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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 typing up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.

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"Who ordered that?" - Isidor Isaac Rabi, Nobel laureate

Today in Science History

Tech Industry Headlines

Tech Industry Headlines - RF Cafe- Archive -

• Ham Bootcamp Program on April 24th

• Student's Physics Homework Picked up by Amazon Quantum Researchers

• Port Congestion Continues to Throttle World Supply Chains

• People May Trust Computers More Than Humans

• FCC Publishes Pirate Radio Enforcement Provisions

• Celebrate World Amateur Radio Day on April 18

• Lockheed Martin, Omnispace Eye Global 5G Hybrid Network

• CCA Urges FCC to Consider Higher-Power Rules for CBRS

• Ericsson Puts 5G to Work in Its Texas Factory

Science & Math Theme Crossword Puzzle for April 18th

Science & Math Theme Crossword Puzzle for April 18th, 2021 - RF CafeThis Science & Math Crossword Puzzle for April 18th has many words and clues related to RF, microwave, and mm-wave engineering, optics, mathematics, chemistry, physics, and other technical subjects. As always, this crossword contains no names of politicians, mountain ranges, exotic foods or plants, movie stars, or anything of the sort unless it/he/she is related to this puzzle's technology theme (e.g., Reginald Denny or the Tunguska event in Siberia). The technically inclined cruciverbalists amongst us will appreciate the effort. Enjoy!

Radio Robot Plane

Radio Robot Plane, August 1945, Radio-Craft - RF CafeRadio-controlled flying drones are commonplace today - so much so that the FAA has enacted legislation to strictly limit who can fly them, where they can be flown, how big they can be, what type of payloads can be carried, how far from the pilot they can be flown, etc. - the typical kind of overreaching and overregulating that governments promulgate (especially in the last few years). Sport model airplane flying has suffered loss of freedoms because of it by getting lumped in with multirotor drones. The military, of course, has been using radio-controlled drones for decades, as highlighted in this 1945 Radio-Craft magazine article. Author Louis Bruchiss extolls the advantages of being able to guide an ordinance payload after being released from an aircraft of after being launched...

New Wave of e-Boats Taking to the Seas

New Wave of e-Boats Taking to the Seas - RF CafeIs this cool or what? Of course I'll never be able to afford one (maybe an R/C model someday, though). "Electric boats of all shapes and sizes are beginning to make a splash in the maritime sector. It's estimated that maritime greenhouse gas emissions account for around 2.5% of the global total, marginally ahead of the 2% that aviation contributes. If shipping were a country, it would be the sixth largest emitter of CO2 after China, the USA, India, Russia and Japan. International shipping - much like long-haul flight - will not be electrified any time soon, as the energy density of batteries simply cannot facilitate it. And for an industry that's recently committed to halve its emissions by 2050..."

A Pathway to Equitable Math Instruction

A Pathway to Equitable Math Instruction - RF CafeIs this the future of engineering, science, medicine, economics, and all other math-intensive fields? If it is, we're in trouble. "A Pathway to Equitable Math Instruction Dismantling Racism in Mathematics Instruction" is being considered for incorporation into school curriculums across the country. Its premise is that requiring students to arrive at the correct answer is White supremacy (p1), and that any wrong answer is the fault of the teacher, who needs to "Recognize mistakes as miscommunicated knowledge." (p9) Get that? If a student screws up, it's not her fault. It is worth a few minutes of your time to look through this. I guarantee you that China demands correct answers of their math students. They are laughing at idiot school systems in the U.S. We're doing their work for them in achieving global technical dominance. The training manual was funded by the Bill and Melinda Gates Foundation. Should we expect future releases of Windows to adopt the anti-White supremacy, results are interpretive philosophy? A BSoD is coming to a computer near you. Apple will need to purge the racist objective measures from their OS as well.

RF Cafe Quiz #48: Introduction to Infrared and Electro-Optical Systems

RF Cafe Quiz #48: Introduction to Infrared and Electro-Optical Systems - RF CafeThis quiz is based on the information presented in "Introduction to Infrared and Electro-Optical Systems," by Ronald G. Driggers and Melvin H. Friedman. All RF Cafe Quizzes make great fodder for employment interviews for technicians or engineers - particularly those who are fresh out of school or are relatively new to the work world. Come to think of it, they would make equally excellent study material for the same persons who are going to be interviewed for a job.

Carl and Jerry: Ham Radio

Carl and Jerry: Ham Radio, April 1955 Popular Electronics - RF CafeHere is another exciting episode of the sleuthing adventures starring Popular Electronics' tech savvy teenagers, Carl and Jerry. The "Hardy Boys of electronics" are the creation of author John T. Frye, who created short story adventures for many years - long enough to at one point require a major modification in the boys' appearances to reflect more modern attire and eyewear (Carl's "The Far Side"-style glasses had to go). This particular adventure begins with Carl considering whether his ham radio hobby is more useful from the standpoint of its technical aspects or of its social aspects. An unrelated electronics-themed comic is included since it appeared on one of the story pages.

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 Atenlab for Their Continued Support!

Atenlab microwave components - RF CafeAtenlab has been operating in Taiwan for more than a decade, and has sold and installed hundreds chambers around the world. Holistic, affordable Over-the-Air (OTA) measurement systems perform comprehensive measurement and test in a controlled environment. Compact Antenna Test Range (CATR) with one-touch operation supports multiple systems - 2G, 3G, 4G, 5G - and major instrument brands. [M]ulti-probe OTA measurement systems offer reduced time measurements over single-probe systems.

Windfreak Intros the World's Smallest 10 MHz - 15 GHz RF Synthesizer

Windfreak Technologies SynthHD Mini RF Signal Generator: 10 MHz - 15 GHz - RF CafeWindfreak Technologies announces the availability of the new SynthHD Mini RF Signal Generator. The SynthHD Mini is the smallest 10 MHz to 15 GHz RF Signal Generator in the world - a mere 1.60 x 1.60 x 0.48 inches (4.06 x 4.06 x 1.22 cm). Expect excellent performance despite the ultra-small size and price of this device. Tune any frequency between 10 MHz and 15 GHz in 0.01 Hz resolution. Adjust calibrated amplitude in 0.01 dB resolution up to +20 dBm and across more than 30 dB of range. Perform FM, AM, Pulse, Sweep, and List Modulations. See the Tabs below to download a full datasheet and other documents. Windfreak Technologies has set the bar on microwave radio frequency generators for quality, size, and price. As always, our products are designed and manufactured in the USA! In Stock.

Single Spin-Orbit Torque Device Senses 3D Magnetic Fields

Single Spin-Orbit Torque Device Senses 3D Magnetic Fields - RF cafe"Sensors that can detect magnetic fields have many potential applications, for instance, in the development of sophisticated medical devices and transportation systems. Most approaches for detecting 3D magnetic fields developed so far, however, require several sensors, which makes them bulky and difficult to implement on a large-scale. With this in mind, researchers at the Nanoscale Energy-Efficient Device and System (NEEDS) Lab at Huazhong University of Science and Technology in China set out to develop a single spin-orbit device that can individually detect 3D magnetic fields. The device they designed, presented in a paper published in Nature Electronics and inspired by their previous work, is based on a Ta/CoFeB/MgO (tantalum / cobalt-iron-boron / magnesium oxide) heterostructure..."

Notable Tech Quote: Isidor Isaac Rabi

Notable Quote by Isidor Isaac Rabi - RF CafeAmerican physicists Carl Anderson and Seth Neddermeyer were studying cosmic rays when they discovered the muon in 1936. The discovery of this particle was so surprising that Nobel laureate Isidor Isaac Rabi exclaimed: "Who ordered that?" Dr. Rabi was an American physicist who won the Nobel Prize in Physics in 1944 for his discovery of nuclear magnetic resonance and was a pioneer in the development of the cavity magnetron.

Klystron: Tube of the Future

Klystron: Tube of the Future, October 1944 Radio-Craft - RF CafeSo much time has passed since an average home garage mechanic could service his car or truck with standard tools - combination wrenches, screwdrivers, socket sets, timing light, and a multimeter - that asking "remember when?" is passé. That era pretty much ended in the late 1980s as computerized cars were becoming the industry norm. A good percentage of people nowadays have never and will never service their own vehicles. In the mid 1940s, the electronics world was lamenting a similar situation with diminishing ability to build and modify electronic components like coils and stacked plate capacitors because of the increasingly higher frequencies being used in communications (way up into the UHF band!). This article introduces the klystron tube, having been around for less than a decade at the time, as being one of the culprits that was enabling the disturbing trend...

Amazing 8-Year Pinhole Camera Sun Trail Photo

8-Year Pinhole Camera Sun Trail Photo - RF CafeI first saw this amazing photograph in the April 2012 issue of Astronomy magazine. It is an 8-year-long image of the sun's path across the sky as recorded by by Fine Art student Regina Valkenborgh from August 2012 through September 2020. She lined some beer cans with photographic paper and punched a tiny hole in the can, mounted them in locations around an observatory in the UK, then forgot about them. Most perished, but this one survived and was found by a staffer. Ms. Valkenborgh now has the honor of being responsible for the longest-ever photographic film time exposure. Pinhole cameras have no lens, since light rays entering the container follow a nearly singular path to the film surface. The smaller the hole, the sharper the focus. Less light enters the camera, so a longer exposure time is required. Pointing it at the sun provides an intense source of light, but it is still little enough to not overwhelm the film over a period of 8 years.

New for 2021! 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 object has been built to fit proportionally on the provided A-, B- and C-size drawing page templates (or can use your own). Stencils 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...

Please Visit Triad RF Systems to Thank Them for Their Support

Triad RF SystemsTriad RF Systems designs and manufactures RF power amplifiers and systems. Triad RF Systems comprises three partners (hence 'Triad') with over 40 years of accumulated knowledge of what is required to design, manufacture, market, sell and service RF/Microwave amplifiers and amplifier systems. PA, LNA, bi-directional, and frequency translating amplifiers are available, in formats including tower mount, benchtop, rack mount, and chassis mount. "We view Triad more as a technology partner than a vendor for our line-of-sight communications product line." Please check to see how they can help your project.

The Electron Tube

The Electron Tube, November 1954 Radio & Television News - RF CafeHere in this 1954 issue of Radio & Television News magazine is one man's (Commander Paul G. Watson, USNR (ret.) collection of early vacuum tubes and a bit about them. It reaches back to Dr. Lee de Forest's farther than even earliest Audion tubes - including the "UltraAudion" - to include the flame-based detector and amplifiers he worked on. For a very thorough history of de Forest's work from the vantage point of both the good Dr. and those who worked with him, including a story by William Howard McCandless (the man who's glass blowing business built the various tubes for de Forest), check out the January 1947 issue of Radio-Craft magazine. It celebrated the 40th anniversary of the de Forest Audio tube. I wonder where this collection of tubes is today. Many priceless collections of technical history artifacts end up being mistakenly or ignorantly disposed of...

2021 to Be Record Year for Semiconductors

2021 to Be Record Year for Semiconductors - RF Cafe"Total semiconductor unit shipments, which include integrated circuits as well as optoelectronics, sensor/actuator, and discrete (O-S-D) devices, are forecast to rise 13% in 2021, to 1,135.3B (1.1353T) units to set a new all-time annual record, according to IC Insights' McClean Report - A Complete Analysis and Forecast of the Integrated Circuit Industry. It would mark the third time that semiconductor units have surpassed one trillion units in a calendar year - the first time being in 2018. The 13% increase to 1,135.3B semiconductor units follows a 3% increase in 2020..."

RF Cafe Quiz #55: Conquer Radio Frequency

RF Cafe Quiz #55: Conquer Radio FrequencyThis quiz is based on the information presented in Conquer Radio Frequency, by Francesco Fornetti. See my review for the online version. This material, which includes a full-color textbook and over 12 hours of video tutorials (in mp4 format on enclosed DVD-R), provides a comprehensive guide for the RF and Microwave engineering student or junior professional. It allows the reader to achieve a good understanding of the foundation theory and concepts behind high frequency circuits as well illustrating the most common design and simulation techniques for passive and active RF circuits. A preview of the textbook, a comprehensive description of the content of the video tutorials and sample video tutorials are available on the Explore RF website.

The Engineering Essentials Behind LiDAR 

The Engineering Essentials Behind LiDAR - RF CafeEdel Cashman has a good article on the Electronic Design website entitled, "The Engineering Essentials Behind LiDAR." LiDAR works by the same principles as sonar and radar, but rather than sound and radio frequencies, it uses light. Its extremely short wavelengths makes it ideal for high precision positioning and navigation - such as with autonomous vehicles. Mr. Cashman (great name, BTW!) begins, "LiDAR (light detection and ranging)... applies the principles of reflected light and accurate timing to measure the distance of an object. LiDAR permits superior depth sensing due to its high levels of depth and angular resolution. In addition, it's able to operate in all light conditions due to the active approach that uses an infrared light transmitter along with a receiver. However, LiDAR is more sophisticated than just a distance measure. It can also be used in 3D mapping and imaging, making it very appealing in an engineering context..."

Belmont 4-Tube Model 408 Battery "Farm" Superhet

Belmont 4-Tube Model 408 (Series A) Battery "Farm" Superhet Radio Service Data Sheet, October 1938 Radio-Craft - RF CafeAt least for now, I am going to only scan and post Radio Service Data Sheets like this one featuring the Belmont 4-Tube Model 408 (Series A) Battery "Farm" Superhet radio in graphical format, rather than run OCR on them to separate the textual content. It appeared in the October 1938 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. No example of this radio could be found on the WWW...

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