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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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- Welcome to the RF Cafe Website -
"By 2005, it will become clear that the Internet's impact on the economy has been
no greater than the fax machine's." - Paul Krugman - Nobel Prize winner (what a maroon)

Today in Science History

Tech Industry Headlines

Tech Industry Headlines - RF Cafe- Archive -

• Ultra-Rich Eco Warriors Driving Private Jet Boom

• Metal Modulated AlGaN Superlattices

• Connecting America's Eastern and Western Power Grids

• China Makes Massive Strides in Supercomputing

• InP-Lithium Niobate Hybrid Laser

• Toshiba Splits in 3 After 146 Years

• 5G FWA Study Supports More Mid-Band Spectrum

• Law Enforces Stripping out Huawei Switchgear

• Most 5G Sites Will Be Sub-6 GHz by 2026

Electronics Themed ASCII Art

Electronics Themed ASCII Art - RF Cafe SmorgasbordASCII Art has been around nearly as long as digital computers have been in existence. It was the only type of "graphics" available to most users before other than text displays were commonplace. Universities, corporations, and government research facilities had crude forms of graphical displays, but it was not until the 16-color, 640x200-pixel CGA (Color Graphics Adapter) monitors began shipping with IBM PCs that most people had access to "real" graphics. To compensate, some pretty clever souls came up with what has become known as "ASCII Art." ASCII (American Standard Code for Information Interchange), for those of you too young to remember when that was part of common computer parlance, is the basic set of numbers, letters, and special characters that all computers are capable of rendering based on unique codes assigned to them. For instance, ASCII character 48D (30H) is the number "0," 65D (41H) is upper case "A,"...

"F-M" Put on Commercial Basis

"F-M" Put on Commercial Basis, August September 1940 National Radio News - RF CafeShortly after Edwin H. Armstrong demonstrated the viability of FM (frequency modulation) for long distance broadcasting in January of 1940, the U.S. FCC (Federal Communications Commission) allocated spectrum to it in the 42-50 MHz band. Armstrong had introduced the FCC to FM originally in 1936. The new modulation scheme was popular due to its immunity to amplitude related noise like that generated by motors, automobile ignition systems, and lightning. However, World War II broke out a little over a year later and most commercial radio advancements were put on hold. This article from a 1940 edition of National Radio News could not have predicted that, or the FCC's decision to relocate the FM spectrum to 88-108 MHz in 1945 in the closing days of WWII. Some speculate that the spectrum shift was a ploy by RCA chairman David Sarnoff to undermine the advantage Armstrong had with his established FM radio production. Nah, it couldn't be so because government bureaucrats...

Jay Last, Fairchild Semi Co-Founder, Dies at 92

Jay Last, Fairchild Semi Co-Founder, Dies at 92 - RF CafeEE Times has a tribute to Fairchild Semiconductor co-founder Jay Last following news of his passing at age 92. "One of the least-well-known heroes of the semiconductor revolution, Jay Last, died on November 11, 2021. Last was one of the famous team of eight people that left Shockley Semiconductor Laboratory to found Fairchild Semiconductor. While there, he was leader of the team that developed the essential technologies that led to the first practical IC. In 1946, between his junior and senior years in high school, Last hitchhiked from Pennsylvania to the orchards of San Jose, Calif., where he picked fruit for the summer. It was probably a lark at the time, but a momentous decision nevertheless. After earning a PhD in Physics from MIT in 1956, he ended up moving to the San Francisco Bay area to work at Shockley Semiconductor Laboratories in Palo Alto, California. His fruit-picking experience influenced his decision to move to California. Shockley Semiconductor was founded in 1956 as a Beckmann Instruments subsidiary. At the time Last was wrapping up his doctoral thesis, working with a balky Beckman spectrophotometer, which led to plenty of interactions with Beckman’s people..."

NASA Laser Demonstrations Extend to Deep Space

NASA Laser Demonstrations Extend to Deep Space - RF Cafe"NASA plans to launch a pair of laser communications missions over the next nine months that would demonstrate high-bandwidth optical relays capable of someday transmitting streaming HD video and other data from planetary probes. The launch of the Laser Communications Relay Demonstration (LCRD) scheduled for Dec. 4 will be followed as early as August 2022 by the launch of the Deep Space Optical Communications flight demonstration, program officials said this week. LCRD, testing laser communications from geosynchronous orbit, is managed by NASA's Goddard Space Flight Center. The Jet Propulsion Laboratory (JPL) is overseeing development of the deep space mission that will operate between the orbits of Mars and Jupiter as part of NASA mission to study a giant metal asteroid..."

RFCafe.com Website Statistics Update

RFCafe.com Website Statistics (July-November 2021) - RF CafeThings are looking up for RFCafe.com website statistics. The trend lines for Page Views, Visits, and New Visits all have a positive slope. I have put a lot of effort into making pages compliant with Google's "Mobile Friendly" requirements, so that probably has something to do with it. Also, you may have noticed that I have been modifying and re-publishing some of the earlier RF Cafe webpages. That involves updating the narrative, verifying hyperlinks (many go dead over time), and cleaning up older graphics. Much has changed in expectations from visitors - especially from the early days in the late 1990s and early 2000s. Competition for visitors is fierce. As always, thank you for your visitorship and stewardship.

How to Construct a 56 Megacycle Magnetron Transmitter

How to Construct a 56 Megacycle Magnetron Transmitter, September 1932 Radio News - RF CafeMagnetrons and klystrons are fairly ubiquitous in society these days for use in heating, radar, industrial processes, cooking, and even lighting. They were probably the first useful means of producing high power microwave signals. The concept was first brought to fruition in the early 1920s as a laboratory curiosity and rapidly developed into a practical type of device with many applications and spin-off products like the klystron, the traveling wave tube, and the cross-field amplifier. This article from a 1932 edition of Radio News magazine reports on the state of the art a decade after the magnetron's inception...

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.

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.


TV DX, July 1958 Radio-Electronics - RF CafeHobbyists in the technical realm have in many ways contributed mightily to the advancement of professional scientific knowledge and practice. This is partly because many hobbyists are also career technologists, but the majority are tinkerers, experimenters and otherwise participants who come from all walks of life geographically, economically, professionally, and socially. Just as with university and corporate laboratories, some of the discoveries are the result of structured, preconceived plans of action and designs of experiments with certain goals in mind; many, however, are due to serendipitous events that are recognized by their participants as being significant. Such is the case of "TV DX" as related in this story. TV DX is the use of unique opportunities in the atmosphere's ionization state to facilitate signal transmission and reception at distance much greater than normally experienced. Data collected by amateurs were, during the era of over-the-air VHF and VHF television broadcasting, included in studies and theories created by professional scientists and engineers...

WKRP in Cincinnati: "As God As My Witness, I Thought Turkeys Could Fly"

WKRP in Cincinnati: "As God As My Witness, I Thought Turkeys Could Fly" - RF Cafe Anyone who watched the WKRP in Cincinnati sitcom back in the 1970s has to remember what was one of the funniest episodes ever. Here is the 4 minutes that made Prime Time history. In this Thanksgiving episode, station owner Arthur Carlson decided he would surprise the community with good deed - that doubled as a promotional stunt for his radio station - by dropping turkeys from a helicopter for lucky shoppers at the local shopping mall. Watch the disaster unfold as Les Nessman reports live, and then see Carlson's final comment that is still used or alluded to in many comic routines. Posting this video is an RF Cafe tradition. Have a Happy Thanksgiving!

AFRL Awards $1B Space Technology Research Contract

AFRL Awards $1B Space Technology Research Contract - RF Cafe"The Air Force Research Laboratory has awarded Utah State University a $1B contract to support space-related research and technology development at its Space Dynamics Laboratory. Under the contract, the Space Dynamics Laboratory will continue to provide an outside source for essential space engineering and capability development as a University Affiliated Research Center, or UARC. 'This contract solidifies the long-term strategic partnership between AFRL and USU/SDL. The partnership will accelerate critical space science and technology projects, especially when we need to quickly respond to urgent and unexpected needs,' said Col. Eric Felt, director of the AFRL Space Vehicles Directorate, in a statement. 'It will allow us to focus on proactively out-innovating our peer competitors to ensure the Space Force continues to have the technology required to deter conflict..."

Are You Prepared for an EMP?

Are You Prepared for an EMP? - RF CafeWell, no, but then who really is? Thanks to vigilant and brilliant scientists and engineers developing detection and protection schemes, mankind has survived some fairly significant solar storms (primarily coronal mass ejections - aka CMEs) which might have profoundly disturbed and/or destroyed some vital communications and electrical distribution capabilities. As with all the behind-the-scenes work that prevented a Y2K catastrophe, most people are not aware of immense effort put into safeguarding mankind against such natural perils. An EMP is a different beast, though, because it would be a manmade electrical disturbance, likely as an act of war. Survivalists think owning an old pickup truck without any electronics in it and a vacuum tube radio is the key to surviving an EMP. It wouldn't be long before they were in the same doodoo as the rest of us if a major EMP event occurred. If you worry about such things, here is an article on the Electronic Design website that might interest you entitled "Are You Prepared for an EMP?"

RF & Electronics Symbols for Office™

RF & Electronics Schematic & Block Diagram Symbols for Office™ r2 - RF CafeIt was a lot of work, but I finally finished a version of the "RF & Electronics Schematic & Block Diagram Symbols" that works well with Microsoft Office™ programs Word™, Excel™, and Power Point™. This is an equivalent of the extensive set of amplifier, mixer, filter, switch, connector, waveguide, digital, analog, antenna, and other commonly used symbols for system block diagrams and schematics created for Visio™. Each of the 1,000 or so symbols was exported individually from Visio in the EMF file format, then imported into Word on a Drawing Canvas. The EMF format allows an image to be scaled up or down without becoming pixelated, so all the shapes can be resized in a document and still look good. The imported symbols can also be UnGrouped into their original constituent parts for editing. Check them out!

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. 

Indoor and Built-In Antennas Their Strong and Weak Points

Indoor and Built-In Antennas Their Strong and Weak Points, November 1949 Radio-Electronics - RF CafeThe virtues and evils of the plethora types of television antennas was the subject of many magazine articles back in the era preceding cable, Internet, and satellite program delivery methods. Over-the-air broadcasts, while available free of cost to recipients, were often fraught with signal and therefore picture and audio degradations due to signal blockage, reflection, and multipath issues. How people dealt with the problems was also the theme of many TV-related comics which also appeared in those magazines. Serious efforts were made by engineers and homeowners to remedy those problems through a combination of antenna design, mounting, amplification, cabling, and other methods. Of course there were also the crazy "solutions" which involved tin foil over, between, and around VHF rabbit ears and/or UHF loops and other things. I must also admit to having also resorted to extreme measures...

Also Indoor Television Antennas

Electronics and the IGY

Electronics and the IGY, March 1958 Radio-Electronics - RF CafeThis second in a series of International Geophysical Year (IGY) articles that appeared in Radio-Electronics magazine in 1958. The author covers basics of satellite configuration, launching, and tracking based on knowledge of the era. Keep in mind, though, that the U.S. had not actually launched its first satellite at the time. In fact, the two satellite models shown possess antennas suggesting active radio circuits within, but Echo, our first passive earth-orbiting satellite, was just a metallized plastic sphere that reflected radio signals back to Earth. The Russian Sputnik, by comparison, did have electronic circuitry onboard for transmitting but not receiving a signal. SCORE, launched in December of 1958, was America's first transponder satellite...

Anatech Electronics Product Update: 3 New Filter Models

Anatech Electronics Product Update: 3 New Filter Models - RF CafeAnatech Electronics offers the industry's largest portfolio of high-performance standard and customized RF and microwave filters and filter-related products for military, commercial, aerospace and defense, and industrial applications up to 40 GHz. Two new filter models have been introduced - a 896-898 MHz / 935-937 MHz cavity duplexer, a 2400 MHz ceramic bandpass filter with sharp roll-off above and below the pass band, and a 300-320 MHz / 360-380 MHz LC duplexer. Custom RF power directional coupler designs can be designed and produced when a standard cannot be found, or the requirements are such that a custom approach is necessary...

A Transistor Dictionary

Transistor Dictionary, May 1958 Radio-Electronics - RF CafeA few new terms have been added to the transistor lexicon since 1958, but this list from Radio-Electronics magazine contains more than 150 definitions that are still useful today. It is amazing that this list was created just a decade after the transistor was invented, and now half a century later the most commonly used terms have not changed much. In looking over the words, there are very few that need to be added to the original (which I did)...

Electronics Themed Comics

Electronics Themed Comics, June 1945 Radio-Craft - RF CafeHere are a few more electronics-themed comics from magazines of the days of yore. Radio-Craft readers submitted ideas for funnies and then artist Frank Beaven would draw the comics based on their ideas. Some months had no comics, and others had half a dozen or more. This June 1945 issue had three. There is also one from the May 1946 Radio News. You website visitors not familiar with vacuum tube construction might need to know that the jailhouse bars in "Control Grid" comic are an allusion to the wire mesh type element in tubes that modulated electron flow from the cathode to the anode. I once again colorized the comics to make them more attractive. Enjoy.

From "Frisco to Paree": A Wireless Op's Adventure

From "Frisco to Paree": A Wireless Op's Adventure, October 1932 Radio News - RF CafeIn case such things interest you, this first-person story of a ship's wireless operator, or "op," - the guy who manned the radio room - provides a little entertainment and insight into transoceanic travel in the 1930s. Per this 1932 Radio News magazine article, the author's trip was made less than two decades after the demise of the "unsinkable" RMS Titanic, where surviving passengers and crewmen were saved partially due to the heroics of the telegraph operators. Having never traveled on the water beyond the Chesapeake Bay, I wouldn't know how to compare today's voyage with those of yesteryear. Do passenger ships nowadays sometimes idle for three weeks in Central American waters while waiting for passage through the Panama Canal? Can anyone identify the story's ship shown in the photo? Evidently Griffin was not permitted to name it because of the less than totally complimentary...

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