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About RF Cafe

Kirt Blattenberger - RF Cafe Webmaster

Copyright: 1996 - 2024


    Kirt Blattenberger,


RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

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Today in Science History

Tech Industry Headlines

Tech Industry Headlines - RF Cafe - Archive -

• China to Boost Tech Research to Best U.S. Industry

• Apple Set to Kill off Lightning Port

• Transistors Integrating High-k Perovskite Oxides and 2D Semiconductors

• Manufacturers and Distributors Optimistic About Future

• Top 5G Wireless Growth Companies in 2022

• Electronic Component Counterfeiting is Big Business

• Ofcom Opens Door for mmWave 5G in UK

• Integrated Lasers Could Make Computers 106x Faster

• T-Mobile Touts 99% Coverage for LTE

Hi-Fi Record Care

Hi-Fi Record Care, July 1958 Radio-Electronics - RF CafeThe proper care and feeding of vinyl records was - and still is - a big topic amongst audiophiles. As with so many things, phonographs and platters have experienced a resurgence in popularity in the couple decades as the world gets nuttier and people crave for a simpler, saner time - imagined or otherwise. I remember back in the barracks at Robins AFB, GA, where there was always at least one guy who would have a very extensive (pronounced "expensive") stereo setup complete with an equipment rack, reel-to-reel tape player, dual cassette tape deck, super-sensitive AM/FM receiver with a huge tuning knob on the front, a turntable with a precisely balanced and weighted tone arm (with a stylus that cost two month's pay for an enlisted man), a multi-hundred watt power amplifier that never had the opportunity to put out more than a small percentage of its capability due to barracks noise rules, a patch cable panel for routing signals, and monster speakers...

Glass Semiconductors Developed

Glass Semiconductors Developed, January 1969 Radio-Electronics - RF CafeThe term "ovonic" - a fairly unfamiliar word these days - appeared in the May edition of Radio-Electronics, in an article entitled, "All About Ovonics," just a few months after this news item ran in the January issue (which I posted last month). Ovonics is a portmanteau of "Ovshinsky" (from Stanford R. Ovshinsky, the inventor) and "electronics." Read the "All About Ovonics" article for a deeper dive into the subject. The big deal, which turned out to be not a big enough deal, was the use of amorphous (strangely spelled "amphorous") glassy compounds as semiconductors rather than the standard crystalline silicon structures. Maybe someday an enterprising genius inventor type will give a rebirth to the concept...

Building NASA's Next Communications Network

Building NASA's Next Communications Network - RF Cafe"It was a great idea for its time - a network of NASA communications satellites high in geostationary orbit, providing nearly continuous radio contact between controllers on the ground and some of the agency's highest-profile missions: the space shuttles, the International Space Station, the Hubble Space Telescope, and dozens of others. The satellites were called TDRS - short for Tracking and Data Relay Satellite - and the first was launched in 1983 on the maiden voyage of the space shuttle Challenger. Twelve more would follow, quietly providing a backbone for NASA's orbital operations. But they've gotten old, they're expensive, and in the 40 years since they began, they've been outpaced by commercial satellite networks. So what comes next? That's the $278M question - but, importantly, it's not a multibillion-dollar question..."

Antenna Matching with Line Segments

Antenna Matching with Line Segments, September 1948 QST - RF CafeHow RF circuits work have long been referred to as "black magic," even sometimes by people who fully understand the theory behind the craft. To me, the ways in which a transmission line - be it coaxial cable, microstrip, or waveguide - can be manipulated and controlled with various combinations of lengths and terminations is what most qualifies as "magic." Sure, I know the equations and understand (mostly) what's happening with incident and reflected waves, etc., and how the impedance and admittance circles of a Smith chart graphically trace out what's happening, but you have to admit there's something mystical about it all. Fortunately, Mr. John Marshall published this "Antenna Matching with Line Segments" article in the September 1948 issue of QST magazine...

Anatech Intros 3 Filter Models for Mid-May 2022

Anatech Electronics Intros 3 Filter Models for Mid-May 2022 - RF CafeAnatech Electronics offers the industry's largest portfolio of high-performance standard and customized RF and microwave filters and filter-related products for military, commercial, aerospace and defense, and industrial applications up to 40 GHz. Three new filter models have been introduced - a cavity bandpass filter with a bandwidth of 15 MHz ±2 MHz, an insertion loss of 3.5 dB; a ceramic duplexer with a Band 1 frequency of 824 to 835 MHz and a Band 2 frequency of 869 to 880 MHz; and an LC highpass filter with a pass band of 402 to 1500 MHz with an insertion loss of less than 1.0 dB. Custom RF power directional coupler designs can be designed and produced when a standard cannot be found, or the requirements are such that a custom approach is necessary...

War Assets Administration Advertisement

War Assets Administration Advertisement, February 1947 Radio News - RF CafeUnlike today when resources of all types seem to be endlessly available, during World War II countries needed to collect and recycle much in the way of metal, rubber, cloth, and other basic materials for re-purposing into products used in fighting the enemy. Media coverage of bottle, metal, and tire drives showed children pulling Radio Flyer wagons loaded to overflowing with such items gathered from trash piles and soliciting neighborhood residents for anything that could be spared. Raw materials were not the only type of items needed, however. "Use it up, Wear it out, Make it do, or Do without" was the slogan. Finished goods like electronic components - vacuum tubes, transmissions cable, transmitters and receivers, tuning capacitors, d'Arsonval meter movements, and other parts - were sorely needed by manufacturers both for building new equipment and for servicing damaged gear. After the war was won, the War Assets Administration made good on the government's promise to reward citizens for performing their patriotic duty. This four-page spread in a 1947 edition of Radio News is an example of the effort to make surplus components available...

RF & Electronics Symbols for Office™

RF & Electronics Schematic & Block Diagram Symbols for Office™ r2 - RF CafeIt was a lot of work, but I finally finished a version of the "RF & Electronics Schematic & Block Diagram Symbols" that works well with Microsoft Office™ programs Word™, Excel™, and Power Point™. This is an equivalent of the extensive set of amplifier, mixer, filter, switch, connector, waveguide, digital, analog, antenna, and other commonly used symbols for system block diagrams and schematics created for Visio™. Each of the 1,000 or so symbols was exported individually from Visio in the EMF file format, then imported into Word on a Drawing Canvas. The EMF format allows an image to be scaled up or down without becoming pixelated, so all the shapes can be resized in a document and still look good. The imported symbols can also be UnGrouped into their original constituent parts for editing. Check them out!

Many Thanks to Withwave for Long−Time Support!

Withwave RF & Microwave Components - RF CafeWithwave manufactures an extensive line of metrology quality coaxial test cable assemblies, connectors (wave-, end-, vertical-launch, board edge, panel mount), calibration kits (SOLT), a fully automated 4-port vector network analyzer (VNA) calibrator, between- and in-series connector adaptors, attenuators, terminations, DC blocks, torque wrenches, test probes & probe positioner. Special test fixtures for calibration and multicoax cable assemblies. Frequency ranges from DC through 110 GHz. Please contact Withwave today to see how they can help your project succeed.

The Amazing G-Line

The Amazing G-Line, March 1954 Radio-Electronics - RF CafeThe G−Line (aka G−String) RF transmission system is a rather amazing invention contrived through out-of-the-box thinking by its inventor, Dr. George Goubau (from whence the "G" in the name derives). 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. The G-Line is designed to efficiently transmit UHF television signals (470 - 806 MHz), and like a waveguide exhibits a lower cutoff frequency (~300 MHz), thus acting like a highpass filter. G−Line has its weak points, like that it must not come near to obstacles that will affect the dielectric-air interface or the line will radiate like an antenna. Also, over time the insulation cracks and/or absorbs moisture and changes the impedance parameters, thus affecting the transmission characteristics...

Many Thanks to Centric RF for Their Continued Support!

Centric RF microwave components - RF CafeCentric RF is a company offering from stock various RF and Microwave coaxial components, including attenuators, adapters, cable assemblies, terminations, power dividers, and more. We believe in offering high performance parts from stock at a reasonable cost. Frequency ranges of 0-110 GHz at power levels from 0.5-500 watts are available off the shelf. Order today, ship today! Centric RF is currently looking for vendors to partner with them. Please visit Centric RF today.

InGaAs/AlGaAS Nanowires on Silicon

InGaAs/AlGaAS Nanowires on Silicon - RF Cafe"Researchers based in Russia report on molecular beam epitaxy (MBE) of indium gallium arsenide (InGaAs) quantum dots/wires (QDs/QWs) in aluminium gallium arsenide (AlGaAs) nanowires (NWs) on silicon (Si) 'for the first time' [Rodion R. Reznik et al, Phys. Status Solidi RRL, p2200056, 2022]. The research team at St. Petersburg State University, Alferov University, Institute for Analytical Instrumentation RAS, Ioffe Physical Technical Institute RAS, and National Research University Higher School of Economics, have previously studied MBE synthesis of GaAs QDs inside AlGaAs nanowires on silicon. The researchers comment that these hybrid nanostructures were effective sources of single photons in a wavelength range of 750–800nm. Thus, they constitute 'promising candidates for use in quantum cryptography and alkali metal..."

CMT Bootcamp 101 Webinar: Starter mmWave Measurements

Copper Mountain Technologies Bootcamp 101 Webinar: Starter mmWave Measurements - RF CafeCopper Mountain Technologies has a webinar coming up in league with Eravant as part of our VNA 101 Bootcamp Webinar series titled "Starter mmWave Measurements." It begins on May 24, 2022, at 2 PM ET. This webinar will demonstrate Eravant's VNA frequency extenders and their ability to perform full two−port S−parameter measurements of millimeter−wave components. The example test system will include Eravant's Proxi−FlangeTM waveguide adapters, as well as the Wave−GlideTM positioning system. The VNA frequency extenders add full waveguide-band frequency coverage to several industry-standard coaxial VNAs, including models available from Copper Mountain Technologies. Proxi-Flange contactless waveguide flanges enable fast and repeatable connections between VNA frequency extenders and the waveguide components being tested. The Wave−Glide positioning system further streamlines component testing by maintaining the alignment between VNA frequency extenders and the components being tested while providing an easy and reliable method...

Build This Radioman's R-C Bridge

Build This Radioman's R-C Bridge, April 1947 Radio News - RF CafeWhile not many people are likely to build this R-C bridge circuit with vacuum tubes for use during design and troubleshooting, this 1947 Radio News magazine article has a good basic description of operation of any calibrated bridge circuit used to measure an unknown value. Interestingly, a "magic eye" or "cat's eye" tube is used in lieu of a meter movement to give a visual indication of an open, short, intermittence, poor power factor, and low "Q," as well as when the selected switch position correctly identifies the value of the resistor or capacitor under test. Note that in that era μfd = μF and μμfd = pF...

RF & Electronics Stencils for Visio

RF & Electronics stencils for Visio r4 - RF CafeWith more than 1000 custom-built stencils, this has got to be the most comprehensive set of Visio Stencils available for RF, analog, and digital system and schematic drawings! Every stencil symbol has been built to fit proportionally on the included A-, B-, and C-size drawing page templates (or use your own page if preferred). Components are provided for system block diagrams, conceptual drawings, schematics, test equipment, racks (EIA 19", ETSI 21"), and more. Test equipment and racks are built at a 1:1 scale so that measurements can be made directly using Visio built-in dimensioning objects. Page templates are provided with a preset scale (changeable) for a good presentation that can incorporate all provided symbols...

Thanks Once Again to everythingRF for Long-Time Support!

everything RF Searchable Database - RF CafePlease take a few moments to visit the everythingRF website to see how they can assist you with your project. everythingRF is a product discovery platform for RF and microwave products and services. They currently have 267,269 products from more than 1397 companies across 314 categories in their database and enable engineers to search for them using their customized parametric search tool. Amplifiers, test equipment, power couplers and dividers, coaxial connectors, waveguide, antennas, filters, mixers, power supplies, and everything else. Please visit everythingRF today to see how they can help you.

Antenna Matching with Line Segments

Antenna Matching with Line Segments, September 1948 QST - RF CafeHow RF circuits work have long been referred to as "black magic," even sometimes by people who fully understand the theory behind the craft. To me, the ways in which a transmission line - be it coaxial cable, microstrip, or waveguide - can be manipulated and controlled with various combinations of lengths and terminations is what most qualifies as "magic." Sure, I know the equations and understand (mostly) what's happening with incident and reflected waves, etc., and how the impedance and admittance circles of a Smith chart graphically trace out what's happening, but you have to admit there's something mystical about it all. Fortunately, Mr. John Marshall published this "Antenna Matching with Line Segments" article in the September 1948 issue of QST magazine...

Please Thank IPP for Their Long-Time Support!

Innovative Power ProductsInnovative Power Products (IPP) has over 35 years of experience designing & manufacturing RF & microwave passive components. Their high power, broadband couplers, combiners, resistors, baluns, terminations and attenuators are fabricated using the latest materials and design tools available, resulting in unrivaled product performance. Applications in military, medical, industrial and commercial markets are serviced around the world. Products listed on website link to detailed mechanical drawings that contain electrical specifications as well as performance data. Please take a couple minutes to visit their website and see how IPP can help you today. 

Carl & Jerry: "All's Fair --"

Carl & Jerry: "All's Fair --", September 1963 Popular Electronics - RF CafeAs is frequently the case, John T. Frye's intrepid teenage technophile experimenters, Carl Anderson and Jerry Bishop, find themselves in an unplanned adventure. Often times they end up applying their electronics knowledge to bail themselves out of trouble, but this time the pair - and a friend - ended up helping the police catch some bad guys (an oft-occurring theme). As you will see after reading "All's Fair --," the device used would some day (today) be used by automobile manufacturers, at the behest of law enforcement agencies, to enable remote control of somebody else's vehicle with a "kill switch." This technodrama appeared in the September 1963 issue of Popular Electronics magazine...

Thermomechanical Fatigue of Electronics

Thermomechanical Fatigue of Electronics - RF Cafe"The airbags in your car… the camera on your video doorbell... the phone or other electronic device you're reading this on right now. The everyday products that make modern life possible wouldn't be able to run without key electrical components maintaining functionality and stability for years at a time. And yet, these electrical components experience complex thermal and mechanical loads during the daily course of their operation, or, in the case of the airbag, during long-term passive cycles of environmental heating and cooling while they wait unused within a car's interior. As producers and consumers require ever more from electronic devices, those devices are becoming more powerful, further increasing the thermal loads being subjected to vital components..."

International Kadette Model 400

International Kadette Model 400 4-Tube Battery-Operated Superhet. Radio Service Data Sheet, July 1936 Radio-Craft - RF CafeFor a long time I have been scanning and posting schematics & parts lists like this one featuring the International Kadette Model 400 4-Tube Battery-Operated Superheterodyne radio in graphical format. As with all the other vintage articles posted, it requires running OCR on them to separate the textual content from the graphics. This particular Radio Service Data Sheet came from the July 1936 issue of Radio-Craft magazine. There are still many people who restore and service these vintage radios, and often it can be difficult or impossible to find schematics and/or tuning information. I will keep a running list of all data sheets to facilitate a search...

RF Cascade Workbook

RF Cascade Workbook - RF Cafe RF Cascade Workbook is the next phase in the evolution of RF Cafe's long-running series, RF Cascade Workbook. Chances are you have never used a spreadsheet quite like this (click here for screen capture). It is a full-featured RF system cascade parameter and frequency planner that includes filters and mixers for a mere $45. Built in MS Excel, using RF Cascade Workbook 2018 is a cinch and the format is entirely customizable. It is significantly easier and faster than using a multi-thousand dollar simulator when a high level system analysis is all that is needed. An intro video takes you through the main features...

Thanks to PCB Directory for Continued Support!

PCB  Directory - RF CafePCB Directory is the largest directory of Printed Circuit Board (PCB) Manufacturers, Assembly houses, and Design Services on the Internet. We have listed the leading printed circuit board manufacturers around the world and made them searchable by their capabilities - Number of laminates used, Board thicknesses supported, Number of layers supported, Types of substrates (FR-4, Rogers, flexible, rigid), Geographical location (U.S., China), kinds of services (manufacturing, fabrication, assembly, prototype), and more. Fast turn-around on quotations for PCB fabrication and assembly.

Antenna Testing Methods

On the Cover: Antenna Testing Methods, March 1954 Radio-Electronics - RF CafeOften, the photo on the covers of magazines is related to a feature article within, but in the case of the March 1954 Radio-Electronics, only a couple paragraphs are devoted to it. Although more commonplace back in the day, mention of a Lecher wire for measuring VSWR values of the antenna under test caused me to look it up. The Wikipedia entry says, "Lecher line or Lecher wires is a pair of parallel wires or rods that were used to measure the wavelength of radio waves, mainly at VHF, UHF and microwave frequencies. They form a short length of balanced transmission line (a resonant stub). When attached to a source of radio-frequency power such as a radio transmitter, the radio waves form standing waves along their length. By sliding a conductive bar that bridges the two wires along their length, the length of the waves can be physically measured. Austrian physicist Ernst Lecher, improving on techniques used by Oliver Lodge and Heinrich Hertz, developed...

A.C. Generator for Automobiles

A.C. Generator for Automobiles, March 1948 Radio-Craft - RF CafeAC alternators replaced DC generators back in the 1940s as demand for conditioned electrical power in vehicles rose beyond that needed for ignition and lighting. Radios are the most notable additions, and because amplitude modulation (AM) broadcasts were the dominant method of the day for commercial stations, noiseless electrical supplies were required. Spark-induced noise from ignition systems was bad enough since its frequency varied with engine RPM, but the DC generator's commutator sparking noise - much of it right smack in the audio frequency range - was just too much for the public to endure if widespread acceptance of radio was to be realized. Remember that in the era, a radio was not standard equipment in cars and trucks so customers needed to be convinced the extra expense would be worth their hard-earned dollars. Use of a 3-phase alternator reduces the component performance requirements for conversion to DC...

Simple Superconducting Circuit Emits Multiple Photons

Simple Superconducting Circuit Emits Multiple Photons - RF Cafe"An on-chip circuit that can produce up to six microwave photons simultaneously has been created by researchers in France and Germany. Gerbold Ménard and Ambroise Peugeot at the University of Paris-Saclay and colleagues built their device by connecting a Josephson junction to a microwave resonator. While the team did not establish that the photons are entangled, previous research suggests that the device could be a source of multiple entangled photons. The ability to produce pairs of entangled photons is vital for many quantum technologies. Most often, it involves a technique called parametric down-conversion, whereby a single photon is split into two lower-energy photons after interacting with a nonlinear optical medium. This technique could be used to produce higher numbers of entangled photons, but such a system would be bulky and complex. Ménard, Peugeot and colleagues have now shown that multiple photons can be produced..."

Crosley "Chief" Model 132−1

Crosley "Chief" 12-Tube Model 132-1 12-Tube Superheterodyne Radio Service Data Sheet, February 1933 Radio-Craft - RF CafeIn a continuing effort to provide archival material for researchers and for anyone seeking information on a particular radio restoration project, this Radio Service Data Sheet for the Crosley "Chief" Model 132-1 radio from a 1933 edition of Radio-Craft is being posted. An Internet search will show that there are many people engaging in such activities. Restoring my Crosley Model 03BC console radio would have been more difficult if not for others who have done similar work to assist the "community." I generally despise the phrase "giving back" because it is usually uttered by people that really owe nothing to anyone, but somehow feel obligated to do so or are conditioned to automatically say such things. This is a case where I benefitted from somebody else's work and there is an opportunity to return the favor...

Antenna and Radome Design Engineer Needed by Raytheon

Antenna and Radome Design Senior Engineer Needed by Raytheon Missiles & Defense - RF CafeThe candidate will be responsible for leading and shaping antenna, radome, and antenna measurement system technology within the Company. The selected Antenna and Radome Design Senior Engineer candidate will also be expected to lead diverse teams, provide technical oversight, delegate tasks, and work with the Engineering organization to establish technology roadmaps, enable modernization, and contribute to general innovation. In addition, the candidate will work with government personnel and programs, and define and refine requirements to validate hardware compliance. The candidate will be responsible for providing guidance, coaching, mentoring, and training to other employees across the business within the candidate's areas of expertise. Responsibilities to anticipate include: Development of antenna or radome hardware and requirements, Working with interdisciplinary engineering teams including thermal, structural, mechanical, systems, etc...

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