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About RF Cafe

Kirt Blattenberger - RF Cafe Webmaster

Copyright: 1996 - 2024

Webmaster:

    Kirt Blattenberger,

    BSEE - KB3UON

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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Homepage Archive - September 2021 (page 1)

See Page 1 | 2 | 3 | 4 of the September 2021 homepage archives.
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Tuesday the 7th

Preservation Engineers Keep Old Technology Alive

Preservation Engineers Keep Old Technology Alive - RF CafeCabe Atwell has an interesting piece on the EE Times website entitled, "Preservation Engineers Keep Old Technology Alive." Although he doesn't mention it, the issue of maintaining old software and hardware really was at the forefront of the Y2K era when doomsdayers tried to convince the world that everything would stop working at the time change between December 31, 1999, and January 1, 2000. People were scrambling for a few year prior to see that the worst case scenario did not happen. It didn't, thanks to them. Truth is though, a lot would have shut down if not for those doomsdayers sounding the alarm, so they cannot be written off as nutballs.

Many Thanks to Electro-Photonics for Their Continued Support

Electro-PhotonicsElectro-Photonics is a global supplier of RF & Microwave components. Their products include SMT hybrid and directional couplers, wire bondable passive components, mounting tabs, filters, transmission lines, and very useful test boards for evaluating components (spiral inductors, single-layer capacitors). The Electro-Photonics team can support your small R&D design requirements with RF & Microwave test fixtures and save you valuable design and characterization time. Please take a moment to visit Electro-Photonics' website and see how your project might benefit. 

Monday the 6th

Electronics-Themed Comics

Electronics-Themed Comics, September 1960 Electronics World - RF CafeIt is Labor Day in America, so a lot of RF Cafe visitors have the day off. Being engineers, technicians, students, etc., even time off is often spent pursuing technical endeavors. Here are a couple good electronics-related comics from a 1960 issue of Electronic World magazine to help entertain you. They are from the days of in-home television repair service, which of course is a thing of a bygone era when even family doctors were still making house calls. The first comic might seem a bit ridiculous, but often times getting a description of a particular type of noise a TV set is making could help diagnose the problem. Enjoy the day wherever you are.

Nanomechanical Qubit May Be Highly Stable

Nanomechanical Qubit May Be Highly Stable - RF Cafe"A quantum bit based on a vibrating carbon nanotube and a pair of quantum dots could be unusually resistant to noise. Although the new nanomechanical qubit is currently at the proposal stage, calculations by Fabio Pistolesi of the French National Centre for Scientific Research (CNRS) at the University of Bordeaux and colleagues in the US and Spain indicate that its so-called 'decoherence time' - a measure of how long fragile quantum information can survive in a noisy environment - would be remarkably long, making it an attractive platform for quantum computing. Quantum computers can, in principle, solve certain problems much faster than classical computers because they exploit a quantum system's ability..."

Transmission Line Matching

Transmission Line Matching, September 1958 Radio-Electronics - RF CafeHere is a short tutorial on how to design a resistive impedance matching circuit for feeding multiple transmission lines of equal impedance. Both series and parallel feeds are presented. As the author mentions, ideally you would like a lossless transformer for matching, but often a resistive network is acceptable, especially if receive signal power is not an issue and if your transmitter power is sufficient to overcome the resistive losses (and doesn't torch the resistors). It is also possible to match transmission lines of different impedances, but the equation would get messy. Although it would mean even more resistive loss, the simplest way to match unequal impedance lines is to first match to a value most of the lines exhibit, then build a separate resistive transformer for the line(s) that are different to connect between the main match network and the unequal line(s)...

Impedance Matching Basics E-Book

Impedance Matching Basics E-Book - RF CafeThe Electronics Design website is offering a free download for Lou Frenzel's "Back to Basics: Impedance Matching" e−Book. "Impedance matching is easy if you know the basics," he begins. "The term 'impedance matching' is rather straightforward. It's simply defined as the process of making one impedance look like another. Frequently, it becomes necessary to match a load impedance to the source or internal impedance of a driving source. A wide variety of components and circuits can be used for impedance matching. This series summarizes the most common impedance-matching techniques."

RF Cascade Workbook 2018

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 Aegis Power Systems for Their Continued Support!

Aegis Power Systems - RF CafeAegis Power Systems is a leading supplier of AC-DC and DC-DC power supplies for custom and special applications. Aegis has been designing and building highly reliable custom power supplies since 1995. They offer a complete line of switch mode power supplies and power converters for a variety of markets including defense, industrial, aircraft, VME, and telecom. Supports military, aircraft, EV, telecom, and embedded computing applications. Design and manufacture of custom power supply solutions to meet each customer's exacting specifications. Please visit Aegis Power Systems today.

Sunday the 5th

Technology Theme Crossword for September 5th

Technology Theme Crossword Puzzle for September 5th, 2021 - RF CafeThis Technology Theme crossword puzzle for September 5th, 2021, contains only words and clues related to engineering, mathematics, chemistry, physics, and other technical words. 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., Hedy Lamarr or the Bikini Atoll). The technically inclined cruciverbalists amongst us will appreciate the effort. Enjoy!

Friday the 3rd

LED Material Shines Under Strain

LED Material Shines Under Strain - RF Cafe"Smartphones, laptops, and lighting applications rely on light-emitting diodes (LEDs) to shine bright. But the brighter these LED technologies shine, the more inefficient they become, releasing more energy as heat instead of light. Now, as reported in the journal Science, a team led by researchers at Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley has demonstrated an approach for achieving near 100% light-emission efficiency at all brightness levels. Their approach focuses on stretching or compressing a thin semiconductor film in a way that favorably changes its electronic structure. The team identified just how the semiconductor's electronic structure dictated interaction among the energetic particles within the material. Those particles sometimes collide and annihilate each other, losing energy as heat instead of emitting light in the process. Changing the material's electronic structure reduced the likelihood..."

Reflect Forward Linearizer for Combined Amplifiers

Reflect Forward Linearizer for Combined Amplifiers - RF CafeRF Cafe website visitor Ray Gutierrez generously provided a paper for publication a few years ago, and now has provided a follow-on article on the subject of intermod cancellation in RF amplifiers. Says Ray, "This paper is a continuation work for the "New High Efficiency Intermodulation Cancellation Technique for Single Stage Amplifiers." Published in January 2008 on RF Cafe's Paper section. The paper describes configurations for dual and multiple parallel amplifiers and uses the basic Reflect Forward technique for intermodulation cancellation. Some new improvements were made to the RFAL technique to improve the efficiency and operation." Further, "I had done much of the work for this new paper back then but got busy doing other things in my retirement time..."

A Simple 5- and 10-Meter Transmitter

A Simple 5- and 10-Meter Transmitter, February 1941 QST - RF CafeThis circa 1941 QST magazine article is provided as a reference to how these early vacuum tube transmitters were designed and built. Modifications in the circuit would be required to adapt this transmitter to modern standards of spectrum purity, and the 5-meter band is no longer allocated to Amateur Radio. The 6-meter band runs from 50 to 54 MHz, so anyone desiring to actually build a version of this radio could easily shift the frequency a couple MHz. The weight of this rig with batteries for running it a a mobile unit would be probably somewhere in the 10 to 20 pound range - a far cry from today's mobile units which tip the scales at under a pound and in a much smaller volume. This article is also a good reference for theory and operation of some of the older equipment...

Near-Field / Far-Field Transition Distance

Near-Field / Far-Field Transition Distance - RF CafeAn article written by Tom Lecklider in the October 2005 edition of Evaluation Engineering titled "The World of the Near Field" presented formulas for three regions of the near field that relate the largest physical dimension of the radiator to the operational wavelength. A great chart shows the transition area between near field and far field. There tends to be a lot of opinions (rules of thumb) about where the transition regions exist. There was also an article in the February 2001 edition of Conformity entitled, "Near and Far Fields - From Statics to Radiation" that did a good job of addressing the near field vs. far field issue. The calculator originally on this page has been removed because of compatibility issues with outdated Microsoft OWC components...

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 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.

Thursday the 2nd

Radio Aids to Aircraft Navigation

Radio Aids to Aircraft Navigation, September 1960 Electronics World - RF CafeThis is the third installment on "Radio Aids to Aircraft Navigation," written by Francis Gicca for Electronics World magazine. The first two appeared in the July (LF Ranges and Direction Finding) and August (VHF Omnidirectional Range - VOR) issues. "Terminal Instrument Navigation (ILS & GCA)" covered here in the September issue, are by far the most technical and complicated systems. The Instrument Landing System (ILS) is a "blind landing" system where the pilot navigates the aircraft (airplane or helicopter) along a set of very narrow RF beams configured to provide glide slope and azimuth courses. Ground Controlled Approach (GCA) involves human guidance via radio communications using ground-based radar equipment. I worked on both Airport Surveillance Radar (ASR) and Precision Approach Radar (PAR) very similar to those shown in the accompanying photos...

LG Records 6G THz Band Milestone 

LG Records 6G THz Band Milestone - RF Cafe"LG Electronics (LG) successfully demonstrated the transmission and reception of wireless 6G terahertz (THz) data over 100 meters in an outdoor setting. This milestone was achieved in collaboration with Fraunhofer-Gesellschaft, Europe's largest applied research lab, on August 13 with the data traveling between Fraunhofer Heinrich Hertz Institute (HHI) and the Berlin Institute of Technology in Germany. As 6G THz has short range and experiences power loss during transmission and reception between antennas, one of the biggest challenges in the evolution of wireless 6G has been the need of power amplification to generate a stable signal across ultra-wideband frequencies. The power amplifier developed by LG, Fraunhofer HHI and Fraunhofer Institute for Applied Solid State Physics (IAF) was crucial to the success of this latest test..."

Drawing a Circle with a Framing Square and 2 Nails

Drawing a Circle with a Framing Square and 2 Nails - RF Cafe"Squaring the circle" may as yet be an unattainable goal for even the best mathematicians, but the November 2012 edition of The Family Handyman magazine had a tip for how to use a square (of the framing type) and two nails to draw a circle. The author comments, "Don't ask us why this process works; all we know is that it does." Out of curiosity, I dug out my father's old Audels Carpenters and Builders Guide (printed in 1945) to see if it described the method and if it did, was there an explanation offered. It did, and he did. Read on...

NAVPERS 10622 - Blueprint Reading and Sketching

9/2

Electricity - Basic Navy Training Courses, NAVPERS 10622, Chapter 16 - Blueprint Reading and Sketching - RF CafeElectrical wiring drawings or blueprints are maps which show you' the location and circuit connections of every piece of electrical equipment aboard ship. Blueprints properly used are an invaluable aid "trouble shooting", in other words, in isolating faults in an electrical circuit. This is undoubtedly the most important work of the naval electrician. You should therefore study the training course Use of Blueprints (NAVPERS 10621) to get a basic understanding of how blueprints are made and used. Then read tills chapter and you will know all the information that goes into Navy wiring blueprints and how to use it...

Axiom Blog: Ease the Loads When Testing AC/DC Sources

Ease the Loads When Testing AC/DC Sources - RF CafeAxiom Test Equipment, an electronic test equipment rental and sales company has published a new blog post that informs people about the versatility of an electronic load. When an AC or DC supply must be evaluated, during design or even for maintenance, an electronic load provides much needed capabilities. Electronic loads provide insights into how the power source behaves under different load conditions for AC or DC power sources. By keeping an electrical parameter such as voltage, current, power, or resistance fixed, it can measure voltage/current or power/resistance under constant-voltage (CV), constant-current (CC), constant-power (CP), and constant-resistance (CR) conditions. Starting the search for an electronic load usually begins by understanding an application's requirements, for AC or DC testing...

FCC 4G LTE Interactive Coverage Map

FCC 4G LTE Coverage Map - RF CafeThe FCC has published an interactive map showing 4G LTE coverage in the U.S. The thumbnail here has all the providers turned on, and you can see in the full-size map that while there is a lot of overlapping coverage in densely populated areas, there are still places in the western mountains and deserts where there is no coverage at all from any provider. It will zoom down to house level for determining coverage. The amount of hardware (towers, cables, antennas, BTS's, etc.) involved is huge, as is the amount of electricity and distribution lines required to power it all. I do not recall seeing a number anywhere estimating the global carbon footprint of the cellular systems - including towers, data centers, mobile devices, batteries, AC power delivery and usage, raw mineral resources, manufacturing, packaging, transportation to end users, landfill impact...

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.

Wednesday the 1st

Short Waves of Tomorrow

Short Waves of Tomorrow, January 1938 Radio-Craft - RF CafeHugo Gernsback, in a 1938 issue of his Radio-Craft magazine, lampooned his contemporaries who boldly declared that by then (1938) there was nothing left to be invented regarding radio equipment for shortwave communications. Wisely citing the well-known instance of a patent examiner who quit his post in 1870 because, as the man put it, all useful things had been invented and there was nothing meaningful left to patent, Mr. Gernsback challenged his readers to keep this article for 25 years and then go back and read it while being aware of all the new and wonderful short wave devices that had been invented since 1938. It has now been more than 80 hence since the challenge was issued, and not only has the state of the art of short waves advanced beyond any of their wildest dreams, but entire new realms of radio and optical communications have been born and evolved that only futurist like Hugo Gernsback, H.G. Wells, Jules Verne, and Edgar Allen Poe (Poe was considered a great sci-fi writer) could ever have even imagined.

Wooden CubeSat to Launch in 2023

Wooden CubeSat to Launch in 2023 - RF Cafe"Wood is an amazing material. It can be strong, flexible or lightweight - and sometimes all of the above depending upon the tree. Wood can be used on its own, or it can be processed to create materials with an even wider range of desirable properties. So, it should come as no surprise that scientists in Japan are looking at how wood could be used in space. Previous studies have shown that wood can withstand the extremes of temperature experienced in space - it holds up well from in the -150 to 150C range - and it is not affected significantly by near-vacuum conditions. Now, Koji Murata at Kyoto University's Biomaterials Design Lab and colleagues are sending several samples of wood to the International Space Station (ISS)...

Guided Missiles

Guided Missiles, January 1948 Radio News - RF CafeWhen this January 1948 issue of Radio News magazine was published, a mere two and a half years had passed since the end of World War II, and military planners were already strategizing about what a future war might look like. Two technologies that had a huge effect on the previous efforts were the atom bomb and the guided missile; therefore, they were prominent in discussions. Germany's use of the V−1 Buzz Bomb is a familiar example of a guided missile that struck terror in the hearts of populations that experienced its devastating destructive power. Ditto for the V−2 rocket. The U.S. developed a few missiles of its own, particularly immediately after WWII when it had the assistance of Werner von Braun and other notable rocket scientists who worked for the U.S. space effort after the war...

Circularly Polarized Dielectric Resonator Antennas

Circularly Polarized Dielectric Resonator Antennas (Artech House) - RF CafeArtech House today announced the publication of Circularly Polarized Dielectric Resonator Antennas, by Raghvendra Kumar Chaudhary, Rajkishor Kumar, and Rakesh Chowdhury. This unique resource introduces wideband circular polarization radiation in dielectric resonator antennas (DRA). It presents five key feeding techniques, including coaxial probe, microstrip, conformal strip, aperture, and coplanar waveguide. It also covers different shapes of dielectric resonator antennas, which will lead to improvement of circularly polarized (CP) performance and explores the advantages and disadvantages of each feeding technique. Important characteristics of DRA, including high radiation efficiency, high gain, wide range of bandwidth, low ohmic losses, high power handling capability, and 3D‐design flexibility, are discussed. New techniques that generate broadside circular polarization (CP) by using sectored DRAs...

Accidental Engineer Blog: Filter Topologies

Filter Topologies Blog - Reactel Accidental Engineer - RF CafeIn his latest The Accidental Engineer blog post, Reactel's Jim Assurian offers his extensive  expertise on the topic of Filter Topologies. He begins thusly: "Have you ever asked yourself, “why did Jim quote me a cavity filter when I was sure a discrete component filter was what I wanted”? In this post, I'll detail several different filter topologies and reasons for using them. In advance, however, please understand that this is a general discussion – each situation is unique, and a given set of requirements may cause a deviation from the guidelines to follow..." The Accidental Engineer has many other blog topics that will interest you including Filter Mounting Options, How Wide Can You Go? (in bandwidth), and Connectors & Power.

Promote Your Company on RF Cafe

Sponsor RF Cafe for as Little as $40 per Month - RF CafeNew Scheme rotates all Banners in all locations on the page!RF Cafe typically receives 8,000-15,000 website visits each weekday. RF Cafe is a favorite of engineers, technicians, hobbyists, and students all over the world. With more than 16,000 pages in the Google search index, RF Cafe returns in favorable positions on many types of key searches, both for text and images. New content is added on a daily basis, which keeps the major search engines interested enough to spider it multiple times each day. Items added on the homepage often can be found in a Google search within a few hours of being posted. I also re-broadcast homepage items on LinkedIn. If you need your company news to be seen, RF Cafe is the place to be.

Many Thanks to LadyBug Technologies for Their Continued Support!

LadyBug Technologies RF Power Sensors - RF CafeLadyBug Technologies was founded in 2004 by two microwave engineers with a passion for quality microwave test instrumentation. Our employees offer many years experience in the design and manufacture of the worlds best vector network analyzers, spectrum analyzers, power meters and associated components. The management team has additional experience in optical power testing, military radar and a variety of programming environments including LabVIEW, VEE and other languages often used in programmatic systems. Extensive experience in a broad spectrum of demanding measurement applications. You can be assured that our Power Sensors are designed, built, tested and calibrated without compromise.

   

These archive pages are provided in order to make it easier for you to find items that you remember seeing on the RF Cafe homepage. Of course probably the easiest way to find anything on the website is to use the "Search RF Cafe" box at the top of every page. About RF Cafe.

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