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Homepage Archive - January 2020 (page 4)
See Page 1 | 2 | 3 | 4 | 5 of the January 2020 homepage archives.

Friday 24

"Frequency" vs. "Amplitude" Modulation

"Frequency" vs. "Amplitude" Modulation, August 1935 Radio-Craft - RF CafeA momentous development that changed the field of radio communications warranted merely a half-page announcement in 1935 when frequency modulation inventor Edwin Armstrong had his article published in Radio-Craft magazine. It indisputably changed the world while causing poor Mr. Armstrong much grief while defending his right to the invention. Spread spectrum modulation / demodulation would be the next big communications advance that began with the frequency hopping (FHSS) scheme dreamed up by Hollywood actress Hedy Lamarr and pianist Antheil George during World War II. Direct sequence spread spectrum (DSSS) followed in the digital age, and since then I do not know of any fundamentally new communications technology in that time...

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 (of course a gratuity will be graciously accepted). 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...

ConductRF Rugged Replacement VNA Coaxial Cables

ConductRF Rugged Replacement VNA Coaxial Cables - RF CafePrecision ruggedized VNA cables from ConductRF offer RF engineers great alternatives to costly OEM cables that are now past their best days, and now you can reach out to Digi-Key for a quick and easy replacement. We have standards for applications at 18 GHz, 27 GHz, 40 GHz, 50 GHz & 70 GHz. Our torque resistant connector heads and phase stable constructions ensure great performance for many tests to come. ConductRF VNA series provides customers with reliable ruggedized solutions for lab and production vector network analyzer testing. We Know, Results Count...

Water Drop Antenna Lens for Directing Radio Waves

Water Drop Antenna Lens for Directing Radio Waves - RF Cafe"Engineers from the ESA and Sweden's Royal Institute of Technology (KTH), have designed a novel 'water drop' antenna lens for directing radio wave signals. In the same way that optical lenses focus light, waveguide lenses serve to direct electromagnetic radio wave energy in a given direction. This can be used to minimize energy loss when sending out a radar or a communication signal. Traditional waveguide lenses have complex electrically-sensitive dielectric material to restrict electromagnetic signals as desired. But once the top plate of this water drop waveguide lens has been added on, it comes down purely to its curved shape for directing signals through it. The inventors of this new lens design, which received an ESA Technical Improvement award in February 2017, likes to call it..."

Designing for Stability in High Frequency Circuits

Designing for Stability in High Frequency Circuits - RF CafeKeysight Technologies' Matt Ozalas and Thomas Winslow will present a free webinar entitled, "Designing for Stability in High Frequency Circuits," on January 29th at 1:00 pm ET. "High-frequency circuit designers often struggle with stability. Learn techniques to identify and solve stability problems in the design phase before they become headaches in the lab. Classical techniques will be discussed, and a new technique will be introduced using a bidirectional impedance probe in PathWave Advanced Design System (ADS) called the 'Winslow Probe.' Techniques to identify and solve stability problems in the design phase Basic design examples to compare various stability techniques Realistic examples of a successful high frequency power amplifier design..."

San Francisco Circuits: PCB Fabrications & Assembly Service

San Francisco CircuitsSF Circuits' specialty is in the complex, advanced technology of PCB fabrication and assembly, producing high quality multi-layered PCBs from elaborate layouts. With them, you receive unparalleled technical expertise at competitive prices as well as the most progressive solutions available. Their customers request PCB production that is outside the capabilities of normal circuit board providers. Please take a moment to visit San Francisco Circuits today. "Printed Circuit Fabrication & Assembly with No Limit on Technology or Quantity."

Thursday 23

Radio Astronomy and the Jodrell Bank Radio Telescope

Radio Astronomy and the Jodrell Bank Radio Telescope, February 1958 Radio & TV News - RF CafeOne of the photos in this 1958 Radio & TV News magazine article on the Jodrell Bank radio telescope shows what appears to be the largest multi-conductor cable connector I have ever seen. It looks like a early Photoshopping of a DB−9 connector with a heavy metal back shell. The cable bundle is three to four inches in diameter. Rather than use slip rings to transfer the control, data, and power signals from the base to the steerable 250-foot diameter parabolic dish of the Jodrell Bank radio telescope (now called the Lovell telescope), a single massive cable does the job. The science of radio astronomy was barely three decades old at the time it was built. It was in 1931 that Karl Jansky first determined that radio signals were coming from our Milky Way galaxy. He eventually ended up working for Bell Labs in Homdel, New Jersey, where he built a radio telescope to investigate background noise in the 10-20 meter wavelength band, where Bell planned to use its microwave relay system...

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...

Asia Pacific Electromagnetic Compatibility Symposium

APEMC 202o event - RF CafeMr. Mark Misfud, chairman of the Asia Pacific Electromagnetic Compatibility Symposium 2020 (APEMC 2020) wrote asking to have the event announced. It will be held May 19-22 at the Hilton Hotel, in Sydney, Australia. Per the website, "Modern Society is increasingly becoming more connected and the technology that is enabling this to happen is operating in a complex and hostile electromagnetic environment. As such knowledge and practical experience in EMC design, mitigation and testing is increasingly in demand. Developing technology such as 5G and autonomous vehicles present exciting possibilities but also provide challenges to those in the field due to the dynamic nature of the electromagnetic environment that the technology operates in. For the uninitiated EMC is black magic but those in the industry know it is application of common sense principles based on established electromagnetic theory and implementation of good design..."

2−D Electronic Devices Using Ultrathin Dielectrics

Strategy to Fabricate 2-D Electronic Devices Using Ultrathin Dielectrics - RF Cafe"2-D semiconductors could have very useful applications, particularly as channel materials for low-power transistors. These materials display very high mobility at extreme thicknesses, which makes them particularly promising alternatives to silicon in the fabrication of electronics. Despite their advantages, implementing these materials in transistors has so far proved to be challenging. In fact, 2-D semiconductors are of a dangling-bond-free nature; thus, it is notoriously difficult to deposit ultrathin high-κ gate dielectrics (i.e., substances with dielectric properties or insulators) on the materials via atomic layer deposition (ALD), often resulting in discontinuous films..."

The Science Behind Epoxies

The Science Behind Epoxies - RF CafeMya Rae Nelson has an excellent article in the current issue of Fine Woodworking magazine entitled, "The Science Behind Epoxies." I was surprised to read that epoxy has only been around since the 1940s, so when I first used it in the early 1970s, it was only a three decade old technology. As with cellphones, now that we have epoxy, how did we ever get along without it? Ms. Nelson uses layman terms to describe the molecular makeup of both the epoxy resin and the hardener, and describes how the bonds between the resin atoms are broken then reestablished with the insertion of hardener atoms into the matrix. If you attended classes for and understood the basics of chemistry, that will help with understanding the technical side of epoxy curing and strength, but even without the nerd knowledge you will still gain a better understanding of how this indispensible modeler's brew works.

Alliance Test Equipment: Used & Refurbished, Purchase & Rental

Allied Test Equipment Products - RF CafeAlliance Test Equipment sells used / refurbished test equipment and offers short- and long-term rentals. They also offer repair, maintenance and calibration. Prices discounted up to 80% off list price. Agilent/HP, Tektronix, Anritsu, Fluke, R&S and other major brands. A global organization with ability to source hard to find equipment through our network of suppliers. Alliance Test will purchase your excess test equipment in large or small lots. Please visit Allied Test Equipment today to see how they can help your project.

Wednesday 22

Popular Electronics Editorial - The 1972 IEEE Show

Editorial IEEE Show, Popular Electronics, July 1972 - RF CafeBefore there was the annual International Microwave Symposium (IMS) trade show, the Institute of Electrical and Electronics Engineers' (IEEE) Microwave Theory and Techniques Society (MTT-S) hosted the show, which was widely known as the MTT-S show. Before that, the event went by a variety of names, including "Intercon," (International Convention and Exposition) as reported in this 1972 issue of Popular Electronics magazine. For the first few decades since its inception in the 1950s, New York City was the venue, often in a hotel. As with tides and solar cycles, enthusiasm and attendance waned and ebbed over the years. 1972 was one of the low years. Per the story, about half the number of people were there compared to two years prior. I could not locate a chart of attendance numbers over the years, nor the numbers to generate my own chart...

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. 

The Lincoln Vocational Technical Center - A Partial Autobio

The Lincoln Vocational Technical Center, Annapolis, Maryland, Kirt's Cogitations #317 - RF CafeOne day in late spring of 1973 I found myself walking around the gymnasium of Annapolis Junior High School (AJHS) trying to decide which courses I would prefer upon beginning tenth grade the following fall. It was one of the final days of ninth grade, which had been by far my least happy year in school. Living in Mayo, Maryland, I and my fellow neighborhood ninth graders should have attended Southern Senior High School (SSHS) in Harwood, Maryland, where our predecessors had gone for ninth grade, but overcrowding caused the Anne Arundel School Board wizards to decide that for at least that year, we would remain at AJHS for another term. Historically, kids from my area went to AJHS only for seventh and eighth grades and then switched to SSHS. Annapolis, being the capital city of Maryland, was significantly more urban than the rural areas to which SSHS type people were accustomed. The clientele was much more aggressive in the big city. Sure, we had our "red neck greaser" rowdies in the southern part of the county, but at least their parents would whip them if they got caught getting into trouble...

III-V and III-N Devices on Si Target 100 GHz FEMs

III-V and III-N Devices on Si Target 100 GHz FEMs - RF Cafe"Researchers at Imec have demonstrated what they believe to be the first functional GaAs-based heterojunction bipolar transistor (HBT) devices on 300 mm Si, and CMOS-compatible GaN-based devices on 200 mm Si for mm-wave applications, showing cut off frequencies in the 40/50 GHz region. In wireless communication, with 5G as the next generation, there is a push towards higher operating frequencies, moving from the congested sub-6GHz bands towards mm-wave bands (and beyond). The introduction of these mm-wave bands has a significant impact on the overall 5G network infrastructure and the mobile devices. For mobile services and Fixed Wireless Access (FWA), this translates into increasingly complex front-end modules..."

Video: Automatic Calibration Module Confidence Check

Copper Mountain Technologies Video: Automatic Calibration Module Confidence Check - RF CafeCopper Mountain Technologies (CMT) has produced a series of videos to help users of its diverse line of vector network analyzers (VNAs) get the most out of their extensive capabilities. Proprietary features in both hardware and software supplies VNAs designed by CMT with capabilities far beyond similar equipment by other companies. This video entitled, "Automatic Calibration Module Confidence Check," is one of a series of videos that can be found on the Copper Mountain Technologies website. "How many times have you completed a series of measurements to find them tainted by a bad cable...

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. 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...

VidaRF: Passive RF & Microwave Components

vidaRF passive RF & microwave components - RF CafeAt VidaRF, the phrase 'Providing Simple Solutions for Complex Connections' is more than just a slogan – it's a mindset, a mission, and a driving force behind everything we do. Their pledge is to design and distribute high performance, cost effective RF Microwave products to fit each customer's unique applications. Please visit VidaRF today to see how their lines of attenuators & terminations, directional couplers, power dividers, coaxial connectors, and circulator & isolators can be of use to your project. "When the standard just will not do, VidaRF has the solution for you!"

Tuesday 21

Mac's Radio Service Shop: Was Ist Los?

Mac's Radio Service Shop: Was Ist Los?, May 1958 Radio News - RF CafeImagine reading an article from a 1958 magazine that references the schematic for a specific radio manufactured in Germany, and then being able to download a copy of it for free on the Internet. Such is the case with this Mac's Radio Service Shop story entitled, "Was Ist Los?" Mac is describing to his sidekick Barney the difficulty in troubleshooting and repairing a Metz Transformatoren: Babyphon 56 that a serviceman had purchased while stationed overseas. The diagram is of course in German, which requires Mac to pull out a language translation dictionary. The problem was that many words unique to technical jargon were not in it. Additionally, units of measure for the capacitors and inductors were not like U.S. units. Mac noted that many capacitor values were labeled with units of "u," "n," and "p," for "micro," nano," and "pico." He mentions the "micro" prefix for the letter "u," but never calls the "n" and "p" by the now-standard terms...

Hazel TV Episode "Stop Rockin' Our Reception"

Hazel TV Episode "Stop Rockin' Our Reception" - RF Cafe Video for EngineersQST reader George P. Orphan, KG4DXJ, wrote in the February 2020 issue's "Letters from Our Members" column about an episode of the old "Hazel" television show entitled, "Stop Rockin' Our Reception," where interference on the Baxters' TV set was blamed on the "shortwave set" operated by a teenager, Bruce, who had recently moved in down the street. George Baxter, the household's impulsive lawyer father, was convinced enough that Bruce, a friend of his son, Harold, was responsible that he paid a visit to the boy's house and spoke to his father about it. Bruce politely informs Mr. B that unless his television was was manufactured before 1950, it was unlikely that his operations on the 10−meter band would be causing the interference, but it fell on deaf ears. Shortly thereafter, a power company investigator was seen walking around the front yard with a box bearing a loop antenna on the top of it. At the request of Bruce's father...

Promote Your Company on RF Cafe

Sponsor RF Cafe for as Little as $175 per Month - RF CafeRF Cafe typically receives 8,000-15,000 website visits each weekday and about half that on weekends. RF Cafe is a favorite of engineers, technicians, hobbyists, and students all over the world. With more than 7,000 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, Facebook, and Twitter. If you need your company news to be seen, RF Cafe is the place to be. Banner advertising begins at $175/month...

Many Thanks to Nova Microwave for Continuing Support!

Nova Microwave Circulators & Isolators - RF CafeNova Microwave is a leader in technically differentiated electronic and radio frequency Ferrite Circulators and Isolators that connect, protect and control critical commercial and military wireless telecommunications systems. Our staff is dedicated to research and development of standard and custom design quality Ferrite Circulators and Isolators from 380 MHz to 26.5 GHz. Available in single or multi-junction topographies, the Nova Microwave product line of is specifically designed for use in varied environmental and temperature extremes. 

Mathematical Model Predicts Knot's Stability

Mathematical Model Predicts Knot's Stability - RF Cafe"In sailing, rock climbing, construction, and any activity requiring the securing of ropes, certain knots are known to be stronger than others. Any seasoned sailor knows, for instance, that one type of knot will secure a sheet to a headsail, while another is better for hitching a boat to a piling. But what exactly makes one knot more stable than another has not been well-understood, until now. MIT mathematicians and engineers have developed a mathematical model that predicts how stable a knot is, based on several key properties, including the number of crossings involved and the direction in which the rope segments twist as the knot is pulled tight. 'These subtle differences between knots critically determine whether a knot is strong or not,' says Jörn Dunkel, associate professor of mathematics at MIT..."

One SDR Software Defined Radio Resources

One SDR Software Defined Radio Resources - RF CafeSam wrote from his One SDR website to request I post a note about the resources he is providing on Software Defined Radios. It is in its start-up phase and already has many articles introducing the concepts of SDR. Topics include low noise amplifiers, filters, bias tees, and how to shop for equipment. Says Sam, "I hope to demystify RF technology and make it more accessible to the growing community of SDR enthusiasts." The amateur radio community is adopting SDR in a major way in order to make existence in the crowded electromagnetic environment more successful.

RF Superstore: Supplier of RF & Microwave Components

RF Superstore coaxial cable, connectors, adapters - RF CafeRF Superstore launched in 2017, marking the return of Murray Pasternack, founder of Pasternack Enterprises, to the RF and microwave Industry. Pasternack fundamentally changed the way RF components were sold. Partner Jason Wright manages day-to-day operations, while working closely with Mr. Pasternack to develop RF Superstore into a world class RF and microwave component supplier. RF coaxial connectors & adapters, coaxial cable & cable assemblies, surge protectors, attenuators. Items added daily. Free shipping on orders over $99. We're leading the way again!

Monday 20

Decoding Numbers Stations

Decoding Numbers Stations, QST November 2019 - RF CafeIf you are a radio guy (or gal) who likes international sleuthing, mystery, and intrigue, then you will probably want to read an article entitled, "Decoding Numbers Stations," from the November 2019 issue of the ARRL's QST magazine. Author Allison McLellan, who is interested in communications history but apparently not a Ham herself, writes, "Scanning through the bands on AM, you stumble upon something odd. It might be the last few notes of a folk song, a sound clip from an old cartoon, or phrases in a different language. A voice cuts through the static, methodically calling out, 'Mike, India, Whiskey, One, Four...' But this isn't a fellow ham announcing their call sign. These are numbers stations, an eerie subset of radio stations that has intrigued hams and non-hams alike for decades. Numbers stations are shortwave AM radio stations that transmit messages via voice or Morse code, believed to be coded in one-time pad (OTP) cryptography. In OTPs, the message is comprised of strings of numbers..."

Howard W. Sams & Co. Ad

Howard W. Sams & Co. Ad, March 1958 Radio News - RF CafeI'm guessing most RF Cafe visitors who are more than 50 years old are familiar with, and even have seen, the Sams Photofacts packages of documentation for consumer electronics appliances that include televisions, radios, phonographs, clock-radios, tape recorders/player, amplifiers, etc. Most electronics service shops couldn't have existed with them since many manufacturers did not distribute technical and service data to anyone who was not a certified, sanctioned dealer. Howard Sams, the company's founder, did the equivalent for electronics of what Chilton did for cars and trucks. They basically reverse engineered models bought off a showroom floor. This advertisement from a 1958 issue of Radio & TV News magazine features the man himself, Howard Sams, so now you'll recognize him if you pass him on the street...

Norway Experiences Unexpected Ground Current "Shockwave"

Norway Experiences Unexpected Ground Current "Shockwave" - RF CafeThis excerpt from SpaceWeather.com reads like the plot from an episode of Star Trek: "Earth may have crossed through a fold in the heliospheric current sheet, described as 'a giant, wavy membrane of electrical current rippling through the solar system'." It comes from a story on the ARRL news webpage entitled, "Norway Experiences Unexpected Ground Current 'Shockwave'." On January 6, "unexpected electrical currents were detected in the soil of northern Norway starting at around 1930 UTC. 'It seemed to be some kind of shockwave,' said Rob Stammes, who monitors ground currents at the Polarlightcenter geophysical observatory in Lofoten. 'My instruments detected a sudden, strong variation in both ground currents and our local magnetic field. It really was a surprise'..."

An SWR-Shifting "T"

An SWR-Shifting "T", QST February 2020 - RF CafeThe American Radio Relay League (ARRL) includes a free online sample article from their monthly QST magazine - definitely a good policy to help sell the publication (and membership in the ARRL). The February 2020 edition offers "An SWR-Shifting 'T'," written by Mr. Bill Conwell, K2PO. It includes some useful Smith chart techniques. "Any feed-line mismatch can be brought to a 1:1 SWR with a single shunt capacitor, provided its value and the location where it bridges the coaxial center and shield conductors is chosen correctly. This is because there are two locations at every half-wave along a mismatched feed line where the impedance is exactly 50 Ω in parallel with a reactive component. By extending or shortening the coax so that one of these locations is at the transmitter-end of the coax, a counter-reactive shunt component can be applied using a coaxial T connector..."

Particle Accelerator in a Silicon Chip

Particle Accelerator in a Silicon Chip - RF Cafe"Researchers in the U.S. are designing a silicon chip that can accelerate electrons to over 94% of the speed of light. The team at Stanford University and the SLAC particle accelerator, backed by the Gordon and Betty Moore Foundation set up by one of the founders of Intel, and the European Union's Horizon 2020 Research and Innovation Programme, used infrared lasers and a nanoscale silicon channel to build the accelerator. The infrared pulses are synchrnised to boost the energy of the electrons. Details of the prototype accelerator-on-a-chip were published in today's issue of Science. The key is the design and fabrication techniques can be scaled up to deliver particle beams..."

Reactel: RF & Microwave Filters of All Types

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.

Sunday 19

Engineering & Science Crossword Puzzle for January 19

Engineering & Science Crossword Puzzle January 19, 2020 - RF CafeAs with my hundreds of previous engineering and science-themed crossword puzzles, this one for January 19, 2020, contains only clues and terms associated with engineering, science, physical, astronomy, mathematics, chemistry, etc., which I have built up over nearly two decades. Many new words and company names have been added that had not even been created when I started in the year 2002. You will never find a word taxing your knowledge of a numbnut soap opera star or the name of some obscure village in the Andes mountains. You might, however, encounter the name of a movie star like Hedy Lamarr or a geographical location like Tunguska, Russia, for reasons which, if you don't already know, might surprise you.


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About RF Cafe

Kirt Blattenberger - RF Cafe Webmaster

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...

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