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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...

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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Today in Science History

Tech Industry Headlines

Tech Industry Headlines - RF Cafe - Archive -

• RF Sem Market to Grow by $961M from 2020 to 2025

• U.S. Space Force's New GPS III Variant Capabilities

• What's Next for the World's Supply Chains in 2022?

• Complex Numbers Essential in Quantum Theory

• What the Heck is a "Bare-Metal cloud?"

• UK Ends Work from Home, Facemasks, Vaccine Passports

• EuMW 2021 to Now Take Place in April 2022

• FCC Takes New Look at Data Breach Rules

• TSMC Plans 2022 Capex of $44B

Google's White Spaces Spectrum Database

Google's White Spaces Spectrum Database - RF Cafe SmorgasbordThere are not many technical realms where Google engineers have not either entered or created. Wireless connectivity is key to their continued dominance in the information domain, so they understandably have a vested interest in the "white space" spectrum debate. White space comprises portions of the electromagnetic spectrum where bands are either unlicensed or where licensed bands are or will be up for grabs. An example of the former is the 2.4 GHz Wi-Fi band, and an example of the latter is some parts of the broadcast television band that is being vacated in areas. Although this information is a few years old, it shows how Google was working early−on with the Federal Communications Commission (FCC) to build a real-time database of what they term "dynamic spectrum" in order to provide useful information about available white space (now directs here) to both users and providers. A separate database is available for fixed and mobile spectrum. Enter your location of interest and the map zooms into that region. For instance, in my town (at the time) of Erie, Pennsylvania (see marker on map below), as of January 2013 when this was first posted there were 21 channels available...

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 Reactel for Their Long-Time Support!

Reactel Filters - RF Cafe

Reactel has become one of the industry leaders in the design and manufacture of RF and microwave filters, diplexers, and sub-assemblies. They offer the generally known tubular, LC, cavity, and waveguide designs, as well as state of the art high performance suspended substrate models. Through a continuous process of research and development, they have established a full line of filters of filters of all types - lowpass, highpass, bandpass, bandstop, diplexer, and more. Established in 1979. Please contact Reactel today to see how they might help your project.

Detecting Aircraft at Night

Detecting Aircraft at Night, February 1942 Radio News - RF CafeMost(?) RF Cafe visitors are probably familiar with British engineer John Logie Baird as being considered "the father of television." His work in the 1920s produced both live and recorded motion pictures transmitted and received electronically. What most visitors (including me) probably did not know is that he also developed television apparatus using infrared imaging; he called it "Noctovision." Noctovision (noct or nox meaning night) was a moving image form of the still imaging "Noctovisor," which was an early night vision system that converted an infrared image into an optical image. Radar was still in its infancy in 1942 when this article appeared in Radio News magazine, and had not been implemented widely enough to provided needed surveillance against nighttime bombing raids from Germany's Luftwaffe (air force) flying across the English Channel. According to author Rosen, infrared wavelengths have 16x the fog penetrating power of optical wavelengths...

Thanks Again to Anatech Electronics for Support!

Anatech Electronics logo - RF CafeAnatech Electronics (AEI) manufactures and supplies RF and microwave filters for military and commercial communication systems, providing standard LP, HP, BP, BS, notch, diplexer, and custom RF filters, and RF products. Standard RF filter and cable assembly products are published in our website database for ease of procurement. Custom RF filters designs are used when a standard cannot be found, or the requirements dictate a custom approach for your military and commercial communications needs. Sam Benzacar's monthly newsletters address contemporary wireless subjects. Please visit Anatech today to see how they can help your project succeed. 

China's GalaxySpace to Challenge SpaceX's Starlink - RF CafeTogether with Amazon's Kuiper and the EU's OneWeb, China's GalaxySpace and SpaceX's Starlink will forever transform the night sky by launching tens of thousands of small LEO satellites, each of which will reflect sunlight to observers situated between them and the sun. Many - if not most - will be visible to the naked eye and will definitely appear as streaks in time exposure astronomical images. These systems will provide global broadband connectivity at a projected cost of about $100 per month to those of us who will actually shell out our wampum for it, which is about the cost of equivalent cable-based Internet connectivity now. As is the case now, our expensive subscriptions will continue to subsidize the many who pay reduced rate or nothing for the service - another instance of a few pulling the metaphoric welfare wagon while rest are in it for the free ride...

How the Stereo Disc Works

How the Stereo Disc Works, July 1958 Radio-Electronics - RF CafeMy first major high fidelity (Hi−Fi) stereo system purchase came during my senior year at Southern Senior High School when I had saved enough money to buy a combination AM/FM receiver, 8-track tape deck, turn table, and two speakers with separate woofers, midranges, and tweeters. At the time I thought the setup might impress friends and relatives... until I learned quite quickly that "serious" stereo sound connoisseurs decidedly did NOT have equipment with "Reader's Digest" logos on it. Oh well, the price seemed like a really good bargain to me give the promised tonal superiority. Compared to the clock radio I used previously for my music listening sessions, the Reader's Digest stereo system produced music hall quality sound. Ah, the deep bass notes were grand. Spending most of my earned money on model airplanes, rockets, and my '69 Camaro left little disposable income for LPs (referred to as "discs" in this article), so the turntable did not get much use. I did, however, read up on how to balance the tone arm...

Tiny Sensor Makes the Invisible Visible

Tiny Sensor Makes the Invisible Visible - RF Cafe"A TU/e research group has developed a new near-infrared sensor that is easy to make, comparable in size to sensors in smartphones, and ready for immediate use in industrial process monitoring and agriculture. This breakthrough has just been published in Nature Communications, with co-first author Kaylee Hakkel defending her Ph.D. thesis on January 14th. The human eye is a marvelous sensor. Using three photoreceptor cells that convert visible light into signals for different colors, the eye gives essential information about the world around us. "When our brain puts the signals together, it makes a prediction of what the signals mean based on our experiences. For example, a red strawberry is sweet, but a green one is not..."

Webinar: HF in a Nutshell

Webinar: HF in a Nutshell - RF CafeOn Friday, January 28th and Monday, the 31st, Rohde & Schwarz (R&S) will be conducting a webinar entitled "HF in a Nutshell." You would be excused to thinking that this an amateur radio event because many of the company's employees are Hams, but in fact it is billed as "An overview of current beyond-line-of-sight communications solutions." Further, "HF communications technology is reliable, proven and has been in service for decades. This webinar is the first in a series covering HF topics and will illustrate that HF communications is in no way your grandparents' technology, but rather THE communications solution for the future. You will receive an overview of currently available Beyond Line of Sight (BLOS) communications solutions and the latest developments in this field, i.e. HF versus satellite communications (SATCOM)..."

Low-Pressure Modulation Facts

Low-Pressure Modulation Facts, July 1953 QST - RF CafeAuthor Howard Wright takes the opportunity here in a 1936 issue of QST magazine to distill the concept of modulation down to its basic operation while dispensing with the garbled mix of "graphs, formulas, charts, vectors, diagrams, and Greek letters which often enter into various discussions of modulation." Mr. Wright describes how to the uninitiated radio dial spinner, the culmination of events occurring behind the scenes in an AM reception process is akin to this: "...it might be compared to the reproduction of a color photograph in a magazine. How would we ever know that, to be reproduced, the picture was broken down into its primary colors, if all we had to go by was the original print and the magazine?" That is a very apt comparison...

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

Engineering Job Board - RF Cafe RF 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 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.

Bell Telephone Labs - How Do You Stop an ICBM?

Bell Telephone Laboratories - How Do You Stop an ICBM?, December 1961 Radio-Electronics - RF CafeThe era of nuclear weapons of course began in August of 1945 when they effectively ended World War II, but it wasn't until around 1955 that another country - the U.S.S.R. - developed a deployable thermonuclear bomb. Even before that happened, the U.S. Department of Defense began planning for systems to detect and ultimately disable enemy ICBMs and aircraft-delivered nuclear bombs. The nuclear arms race had begun, and continues to this day. Now, there are five countries recognized as possessing thermonuclear weapons, three countries declaring possession, and one country implying possession. A somewhat insane concept dubbed MAD asserts that if everyone can strike and counterstrike with equal capability, that will prevent nuclear warfare because the aggressor will suffer as significantly as the victim. This 1961 Bell Telephone Labs promotion in Radio−Electronics magazine introduced one of the early concepts for intercepting inbound ICBMs. The most familiar and successful system...

Modelithics' New Model Rap Blog Series

Modelithics' New Model Rap Blog Series - RF CafeModelithics is excited to launch a new monthly blog series - Model Rap! These blog posts will provide helpful tips for RF & Microwave design success using high-accuracy simulation models in the industry's leading simulation software. EM/circuit co−simulations are both accurate and painless when using Keysight Technologies' RFPro EM environment in conjunction with Modelithics models. In this blog post, learn why this approach for EM/circuit co-simulations offers tremendous advantages in comparison to traditional methods. The premier edition is entitled, "EM/Circuit Co-Simulation Made Easy and Accurate with Keysight RFPro and Modelithics Models..."

Reactivating Leaky Electrolytic Capacitors

Reactivating Leaky Electrolytic Capacitors, January 1956 Popular Electronics - RF CafeUnlike the Roll Your Own Foil Capacitors article in the same issue of Popular Electronics magazine, this one advising how to reactivate leaky capacitors might be of use to a lot more people. The process is called "reforming," and consists of applying a DC voltage to the faulty capacitor, beginning at a very low voltage, and then slowly raising the voltage until the rated working voltage (WVDC) is reached. Doing so, if the capacitor is not beyond rehabilitation, will reconstitute the oxide layer that serves as the dielectric. This particular item was presented as the answer to a question posed by a reader. A Google search on "reform capacitor" will turn up more detail about the procedure. Most people recommend against reforming unless you have no other option, as this writer from India might have faced at the time...

Satellites on the Air

Satellites on the Air, December 1962, March, April, May, June 1963 - RF CafeBy late 1962, the United States was launching new satellites at a very rapid pace. Many were destroyed on the launch pad, others never turned on once in orbit, still more turned on and operated in a crippled form and/or only for a small portion of their intended lifespans. It was a learning period for the entire satellite, rocket, mission control, Earth-based tracking stations, and the communications equipment that dialoged with the satellites. The "race" part of the Space Race moniker was literal. Popular Electronics, QST, Electronics World, and other electronics communications publications regularly printed a list of newly commissioned satellites. The lists presented here came from five different 1962-1963 editions of Popular Electronics. The feature was repeated for many years. Incidentally, the "mc" frequency unit used at the time was the common abbreviation for "million cycles per second." In 1960, the Hertz was adopted by the General Conference on Weights and Measures...

Please see the RF Cafe Homepage Archives for previous items of interest...

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