an R + jX Ω format. Frequency limits
are imposed by a combination of the self-resonant frequencies of the resistors and
capacitors as well as the GBWP of the opamp, and power handling is primarily limited
by the opamp's voltage and current capabilities. You might ask why, with all those
constraints on its use you would even want to use a gyrator circuit? The answer
is that within its limitations, the gyrator often represents a less expensive and
more compact version of a physical inductor. This is particularly true with ICs
where, unless it is a MMIC operating in the tens of gigahertz region, there is no
space available on the die for a printed metallic inductor with enough inductance
to be useful. Any inductors would need to be mounted off-chip on the PCB with I/O
pins interfacing to the IC. Gyrators... |
