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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 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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"Consider that typewriters had ¢ keys. Computers have $ keys. There's inflation for you." - Kirt Blattenberger

Today in Science History

Tech Industry Headlines

Tech Industry Headlines - RF Cafe - Archive -

• SpaceX Says Dish's 12 GHz 5G Would Kill Starlink

• Canadian Telcos Finally Get up to Speed

• LinkedIn Likes Audacy

• Moore's Law Slowdown and Chip Shortage

• Huge Carbon Footprint from Manufacturing Lithium Batteries

• U.S. Chips Act Nears Cut-off Point

• Electrically Conductive Paints & Polymers Now Easily Produced

• Platform for Quantum Technologies Using Gold

• Call for Greater Safety and Sustainability in Space

Transparency on Demand

Transparency on Demand - RF Cafe"Scientists at the University of Rostock, in close collaboration with partners from the Vienna University of Technology, have developed a novel process that can render artificial materials transparent or even entirely invisible, on demand. Their discovery was recently published in the renowned journal Science Advances. Turning something invisible is a common trope in science fiction, such as the Cloak of Invisibility in Harry Potter. Certainly, it sounds cool, but the reason it is so common in stories is that it would be incredibly useful technology. The uses for espionage and the military are obvious, but there are far more applications. Given its immense usefulness, it may not come as a surprise that this is something scientists and engineers have been actively working on. They've had quite a bit of progress too, using molybdenum trioxide, metamaterials, metascreens, and dielectric materials to fashion invisibility cloaks. It all comes down to manipulating light in the proper way, and what is especially marvelous is that innovation in this

Please Visit Empower RF's Website in Appreciation of Their Support

Empower RF Systems - RF CafeEmpower RF Systems is a global leader in power amplifier solutions. Empower RF Systems is an established and technologically superior supplier of high power solid state RF & microwave amplifiers. Our offerings include modules, intelligent rack-mount amplifiers, and multi-function RF Power Amplifier solutions to 6 GHz in broadband and band specific designs. Output power combinations range from tens of watts to multi-kilowatts. Unprecedented size, weight and power reduction of our amplifiers is superior to anything in the market at similar frequencies and power levels.

Antenna Pattern Editor 2.0 Software Introduced

Antenna Pattern Editor 2.0 Software Introduced - RF CafeCenter of Telecommunication Technologies (CTT) is proud to announce immediate availability of version 2.0 of their popular Antenna Pattern Editor. Antenna Pattern Editor 2.0 is a universal tool to view, create, edit and convert antenna patterns. See the New Features in Antenna Pattern Editor 2.0 list at the left. The main idea embedded in the program is to provide the user with the opportunity to quickly create an antenna pattern file using various methods. Antenna pattern file is a simple text or xml file that describes the main characteristics of the antennas - radiation patterns, gain, frequency range, name, manufacturer and other data. These files are used in various radio planning tools including our RadioPlanner, Indoor Radio Planner, and MLinkPlanner. There are a large number of antenna pattern file formats, but it often happens that there is no file in the required format. In this case, using the Antenna Pattern Editor, you can easily convert the file to the format you need. Sometimes the antenna information is just a picture of the antenna pattern...

Measuring Inductance and Capacity

Measuring Inductance and Capacity, June 1931 Radio-Craft - RF CafeThis reactance measuring bridge circuit which appeared in a 1931 issue of Radio−Craft magazine employs a very unique element for generating an alternating current: an electromechanical buzzer which doubles as an audio source. Sure, it doesn't produce a pure sinewave, but for the method used here to determine inductance and capacitance it does not matter. Rather than attempting to measure an absolute value of inductance or capacitance, a known reactance is used as part of a balanced bridge. This is by no means a precision instrument since accuracy depends on the user's interpretation of the presence or absence of an audible "buzz" in a pair of headphones, but in an era when "real" test equipment was beyond the budgets of many (maybe most) hobbyists, the scheme was better than nothing at all...

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...

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.

Making Modern Tubes

Making Modern Tubes, June 1932 Radio-Craft - RF CafeIn no way do I advocate going back to the "old ways" for manufacturing electronic components, but I do admire and like to give credit to the people who used to perform the tedious procedure of building vacuum tubes, hand-wire chassis assemblies, circuit boards, etc. This 1932 issue of Radio−Craft magazine article is good example. The process required being able to sit or stand at the same work station and perform the same range of operations day after day, often for years on end. Of course at the time, automation processes were not what they are today and machinery needed to be driven by mechanical means using motors, solenoids, and limit switches. That made employing people more financially rewarding than using a machine. You can find details on the algorithms and methodology for designing those contraptions in older engineering handbooks. It is an amazing sight to to tour a WWII vintage battleship and look at the hardware that stabilized and steered the cannons without an electronic computer in sight...

Smart Molecules Act as Computer Transistors

Smart Molecules Act as Computer Transistors - RF Cafe"Researchers have discovered a single-molecule switch that can act like a transistor and store binary information such as the 1s and 0s used in classical computing. The molecule is around five square nanometers in size - more than one billion of them would fit onto the cross-section of a human hair. The researchers believe that molecules like the ones they have discovered could offer information density of around 250 terabits per square inch, which is around 100 times the storage density of current hard drives. The smart molecular switches as seen with a scanning tunneling microscope. In the study, molecules of an organic salt can be switched using a small electrical input to appear either bright or dark, providing binary information. This information can be written, read, and erased at room temperature and in normal air pressures. These are important characteristics for practical application of the molecules in computing storage devices..."

Raytheon Bonded Electronic Technician

Raytheon Bonded Electronic Technician Ad, January 1946 Radio News - RF CafeThere was a time when having a career in any field of electricity or electronics related work was an enviable mark of a person's technical prowess that conveyed a degree of respect. The whole controlling of electrons thing boggled the minds of most people, whether it meant wiring homes and buildings for lights, receptacles, and motors, or designing "all wave" radio sets for listening to the evening broadcast of "The Lone Ranger." Today, with nearly everyone alive having grown up with such conveniences, the "wow factor" is pretty much gone, except maybe with those of us who still chose to engage. If an electronics appliance or device stops working nowadays, it is discarded rather than repaired. This 2-page advertisement from a 1946 edition of Radio News magazine inviting men to become a "bonded electronic technician" is typical of those found in the era, and even in the 1920s and 1930s...

Lafayette Chassis Model B-100, -102, -103 Radio Service Data Sheet

Lafayette Chassis Model B-100 (Table Model B-103; Console Models B-101, B-102) Radio Service Data Sheet, August 1941 Radio-Craft - RF CafeThe Radio Service Data Sheets that were published in Radio−Craft magazine usually seem to have more information included than those published in other magazines, at least in the same era (1940-ish). It might have to do with how much material is provided by the manufacturer rather than a decision by the magazine editors. Either way, here are the schematics, chassis layout, and service info for the Lafayette Model B−100 through B−103. As with most radios built in the era, the woodwork and artistic design of the cabinet are exquisite. There are still people searching for such data, but fortunately the Internet is making it much easier to locate. None of the three models show up on eBay as of this writing...

Promote Your Company on RF Cafe for as Little as $40/Month

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 12,000 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 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.

Trio Manufacturing Company Zig−Zag Antenna

Trio Manufacturing Company Zig-Zag Antenna, October 1952 Radio-Electronics - RF CafeThis advertisement for a Zig−Zag Antenna, offered by Trio Manufacturing, appearing in a 1952 issue of Radio−Electronics magazine, states "patent pending." When I looked up "zig−zag antenna" at the U.S. Patent and Trademark Office (USPTO), the earliest assignment I could find for that configuration was US3213457A, "Zig−zag antenna," designed by John W. Carr and assigned to Lockheed Corporation, in 1961. Maybe Trio never received a patent, or my search wasn't thorough enough. The claim to fame from Trio's design is that the zig−zag pattern consisted of various element lengths that resonated on specific channels while all others acted as parasitic elements. I don't know if it is coincidence or intention (probably the latter), but there are twelve sections that might correspond to channels 2 through 13. There are not many (if any) zig−zag antennas being sold by companies today for amateur or other uses. It evidently was just another fad to have something different from all the rest - and there were lots of unique TV antenna configurations back in the day which promised to pull in far-away stations, reduce ghosts, noise, etc...

ESA's New Hybrid Channel Emulator for Satellite-Terrestrial 5G

ESA's New Hybrid Channel Emulator for Satellite-Terrestrial 5G - RF Cafe"The Hybrid Channel Emulator is one of the projects that is currently being developed as a part of ESA's ongoing ARTES (Advanced Research in Telecommunication Systems) program. The HCE is developed under a strategic goal namely 'Space for 5G' and the aim of the project is to design an emulator which can emulate radio propagation conditions of two bi-directional 5G carriers with accurate emulation of satellite-satellite and satellite-terrestrial link characteristics. The objective of the Hybrid Channel Emulator project is the development and validation of a single solution capable of emulating the radio propagation conditions of two bi-directional 5G carriers (satellite-satellite or satellite-terrestrial). This has the twin challenges of providing an emulator that accurately models the dynamics, and tightly controls the channel impairments, of a wide variety of scenarios, and one that covers frequency bands spanning nearly 30 GHz..."

Quantic PMI June 2022 Product Announcement

Quantic PMI June 2022 Product Announcement - RF CafeQuantic PMI, a leading supplier of custom, high-reliability MIC/MMIC components and subsystems for applications in space, military, communications, commercial and consumer electronics systems for more than three decades, recently introduced five new products in their extensive line of RF and microwave components. Included are an 8-12 GHz digitally tuned phase attenuator, a 333 to 368 MHz variable frequency comb generator, a 0.5 to 18 GHz 4−way power divider, an 8 to 12 GHz digitally tuned phase shifter, and a 0.1 to 40 GHz SP2T absorptive switch. Contact Quantic PMI today for more information...

SymMos Transfer Function Equation Generator

SymMos Transfer Function Equation Generator - RF Cafe Cool ProductThis item from Tarek Mealy showed up on my LinkedIn feed. He created a nifty software app called "SymMos" that allows you to use a drag-and-drop interface to create a schematic using MOSFETs, resistors, inductors, capacitors, bias voltages, and signal sources. Then, click on the appropriate button to get the transfer function equation for input impedance, gain, transconductance, or noise figure. SymMos is a work in progress and is available as a free download. After unzipping the file, you need to change the SymMos.txt file extension to .exe. Launch the executable and then you'll need to wait many seconds while the program loads (a black screen is displayed while waiting). BTW, Norton flagged the file as dangerous since it is new and hasn't seen it before, but I allowed it to run anyway with no problems. I recreated the example shown in the YouTube video and it works as advertised...

Publicity Means Sales!

Publicity Means Sales!, December 1947 Radio News - RF Cafe"If you have dark eyes and blonde hair and are under 30, you're due for some easy squeezing. Milligan's Appliance Center, 84 Main Street, is giving every girl between 16 and 30 who has these striking features a newly patented orange squeezer, to introduce the new item ... Note: Any traces of recent peroxide rinse will disqualify applicants." That is advertising copy offered as an example of effective promotional material in a 1947 edition of Radio News magazine. My first reaction was to think how something like that would never fly today, but then I wasn't so sure. It seems there must be anti-discrimination laws in this "offend nobody" climate today that prohibits singling out a certain demographic for inclusion or exclusion; however, there are many such promotions run today such as members only, active military and student discounts, senior citizens, etc. It is clear that these days only certain privileged sectors of society are still allowed to discriminate...

RF Cascade Workbook

RF Cascade Workbook - RF Cafe RF Cascade Workbook 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 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.

Science Theme Crossword Puzzle for June 26th

Science Theme Crossword Puzzle for June 26th, 2022 - RF CafeWith few exceptions, I, RF Cafe webmaster Kirt Blattenberger, have for more than two decades designed a custom crossword puzzle every week for the benefit of website visitors. This Science Theme Crossword Puzzle for was created for June 26th, 2022. All crossword puzzles use a personally built dictionary of thousands of words and clues related to RF, microwave, and mm-wave engineering, optics, mathematics, chemistry, physics, and other technical subjects. As always, this crossword puzzle 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!

Thanks to TotalTemp for Long-Time 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.

Supreme Publication Service Manuals

Supreme Publication Service Manuals, April 1948 Radio News - RF CafeSupreme Publications was another of the more prominent publishers of electronic equipment service manuals back in the middle of the last century. Howard W. Sams Photofact was of course the most well-known, but there were others including this one and Rider Service Manuals. Supreme Publications claims their content is provided by the manufacturers; to wit, " factory instructions for troubleshooting, repairing, and alignment." For a mere $2.00, a service shop could have the required data to service every AM and FM radio and television receiver produced for model year 1948, when this issue of Radio News magazine was published. According to the BLS Inflation Calculator, that's the equivalent of $24.56 in 2022 - a pretty good deal. A version of the manual with extra diagrams could be had for an additional 50¢...

1952 National Company Advertisement

National Company Advertisement, December 1952 QST - RF CafeAs the opening sentence indicates, National Company ran a very long series of advertisements in QST magazine that were in a format more reminiscent of a short essay than a company promotion. This installment for the December 1952 edition was number 224. Subjects ran the gamut from technical innovations from the company's research and development laboratory to social and political issues relevant to electronics technicians, hobbyists, students, and engineers. Being that it was a presidential election year in the U.S., National Company felt compelled to remind readers of their patriotic duty to vote. Although this was the December issue, it would reach readers' mailboxes prior to the election. Dwight D. Eisenhower ran against Adlai Stevenson. The latter won the South and the former won everything else. Note the thinly veiled criticism at the bottom about why amateur radio participation rate was down at the time...

Kazakhstan Broadcast Facility in Balkhash

Kazakhstan Broadcast Facility in Balkhash - RF CafeRF Cafe visitor Jonathan Zane (KC2SHO) recently sent me a hyperlink to his collection of photos taken when he visited a broadcast facility in Balkhash, Kazakhstan. A sample of his extensive image cache is shown here. You can view the entire set that includes vintage electronic equipment, facilities, and city streets on his kc2sho.com website. You will see a huge stash of vacuum tube assemblies, large coaxial cables, operation and maintenance manuals, and spare parts. These kinds of treasure troves exist all over the world; it's a matter of finding them. Imagine what all that abandoned equipment and components would sell for on eBay! Along with requesting permission to post a few of his photos, I invited him to provide some text to accompany them. Here is what he wrote - you will definitely like the anecdote at the end. Many thanks to Jonathan for this!

Questions and Answers on Oscilloscopes

Questions and Answers on Oscilloscopes, April 1957 Radio & TV News - RF CafeSimpson Electric is a name most RF Cafe visitors are probably familiar with as being the maker of high quality analog multimeters, with the Simpson 260 line being the most famous (it is still manufactured today). Not as many people, however, know that Simpson also used to make oscilloscopes. This article from a 1957 issue of Radio & TV News magazine was written by a Simpson Electric engineer whose job was, in part, to respond to questions asked by users. It covers basic operations like how to calibrate the display, adjust the horizontal time base and vertical amplitude scales, and how to synchronize the display with the input signal. Some explanation of how to interpret periodic and pulse type waveforms is provided as well as tips on how to avoid overloading and possibly damaging the instrument...

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

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