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Log Periodic V Antenna

Log Periodic V Antenna, June 1963 Radio-Electronics - RF CafeIn his June 1963 Radio-Electronics magazine article, Edward Finkel introduces the Log Periodic V (LPV) antenna, a breakthrough in VHF TV reception, overcoming the narrow-band limitations of traditional Yagi designs by employing log-periodic scaling (τ = 0.9, σ = 0.085) to achieve uniform gain (8 dB low-band, 11.5 dB high-band), constant impedance (~1.2 VSWR), and a 35 dB front-to-back ratio across 54-216 MHz. Developed by University of Illinois researchers and JFD Electronics, the LPV uses "active cells" where resonance shifts smoothly with frequency, leverages third-harmonic resonance for high-band channels (7-13), and enhances directionality via forward-V elements and a phase-reversed feeder harness to cancel rear/side signals (Figs. 5-7). Reinforced...

Superconductor, Metal, Semiconductor, Insulator

Superconductor, Metal, Semiconductor, and Insulator - RF Cafe"RIKEN scientists have discovered how to manipulate molybdenum disulfide into acting as a superconductor, metal, semiconductor, or insulator using a specialized transistor technique.. By inserting potassium ions and adjusting conditions, they could trigger dramatic changes in the material’s electronic state - unexpectedly even turning it into a superconductor or insulator. This new level of control over a single 2D material could unlock exciting breakthroughs in next-gen electronics and superconductivity research. A team of physicists at RIKEN has developed a transistor-based technique that allows a single-layered material to take on a wide range of electronic behaviors, functioning as a superconductor, metal, semiconductor, or insulator..."

Senseless Orbiting

Senseless Orbiting, December 1962 Radio-Electronics - RF CafeHugo Gernsback, publisher of Radio-Electronics magazine, penned this 1962 article critiquing the U.S. for lagging behind the Soviets in manned spaceflight, noting their superior orbital achievements (130.5 orbits vs. America's 12). He argues that prolonged Earth-orbiting tests are unnecessary, as weightlessness and space sickness - predicted decades earlier - are now proven manageable. Gernsback traces U.S. delays to the government's historical neglect of rocketry pioneer Robert H. Goddard, whose early 20th-century work could have secured American leadership. Instead of mimicking Soviet Earth orbits, he urges immediate focus on the Moon, prioritizing an unmanned electronic...

CMT White Paper: External Triggering the VNA

Copper Mountain White Paper: External Triggering the VNA - RF CafeCopper Mountain Technologies' Brian Walker, has published a new white paper entitled "Hardware Triggering a Vector Network Analyzer." In it, he details the use of hardware triggering in VNAs to synchronize measurements with external test equipment, such as programmable power supplies or pulsed RF signals. It explains how external triggering - either "On Sweep" or "On Point" - enables precise control over VNA operations, reducing power dissipation in devices like RF power amplifiers. The paper outlines SCPI commands for automation, including triggering, polling data, and checking VNA status, with examples in Python-like syntax. It also covers trigger voltage levels, polarity settings, and timing modes, including programmable delays for pulsed RF measurements. The document highlights Copper Mountain Technologies' VNAs, which support these features...

Man's World? Not to These Women!

Man's World? Not to These Women!, July 1967 Radio-Electronics - RF CafeIn this 1967 Radio-Electronics magazine article, Sally O. Smyth highlights pioneering women in electronics, challenging the male-dominated industry stereotype. Muriel Burke and Kathi Kramer, sisters running a successful TV repair shop for a decade, emphasize problem-solving and customer trust. Cecilia Jacobs, a financial consultant turned electronics firm owner, showcases innovation in military and security tech. Vicki Labes, trained by her husband, co-manages an audio-visual business and produces films. Self-taught technician Mrs. William Nolan transitioned from fixing a tape recorder to technical writing. Francis Brooks, an RCA Institutes graduate, designs circuit boards while...

Shortwave - Your Ear on the World

Shortwave - Your Ear on the World, August 1968 Radio-Electronics - RF CafeCharles J. Vlahos' 1968 Radio-Electronics magazine article highlights the growing popularity of shortwave listening (SWL), still a popular pastime, with around 3,000 stations worldwide broadcasting diverse content - news, propaganda, language courses, and entertainment - often in English. SWL offers unique perspectives, from Hanoi's war coverage to Radio Tokyo's language lessons. Enthusiasts log stations using SINPO codes and collect QSL cards as verification. The article details receiver specifications, emphasizing selectivity, sensitivity, and stability, with price comparisons from budget kits to high-end models. Antennas, like long wires or whip antennas, are crucial...

"Radio Pen" 28 Years Old

"Radio Pen" 28 Years Old, June 1946, Radio-Craft - RF CafeIn response to a controversial article about Hugo Gernsback's former "employee," Mohammed Fips, and his "Radio Pen," Dr. Lee de Forest wrote to Radio-Craft magazine claiming he had invented a similar device decades earlier. De Forest recalled publishing detailed plans for a miniature radio receiver shaped like a fountain pen as early as 1917-1920, using Western Electric's "peanut" tube. Radio-Craft verified his claim by locating the original 1918 Electrical Experimenter magazine article, which described his pen-sized spy radio. Unlike Fips' later version, de Forest's design required an external antenna and ground connection. The device used an Audion tube for detection, tuned via a sliding coil, and was powered by a small battery. Operators concealed wires in a cane (antenna) and...

Failed 1972 Kosmos Venus Probe Returns to Earth

Failed 1972 Kosmos Venus Probe Returns to Earth - RF Cafe"Launched in 1972 by the Soviet Union (USSR), the spacecraft known as Kosmos 482 was part of a series of missions bound for Venus. But this one never made it out of orbit around Earth, stranded there by a rocket malfunction. Much of the spacecraft came tumbling back to Earth within a decade of the failed launch. The European Union Space Surveillance and Tracking confirmed its uncontrolled reentry, based on analysis and no-shows of the spacecraft on subsequent orbits. The ESA's space debris office also indicated that the spacecraft had reentered after it failed to appear over a German radar station. It was not immediately known..."

The Tunnel Diode Really Works

The Tunnel Diode Really Works, October 1960 Radio-Electronics - RF CafeThe tunnel diode, with its unique negative resistance region, excels as an oscillator and switch. As described by Mr. Queen in this 1960 Radio-Electronics magazine article, is operating bias is critical - typically around 0.2V for oscillation. The article details a 27-30 MHz crystal oscillator using a 1N653 diode, requiring precise voltage division via a potentiometer (R1) and fine-tuning with R2. The load resistance must be less than the diode’s negative resistance (-40 Ω). A 16-turn inductor and adjustable capacitor (C2) optimize output. The circuit can self-oscillate without a crystal but becomes unstable. For switching, the diode's characteristic curve allows triggering via weak pulses or resistance changes. A light-sensitive version uses a solar cell in series with a relay - illumination increases...

Indian Summer: What, Why, and When?

Indian Summer: What, Why, and When?, 1985 Old Farmer's Almanac - RF CafeThe 1985 Old Farmer's Almanac clarifies that Indian Summer is not just any warm fall day but a specific weather phenomenon marked by warmth, haze, calm winds, high pressure, and chilly nights, caused by a stalled high-pressure system trapping dust and smoke near the ground; it must follow a cold spell or frost and traditionally occurs between November 11 (St. Martin's Day) and November 20, differing from England's earlier warm spells like St. Luke's summer. The term's origin is debated - some tie it to Native American beliefs or autumn foliage resembling Indigenous attire, but the most likely explanation stems from early New England...

Carl & Jerry: The "Meller Smeller"

Carl & Jerry: The "Meller Smeller", January 1957 Popular Electronics - RF CafeCarl Anderson and Jerry Bishop, John Frye's techno-teens featured in may Popular Electronics magazine stories, bored during winter break, decide to invent an "electronic odor killer" called the Meller Smeller - a helmet with charged screens to neutralize foul smells. Using salvaged TV parts, they build prototypes with three wire screens: a positively charged outer layer, a grounded middle layer, and a negatively charged inner layer. The theory is that odor particles would lose electrons to the grounded screen, then stick to the negatively charged inner screen. Testing it with a cardboard box reeking of soap and fish proves inconclusive, so they head to a local soap factory for a stronger challenge. On the way, they encounter a skunk and foolishly test their...

What Are Microvolts/Meter?

In the Shop ... With Jack - What Are Microvolts/Meter? - RF CafeThe "In the Shop ... with Jack" column appeared monthly in Radio-Electronics magazine, although the title changed occasionally. In it, Mr. Darr, a celebrated circuits troubleshooter, addressed reader questions on electronics, offering free troubleshooting help via mail. One inquiry concerned microvolts per meter (μV/m), a measure of RF field strength. The author clarified that μV/m represents the voltage induced across a 1-meter wire in free space, aligned with the transmitter's polarization. Note that μV/m in the case of RF field strength is NOT a scaling factor for distance form the emitter; it refers to the field strength induced in a 1-meter length of wire. Hence, a 2-meter length of wire will have twice the value of a 1-meter wire. This assumes a far field measurement where the wavefront is planar and at a right angle to the detection wire...

Ferroelectric RAM Calculations Within Memory

Ferroelectric RAM Calculations Within Memory - RF Cafe"Researchers have developed an in-memory ferroelectric differentiator capable of performing calculations directly in the memory without requiring a separate processor. The proposed differentiator promises energy efficiency, especially for edge devices like smartphones, autonomous vehicles, and security cameras. Traditional approaches to tasks like image processing and motion detection involve multi-step energy-intensive processes. This begins with recording data, which is transmitted to a memory unit, which further transmits the data to a microcontroller unit to perform differential..."

Space Handicaps

Space Handicaps, February 1964 Radio-Electronics - RF CafeIn April of 1961, Yuri Gagarin was the first human being to "slip the surly bonds of Earth*," and venture into space, to be followed the next month by Alan Shepard. Just as those flights relied upon data gained from launching monkeys into space, future manned missions depended on a rapid ramp-up on methods and machinery needed to extend duration times and safety. Hugo Gernsback's 1964 Radio-Electronics editorial, "To Remain Alive in Space Is Difficult," underscores the extreme challenges humans face in the vacuum of space. Earth's atmosphere provides vital protection, but in space, astronauts must contend with lethal radiation, temperature extremes, and the constant heat output of their own bodies. A punctured suit means rapid death as internal pressure causes the body to swell like a balloon. Gernsback highlights...

Engineering & Tech Headlines <Archives>

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• $23B Korea Subsidy to Chip Industry

• EV Making ICE Engineers Obsolete?

• FCC Commish Starks Steps Down

Belmont Radio Christmas Ad

Belmont Radio Christmas Ad, December 27, 1943 Life - RF CafeIt's a little out of season for posting this Belmont Radio advertisement, but it has been on my to-do list for a long time. Back in 1943 when this full-page promotion appeared in Life magazine, many companies unabashedly acknowledged America's traditions for celebrating Christmas by including a noel message in advertisements. Products from military bomber aircraft to washing machines, to cars, to canned hams were included in the lineup. It was two years into World War II when this December 27th issue came out, and the theme not surprisingly focused on our service members who were serving in the fields of Europe and northern Africa, and in the South Seas. Unlike most of the conflicts our men are involved in...

Paperthin Radio

Paperthin Radio, April 1960 Radio-Electronics - RF CafeIn this April 1960 Radio-Electronics magazine article by the fictitious electronics wizard Mohammed Ulysses Fips (a Hugo Gernsback pseudonym), the narrator presents the "Paperthin Radio" - an ultra-thin, lightweight transistor radio designed to undercut Japanese competition. Built on a stiff paperboard chassis just 1/16-inch thick, the radio uses standard components cemented into place, with conductive ink for wiring. Key innovations include a flat ferrite-loop antenna, a modified trimmer capacitor for tuning, and the "Leptospeaker" - a slim electromagnetic speaker using an Alnico disc magnet. The two-transistor circuit...

McMurtry Spéirling e-Hypercar Drives Upside Down

McMurtry Spéirling e-Hypercar Drives Upside Down - RF Cafe"Claimed to be a world first, the demonstration took place at Swinhay House. A McMurtry Spéirling PURE Validation Prototype 1 (VP1) was driven on to a custom-built platform which then rotated 180 degrees to invert the stationary vehicle. Relying on the huge 'Downforce on Demand' created by twin 23,000 RPM fans on the car's undercarriage, the Spéirling remained firmly attached to the platform and was driven a few feet forward before the rig rotated it back to ground. 'This demonstration was an exciting proof-of-concept using a small purpose-built rig, but is perhaps just the beginning of what's possible. With a longer inverted track or a suitable tunnel, we may be able to drive..."

Your Future in Microwave

Your Future in Microwave, May 1966 Radio-Electronics - RF CafeIn this 1966 Radio-Electronics magazine article, Ray Thrower highlights the booming demand for microwave communication technicians and engineers due to population growth and industrial expansion. With only 36,000 licensed technicians available nationwide, the field faces a severe shortage - microwave alone requires 24,000 workers. Companies prefer microwave over vulnerable cable systems for its reliability, cost efficiency, and ability to handle high-capacity voice, video, and data circuits. The article profiles Jim Reeve, a technician trained via military service, and Don Shaffer, an engineer designing microwave paths, emphasizing hands-on experience and continuous learning. Entry-level opportunities exist...

Capitol Radio Engineering Institute

Capitol Radio Engineering Institute, September 1964 Radio-Electronics - RF CafeThis 1964 CREI (Capitol Radio Engineering Institute) advertisement in Radio-Electronics magazine served to alert electronics professionals that the Space Age was rapidly transforming their industry. Automation and advanced aerospace technologies were eliminating routine jobs while increasing demand for specialists in cutting-edge fields like space data systems, spacecraft tracking, and aerospace radar engineering. The ad emphasized that outdated skills could render workers obsolete, but those who upgraded their knowledge through CREI's home study programs could secure high-demand careers. Founded in 1927, CREI (now Capitol Technology University) was an accredited home-study institution that collaborated with NASA and private aerospace firms to design its curricula. Its Space Electronics Programs were developed with input from government and industry experts, offering flexible, mail-order education for ele

Horseflies, Tractors and Mr. Kirchhoff

Horseflies, Tractors and Mr. Kirchhoff, March 1968 Radio-Electronics - RF CafeIn this 1968 Radio-Electronics magazine educational fiction article, high school student Jerry Whipple challenges Kirchhoff's voltage law in an AC circuit, convinced he's found a flaw. His experiment measures 7.1 volts across both a resistor and inductor in series, totaling 14 volts - contradicting the expected 10 V source voltage. His instructor, Mr. Bean, explains that the discrepancy arises from phase differences in AC circuits: the voltages are out of phase, not additive. Using a tractor analogy, Bean illustrates how forces (or voltages) at angles combine vectorially, not arithmetically. He introduces Pythagoras' theorem to resolve the apparent paradox...

G-Line Single-Wire, Low Loss Transmission Line

G-Line Single-Wire, Low Loss Transmission Line, June 1963 Radio-Electronics - RF CafeThe G-Line transmission line is another of those things where I can't imagine being smart enough to come up with the idea, and then implement a working model - like with the enclosed waveguide. Dr. George Goubau (from whence the "G" in the name derives) is the genius in this case. He determined that a sort of waveguide could be made with a single conductor surrounded by insulation with a specific dielectric constant that would cause the dielectric-air interface to reflect the wave in a manner similar to atmospheric channels that facilitate long distance communications. I'm guessing the Surface Conduction company advertising the G-Line for sale in this 1963 issue of Radio-Electronics magazine is Dr. Goubau's enterprise. That was ten years after inventing it. The G-Line's boasts are low loss (6 dB/mile), no radiation, and a 300-ohm impedance. The primary disadvantage...

Understanding and Dealing with Radiated Immunity

Understanding and Dealing with Radiated Immunity - RF Cafe"Let's deal with some common radiated and conducted emissions immunity issues for the next series of articles. One that's becoming more prevalent is radiated immunity (or radiated susceptibility, in MIL-STD-461 terms). It seems this problem has been increasing over the last decade, and the reasons are threefold: (1) electronic devices are getting smaller and using plastic enclosure, (2) the proliferation of electronic and body-worn devices has increased exponentially, and (3) as we're powering circuits with lower voltage levels (3.3V, or less) resulting in a greatly reduced noise margin. That is, it takes less energy to disrupt sensitive..."

G-10 Germanium Dot Rectifier

The New G-10 Germanium Dot Rectifier, June 1952 Radio & Television News - RF CafeThis 1952 Radio & Television News magazine article details General Electric's new G-10 Germanium Dot Rectifier, a high-efficiency semiconductor device for radio, television, and power applications. Unlike conventional rectifiers, the G-10 avoids critically scarce materials while offering superior performance - lower forward resistance, higher back resistance, and extended lifespan. Its design features germanium pellets sealed in butyl-rubber-insulated metal cups, mounted on aluminum or copper fins for heat dissipation. Key advantages include 98% efficiency, stable operation across temperatures (25–75°C), and minimal power loss (under 1 W at 50° C). The rectifier's low capacitance (20 μμfd) enables use in high-frequency...

Task Force: The Big Bomber Learns Its Job

Task Force: The Big Bomber Learns Its Job - Boeing B-17 Flying Fortress, April 6, 1942 Life - RF CafeThis 1942 Life magazine article profiles a B-17E Flying Fortress bomber and its nine-man crew, detailing their roles in America's early WWII air campaign against Japan. The bomber, part of the 342nd Bombardment Squadron, operates as a self-contained "task force," capable of delivering devastating strikes like Colin Kelly’s sinking of the battleship Haruna. The crew - four officers (pilot, copilot, navigator, bombardier) and five enlisted gunners - undergo six weeks of operational training at MacDill Field to forge teamwork essential for survival. The B-17E's firepower includes eight .50-caliber machine guns manned by the enlisted crew...

Exodus AMP20016, 500-1300 MHz, 1 kW SSHPA

Exodus AMP20016, 500-1300 MHz, 1000 W SSHPA - RF CafeExodus Advanced Communications, is a multinational RF communication equipment and engineering service company serving both commercial and government entities and their affiliates worldwide. Exodus' model AMP20016 is a high-performance amplifier designed for EMI/RFI, lab, and communication applications. Class A/AB linear design, 1000 W minimum with 60 dB gain. Features advanced linear device technology for wide bandwidth, built-in protection circuits, and monitoring. Local LCD & remote interfaces for superior control. High efficiency, rugged reliability. Nominal weight: 40 kg in a compact 5U chassis...

What's Your EQ?

What's Your EQ?, July 1966 Radio-Electronics - RF CafeMr. E.D. Clark has provided three new "What's Your EQ?" puzzlers for your attention, whether you be a student, a theoretician or just a "practical man." Simple? Double-check your answers before you say you've solved them. Radio-Electronics magazine ran this feature regularly, and there is a huge list on the page of the ones I have posted. The invitation for reader submissions read thusly: "If you have an interesting or unusual puzzle (with an answer) send it to us. We will pay $10 for each one accepted. We're especially interested in service stinkers or engineering stumpers on actual electronic equipment. We get so many letters we can't answer individual ones, but we'll print the more interesting solutions - ones the original authors..."

Today in Science History

Today in Science History - RF Cafe

Homepage Archives for December 2024

Homepage Archives for December - RF CafeHomepage Archives for December 2024. Items on the RF Cafe homepage come and go at a pretty fast rate. In order to facilitate fast page loading, I keep the size reasonable - under a megabyte (ebay, Amazon, NY Times, etc., are multiple megabytes). New items are added at the top of the content area, and within a few days they shift off the bottom. If you recall seeing something on the homepage but now it is gone, fret not because many years I have maintained Homepage Archives.

Sylvania Solid State Replacement Parts Advertisement

Sylvania Solid State Replacement Parts Advertisement, August 1969 Radio-Electronics - RF CafeIf 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...

Carl & Jerry: Succoring a Soroban

Carl & Jerry: Succoring a Soroban, March 1963 Popular Electronics - RF CafeDo you know what a soroban is? I have to admit ignorance prior to reading this 1963 "Carl and Jerry" adventure in Popular Electronics. As with many of these stories, real equipment, people, and companies were referenced; this time it was the Pastoriza Personal Analog Computer, a modular electronics system for calculating differential equations. The cost was around $300 (~$2,700 in c2021 money per BLS Inflation Calculator). Analog Devices bought the company from James Pastoriza in 1969. What does the Pastoriza computer have to do with the story, you might ask? Nothing, really; it was mentioned in a discussion Carl and Jerry had when accepting a calculating speed challenge from obnoxious dormitory mate, Bruce. Jerry would add a series of numbers on his soroban while Bruce would add them with a pencil and paper. The winner got bragging rights...

Transmission Line Matching

Transmission Line Matching, September 1958 Radio-Electronics - RF CafeHere is a short tutorial on how to design a resistive impedance matching circuit for feeding multiple transmission lines of equal impedance. Both series and parallel feeds are presented. As the author mentions, ideally you would like a lossless transformer for matching, but often a resistive network is acceptable, especially if receive signal power is not an issue and if your transmitter power is sufficient to overcome the resistive losses (and doesn't torch the resistors). It is also possible to match transmission lines of different impedances, but the equation would get messy. Although it would mean even more resistive loss, the simplest way to match unequal impedance lines is to first match to a value most of the lines exhibit, then build a separate resistive transformer for the line(s) that are different to connect between the main match network and the unequal line(s)...

How to Target RFCafe.com for Your Google Ads

Google AdSense - it makes good sense - <em>RF Cafe</em>One aspect of advertising on the RF Cafe website I have not covered is using Google AdSense. The reason is that I never took the time to explore how - or even whether it is possible - to target a specific website for displaying your banner ads. A couple display opportunities have always been provided for Google Ads to display, but the vast majority of advertising on RF Cafe is done via private advertisers. That is, companies deal with me directly and I handle inserting their banner ads into the html page code that randomly selects and displays them. My advertising scheme is what the industry refers to as a "Tenancy Campaign," whereby a flat price per month is paid regardless of number of impressions or clicks. It is the simplest format and has seemed to work well for many companies. With nearly 4 million pageviews per year for RFCafe.com, the average impression rate per banner ad is about 225,000k per year (in eight locations on each page, with >17k pages)...

Semiconductor Quiz

Semiconductor Quiz, February 1967 Popular Electronics - RF CafeOut of the nearly half a hundred quizzes I have posted from vintage Popular Electronics magazines, this Semiconductor Quiz that appeared in a 1967 issue is the first I can remember that was not created by Robert P. Balin. A fellow named Warren Todd made it. If you are younger than maybe 50 years old, symbols B and I might stump you, but the rest are still pretty common. Some of the labels (names) presented in the quiz are a little outdated so I have identified the abbreviations for you. That will make things much easier. For example, SBS is a silicon bidirectional switch. Bonne chance...

After Class: Working with Selenium Rectifiers

After Class: Working with Selenium Rectifiers, September 1957 Popular Electronics - RF CafePer Wikipedia, "A selenium rectifier is a type of metal rectifier, invented in 1933. They were used to replace vacuum tube rectifiers in power supplies for electronic equipment, and in high current battery charger applications. The photoelectric and rectifying properties of selenium were observed by C. E. Fitts around 1886 but practical rectifier devices were not manufactured routinely until the 1930s. Compared with the earlier copper oxide rectifier, the selenium cell could withstand higher voltage but at a lower current capacity per unit area." Electronics magazines of the era published many articles about selenium rectifiers...

The Walkie-Talkie

The Walkie-Talkie, March 1955 Popular Electronics - RF CafeJust as early cellphones (Motorola's Bag Phone, e.g.) required large carrying cases to contain both the large electronics and the large battery required to operate the phone, some of the first commercially available portable personal radio sets came with shoulder straps. Those that didn't have straps had wheels and a handle. The "walkie-talkie" (originally called "handi-talkies") designs were first seen during World War II and then in Korea. In fact, this 1955 article from Popular Electronics was printed shortly after the end of the conflict in 1953. Don't confuse the radio-based portable field telephones with the ones that had a pair of wires (sometimes thousands of feet of it) that did not need complicated circuitry for over-the-air transmitting and receiving...

X-Rays from TV Sets - Are They Harmful?

X-Rays from TV Sets - Are They Harmful?, November 1958 Radio News - RF CafeMost of us are likely familiar with the ongoing debate over whether radiation from cellphones, Wi-Fi routers and laptop computers, cell towers, smart meters, and other such modern gadgetry is harmful to humans. It is not ionizing radiation like nuclear decay, but there are heating effects that can cause damage under the right conditions. One week news breaks from the latest organization shocking the public with proof of tissue cell damage to brain, hand, face, eyeball, and groin tissue (from laptops). The next week brings a counter report refuting apocalyptic claims of previous studies... then the cycle repeats. Early in the age of ubiquitous wireless devices, those seeking to mitigate worries of radiation argued - somewhat correctly - that enough time had not yet passed to collect statistically meaningful data. If significant harm could be proven right away, dismissing the empirical results...

The Field That Stays at Home

The Field That Stays at Home, April 1942 QST - RF CafeHere is a really good introductory article on electromagnetic (EM) fields as they pertain to inductors, transformers, and antennas. It appeared in the April 1942 edition of QST magazine. The FCC had only been in existence for eight years at the time and was pretty much just figuring out how to regulate the heck out of everything. The author discusses compliance issues for these newfangled RF devices that were becoming more and more numerous. Interestingly, the first sentence says, "Every time you threw the transmitting switch in pre-war days...," bringing to mind how the Feds banned Amateur Radio during most of World War II for security reasons as well as to assure that scarce resources went toward building and servicing military gear as needed. Many Hams offered their gear either as a donation...

How's Your Radio Geography?

  How's Your Radio Geography? August 25, 1945 Saturday Evening Post - RF CafeWith a cover date of August 25, 1945, this issue of The Saturday Evening Post obviously went to print some time prior to the dropping of the two nuclear bombs on Japan that ended World War II. Victory in Japan Day (V-J Day), was August 14, 1945. There is no hint inside the magazine that the end of the war was nigh. There were, however, plenty of ads by companies touting their contributions to the war, and even some ads, particularly food ads, anticipating the end of rationing. Within this edition is also a short quiz entitled, "How's Your Radio Knowledge?" The author, Captain James F. C. Hyde, Jr., challenges readers to identify the locations of radio stations just by looking at their call signs. As is done today, most stations attempt to get call signs that are relevant to their location...

Mary Burke, W3CUL Wins 1956 Edison Award

Mary Burke, W3CUL Wins 1956 Edison Award, April 1957 Radio & TV News - RF Cafe$5,000 in 1956 currency is equivalent to about $46,000 in 2020, per the U.S. Bureau of Labor Statistics' "Inflation Calculator." That is the value of the amateur radio equipment used by Mrs. Mary Burke in her work handling "an average of 3000 messages per month, principally for service personnel overseas." For her tireless wireless efforts, she was the first woman to win the coveted Edison Award Cup (sponsored by General Electric). Most of Mrs. Burke's communications was via Morse code, where she restrained herself to "about 30 words a minute to maintain accuracy". Way to go, Mary!

Amateur Radio Crossword Puzzle for June 14

Amateur Radio Crossword Puzzle for June 14, 2020 - RF CafeEach week, for the sake of all avid cruciverbalists amongst us, I create a new technology-themed crossword puzzle using only words from my custom-created lexicon related to engineering, science, mathematics, chemistry, physics, astronomy, etc. In this crossword for June 14th 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 who or that is directly related to this puzzle's theme, such as Hedy Lamarr or the Bikini Atoll, respectively. Enjoy!

Ruggedized VNA Cables to Replace the Tired and Worn!

Replacement Ruggedized VNA Cables up to 40 GHz, 1-30-2018 - RF CafePrecision Ruggedized VNA Cables from ConductRF offer RF Engineers great alternatives to costly OEM cables that are now past their best days. We have many standards for applications at 18 GHz, 27 GHz and 40 GHz. Our torque resistant connector heads and phase stable constructions ensure great performance for many tests to come. ConductRF VNA series provides customers with reliable ruggedized solutions for lab and production VNA testing...

Field-Effect Transistors

Field-Effect Transistors, October 1966 QST - RF CafeThe concept of a field effect transistor (FET) has been around in theory for a long time*, but manufacturable devices arrived in designers' labs not until the early 1960s. This article from the October 1966 edition of QST magazine gives a good introduction to the physics of a basic FET as well as the junction FET (JFET) and the insulated gate FET (IGFET), all of which are still in widespread use today. What you learn about them here is applicable today. In fact, I swear some of the drawings are the same ones that appeared in my college semiconductor physics text books (admittedly from the late 1980s, so not too much of a surprise)...

Spectral Domain Simulation Vitally Important When Designing Complex Systems

Why Using Spectral Domain Simulation is Vitally Important When Designing Complex RF, Microwave, and Wireless Systems (by Ed TRoy) - RF CafeEd Troy, owner of Aerospace Consulting, was kind enough to offer a few of his articles for posting on RF Cafe. With more than 30 years in the electronics communications design field, Ed has a lot of valuable knowledge to impart to us mortals ;-) This third paper demonstrates why using a highly capable software simulator for system design work is essential because of its ability to predict and facilitate mitigation of system-generated problems prior to building and testing the prototype. Case in point are spurious spectral components generated by the local oscillator and SSB to PM conversion created in a frequency doubler circuit. This paper was adapted from an example circuit provided in Keysight (formerly Agilent) Genesys Spectrasys. Spectrasys is a spectral domain block diagram simulator that allows the user to construct a system model and quickly determine the system performance. Whether you are involved...

Mac's Radio Service Shop: Summer Seminar

Mac's Radio Service Shop: Summer Seminar, June 1956 Radio & Television News - RF CafeSummer begins this week in the northern hemisphere, and winter begins south of the equator. Counterintuitive to northerners not familiar with the geometric cause of seasons (axis tilt) is that the Earth is actually closest to the sun in January than it is in July. Our orbital path is nearly circular, with an eccentricity of just 0.0167. Anyway, I thought the onset of summer would be a good time to post this installment of Mac's Radio Service Shop entitled, "Summer Seminar." Typical of author John Frye's techno-sagas, more than one theme runs through the story. It begins with shop owner Mac admonishing technician Barney for throwing away a faulty selenium rectifier when he knows there is an industry-wide shortage on supplies of the element and the bad components should be submitted for recycling. Fretting over as common an element ...

Japan Short-Wave Phone to America Open

Japan Short-Wave Phone to America Open, March 1935 Short Wave Craft - RF Cafe"Tokyo is now a next-door neighbor-thanks to the magic of short-waves." That statement was made in a 1935 edition of Short Wave Craft magazine after the American Telephone and Telegraph (AT&T) company completed its wireless phone (voice) link between the U.S. and Japan; which is the first 'T' in AT&T. Most people today would probably have a hard time guessing that the second 'T' in AT&T stands for 'telegraph.' Its surprising that the name has not been changed to reflect the outdated-ness. Western Union sent its final telegraph in 2006. Another news headline a couple years ago reported on India sending its final official telegraph message...

Engine Detonation Indicator

Engine Detonation Indicator, Sperry Gyroscope Company, June 1945 Radio-Craft - RF CafeElectronics has dominated our lives ever since the first commercially available radios became available in the early twentieth century. It was a mysterious miracle science then and still is today. Most people have no understanding of electronics; they just know that life without it is unimaginable. Fantastic new applications for electronics are continually being introduced to supplement or replace mechanical devices. Sensing and control are prime applications for electronics that improve functionality and safety. This promotion of the MIT-Sperry Detonation Indicator, aka the "Knock-O-Meter," is a good example. It appeared in a 1945 issue of Radio-Electronics magazine, near the end of World War II. Today, such a name invokes chuckles and usually implies a joke of a product, but not so at the time...

Analysis of Radio Interference Phenomena

Analysis of Radio Interference Phenomena, June 1946 Radio News - RF CafeImage response, harmonic of the IF, direct IF response, harmonics of the oscillator, combination of the IF, heterodyne oscillator radiation, cross modulation within the receiver, cross modulation external to the receiver, same channel beat, adjacent channel beat and "monkey chatter" are all sources of radio interference addressed in this article that appeared in a 1946 edition of Radio News. I don't know about you, but I've never heard of the term 'monkey chatter.' According to the troubleshooting table it is, "Unintelligible modulation superimposed upon desired station, having the character of 'inverted speech'." Recommendations on how to mitigate "monkey speech" are provided...

The Citizens Radiocommunication Service

The Citizens Radiocommunication Service, March 1945 QST - RF CafeIt's hard to imagine a time when unlicensed radio frequency bands were not the norm, but early in the history of radio, strict spectrum control was necessary in order to prevent unintentional radiation from crappy equipment from interfering with services. Remember that even in the mid 1940s, many, if not most, casual users were cobbling together their own transmitters and receivers from scratch. Transmitter powers were easily high enough to interfere with nearby and distant receivers, but even improperly shielded receiver oscillator ("exciters") could cause interference with a neighbor's nightly Lone Ranger broadcast. Around 1945, the FCC began entertaining the idea of allocating bandwidth for the use of the newfangled "walkie-talkies" that were developed for field communications during World War II. This 460 to 470 MHz band was the first of the Citizens' Bands that eventually...

Crane Aerospace Electronics Microwave Solutions


Amplifier Solutions Corporation (ASC) - RF Cafe

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