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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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"Wind and sun energy is never 'renewed,' hence, it is not 'renewable.'" - Kirt Blattenberger

Today in Science History

Tech Industry Headlines

Tech Industry Headlines - RF Cafe - Archive -

• NFC Forum Launches NFC Wireless Charging Cert Program

• Pentagon's $5.7B Lab "Wish List" Likely to Stay Unfunded

• 5G Small Cell Trial for City of London

• TSMC Hikes Prices

• Mitigate EMI in Your 400-Hz Systems

• 2023 IC Market to Fall 22%

• Tech Titans Curb Hiring in "Challenging Environment"

• Kids' Screen Use Sees Fastest Rise in 4 Years

• Micro-Supercapacitors Enable Fast Charging

The Radio Month, March 1954 Radio-Electronics

The Radio Month, March 1954 Radio-Electronics - RF CafeThis 1954 issue of Radio-Electronics magazine reported on the death of electronics communications pioneer Major Edwin H. Armstrong. Most famously known for his wideband FM (frequency modulation) scheme, Maj. Armstrong also developed the superheterodyne circuit, the superregenerative circuit, and was an independent inventor of regeneration. As with many prodigious, prolific inventors throughout the ages, he spent much time and fortune battling legal claims against himself and against others. Interestingly, the news item does not mention that Major Armstrong, who was famous for his daring antics at the tops of extremely high antennas, died after jumping out of his New York City apartment window. It was ruled a suicide based on a note he left for his wife. Also included is a bit about a judge allowing radar data from police as evidence in a speeding charge, and a statistic showing 47,000 people injured themselves in the past year during TV antenna installations...

Before GPS, There Was the Fresnel Lens

Before Ships Used GPS, There Was the Fresnel Lens - RF CafeAugustin-Jean Fresnel, the same guy who developed the "Fresnel zone" equation for determining the effective RF propagation region between a transmitter and a receiver, also invented this prismatic lens for concentrating the source of illumination of a lighthouse in the direction most useful to seafaring vessels (aka ships and boats). This IEEE Spectrum article entitled "Before Ships Used GPS, There was the Fresnel Lens" dives into the history of the world-changing device. It begins: "Ships today use satellite-based radio navigation, GPS, and other tools to prevent accidents. But back at the beginning of the 19th century, lighthouses guided ships away from rocky shores using an oil lamp placed between a concave mirror and a glass lens to produce a beam of light. The mirrors were not very effective, though, and the lenses were murky. The light was difficult to see from a distance on a clear night, let alone in heavy fog or a storm..." Here is a nice video explaining the Fresnel lens and its nautical import.

Zenith Models 5D011-5D027 Schematic & Parts List

Zenith Models 5D011-5D027 Schematic & Parts List, February 1947 Radio News - RF CafeHere is Zenith Models 5D011-5D027 schematic and parts list as featured in a 1947 edition of Radio News magazine. Unlike with most of the Radio Service Data Sheets, this came from group of three which also included the Bendix Models 636A, C, D and the Coronet Model C-2, al three of which are tabletop models. As mentioned many times in the past, I post these online for the benefit of hobbyists looking for information to assist in repairing or restoring vintage communication equipment...

Planar Monolithic Industries dba Name Change to Quantic PMI

Planar Monolithic Industries dba Name Change to Quantic PMI - RF CafePlanar Monolithic Industries (PMI), a leading supplier of custom, high-reliability MIC/MMIC components and subsystems for applications in space, military, communications, commercial and consumer electronics systems for more than three decades, announces a dba (doing business as) name change to Quantic PMI. They also have introduced a new 6−Channel Switch Filter Bank that operates over the frequency range of 55 to 18.5 GHz, with a typical VSWR of 1.7:1, a maximum switching speed of 200 ns, and a typical insertion loss of 4.0 dB. Contact PMI today for more information...

Electronics-Themed Comics

Electronics-Themed Comics March 1952 Radio & TV News - RF CafeThese two electronics-themed comics appeared in a 1952 edition of Radio & Television News magazine. In the early days of television, it was common in comedy skits and in cartoons to have someone on a television show interact, to the viewer's great shock, directly with the viewer or to reach out of the set and do something, as in the first comic here. The Three Stooges show did that in a couple shows. One in particular I remember was when they were doing plumbing in a house and had water coming out of light sockets and telephones. The homeowners were watching the TV with a film of Niagara Falls when suddenly water came gushing out of the picture tube (begins at 13:20 in video)...

Get Your Custom-Designed RF Cafe Gear!

Custom-Designed RF-Themed Cups, T-Shirts, Mouse Pads, Clocks (Cafe Press) - RF CafeThis assortment of custom-designed themes by RF Cafe includes T-Shirts, Mouse Pads, Clocks, Tote Bags, Coffee Mugs and Steins, Purses, Sweatshirts, and Baseball Caps. Choose from amazingly clever "We Are the World's Matchmakers" Smith chart design or the "Engineer's Troubleshooting Flow Chart." My "Matchmaker's" design has been ripped off by other people and used on their products, so please be sure to purchase only official RF Cafe gear. My markup is only a paltry 50¢ per item - Cafe Press gets the rest of your purchase price. These would make excellent gifts for husbands, wives, kids, significant others, and for handing out at company events or as rewards for excellent service. It's a great way to help support RF Cafe. Thanks...

Many Thanks to Berkeley Nucleonics for Continued Support!

Berkeley Nucleonics Corp - RF CafeBerkeley Nucleonics Corporation (BNC) is a leading manufacturer of precision electronic instrumentation for test, measurement, and nuclear research. Founded in 1963, BNC initially developed custom pulse generators. We became known for meeting the most stringent requirements for high precision and stability, and for producing instruments of unsurpassed reliability and performance. We continue to maintain a leadership position as a developer of custom pulse, signal, light, and function generators. Our designs incorporate the latest innovations in software and hardware engineering, surface mount production, and automated testing procedures.

Radio Stamps Make Rare Collection

Radio Stamps Make Rare Collection, July 1956 Popular Electronics - RF CafeBoth my father and grandfather were stamp collectors - philatelists is the technical word - who dabbled in a recreational way with commemoratives from foreign countries. Nearly all were canceled (used) stamps that today, as back in their day, have no real value other than to someone interested in history. Of course none are the rare types. I now possess many of those stamps in an album that was painstakingly hand-illustrated and assembled to arrange each stamp according to its country and issue date. At one time I, too, dabbled in the hobby, having collected many plate blocks and special issue U.S. stamps in the 1970s and 1980s, along with purchasing a few designs of special purpose such as those with aerospace and communications themes. Sad to say, most of those stamps, even those in mint condition, are valued at the denomination printed on the face - meaning inflation has reduced their worth to even less than when originally purchased. If indeed "what's past is prologue...

Universal Access Akin to Electrification of Rural America

Universal Access Akin to Electrification of Rural America - RF CafeThis story entitled "Universal Access Akin to the Electrification of Rural America" is right from the standpoint of making Internet available in nearly every region of the country. However, there's one huge difference between the Internet for All (IFA) scheme and the Rural Electrification Act (REA) of 1936. Whereas he REA made electric power available to users, the end user paid for energy consumed. The IFA either gives away the data usage or provides deep discounts, while those of us who pay full price for service and pay income taxes foot the bill - while being demonized by the government and the (often) freeloaders. Also, the REA did not provide the implements which would benefit from the electric power (motors, radios, refrigerators), but the government will be handing out cellphones and PCs to connect to the Internet. Whether through direct taxes or inflation due to money printing, the rest of us pay dearly for it. The article begins: "Step by step the $1T infrastructure package is becoming reality The next phase of the U.S. "Internet for All" initiative has kicked off with governors and other eligible leaders being invited to submit a letter of intent as a step towards unlocking $45B to give every U.S. resident access to high-speed internet by 2028. Each state will then get $5M..."

How to Make the World's Smallest 3-Tube Radio Set

How to Make the World's Smallest 3-Tube Radio Set, December 1936, Radio-Craft - RF CafeMy first thought when seeing the cover for this December 1936 edition of Radio-Craft magazine was that it was an April Fools gag, but it turns out the "Hat" being worn by the radio receiver's designer is a loop antenna for AM reception. In a way it is the opposite of a tinfoil hat in that this headgear invites electromagnetic energy around the wearer's head rather than shielding it. Back in 1936, being seen in public donning a contraption like this radio would have been akin to wearing Google Glass (a failed concept) a few years ago - you'd be a superhero to fellow nerds, and just be confirming your otherworldly nerd status to non-nerds. Note the very nicely done drawings...

Post Your Engineer & Technician Job Openings on RF Cafe for Free

Engineering Job Board - RF CafeRF Cafe's raison d'être is and always has been to provide useful, quality content for engineers, technicians, engineering managers, students, and hobbyists. Part of that mission is offering to post applicable job openings. HR department employees and/or managers of hiring companies are welcome to submit opportunities for posting at no charge. 3rd party recruiters and temp agencies are not included so as to assure a high quality of listings. Please read through the easy procedure to benefit from RF Cafe's high quality visitors...

Many Thanks to Amplifier Solutions Corporation (ASC) for Continuing Support!

Amplifier Solutions Corporation (ASC) - RF Cafe 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.

Analog Engineering Crossword Puzzle for May 22

Analog Engineering Crossword Puzzle for May 22, 2022 - RF CafeThis custom made Analog Engineering theme crossword puzzle for May 22nd is provided compliments of RF Cafe. All RF Cafe crossword puzzles are custom made by me, Kirt Blattenberger, and have only words and clues related to RF, microwave, and mm-wave engineering, optics, mathematics, chemistry, physics, and other technical subjects. As always, this crossword puzzle contains no names of politicians, mountain ranges, exotic foods or plants, movie stars, or anything of the sort unless it/he/she is related to this puzzle's technology theme (e.g., Reginald Denny or the Tunguska event in Siberia). The technically inclined cruciverbalists amongst us will appreciate the effort. Enjoy!

RF & Electronics Symbols for Visio

RF Electronics Wireless Analog Block Diagrams Symbols Shapes for Visio - RF CafeWith more than 1000 custom-built symbols, this has got to be the most comprehensive set of Visio Symbols available for RF, analog, and digital system and schematic drawings! Every object has been built to fit proportionally on the provided A-, B- and C-size drawing page templates (or can use your own). Symbols are provided for equipment racks and test equipment, system block diagrams, conceptual drawings, and schematics. Unlike previous versions, these are NOT Stencils, but instead are all contained on tabbed pages within a single Visio document. That puts everything in front of you in its full glory. Just copy and paste what you need on your drawing. The file format is XML so everything plays nicely with Visio 2013 and later...

Many Thanks to Exodus Advanced Communications for Their Support

Exodus Advanced Communications - RF CafeExodus Advanced Communications is a multinational RF communication equipment and engineering service company serving both commercial and government entities and their affiliates worldwide. Power amplifiers ranging from 10 kHz to 51 GHz with various output power levels and noise figure ranges, we fully support custom designs and manufacturing requirements for both small and large volume levels. decades of combined experience in the RF field for numerous applications including military jamming, communications, radar, EMI/EMC and various commercial projects with all designing and manufacturing of our HPA, MPA, and LNA products in-house.

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...

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...

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