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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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- Welcome to the RF Cafe Website -
"Who ordered that?" - Isidor Isaac Rabi, Nobel laureate

Today in Science History

Tech Industry Headlines

Tech Industry Headlines - RF Cafe- Archive -

• Global Cellular IoT Module Shipments Declined 6% YoY in Q4 2020

• Senators Push Quantum Computing at DoD

• Ulrich Rohde, N1UL, Awarded Germany's Cross of Merit

• 93% of Manufacturing Personnel Want to get Back to Work

• Atom Interferometry Demonstrated in Space

• 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

ConductRF High Flex VNA Test Cables for 40, 50 & 70 GHz

ConductRF High Flex VNA Test Cables for 40, 50 & 70 GHz - RF CafeConductRF offers RF Engineers a large selection of Hi Flex cable for vector network analyzers (VNAs). We have standards for applications at 18-40 GHz, 50 GHz & 70 GHz. Our torque resistant connector heads and phase stable constructions ensure great performance for many tests to come. Other key features include: 2.92 mm, 2.4 mm & 1.85 mm connector options, low VSWR & insertion loss, low phase change with flexing, options available swept right angle connectors. ConductRF VNA series provides customers with reliable ruggedized solutions for Lab and Production Vector Network Analyzer testing. With options for 18 GHz, 26.5 GHz, 40 GHz, 50 GHz, & 70 GHz, these cables offer cost leading alternatives to original OEM VNA cable solutions...

Atom-Based Sensors Determine Direction of Incoming Radar Signal

Atom-Based Sensors Determine Direction of Incoming Radar Signal - RF Cafe"Researchers at the National Institute of Standards and Technology (NIST) and collaborators have demonstrated an atom-based sensor that can determine the direction of an incoming radio signal, another key part for a potential atomic communications system that could be smaller and work better in noisy environments than conventional technology. NIST researchers previously demonstrated that the same atom-based sensors can receive commonly used communications signals. The capability to measure a signal's angle of arrival helps ensure the accuracy of radar and wireless communications, which need to sort out real messages and images from random or deliberate interference..."

Radio to the Moon

Radio to the Moon, April 1946, Radio-Craft - RF CafeAs with so many things we take for granted today, the U.S. Army Signal Corps' nationwide announcement on January 25th, 1946, that the first earth-to-moon-to-earth (EME, aka moonbounce) contact had been made by radar was a big deal. Hams make EMEs on a regular basis, although it still is not a simple accomplishment and takes some special equipment. The term "selsyn" used in the article is a portmanteau of "self-synchronous," and refers to a device for precisely positioning something like an antenna. Magazine editor Hugo Gernsback included some kudos from contemporary notables like Audion inventor Lee DeForest and Radio Corporation of America (RCA) president David Sarnoff for having predicted the method and results in a 1927 article entitled "Can We Radio the Planets? See "Moon-Radio Predicted in 1927" at the bottom of the page.

CubeSats: An Emerging Market for the Microwave Industry

CubeSats: An Emerging Market for the Microwave Industry - RF CafePasternak has an interesting article on the Microwave Product Digest website entitled, "CubeSats: An Emerging Market for the Microwave Industry." In framing the story with the history of satellite communications, the author hearkens back to 1945 when Arthur C. Clarke ("2001: Space Odyssey") described in Wireless World magazine a way that communications could be achieved via Earth-orbiting "Extra-Terrestrial Relays." Pasternak begins, "Spacecraft in low, mid, and high orbits provide a diverse array of services from TV and radio broadcast to terrestrial and maritime communications, remote sensing, and navigation and timing. Not surprisingly, the satellite industry has been a steady consumer of RF and microwave components for more than five decades, and the pace is likely to increase. The driver of this good fortune is the 'smallsat' that makes it possible for even companies and governments without enormous financial resources to create space-based services..."

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...

Thanks to NextPCB for Continued Support!

NextPCB - RF CafeNextPCB is one of the most experienced PCB manufacturers in China, has specialized in the PCB and assembly industry for over 15 years. NextPCB provides the most innovative printed circuit boards and assembly technologies in the highest quality standards, turnaround time as fast as 24 hours, the lowest manufacturer direct prices, and the most dedicated customer service in the industry. Turnkey service without a broker including components sourcing, PCB prototyping, manufacturing, assembly, quality testing, and final shipment. Certified by IATF16949, ISO9001, ISO14001, UL, CQC, RoHS and REACH.

NASA Ingenuity Helicopter Makes 1st Flight on Mars

NASA Ingenuity Helicopter 1st Flight on Mars - RF Cafe"Monday, NASA's Ingenuity Mars Helicopter became the first aircraft in history to make a powered, controlled flight on another planet. The Ingenuity team at the agency's Jet Propulsion Laboratory in Southern California confirmed the flight succeeded after receiving data from the helicopter via NASA's Perseverance Mars rover at 6:46 a.m. EDT. 'Ingenuity is the latest in a long and storied tradition of NASA projects achieving a space exploration goal once thought impossible,' said acting NASA Administrator Steve Jurczyk. 'The X-15 was a pathfinder for the space shuttle. Mars Pathfinder and its Sojourner rover did the same for three generations of Mars rovers. We don’t know exactly where Ingenuity will lead us, but today's results indicate the sky – at least on Mars – may not be the limit'..."

Air Adventures Magazine Promo in Radio News

Air Adventures Magazine Promo, December 1939 and January 1940 Radio News - RF CafeUntil the last couple decades, people of the world recognized and called out evil by name when it reared its ugly head. Except for subversive imbedded agents, media outlets - radio, television, print, speeches, etc. - openly and vigorously condemned and attacked the enemy of its country's traditional way of life. The theme ran deep and wide in news reports and in magazine features. This advertisement for Air Adventures magazine which appeared in early 1940s Radio News magazine is an example. In the place of politically correct speech that doesn't dare to offend an entity which openly and maniacally seeks to kill you we had the vast majority of media promoting nationalism and patriotism in order to defeat the enemy. As with just about everything, eBay is a good source of these vintage Air Adventures magazines. This particular publication only ran for three editions. However, there were plenty of other titles that featured stories of heroic adventures against the Nazi scum ;-) Flying Aces magazine...

Copper Filled Thermal Vias for High Power Dissipation

Copper Filled Thermal Vias for High Power Dissipation - RF Cafe"Technology continues to advance with solutions that demand more and more performance in terms of energy efficiency and data processing. Kuprion, Inc., has patented a copper-filled via technology that addresses the heat problem at the board level. In an interview with EE Times, Kuprion president & founder Alfred Zinn pointed out that thermal management of PCBs is very important, as improving heat transfer can increase mean time between failures (MTBF) while at the same time increase the performance of heat-generating components. Zinn said Kuprion's Copper Filled Thermal Vias technology is an easy and cost-effective method that, placed directly under a component that needs to be cooled, opens a second heat dissipation duct doubling the cooling rate..."

Tropospheric Scatter: A Bridge to Alaska

Tropospheric Scatter: A Bridge to Alaska, October 1963 Popular Electronics - RF CafeCommunications links are so ubiquitous these days that we pretty much take for granted the ability to connect to the Internet and to other people. How many times have you been in public and heard someone have a fit because she couldn't get a good enough signal to make a call? It requires the person to get up and walk a few feet or maybe turn her chair in another direction to get an extra bar on the iPhone. How inconvenient. Even when placing a call to Hawaii or Alaska the expectation is that things just work. In 1963 when this tropospheric scattering network was installed for linking Alaska to the lower 48 states, satellite communications was still in its infancy and coverage was nowhere close to global. Even radio relay towers were relatively scarce across the landscape...

New for 2020! 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...

Thanks to Copper Mountain Technologies for Continued Support

Copper Mountain TechnologiesCopper Mountain Technologies develops innovative and robust RF test and measurement solutions for engineers all over the world. Copper Mountain's extensive line of unique form factor Vector Network Analyzers include an RF measurement module and a software application which runs on any Windows PC, laptop or tablet, connecting to the measurement hardware via USB interface. The result is a lower cost, faster, more effective test process that fits into the modern workspace in lab, production, field and secure testing environments.

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.

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