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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...

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Today in Science History

Tech Industry Headlines

Tech Industry Headlines - RF Cafe- Archive -

• Huawei Buys $Billion of U.S. High Tech Products Despite Blacklist

• Scottish Space Strategy Launched

• Using Tech to Build More Resilient Supply Chains

• EU Market Surveillance Regulation Takes Effect

• T-Mobile Extends CDMA Shutdown by 3 Months

• iPhone 13 Production Hit by Chip Shortages

• Chinese Anti-Satellite Weapon That Explodes Target

• O-RAN Alliance Announces New Specifications

• U.S. House Passes 4 Bills Related to Telecom Security

Electronics-Themed Comics, August 1949 Radio-Electronics

Electronics-Themed Comics, August 1949 Radio-Electronics - RF CafeHere are three more electronics-themed comics for you, these from a 1949 issue of Radio−Electronics magazine. The first one is probably still a concern for parents today, although the dilemma would probably be with the kid fiddling with the remote control rather than with the buttons on the TV set. The second might require you to be old enough to remember when both doctors and electronics servicemen made house calls. The third comics is my favorite due to its cleverness at portraying what was a common occurrence with boys wanting to watch a baseball game but not having the money for entrance to the ballpark. Spanky and the gang of The Little Rascals used to pull that stunt a lot. I took the liberty of colorizing the comics...

"I Didn't Know Ham Radio People Were Still Around"

"I Didn't Know Ham Radio People Were Still Around" - RF CafeEvery week while sitting in the studio where Melanie takes her violin lessons, I usually read technical and hobby magazines, but at the time I was been studying the ARRL General Class License Manual in preparation for taking the written exam in a couple months. One time a lady saw the book title and remarked, "I didn't know ham radio people were still around." Wow. It would be tempting to blame her for being ignorant, or to blame the ARRL for not adequately getting the word out, but the reality is that for the most part the mass media does not consider Ham radio's contribution to be significant enough to cover in news stories. Amateur radio operators perform a mighty public service in times of trouble, but they do it so efficiently and effectively, without actively seeking credit, that their efforts are lost in the noise. Ham radio operators have been on the front lines of national and civil defense since World War II and even a bit before (see links below). So important have been the contributions of Ham operators that the FCC has consistently protected the very valuable spectrum reserved for amateur radio...

EMI Shielding for Drones and UAVs

EMI Shielding for Drones and UAVs - RF Cafe"Most every electronic circuit will pose the threat of EMI radiation on other circuitry, with drones and UAVs being particularly susceptible. There’s one simple but important solution: implement EMI shielding. Most drones and unmanned aerial vehicles (UAVs) rely heavily on seamless communication from ground systems. Cell-phone towers, buildings and large metal structures, high-voltage power lines, and a high concentration of Wi-Fi networks in an area can cause serious electromagnetic interference (EMI) in drone performance. EMI effects on drone operations are unpredictable. They can severely disrupt a drone’s navigation system by shifting the drone's compass out of alignment. When flying close to large structures, EMI can degrade the quality of GPS reception..."

Two-Tone IMD Measurement Techniques

Two-Tone IMD Measurement Techniques - RF CafeKeith Barkley published an article in the June 2001 issue of RF Design magazine entitled, "Two-Tone IMD Measurement Techniques." Seven rules to ensure the best characterization of non-linear RF components. He writes: "Two-tone testing for intermodulation distortion (IMD) has a long and venerable history. Since the dawn of RF engineering, it has been used to characterize the non-linearity of RF components, both active and passive Measurement methods, pitfalls and tidbits of information have been gathered over the years by myriad sources, here and elsewhere. A few simple rules can help in setting up a test system that can accurately measure two-tone IMD for RF power transistors. For this discussion, f1 and f2 will denote the two signals' input into the device and Δf will be the frequency separation between them..."

Dipoles and Yagis

Dipoles and Yagis, November 1958 Radio-Electronics - RF CafeHere is a very useful article on the benefits and technical challenges of stacking antennas; it appeared in a 1958 issue of Radio−Electronics magazine. It avoids rigorous mathematical analysis and instead presents recommended guidelines and includes some very nice measured antenna patterns (no computer-generated predictions in 1958) of the various configurations. The authors discuss radiation pattern changes based on horizontal versus vertical stacking, and a combination of both. Plotting all the vertical and horizontal radiation patterns would have take a lot of time with a slide rule back in the day. This is the first of a series written by engineers at the Scala Radio Company...

RF Cascade Workbook

RF Cascade Workbook 2018 Is Available Now! - RF CafeRF Cascade Workbook 2018 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...

Many Thanks to KR Electronics for Helping Deliver RF Cafe!

KR ElectronicsKR Electronics designs and manufactures high quality filters for both the commercial and military markets. KR Electronics' line of filters includes lowpass, highpass, bandpass, bandstop and individually synthesized filters for special applications - both commercial and military. State of the art computer synthesis, analysis and test methods are used to meet the most challenging specifications. All common connector types and package form factors are available. Please visit their website today to see how they might be of assistance. Products are designed and manufactured in the USA.

Radio-Electronics Monthly Review

Radio-Electronics Monthly Review, June 1945 Radio-Craft - RF CafeRadio-Craft magazine ran a regular feature entitled "Radio-Electronics Monthly Review," which reported on industry news and events. The death of diode electron tube inventor Sir Ambrose Fleming appeared as a major item. He lived to the ripe old age of 95½ - an amazing feat at a time when the average lifespan of a male born in 1949 was less than 40 years. Regardless of the year born, your life expectancy increases as you get older both due to better available lifestyles, nutrition, and medicine, and because you continually cross benchmarks of genetic and environmental factors that take out others born in the same era. Another interesting item was the call for more ubiquitous deployment of 2-way radios (walkie-talkies) in rural areas to compensate for a relative lack of telephone service...

Quantum Technologies Based on Magnetic Molecules

Quantum Technologies Based on Magnetic Molecules - RF Cafe"An international research team, with the participation of the Institute of Molecular Science (ICMol) of the University of Valencia, has achieved spin-electric control in molecular nanomagnets. This fact offers great advantages when preparing quantum devices based on magnetic molecules. The work has been published in the journal Nature Physics. For some time, science has been looking for viability in the development of devices based on quantum bits (qubits), basic units of a quantum computer. In magnetic materials, a possible qubit is provided by the spin-quantum property of elementary particles such as the electron. In this context, the electrical control of spin offers important advantages for the development of quantum computing and, in general, quantum technologies. An international research team with the participation of ICMol has taken a step forward in this field by achieving..."

Skyworks SKY68031-11 Low Profile, Multi-band Massive IoT FEM

Skyworks SKY68031-11 Low Profile, Multi-band Massive IoT Front-End Module - RF CafeSkyworks is pleased to introduce SKY68031-11, the world's smallest, multi-band RF front-end (RFFE) module for licensed, low-power, wide-area network (LTE-M/NB-IoT) applications including asset tracking, health and fitness wearables, smart metering and industrial monitoring. This module integrates the entire RF front end necessary for a cellular IoT radio operating in low-band (5, 8, 12, 13, 14, 17, 18, 19, 20, 26, 28, 85) and mid-band (1, 2, 3, 4, 25, 39, 66, 70) frequencies. The FEM monolithically integrates a broadband power amplifier, transmit harmonic filters, antenna switch and MIPI RFFE controller, all in a compact 3x3 mm package...

All About Audio and Hi-Fi: The Listening Ear

All About Audio and Hi-Fi: The Listening Ear, May 1957 Radio & TV News - RF CafeWharfdale is a brand well known to stereo hobbyists and professionals for more than half a century - particularly in Europe. Wharfdale Wireless Works was founded by British entrepreneur Gilbert Briggs in 1933, and still sells speakers under the name "Wharfdale." As a pioneer in high fidelity sound reproduction, Mr. Briggs was highly sought as an author by electronics and audio media. In May 1957, he wrote this article for Radio & TV News magazine. Studies of the audio response of the human ear and the physics of the space where speakers and listeners would be were undertaken as the electronics age progressed in the post-war years and consumers began seeking more than simply noise emanating from a loudspeaker...

Quantum Technology: Qiskit and RasQberry

Quantum Technology: Qiskit and RasQberry - RF CafeIs it my imagination, or do the SMA connectors at the arrows appear to be not fully seated? Per the article: "Proponents of quantum technology believe its will change the world. Others remain skeptical, as they do of technologies like fusion energy. Speaking at a quantum developers' forum, IBM Distinguished Engineer Jan-Rainer Lahmann retraced the history of quantum computing, reviewing IBM's hardware and development roadmaps and describing the ingredients of 'Raspberry Pi Quantum.' The history of quantum computing goes back four decades to a conference where the Nobel laureate Richard Feynman introduced the idea of simulating quantum mechanical systems on a traditional computer. At the time, this required a significant computational resources. Even with Moore's Law scaling, it was clear to Feynman and many others..."

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 ISOTEC for Continued Support!

ISOTEC Corporation - RF CafeSince 1996, ISOTEC has designed, developed and manufactured an extensive line of RF/microwave connectors, between-series adapters, RF components and filters for wireless service providers including non-magnetic connectors for quantum computing and MRI equipments etc. ISOTEC's product line includes low-PIM RF connectors components such as power dividers and directional couplers. Off-the-shelf and customized products up to 40 GHz and our low-PIM products can meet -160 dBc with 2 tones and 20 W test. Quick prototyping, advanced in-house testing and high-performance. Designs that are cost effective practical and repeatable.

Morse Code vs. Texting on Jay Leno Show

Morse Code vs. Texting Contest on the Jay Leno's "The Tonight Show" - RF Cafe Video for EngineersOn the May 13, 2005 episode of The Tonight Show, Jay Leno held a Morse code vs. SMS speed contest between two Ham Radio operators using Morse code and two Millennials using their smartphones for texting (SMS). At least one member of the audience thought texting would win. Watch the video to see if she was right. Mr. Chip Margelli (K7JA) did the sending. He declares, "Let me assure you that we never saw that message before I flipped the blue card over. Each message, in rehearsal, was different. The character count was the same as the one during dress rehearsal, though, to account for the time slot. And they put the card on the table "upside down" creative to how I flipped it, as you can see on the video." Mr. Ken Miller (K6CTW) did the receiving...

Station Design for DX (Part IV)

Station Design for DX (Part IV), December 1966 QST - RF CafeIn 1966, Paul Rockwell wrote a 4-part series for the ARRL's QST magazine on station design for long distance communications (DX) that covered antenna selection and siting (Part I), economics and construction (Part II), Station Configuration and Receiver Topics (Part III), and Propagation Quirks and Operating Tips (Part IV). This the the forth and final installment. One of the handy-dandy items shown is a Geochron Map-Clock which had a template of the familiar day-night analemma-based curve superimposed on the projection map of the earth. It was quite a deal in its day, and believe it or not, the company is still in business offering software-based Map-Clocks and restoring models all the way back to when they first came out in 1965 (only a year before it appeared here)...

Anisotropic Film Packs Transistors More Densly

Anisotropic Film Packs Transistors Closer Together - RF Cafe"Stacks of atomically thin sheets of molybdenum disulfide both move and block heat. Packing transistors close together raises the problem of heat frying the devices. Now scientists have developed an artificial material that is one of the best ever at conducting heat in one direction while keeping that heat insulated from its surroundings in other directions. The research might one day help microchips grow more powerful without breaking from overheating. As electronics continue to miniaturize, greater amounts of heat are getting produced in a given space, which makes heat control a key challenge in electronic design..."

Carl & Jerry: Succoring a Soroban

Carl & Jerry: Succoring a Soroban, March 1963 Popular Electronics - RF CafeDo you know what a soroban is? I have to admit ignorance prior to reading this 1963 "Carl and Jerry" adventure in Popular Electronics. As with many of these stories, real equipment, people, and companies were referenced; this time it was the Pastoriza Personal Analog Computer, a modular electronics system for calculating differential equations. The cost was around $300 (~$2,700 in c2021 money per BLS Inflation Calculator). Analog Devices bought the company from James Pastoriza in 1969. What does the Pastoriza computer have to do with the story, you might ask? Nothing, really; it was mentioned in a discussion Carl and Jerry had when accepting a calculating speed challenge from obnoxious dormitory mate, Bruce. Jerry would add a series of numbers on his soroban while Bruce would add them with a pencil and paper. The winner got bragging rights...

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...

Thanks to TotalTemp Technologies for Continued Support!

TotalTemp Technologies - RF CafeTotalTemp Technologies has more than 40 years of combined experience providing thermal platforms. Thermal Platforms are available to provide temperatures between −100°C and +200°C for cryogenic cooling, recirculating circulating coolers, temperature chambers and temperature controllers, thermal range safety controllers, space simulation chambers, hybrid benchtop chambers, custom systems and platforms. Manual and automated configurations for laboratory and production environments. Please contact TotalTemp Technologies today to learn how they can help your project.

Science Theme Crossword Puzzle for October 24th

Science Theme Crossword Puzzle for October 24th, 2021 - RF CafeThis Science Theme Crossword Puzzle for October 24 has many words and clues related to RF, microwave, and mm-wave engineering, optics, mathematics, chemistry, physics, and other technical subjects. The letter "P" figures Prominently in this crossword. 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!

Please Thank IPP for Their Long-Time Support!

Innovative Power ProductsInnovative Power Products (IPP) has over 30 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. Please take a couple minutes to visit their website and see how IPP can help you today.

Radio in the Atom Tests

Radio in the Atom Tests, July 1946 Radio-Craft - RF CafeA year after the two atom bombs were dropped to end World War II, the newly formed Atomic Energy Commission conducted detailed detonation tests at the Bikini Atoll, in the South Pacific. Most people more than 40 years old are very familiar with the images of the giant mushroom cloud that formed over the site. This "Radio in the Atom Tests" article from the July 1946 issue of Radio−Craft magazine reports on plans being made to measure and record sound pressure, nuclear radiation, radio and radar signatures, temperature, light spectrum and intensity, and other parameters. The information would be used for improved bomb making, nuclear power generation, medical imaging and treatment, and general research on nuclear fission and fusion (a fission implosion is to initiate a fusion reaction)...

Drones for Safer & Better Cellular Connectivity

Drones for Safer & Better Cellular Connectivity - RF Cafe"Researchers from King Abdullah University of Science & Technology have proposed a solution to address the widespread public concern about electromagnetic fields (EMF) exposure from mobile networks. Masters' student Zhengying Lou, postdoctoral student Ahmed Elzanaty and distinguished professor Mohamed-Slim Alouini of KAUST proposed that mobile tethered drones might offer a speedy and environmentally friendly alternative for receiving terrestrial base stations while alleviating public concerns about exposure to EMF. Ahmed Elzanaty stated that it is mainly a problem of perception, but this concern has led to attempts to destroy signaling towers, especially those associated with the 5G network. He does point out, however, that recent experiments on animals link some adverse health impacts with long-term exposure to EMF..."

Radar Network for Air Traffic Control

Radar Network for Air Traffic Control, February 1957 Radio & Television News - RF CafeThe Civil Aeronautics Administration (CAA), born in 1940 and now known as the Federal Aviation Administration (FAA, since 1958), was established originally to regulate the burgeoning commercial airline and cargo transport air traffic as well as the private aviation activity. According to an FAA document, on April 3, 1947, CAA controllers began in-service evaluations of the ground approach control (GCA) radar system at Washington National and Chicago Municipal airports. It was commissioned for official use by the CAA on January 7, 1952, at Washington National Airport. This story from a 1957 edition of Radio & Television News magazine reports on the system upgrade to long-range radars that would permit, eventually, continuous coverage across the entire USA...

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.

Crosley Radio Advertisement

Crosley Radio Advertisement, February 1932 Radio-Craft - RF CafeCommercially available radio receivers for the home had only been around for a couple decades when this advertisement from Crosley appeared in a 1932 issue of Radio-Craft magazine. I keep looking in old electronics magazines for an ad featuring my 1941 Crosley model 03CB console radio, but thus far with no luck. There is a chance, although I have not seen any direct evidence of it, that the 03CB chassis was sold as a special upgrade to the less ornate 02CA model. What makes it special is that it was probably one of the last new radios sold prior to the shift of material usage to military equipment in World War II...

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