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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 -

Microsoft Pulls LinkedIn out of China - RF Cafe• Microsoft Pulls LinkedIn out of China

• U.S. 3.45 GHz Auction Hits Make-or-Break Stage

• 45M 5G Small Cells Deployed by 2031

• From Windows 95 to Windows 11

• Army Wants Air Defense Laser Weapons

• TSMC to Build Chip Fab in Japan

• FAA Fumbled Response to Surge in GPS Jamming

• Army to Release New Digital Transformation Strategy

• Need to Store Data for a Thousand Years?

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 for 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...

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 Bittele Electronics for Continued Support!

Bittele Electronics PCB Fabrication - RF CafeSince 2003, Bittele Electronics has consistently provided low-volume, electronic contract manufacturing (ECM) and turnkey PCB assembly services. It specializes in board level turnkey PCB assembly for design engineers needing low volume or prototype multi-layer printed circuit boards. Free Passive Components: Bittele Electronics is taking one further step in its commitment of offering the best service to clients of its PCB assembly business. Bittele is now offering common passive components to its clients FREE of Charge.

Mac's Radio Service Shop: Salesmen and Service Technicians

Mac's Radio Service Shop: Salesmen and Service Technicians, June 1952 Radio & Television News - RF CafeDealing with on-site traveling salesmen has always been a sort of love-hate (or maybe a necessary evil, to put it less extremely) relationship - for both the salesman and the engineer/technician. Not having been in the engineering design environment for nearly two decades, I don't know how much face-to-face contact is made anymore. Up through the early 2000s, I was still occasionally meeting with components salesmen. In this June 1952 issue of Radio & Television News magazine's Mac's Radio Service Shop technodrama, proprietor Mac McGregor takes the occasion of an afternoon rain torrent to discuss the situation with two of his regular sales representatives. The open trading of pet peeves and appreciated behavior on both sides is common sense stuff, but are courtesies often forgotten while in the throes of the daily work grind. Mac references a book...

19 Smaller Carriers Urge FCC to Auction 2.5 GHz

19 Smaller Carriers Urge FCC to Auction 2.5 GHz - RF Cafe"A coalition of 19 smaller U.S. carriers are calling on the Federal Communications Commission to move on scheduling a spectrum auction for licenses in the 2.5 GHz band, saying it’s a critical opportunity for rural and underserved areas. The service providers, all members of the Competitive Carriers Association (CCA), sent an October 11 letter (PDF) to Acting Chairwoman Jessica Rosenworel that urges the regulator to immediately set an auction date for the more than 8,000 mid-band licenses in its inventory. C Spire, GCI Communications, Union Wireless, Carolina West, Viaero Wireless, and Nex-Tech Wireless are among some of the signatories..."

Many Thanks to Anatech Electronics for Long-Time 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. 

Electrical Conductors, Wiring Techniques, & Schematic Reading

Introduction to Electrical Conductors, Wiring Techniques, and Schematic Reading - RF CafeNavy Electricity and Electronics Training Series (NEETS) Module 4 - Introduction to Electrical Conductors, Wiring Techniques, and Schematic Reading. Upon completing this chapter, you should be able to: 1. Recall the definitions of unit size, mil-foot, square mil, and circular mil and the mathematical equations and calculations for each. 2. Define specific resistance and recall the three factors used to calculate it in ohms. 3. Describe the proper use of the American Wire Gauge when making wire measurements. 4. Recall the factors required in selecting proper size wire. 5. State the advantages and disadvantages of copper or aluminum as conductors. 6. Define insulation resistance and dielectric strength including how the dielectric strength of an insulator is determined. 7. Identify the safety precautions to be taken when working with insulating materials...

Build This Novice CW Transmitter

Build This Novice CW Transmitter, February 1955 Popular Electronics - RF CafeEven though this CW (continuous wave, for sending Morse code) transmitter circuit was published in 1955 in Popular Electronics magazine, it is still legal for today's Amateur radio operator. Portions of the 40-meter and 80-meter bands are still reserved exclusively for CW operation. As of 2021, the 40−meter band (7.025-7.125 MHz) and the 80−meter band (3.525-3.600 MHz) are both reserved for CW for Hams holding either Novice (no longer issued) or Technician licenses. Additionally, the 15−meter band (21.025-21.200 MHz) and the 2−meter band (144.0-144.1 MHz) have CW-only areas. That is different than the frequencies given in the article, so beware if you are tempted to throw one together for old time's sake. The value for XTAL will need...

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 Again for Windfreak Technologies' Continued Support!

Windfreak TechnologiesWindfreak Technologies designs, manufactures, tests and sells high value USB powered and controlled radio frequency products such as RF signal generators, RF synthesizers, RF power detectors, mixers, up / downconverters. Since the conception of WFT, we have introduced products that have been purchased by a wide range of customers, from hobbyists to education facilities to government agencies. Worldwide customers include Europe, Australia, and Asia. Please contact Windfreak today to learn how they might help you with your current project.

Secret Communications

Secret Communication, July 1946 Radio-Craft - RF CafeIn this 1946 issue of Radio-Craft magazine, editor and über electronics guru Hugo Gernsback reviews "Secret Communications" methods used throughout history, including Alexander Graham Bell's "Photophone" that used a modulated light beam for transmission. With World War II having recently ended and devices such as the "Enigma Machine" developed by the Germans for secure encryption of messages, secure communications was high on the priority list of government and military strategists. Gernsback also suggests ultrasonic systems for wireless communications, and a multiple channel scheme suggestive of the m−ary method widely used today...

Rethinking Wireless Power

Rethinking Wireless Power - RF Cafe"Can a small wireless power startup really use its 'RF Holography' technology to charge personal electronics from several meters away, without irradiating their users? Join ED's Lee Goldberg as he takes a deep dive into the theory behind the system. Our recent story 'Wireless Power System Approved by EU and UK Claims to Charge Mobile Devices Without Frying Users' caused quite a stir amongst our loyal reader community. In fact, more of our sharp-eyed readers took the time to weigh in on the technology's relative merits than any other story I've written in the last decade (or two). Nearly all of their responses were even more skeptical than I was of Ossia's claims to be able to deliver meaningful amounts of power to devices multiple meters away via either 2.4- or 5.8-GHz RF beams..."

Fundamentals of Color TV, Tri-Gun Receiver Circuits

Fundamentals of Color TV, Tri-Gun Receiver Circuits, June 1954 Radio & Television News - RF CafeThis was a multi-part series published by Radio & Television News magazine in the days when color TV was the domain of the more well-to-do folks on the block. Needless to say (but I'll say it anyway), nobody I knew had color TV before around 1968. One of my friend's father owned a fairly profitable gas station and service garage, so they were the first to have one. For some inexplicable reason (I jest), his mother never allowed more than one or two of us into the house at a time, so we drew straws to see who got to witness that fabled miracle of technology. I was about third in line. Insomuch as the 1960s were a much more polite and private time than the present, peeking through a living room window for a preview was expressly verboten. In fact, going into a friend's house for any reason was rare. The privileged appointments were strictly adhered...

ConductRF FlexiForm Cables w/SMPM and 0.047" Cable at DigiKey

ConductRF FlexiForm RF Cable Assemblies w/SMPM and 0.047" Cable - RF CafeConductRF FPA Cable Assemblies use a unique, Low Loss, high performance Semi-"FlexiForm" Cable that is formable, but flexible, providing system designers with a versatile solution for High Frequency applications. The product also allows for very tight phase matching to ±0.2º. Available in three common cable diameters, with the benefits of higher operating frequencies, shielding effectiveness and stability performance over traditional standard Hand Formable cables, these solutions enhance any application requiring higher performance. ConductRF's FPA Cable Assemblies are manufactured using the latest induction soldering techniques to best ensure the highest quality and performance...

Radio Mobile: Point-to-Point System Planner Freeware

Radio Mobile: Point-to-Point System Planner Freeware - RF Cafe Cool ProductThanks to a tip by RF Cafe visitor and contributor Bob Davis for letting me know about a very capable point-to-point RF system planner called Radio Mobile (URL updated since original expired), by Canadian Ham radio operator Roger Coudé (VE2DBE). There is another similar freeware program available called AlphiMax, but it requires that you upload your system data to a remote server - a potential confidentiality conflict. Radio Mobile uses GPS-based terrain information obtained from the U.S. Department of Commerce NTIA/ITS Institute for Telecommunication Sciences Irregular Terrain Model (ITM) database...

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...

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.

Map Your Fringe Area Signal Level

Map Your Fringe Area Signal Level, July 1952 Radio & Television News - RF CafeHave you noticed how heavily burdened utility poles (formerly referred to as electric poles or telephone poles) are these days? Many of the decades−old creosoted wooden poles originally were designed to carry a single set of high voltage distribution lines (13.8 kV) and a multiconductor telephone cable containing twisted pairs. Look around now and you will see at least twice that number of cables, and often three times as many due to multiple coaxial and fiber optic cables and needing to route extra AC power circuits (of larger gauge to handle higher current) in increasingly crowded areas. Notice how many are leaning over (particularly at corners) and/or are being supported with additional guy cables and/or splints. Half a century ago when music, talk, and television was broadcast over the air, the need to string wire all over the landscape was not necessary. Some people complained about "ugly" TV and radio station broadcast antennas...

RF Cascade Workbook 2018 - RF Cafe

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