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 The
1-dB compression point, usually written P1dB, is a practical large-signal linearity
limit for RF and microwave components such as low-noise amplifiers, power amplifiers,
mixers, active frequency multipliers, driver stages, variable-gain amplifiers, attenuators,
limiters, isolators, filters, switches, and receiver front-end modules. It is the
input or output power level at which the measured gain has fallen 1 dB below the
gain predicted by the small-signal linear gain line. In symbols, if the small-signal
gain is GSS in dB, then at the 1-dB compression point: Pout(measured,
dBm) = Pin(dBm) + GSS(dB) - 1 dB When the input power at that condition
is quoted, it is called input...
 Anytime I see an airplane in a photograph,
my interest is immediately piqued to learn the story behind it - sort of like with
the "MPATI - Its Problems & Solutions" feature in the May 1963 edition of
Electronics World magazine. This "Aerial 'Private Eye' Traces TV Signals" story also involves
airplanes and television broadcasting, albeit in a completely different way. A couple
enterprising broadcast engineers created a company called Tele-Beam Industries,
in Napa, California, that measured and mapped TV signal strength in the region surrounding
transmission towers to provide the stations with information useful in marketing
and radiation characteristic planning. Signal strength...
 Two major radio events were covered in this
1954 issue of Radio & TV News magazine's monthly "Spot Radio News"
column - the rapid advance of microwave technology for building out
high capacity voice and television transmission systems, and the
ever-increasing number of new TV station operation license grants since the ending
of the Federal Communications Commission (FCC) moratorium in 1952. In 1944, the
FCC stopped issuing broadcast permits due to serious unforeseen interference from
co-location interference issues as post-war households enthusiastically adopted
TV. Unlike today's microwave relay networks, in the 1950s most systems were
still analog in nature. Coaxial...
 The first video below is my favorite. It
is a one-minute clip from a 1960s episode of "The
Twilight Zone" television show. It is an outrageous slam on amateur radio operators
by a family whose radio and TV shows are being interrupted by interference. Dad
looks out the window and sees what are actually television antennas on the guy's
roof and when Mom asks if there is anything they can do about the neighbor, he walks
toward the telephone saying he can at least check to find out whether neighbor man
has a license to operate. Mom then says, "Do you think you should, Stu? Those men
seem kind of...threatening somehow." Those d**n evil Hams! As you might expect if
your are familiar with the series...
 Empower RF Systems announces the release
of its new
Model 1240, a compact, high-performance RF amplifier module delivering a guaranteed
minimum of 200 watts across the 900-1700 MHz frequency range. Designed to address
the evolving demands of modern electronic warfare (EW) and counter-unmanned aerial
systems (C-UAS), the Model 1240 expands Empower RF's portfolio of tactically deployable,
high-reliability solutions. The Model 1240 is a full gain "smart module" built on
advanced GaN transistor technology, integrating comprehensive control and monitoring
features to ensure consistent RF performance under all environmental conditions.
What sets the Model 1240 apart is its strategically targeted frequency coverage.
The 900-1700 MHz range aligns...
 Pulse compression (aka "chirp") radar was invented in the 1950s by Sperry and a couple
other defense contractors. It was new enough by the time the radar I worked on as
a technician in the USAF that it was not incorporated. Our MPN-13 and MPN-14 radar
systems used simple single-frequency pulses. Pulse compression employs a swept frequency
within a fairly narrow bandwidth to exploit the benefits outlined in this 1965
Electronics World magazine article. If you were to listen to the signal
used to sweep the RF pulse in frequency, it would sound a lot like a bird's chirp,
hence the name. Treatment by author Donald Lancaster is fairly heavy in that it
fearlessly presents the mathematical...
 Raise your hand if you have ever owned a
CB (Citizens Band) radio. Waaaaay back before everyone carried a cellphone (pre-late-1990s),
the most common form of
unlicensed communication was CB radio. Actually, up through the
mid 1970s you were supposed to purchase a license from the FCC, although no test
was required as it was for amateur radio. My first CB was a 23 channel job that
I installed in my 1969 Chevy Camaro SS, during my senior year in Southern Senior
High School. It was right in the middle of big CB radio craze with CW McCall's
"Convoy" song topping the U.S. Billboard charts. My self-appointed 'handle'
was "RC Flyer." Most people had no idea what it referred...
 Admittedly, with all the reading I have
done of vintage electronics magazines, news of this
Crystron (crystal-electron) vacuum tube device invented by Mr. Mohammed
Ulysses Fips, as reported in the April 1947 issue of Radio Craft magazine,
evaded my attention. The article came only a couple months after publication of
the 40th anniversary edition that celebrated Dr. Lee de Forest's invention
of the Audion tube. According to Mr. Fips, his Crystron one-upped the Audion
by virtue of its containing a small amount of radio isotope which obviated the need
for the traditional "B-battery" concept also developed by de Forest to supply
a high voltage for driving the output stage circuit...
 On July 14, 2026, the U.S. Congress voted
to
make Daylight Saving Time (DST) permanent, thereby eliminating the biannual
clock change routine. Daylight Saving Time (DST) is the practice of advancing civil
clocks by one hour during part of the year so that more daylight falls in the evening.
In the U.S., DST has been used intermittently since WWI, standardized nationally
in 1966, and briefly tried as a near-permanent winter policy during the 1974 Oil
Embargo / Energy Crisis (which was such a disaster it was repealed in less than
a year). The Emergency Daylight Saving Time Energy Conservation Act of 1973 put
most of the country on year-round DST beginning January 6, 1974. The idea sounded
attractive: an extra hour of daylight after work and school, but the public quickly
discovered...
 Sam Benzacar, of Anatech Electronics, an
RF and microwave filter company, has published his June 2026 Newsletter that, along
with timely news items, features his short op-ed titled "Overlooked, Not Obsolete:
CB Radio at 27 MHz." Being "old" myself, the bit of nostalgic nearly brought
a tear to my eye. Having "come of age" myself in the 1970s, I was quick to jump
onto the CB radio craze, installing my first 23-channel rig under the dash of my
1969 Camaro SS hot rod. Every guy I hung out with knew all the words to C.W.
McCall's "Convoy" hit song. ...but I digress. Sam points out that while CB radio
is not the hot item is was decades ago, niche groups still occupy the band in number
large enough for the FCC to not reallocate the frequencies to paying clients...
 Welcome to the RF Cafe
Coaxial Connectors
Quiz, an essential module for any engineer or radio hobbyist focused on maintaining
interconnect integrity across their signal chain. Whether you are standardizing
your station hardware, troubleshooting high-frequency signal leakage, or verifying
the physical port interfaces for your test bench equipment, a thorough understanding
of coaxial connector characteristics - from the rugged reliability of the Type N
to the precision of the SMA - is vital. This assessment challenges your proficiency
in connector selection, exploring the differences in mating mechanisms, cutoff frequencies,
constant-impedance geometries...
 This installment of the multi-month series
of articles on antenna principles covers
directional arrays for 300 MHz and higher. Keep in mind that
in 1947 when this appeared in Radio-Craft magazine, wavelengths of a meter
or less were considered to be at the upper end of the operational range. Parabolic
reflector antennas were the domain primarily of ground-based installations due to
the physical size and weight being prohibitive in airborne platforms, and even then
they were rarely used at the time. Most ground and airborne installations were composed
of dipole antennas with various configurations of reflector and director elements
for desired gain and directivity characteristics. Special...
 Echo 1 launched in August of 1960,
finally allowing America to participate in the Space Race, which until then was
roundly being won by the USSR. Electronics magazines of the day were filled with
prognostications of the future of
space communications. Electronics World dedicated most of their
November issue to satellite Earth stations and advancements being made in ultra
sensitive receivers and powerful transmitters. Since the earliest satellites were
literally metallic balls for reflecting radio signals, it was necessary to optimize
both ends of the communications path since there were no circuits onboard the satellite
to perform signal processing and re-transmission. Bell Labs, of course, was at the
forefront...
 As with many relatively new technologies,
the
exuberance over radio peaked quickly once the benefits of communications
over long distances without the need for wires was realized by the public. After
a couple decades a lot of "authorities" began pontificating about how all the useful
applications of radio waves had been discovered and that any new innovation would
be merely incremental improvements in existing technology. Novel circuits for minimizing
static over the radio or maybe building more powerful transmitters for longer range
were the only concepts within reach of their limited imaginations. Similar phenomena
occurred for those who thought airplanes would always have...
 The Klondike / Yukon Gold Rush is generally
credited with opening up the Alaskan territory to exploration and habitation. Gold
was first reported in August of 1896, just three decades prior to this advertisement
in a 1931 issue of QST magazine by the
De Forest Radio Company extolling its domination of the region
with radio communications stations. Company founder Lee De Forest was very
successful in exploiting the virtues of his famous Audion amplifier tube. A back-handed
swipe is taken at Government installations that used "whatever tubes the Government
has...
 Fixed-value resistors are among the simplest-looking
components in electronics, but their development reflects nearly the entire history
of electrical science, telecommunications, electric lighting, industrial power,
radio, military electronics, printed circuits, hybrid microelectronics, and surface-mount
manufacturing. Partly out of curiosity of how extensive, comprehensive, and accurate
an AI-generated report on topics of science and engineering, I instructed ChatGPT
to generate the following thesis titled
History of Fixed-Value Resistor Electronic Components. Most useful AI interactions,
I have found, require more than one input...
 Since we seem to be on a roll of FM radio
theme articles printed in vintage electronics magazine, here is one from a 1973
issue of Popular Electronics magazine. The author never explicitly tells
us the date when the Institute of High Fidelity (IHF) updated its
FM tuner specifications, and neither does he mention groundbreaking
work of IHF's Julian Hirsch, who is largely responsible for both the initial and
updated standards. If you read magazine stereo equipment reviews in the 1960s and
1970s, then you probably recall the name. Anyway, this article discusses the improved
specifications made possible by more sophisticated circuits made possible by semiconductors
and miniaturized...
 Comics in modern magazines are a rather
rare phenomenon for some reason, but they were fairly regular features up until
a couple decades ago. This set of
comics from the July 1963 edition of Popular Electronics
magazine deals with high fidelity (Hi-Fi) stereo equipment, which was considered
somewhat exotic and high-end for many people's budgets in the day. Inexplicably
(not), that is about the time that increases in hearing losses among younger people
were first being noticed in audiograms. I listened to my share of loud music beginning
in the late 1960s, and operated many model airplane engines and lawnmower type engines
my whole life, and still, at 68 years...
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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.
 Have you heard of an
Alford Loop antenna? I hadn't until reading this article. It is a four-sided
structure consisting of identical folded ½-wave dipoles on each side, with a common
feed. Opposing sides have their elements 180° out of phase with respect to each
other. The intention is to provide nearly omnidirectional FM radio reception across
the entire 88-108 MHz band. A little research on the Alford Loop reveals that
Mr. Andrew Alford developed this configuration to enable simultaneous, co-located
transmissions of FM radio stations. In that case the four antennas are individually
fed by transmitters on different frequencies. Alford is credited with inventing
antenna...
 It is common in electronics courses for an
analogy to be drawn between electrical and mechanical phenomena. In fact, a lot
of circuit analysis methods and equations apply directly to mechanics, and vice
versa. An LC (inductor-capacitor) oscillating tank circuit is akin to a spring and
dashpot. Resistance of a wire is likened to skin friction of water flowing through
a hose. Who among us can forget those lessons? This
Electronic Analogy Quiz from the November 1961 edition of Popular Electronics
presents a challenge both because some not-so-familiar examples of analogies are
offered, and because some are a real stretch. Therefore, don't feel too bad if you
don't get...
 For twenty years now, I have been creating
weekly crossword puzzles for the education and enjoyment of the technically minded
visitor like you. This
Science Theme Crossword Puzzle for May 23rd 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...
 During the
Golden Age
of Radio (admittedly a subjective term), electronics innovators were generally
as likely to be hobbyists (amateurs) as they were to be professionals with college
degrees. In fact, according to this open letter from Eugene F. McDonald, president
of Zenith Radio Corporation, in 1939, his company recognized the fact that most
of their best ideas came from amateur radio operators, and that their engineering
staff was populated overwhelmingly with Hams. Accordingly, the letter was a solicitation
to amateurs to submit their ideas to the company to give designers not just valuable
technical information gleaned from real-world experimentation (aka the School of
Hard Knocks) but also insight into what type of equipment the Ham world would like
to have made available for...
 The August 1962 issue of Electronics
World magazine featured what could be considered as an early
"infographic" on the topic of sound, music, and audio. Frequency and volume,
perceived equal loudness levels, the audible frequency spectrum, musical frequency
ranges, typical age-related hearing loss, relative sound levels in decibels, and
the musical scale are included. The sound power level chart ranges from the threshold
of hearing value of 10-16 watts/cm2 (0 dBA) to standing
80 feet from the tail of a North American F-86 Sabre Jet taking off, which is a
couple dB above the threshold of pain at 10-3 watts/cm2 (130 dBA).
The charts were useful (and still...
 A mere five years had elapsed from the time Echo,
a gas-filled metallized plastic sphere that passively reflected radio signals back
to Earth, was launched and the time that 35 television cameras had been launched
into space. The
Space Race was at a fever pitch. Although the Ruskies beat us in being the
first to launch both an active satellite (Sputnik) and a man (Yuri Gagarin) into
space, America's deep pool of intellectual resources, consisting of both native
scientists and many of the world's top scientists who chose to flourish in
freedom here rather than oppression behind the Iron Curtain, fostered the
advantage that in short order established the U.S. as the leading...
 Crystal diodes have been used as detectors
in radio circuits since the 1910s. Originally, the rectification process was effected
via a point contact "whisker" (aka "cats whisker") pressed against the crystal's
face. It was not mechanically rugged (vibration could cause erratic operation),
was sensitive to heat and humidity (if not contained in a hermetic case), and operated
at fairly low frequencies. Vacuum tube diodes provided some improvement, but were
still limited to operation in the lower hundreds of MHz. Once germanium and silicon
crystals became available, operational frequencies climbed into the upper MHz to
lower GHz realm, even though, as shown in...
 Pliers of the amateur radio hobby have since
the beginning put forth a lot of effort training fledgling entrants in the realm
of electronics and communications. Up until the latter part of the last century,
there were a number of magazines - Popular Electronics among them - that
would regularly print articles covering the basics of electronics. Other than the
ARRL's QST magazine, it seems maybe Nuts and Volts is the only
monthly still in print that you can go to for such information. I suppose it was
inevitable with the emergence and now domination of the Internet as a source for
most knowledge. The "Among
the Novice Hams" column in Popular Electronics often...
 While everyone greatly welcomed the ending
of World War II, in its wake was a huge number of people that would be in need
of jobs. Many thousands of men had been trained in the field of electronics maintenance
and hope to exploit those skills in doing service work in radio, television, industrial
controls, and other related fields. Other planned to go into sales, or a combination
of both. Some had been in the business prior to either volunteering or getting drafted
into the war, but not all could expect to simply pick up where they had left off.
In order to assist the country's servicemen in transitioning into civilian life,
Radio-Craft provided a free service where
individuals could list...
 While listening to the radio the other day,
I heard a guy who is very technically astute and is a Ham radio operator pronounce
the word "schematic" as "skem-E'-at-ik." He wasn't just joking because he kept saying
it that way throughout the show. It came to mind while posting this chapter entitled,
"The
Electrical Circuit Diagram," and I thought you might appreciate it (especially
if you also routinely mispronounce the word). But I digress... The U.S. Navy over
the years has produced a number of series of training courses for electricity, communications,
mechanics, navigation, etc., that are held in high regard by the military and private
industry...
 "Disruptive"
is the early 21st century buzzword. Merely placing the adjective in the vicinity
of any noun or phrase elevates the topic to a level reserved for only the most outside-of-the-box,
ground-breaking, awe-inspiring events. Any technology described as disruptive, that
is to say, as a "disruptive
technology," is certain to cause a hush to fall across the room where it is
introduced. Captains of industry are humbled at the announcement. Kings kneel in
the presence of said disruptiveness. No amount of adulation, worship, exaltation
and praise is sufficient to acknowledge its progenitor(s). Seriously, though, although
the term "disruptive technology" is grossly overused, it is...
 In "The River Sniffer," our intrepid sleuthing
heroes
Carl and Jerry, the creation of John T. Frye, apply their electronics prowess
and lessons remembered from chemistry class at Parvoo University in order to catch
polluters who are dumping chemicals into the river where they like to fish. I always
like being reminded of something long forgotten when reading an article from vintage
magazines like this 1962 issue of Popular Electronics, and this one did not disappoint.
Do you recall what 'pH' stands for as a measure acidity or alkalinity? It means
'potential Hydrogen ion concentration.' Don't thank me if it jogged your memory
as well - thank Carl and Jerry...
 This
Radio
Theme Crossword Puzzle for May 9th has many words and clues related to RF,
microwave, and mm-wave engineering, optics, mathematics, chemistry, physics, and
other technical subjects. Also, it contains at least six (6) instances of this
puzzle's theme word. 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...
 Website visitor Daniel O. wrote to request
that I post this "Designing
a Low-Distortion 12-Watt Amplifier" article from the August 1958 issue of Radio-Electronics
magazine, which of course I was glad to do. It is nice to know there is still some
interest in building vacuum tube circuits, just to keep the knowledge alive. When
reading through the vintage magazines in search of good articles, I typically do
not include ones like this not because I don't think they are worthy of posting,
but because they are narrowly focused and would not be of interest to a wide number
of people. If you run across an article which appears in the table of contents of
one of the hundreds of old...
 Here is an electronics
Lamp Brightness Quiz for you to try, compliments of Popular Electronics
magazine. Intuition from experience goes a long way here, but if all else fails
you can work out the details of the rectifier circuits to determine which lamp received
the most current. Keep in mind that the diode symbols are not LEDs; it is the 'A,'
'B,' and 'C' symbols inside circles that are the lamps whose brightnesses are being
considered. LEDs did exist at the time this quiz was created in 1969, but the circuits
would perform differently if in fact LEDs were used for double duty of rectification
and illumination. Good luck... |
