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Homepage Archive - February 2026 (page 1)

See Page 1 | 2 | of the January 2026 homepage archives.

Friday the 6th

Thursday the 5th

Wednesday the 4th

Tuesday the 3rd

Statistical Measurement Techniques

Electronic Measurements Using Statistical Techniques, June 1968 Electronics World - RF CafeI 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...

Radio Telemechanics

Radio Telemechanics, September 1934 Radio-Craft - RF CafeOnce 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...

Century-Old Solar Records Refine Cycle Forecasts

Century-Old Solar Records Refine Future Cycle Forecasts - RF Cafe"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..."

IF Coil & Transformer Design

I.F. Coil & Transformer Design, April 1932 Radio-Craft - RF CafeThe 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...

Beware the Service Gyp!

Beware the Service Gyp!, September 1934 Radio-Craft - RF CafeRepair service businesses have always gotten a bad rap for deliberately inflating part and labor costs - often deservingly so - but it's a shame the honest brokers are dragged down by the scum (or "gyps" as this article calls them). Come to think of it, the word "gyp" is likely short for "gypsy," which is sure to offend someone these days. Along with admonishing customers to beware of shyster servicemen, there is an example of an orchestrated "sting" operation whereby a radio set was intentionally "broken" in a certain way with witnesses as to the fault, and then a couple dozen repair services were called upon to troubleshoot and fix it, then present a bill for their work. The result is interesting, and even resulted in one guy being...

Famous Radio Beginners

Famous Radio Beginners, March 1936 Radio-Craft - RF CafeThis is an all-star cast of radio pioneers if there ever was one. It's not comprehensive by any means, but most of the first-string players are here in this 1936 Radio-Craft article. One thing I like about reading these old pieces is that they, for the most part, are reporting on contemporary events; they are not merely a historian's interpretation of what the original witnesses recorded. That is not to say early writers did not editorialize, err, or outright lie about content, but I give these guys the benefit of the doubt based on the sources. You have certainly heard of people like Hertz, deForest, and Marconi, but what about coherer (early detector) inventor Edouard Branly and ground-breaking commercial radio broadcast engineer Frank Conrad? Magazine editor, publisher, and inventor Hugo Gernsback properly give a short...

Join Now! The Official Radio Service Men's Association, Inc.

Official Radio Service Men's Association, Inc., April 1932 Radio-Craft - RF CafeAs the advertisement for membership in the Official Radio Service Men's Association says, structured organizations for people of like mind and interests have long been the hallmark of an advanced society where there is a need for directed socialization and the 'strength in numbers' benefit. I suppose most people reading this piece belong to at least one such association like the Institute for Electrical and Electronics Engineers (IEEE), American Radio Relay League (ARRL), Armed Forces Communications and Electronics Association (AFCEA), Association of Old Crows (AOC), Electronics Technicians Association (ETA), etc. Having significant representation in government in the form of lobbyists is essential these days in order to obtain and retain fair treatment...

Radio Telescope on the Moon

Lunar Radio-Telescope - RF Cafe"Isolation dictates where we go to see into the far reaches of the universe. The Atacama Desert of Chile, the summit of Mauna Kea in Hawaii, the vast expanse of the Australian Outback -- these are where astronomers and engineers have built the great observatories and radio telescopes of modern times. The skies are usually clear, the air is arid, and the electronic din of civilization is far away. It was to one of these places, in the high desert of New Mexico, that a young astronomer named Jack Burns went to study radio jets and quasars far beyond the Milky Way. Could there be a better, even lonelier place to put a radio telescope? Sure, a NASA planetary scientist named Wendell Mendell, told Burns: How about the moon..."

Chebyshev Filter Equations for Magnitude, Phase, and Group Delay

Chebyshev Filter Equations for Magnitude, Phase, and Group Delay - RF CafeFor decades - literally - I searched in vain for explicit , but could never find more equations for calculating Chebyshev filter phase and group delay than textbook definitions, with instruction to extract phase from the real and imaginary parts of the magnitude equation, and then take the negative first derivative of the phase to get group delay. A lot of good that did - not! I have perused dozens of filter design books, to no avail. Even the filter bible - Zverev's Handbook of Filter Synthesis - did not provide the needed equations. Most online resources present Mathcad, MATLAB, Mathematica, or similar scripts that call the built-in functions, without exposing the gory detail behind them. What I wanted was something I could implement in a spreadsheet or a program. Finally, with the help of AI (through many iterations of...

Planetary Exploration Crossword Puzzle

2015 Planetary Exploration Crossword Puzzle for July 19, 2015 - RF CafeNews services have been busy lately reporting on the latest feat of America's national space agency's resounding success with its interplanetary space probe's closest encounter with our solar system's most remote [minor] planet. Prior to the flyby, even the most powerful Earth- and space-based telescopes could never resolve more than a few lightly contrasted splotches on the celestial orb's surface, and its largest moon was a few pixels worth of indeterminate light. All that changed on July 14, 2015. We now have, for the first time ever, high resolution images of the surface, and are in the process of collection terabits worth of additional physical data from onboard instruments. No doubt many Ph.D.'s will be earned through assimilation...

Many Thanks to Amplifier Solutions Corporation for Continued Support!

Amplifier Solutions Corporation (ASC) - RF CafeAmplifier Solutions Corporation (ASC) is a manufacturer of amplifiers for commercial & military markets. ASC designs and manufactures hybrid, surface mount flange, open carrier and connectorized amplifiers for low, medium and high power applications using Gallium Nitride (GaN), Gallium Arsenide (GaAs) and Silicon (Si) transistor technologies. ASC's thick film designs operate in the frequency range of 300 kHz to 6 GHz. ASC offers thin film designs that operate up to 20 GHz. ASC is located in an 8,000 sq.ft. facility in the town of Telford, PA. We offer excellent customer support and take pride in the ability to quickly react to evolving system design requirements.

Monday the 2nd

Mac's Service Shop: The Customer Revolt

Mac's Service Shop: The Customer Revolt, November 1969 Electronics World - RF CafeIn the late 1960s, there was evidently a brewing consumer revolt against shoddy merchandise, worthless warranties, and sloppy service. Mac attributed this to a post-WWII seller's market fueled by wartime shortages, black markets, and inflation. Many workers had pent-up money to spend on products not readily available during the war. Ensuing conflict eras like Korea and Vietnam prioritized volume production and advertising over quality. Demand escalated prices. Customers, once kings in a competitive free-enterprise system, became expendable amid abundant demand. By 1969, when this story appeared in Electronics World magazine...

Electronics-Themed Comics

Electronics-Themed Comics, October 1961 Electronics World & October 1956 Popular Electronics - RF CafeHere are three electronics-themed comics from vintage issues of Electronics World and Popular Electronics magazines. My favorite is the page 84 comic where the sign on the Telco Rectifier Components president's wall is apropos. Maybe one of the interview questions for job applicants was #1: "Did you notice the sign on the wall in the waiting room," and #2: "Did you 'get it?,' and please explain." In 1956 when that comic appeared, AC-to-DC power supplies used high voltage vacuum tubes, typically 300 volts or more. Hefty capacitors were needed to remove enough ripple from the "top" of the DC to render it undetectable in the circuit output - especially if the output was audio where a 60 or 120 Hz (50 or 100 Hz in Europe) "hum"...

Manufacturing Electronics on the Moon

Manufacturing Electronics on the Moon - RF Cafe"Future lunar missions face a fundamental challenge: the high cost and difficult transport of materials from Earth. Now, a new project supported by the European Space Agency (ESA) will demonstrate how lunar soil -- after releasing its oxygen for rocket propulsion and potentially air for astronauts -- can also be converted into metal-rich compounds which can conduct electricity. This compound can either be transformed to inks for printing electronic circuits or powder for 3D printing of larger components. Danish Technological Institute..."

Not Quite Grasping the Concept...

A mathematics professor explained to students through various lectures and examples:

Not Quite Getting It (math limit problem) - RF Cafe

It became obvious not everyone understood after one student submitted the following on a pop quiz:

Not Quite Getting It (math limit answer) - RF Cafe

 - originator unknown. 

Microelectronics Circa 1963

Microelectronics, January 1963 Electronics World - RF CafeIt seemed weird to read of microelectronics device density expressed in parts per cubic foot of semiconductor substrate. Describing density that way makes some sense when considering 3-dimensional devices with vertically stacked elements, but this was in a 1963 article in Electronics World, so that could not have been the case. The motivation, evidently was to be able to compare microcircuit density with that of the human brain in terms of neuron density. In fact, there is an interesting chart presented that shows the evolution in circuit density beginning with vacuum tube circuits, progressing through the state of the art in 1963, projecting for future years, and finally peaking with the brain's density. Interestingly, the brain density shows as about 5x1011/ft3, while the "nonredundant semiconductor device" limit is...

Thanks to LadyBug Technologies for Continued Support!

LadyBug Technologies RF Power Sensors - RF CafeLadyBug Technologies was founded in 2004 by two microwave engineers with a passion for quality microwave test instrumentation. Our employees offer many years experience in the design and manufacture of the worlds best vector network analyzers, spectrum analyzers, power meters and associated components. The management team has additional experience in optical power testing, military radar and a variety of programming environments including LabVIEW, VEE and other languages often used in programmatic systems. Extensive experience in a broad spectrum of demanding measurement applications. You can be assured that our Power Sensors are designed, built, tested and calibrated without compromise.

Sunday the 1st

Espresso Engineering Workbook™ v2.2.2026

Espresso Engineering Workbook™ for Excel - RF CafeBreaking News! Espresso Engineering Workbook™ v2.2.2026 has just been released. This makes the 49th worksheet added. It calculates magnitude, phase, and group delay for Chebyshev Type 1 lowpass, highpass, bandpass, and bandstop filters. Outside of the kilobuck simulators, finding a calculator for phase and group delay is extremely difficult - believe me, I've searched extensively for years. It also has a Butterworth filter for the same. Espresso Engineering Workbook™ can be downloaded free of charge. All you need is Excel™ v2007 or newer. It is provided compliments of my advertisers. Contact me if you would like your company added to the next release.

 

Making Modern Tubes

Making Modern Tubes, June 1932 Radio-Craft - RF CafeIn 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...

--The Lorentz Force

Hendrik Antoon Lorentz - RF CafeHere 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...

The Skin Effect Talking Lightbeam

The Skin Effect Talking Lightbeam, January 1939 Radio-Craft - RF CafeModulating 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...

New Radio Altimeter Increases Air Safety

New Radio Altimeter Increases Air Safety, January 1939 Radio-Craft - RF CafeIn 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...

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Trade Secrets: The Courts and You, June 1968 Electronics World - RF CafeThis 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...

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2015 August - 1

 

 

Highest Thermal Conductivity Metal Found

Highest Thermal Conductivity Metal Found - RF Cafe"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..."

Compostable Electronic Circuit Board

Compostable Electronic Circuit Board - RF Cafe"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..."

Flexible RF Switch for 6G Communication

Flexible RF Switch for 6G Communication - RF Cafe"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)..."

Antenna Impedance Change Gesture Detection

Antenna Impedance Change Gesture Detection - RF Cafe"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..."

Donut-Shaped Light for More Reliable Wireless

Donut-Shaped Light Could Make Wireless Signals Far More Reliable - RF Cafe"A new metasurface lets scientists flip between ultra-stable light vortices, paving the way for tougher, smarter wireless communication. Scientists have developed a new optical device capable of producing two different types of vortex-shaped light patterns: electric and magnetic. These unusual light structures, called skyrmions, are known for their exceptional stability and resistance to interference. Because they hold their shape so reliably, they are strong candidates for carrying information in future wireless communication systems. 'Our device not only generates more than one vortex pattern in free-space-propagating..."

Twisting Crystal Changes Electricity Flow

Twisting a Crystal at the Nanoscale Changes How Electricity Flows - RF Cafe"Scientists have shown that twisting a crystal at the nanoscale can turn it into a tiny, reversible diode, hinting at a new era of shape-engineered electronics. Researchers at the RIKEN Center for Emergent Matter Science, working with collaborators, have created a new technique for building three-dimensional nanoscale devices directly from single crystals. The approach uses a focused ion beam instrument to precisely carve materials at extremely small scales. Using this method, the team shaped tiny helical structures from a topological magnetic material made of cobalt, tin, and sulfur, known by its chemical formula Co3Sn2S2..."

2D Transistor Transforms Logic, Power Devices

2D Transistor Transforms Logic, Power Devices - RF Cafe"CDimension recently unveiled a technology that enables conventional semiconductor fabs to use ultra-thin semiconductor materials to manufacture vertically integrated arrays of extremely small, fast, and efficient "2D" transistors. It has the potential to change what's possible for both digital and power devices. According to the company, it's already helping several chipmakers explore how to apply their technology to produce digital and analog ICs that offer dramatically higher logic densities, operating speeds, and energy efficiency..."

DIY Stratosphere Pico Balloon

DIY Stratosphere Pico Balloon - RF Cafe"There's an interesting development in amateur ballooning: using so-called superpressure balloons, which float high in the atmosphere indefinitely rather than simply going up and up and then popping like a normal weather balloon. Superpressure balloons can last for months and travel long distances, potentially circumnavigating the globe, all the while reporting their position. You might imagine that an undertaking like this would be immensely difficult and cost thousands of dollars. In fact, you can build and launch such a balloon for about the cost of a fancy dinner out. You just have to think small! That's why amateur balloonists call them pico balloons. The payload of a pico balloon is so light..."

Steerable Beam "Leaky" 6G Chip

"Leaky" 6G Chip Tech Beats Narrow Terahertz Beam Constraints - RF Cafe"Sixth-generation wireless networks, or 6G, are expected to achieve terabit-per-second speeds using terahertz frequencies. However, to harness the terahertz spectrum, complicated device designs are typically needed to establish multiple high-speed connections. Now research suggests that advanced topological materials may ultimately help to achieve such links. The experimental device the researchers have made, in fact, achieved 72 gigabits-per-second data rates, and reached more than 75% of the three-dimensional space around it. Current solutions typically achieve only one or two of these features at a time and often rely on complex antenna arrays or mechanical steering..."

Blue Ghost Lunar Radio Telescope

Blue Ghost Lunar Radiotelescope - RF Cafe"Firefly Aerospace's Blue Ghost Mission 2 with the LuSEE-Night radio telescope aboard will attempt to become the third successful mission to land there. The moon's far side is the perfect place for such a telescope. The same RF waves that carried images of Neil Armstrong setting foot on the lunar surface, Roger Waters's voice, and hundreds of Ned Potter's space and science segments for the U.S. broadcast networks CBS and ABC interfere with terrestrial radio telescopes. If your goal is to detect the extremely faint and heavily redshifted signals of neutral hydrogen from the cosmic Dark Ages, you just can't do it from Earth..."

EW Vying for Control of EM Spectrum

Electronic Warfare: Vying for Control of the Electromagnetic Spectrum - RF Cafe"Advanced threats lead to open architecture approaches and new analysis of electronic countermeasures. Over the past decade, preeminent countries involved in major military conflicts mainly focused on asymmetrical warfare - surprise attacks by small groups armed with modern, high-tech weaponry. During that same period, however, near-peer adversaries began attaining impressive electronic warfare (EW) capabilities. As a result, a plethora of new, dynamic threats flooded the EW spectrum, pushing threat detection and analysis to keep pace. Large military forces must now engage in ongoing..."

 

 

 

 

 

 

 

 

 

 

 

 

 

 


These archive pages are provided in order to make it easier for you to find items that you remember seeing on the RF Cafe homepage. Of course probably the easiest way to find anything on the website is to use the "Search RF Cafe" box at the top of every page. Some quoted items have been shortened to save space. About RF Cafe.

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- Christmas-themed items

KR Electronics (RF Filters) - RF Cafe


Innovative Power Products (IPP) Directional Couplers - RF Cafe

Tennode RF Connectors and Cables - RF Cafe