Homepage Archive - May 2019 (page 1)

These archive pages are provided in order to make it easier for you to find items that you remember seeing on the RF Cafe homepage. Of course probably the easiest way to find anything on the website is to use the "Search RF Cafe" box at the top of every page. About RF Cafe.

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See Page 1 | 2 | 3 | 4 | 5 of the May 2019 homepage archives.

Friday 3

Room Acoustics for Stereo

Room Acoustics for Stereo, January 1960 Electronics World - RF CafeIn the beginning, man created monophonic (mono) radios and phonographs that had sound with no spatial separation (left and right) in the source(s) and featured a single speaker. As such, except for being sure to not locate your radio or phono behind the sofa, sound perception at any point the room was fairly consistent - except maybe for volume level. Still, there was ample opportunity for the time of arrival due to multipath effects to distort the sound. Up until the 1950s or so, most homes had hardwood floors (with a few rugs) and rock-hard plaster walls to reflect sound waves, and rooms were relatively sparsely populated with furniture and wall hangings (look at photos in vintage magazines for proof), all of which provided means for distorted sound at a distance. And man said, "Let there be stereophonic (stereo) sound," which ...

Design PCBs for EMI, Part 3: Partitioning and Routing

Design PCBs for EMI, Part 3: Partitioning and Routing - RF CafePart 3 of Kenneth Wyatt's "Design PCBs for EMI" series focuses on Partitioning and Routing. Part 1 covered "How Signals Move" and Part 2 dealt with Basic Layer Stack-up. "Besides proper layer stack-up, the next most important consideration when laying out the circuitry on your board is partitioning of circuit functions, such as digital, analog, power conversion, RF, and things like motor control or other high-power circuits. Before we get to circuit layout, we must first understand and visualize how return currents flow and how the electromagnetic fields are distributed under high-speed circuit traces. At low frequencies - below about 50 kHz - return currents tend to follow the path of lowest resistance. They tend to travel along the shortest distance between source and load, as simulated by the green area in Figure 1 ..."

Carl and Jerry: Wired Wireless

Carl and Jerry: Wired Wireless, January 1962 Popular Electronics - RF CafeIn the continuing saga of Carl and Jerry, our two young electronics hobbyists visit a college radio station where the manager gives a tour while explaining the technical aspects of the equipment. RF bridges, hybrid junctions, oscillator coils and plate-tank pi-networks, cue amplifiers, limiter amplifiers, patch board, power supplies, and a lot of other terms that cause RF Cafe visitors to salivate are woven into the story. Carl and Jerry are surprised to learn that the transmitter output power is high enough that dormitory residents can pick up the signal with "only a pair of earphones clipped across a 1N34 diode" as well as with a standard AM radio. In fact, that's the whole point of the story because the broadcast is not over the air, but via the campus' AC electrical system - hence, "wired wireless." ...

Calibration Technicians Needed by Advanced Test Equipment

/2019/Advanced-Test-Equipment-Calibration-Technician-5-2-2019.htm" target="_top"> Calibration Technicians Needed by Advanced Test Equipment - RF CafeAdvanced Test Equipment Rentals (ATEC) is looking for multiple /2019/Advanced-Test-Equipment-Calibration-Technician-5-2-2019.htm" target="_top"> Calibration Technicians who will apply knowledge of measurement science, mathematics, physics, and electronics to troubleshoot and calibrate inspection, measurement, environmental and a wide variety of equipment such as AC/DC, RF Frequency, EMC, RF/Microwave, ESD Guns, Temperature Chambers, Power Supplies, Transit Generators, High Voltage, Flow, Pressure, etc. /2019/Advanced-Test-Equipment-Calibration-Technician-5-2-2019.htm" target="_top">...

Loon Partners with HAPSMobile for Stratospheric Connectivity

Loon Partners with HAPSMobile for Stratospheric Connectivity - RF Cafe"Softbank's HAPSMobile this week announced it's investing $125M in Alphabet's Loon business, as the two companies form a long-term strategy partnership to advance high-altitude connectivity. Both companies are exploring ways to deliver internet services to remote areas using high altitude vehicles. HAPSMobile, which includes the acronym for high-altitude platform station (HAPS), began in 2017 as a joint venture between Softbank and Aerovironment, a U.S.-based aerospace company. The venture has developed a solar-powered drone, called Hawk 30, which travels up to 20 km above Earth's surface for stratospheric telecommunications delivery ..."

Transient Specialists: EMC, EMI, RFI Test Equipment Rentals

Transient Specialists - RF CafeTransient Specialists specializes in EMC test equipment rentals and carries a complete line of ESD guns, surge immunity test equipment, and EFT generators. Rentals available for military (Mil-Std 461), automotive (ISO 7637), and commercial (IEC 61000-4) EMC testing. Flexible terms, accredited calibrations and technical support on EMC testing equipment offered. Equipment consists of top EMC Test System manufacturers, including Teseq, Thermo Keytek, EM Test and EMC Partner ...

Thursday 2

Notice: I will be travelling today and will have limited access to e-mail, so responses will probably not happen until the evening. I apologize for any inconvenience.

   - Kirt B.

JFETS: How They Work, How to Use Them

JFETS: How They Work, How to Use Them, May 1969 Radio-Electronics - RF CafeLast Fall I posted part 2 of this Radio-Electronics article first because I did not yet have the May issue that contained part 1. So, if you read "JFET's - Put Last Month's Theory to Work" and have been waiting with bated breath for part 1, you may breathe easily again; here it is. Author Thomas Haskett enthusiastically introduces readers to the junction field effect transistors (JFET) as a more natural replacement than the bipolar junction transistor BJT) for vacuum tubes because of JFET (and other varieties of the FET) operational parameters being much more those of tubes than a BJT. Regarding his conversion, Haskett refers to himself as a "die-hard 'fire-bottle'" man - a term with which I am not familiar. My assumption is that "fire-bottle" is a slang name for vacuum tubes because of how hot they get, and they glow orange like a fire in a glass bottle ...

Delivering the World's First Digital Radar on Chip

Delivering the World's First Digital Radar on Chip - RF CafeWhen I first saw this line drawing in High Frequency Electronics magazine' article entitled, "Delivering the World's First Digital Radar on Chip," my first thought of was an Escher drawing like Relativity. Per the authors, "Uhnder, a stealth startup company based in Austin, Texas, has developed the world's first automotive digital radar on chip (RoC). The company, co-founded by Manju Hegde and Curtis Davis in 2015, has been working furiously to transform the automotive industry by delivering a new generation of radar chips capable of achieving unprecedented levels of performance in the new mmWave automotive radar band of 76 GHz to 81 GHz. Sensors based on Uhnder's digitally coded modulation (DCM) technology easily exceed current requirements for Advanced Driver Assistance Systems ..."

A New Antenna Rotor

A New Antenna Rotor, January 1960 Electronics World - RF CafeAt the end of the last century (the 20th), aside from the impending total collapse of the world's electrical infrastructure due to Y2K computer date issues, technovisionaries (a word I just made up) predicted the near-term demise of local over-the-air (OTA) broadcasting of both commercial radio and television. Cable and satellite was going to supplant it all. For a short while things seemed to be going that way, particularly as both forms of media (radio and TV) began being available via smartphones. The FCC (Federal Communications Commission) was so sure OTA television was dead that it wanted to reallocate unused spectrum (white space) for other uses. It also mandated a conversion of all TV broadcasting to be done in digital form. The plan forced either trashing of existing television sets and purchase of new models or the purchase of analog-to-digital conversion boxes. The compliant public folded like a cheap suit ...

QuinStar Scheduling 1:1 Appointments for IMS 2019

QuinStar Scheduling 1:1 Appointments for IMS 2019 - RF CafeQuinStar Technology, a California-based microwave and millimeter-wave engineering company, is exhibiting June 4 - 6 at the International Microwave Symposium. The IMS will convene at the Boston Convention and Exhibition Center. We'll unveil some new products and prototypes. In addition, QuinStar is offering the opportunity to schedule a one-on-one appointment with our Product Sales Specialist. We understand that the requirements change rapidly in the emerging technologies that rely on millimeter-wave components. To that end, QuinStar is continually working to meet your requirements. To discuss your project and requirements or just learn firsthand what's new at QuinStar ...

Copper-Based Alternative for Next-Generation Electronics

Copper-Based Alternative for Next-Generation Electronics - RF Cafe"Japanese scientists have developed a technique to transform a copper-based substance into a material that mimics properties of precious and pricey metals, such as gold and silver. The new medium, made of copper nanoparticles (very small copper-based structures) has promising applications in the production of electronic devices that would otherwise depend on expensive gold and silver counterparts. It is also suitable in the fabrication of electronic components using printing technologies that are recognized as environmentally friendly production methods. The study was published ..."

Nova Microwave: RF & Microwave Circulators & Isolators

Nova Microwave circulators & isolatorsNova 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. Please visit Nova Microwave today ...

Wednesday 1

Arc, Surge, and Noise Suppression

Arc, Surge, and Noise Suppression, April 1967 Electronics World - RF CafeEven though this article was written more than 50 years ago, the fundamentals of protecting relays against interference from either internally generated or externally generated noise haven't changed. Sometimes a datasheet will recommend protection and noise suppression techniques, and when that is that case, the manufacturer's advice should be followed (unless you have a really good reason to deviate, possibly voiding a warranty). When you find yourself on your own with the design, whether a new creation or modifying an existing circuit, use this article and the very comprehensive table of application examples ...

Transistor Topics: Semiconductors Other Than Transistors

Transistor Topics: Semiconductors Other Than Transistors, March 1958 Popular Electronics - RF CafeIn March of 1958 when this article appeared in Popular Electronics, learning of semiconductor devices other than transistors was usually new to experienced professionals as well as to hobbyists. Vacuum tubes still dominated electronic products in the day. Companies like General Electric, Sylvania, and RCA were the pioneers for development of Zener diodes, photodiodes, SCRs, thyristors, etc. Relatively simple compounds like selenium, germanium, silicon, and lead and cadmium sulphides were used. The exotic witch's brew of elements in modern semiconductors - particularly those used to photovoltaics - were likely not even envisioned in 1958. This article discusses some of "new" devices using simple compounds ...

Many Thanks to San Francisco Circuits for Continued Support!

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 ...

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

Engineering Job Board - R CafeRF Cafe's raison d'ĂȘtre 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 ...

Internet of the Skies: The Future of Cellular Drones

Internet of the Skies: The Future of Cellular Drones - RF Cafe"What's needed for us to move towards the future of drones? According to experts, the next step must be towards ensuring that future drones are connected via cellular networks and there is collaboration between the aviation and telecom industries in order to secure public trust in drones. The Global Unmanned Traffic Management Association (GUTMA) on Connected Skies, a major conference on drones and UTM, aims to work on this prospect, and for the first time ever will bring the aviation and telecoms industry together under one roof. The event will consider key technical concepts, aerial LTE coverage, 5G in aviation deployment road mapping and much more. GSMA, the trade body ..."

PCB Directory: Printed Circuit Board Fabrication & Assembly

PCB  Directory - RF Cafe

PCB 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 (e.g., material, flexible, rigid), Geographical location, and more ...

Tuesday 30

Anatech Electronics April 2019 Newsletter

Anatech Electronics April 2019 Newsletter - RF CafeAnatech Electronics, an RF and microwave filter company, has introduced a new line of suspended stripline and waveguide type RF filters. Also, Sam Benzacar wrote as part of his April newsletter an article entitled "5G Brings EM Radiation Front and Center," which discusses the physiological implications of cellphone and WiFi radiation on humans. As with so many things, politics and money (intimately entwined) drive the issue with little concern for the truth. On a lighter note, the topics of FCC spectrum auctions, Google Fiber disappearance in some locations, and rural broadband delivery schemes are covered ...

I Married a Hobby

I Married a Hobby, August 1948 QST - RF CafeMrs. Helen McKee knew exactly what she was signing up for when she agreed to marry Mr. McKee. After all, she met and got familiar with the guy over the air during some rag chewing sessions. This story is a humorous (and true) account of what life can be like for the spouses of enthusiastic Ham radio operators. We all hope for such an understanding 'significant other.' Melanie has certainly endured and supported a lot of my pastime endeavors over the past 32 years. It's a short read, so take a break and put a smile on your face ...

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 ...

Understanding Low Loss Coaxial Cables and Their Applications

Understanding Low Loss Coaxial Cables and Their Applications - RF CafeDan Birch has a useful article on the High Frequency Electronics website entitled, "Understanding Low Loss Coaxial Cables and Their Applications." It is a concise intro to the cables we typically use for distributing RF signals including impedance, shielding, dielectric types, loss, etc. "Coaxial assemblies form the wired backbone necessary to accomplish wireless systems. They are therefore utilized in a broad range of environments and circumstances. The military-style RG coaxial cables have been the go-to standard when first understanding what cables to leverage in a particular installation. However, there are times where these cables will not suffice and a low loss alternative is necessary. This article attempts to cover the general construction of a low loss cable. Thanks to Joe B. for the tip ..."

Shielded Anode PIN Diode Breathes New Life into a 1950s Technology

Shielded Anode PIN Diode Breathes New Life into a 1950s Technology - RF Cafe"A novel PIN diode concept is said to achieve 10 to 50 times better isolation than a typical PIN diode. The RF PIN diode as we know it today was invented by J. Nishizawa in 1950. Now, almost 70 years later, a new PIN diode concept - shielded-anode PIN diode (SAPIN) - has emerged. This new PIN diode offers 10 to 50 times better 'OFF' isolation thanks to the introduction of a simple electrostatic shield. An 'OFF' isolation greater than 40 dB at 2 GHz and 0 Vdc is achieved from a single series device. The theory of operation will be presented here along with measurements on fabricated silicon (Si) SAPIN didoes. A PIN diode is built with a wide undoped intrinsic ..."

Empower RF Systems: RF & Microwave Power Amplifiers

Empower RF SystemsEmpower 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 ...

Monday 29

Vintage Collins Radio Company Advertisement

Vintage Collins Radio Company Advertisement, April 1945 QST - RF CafeCollins Radio Company (later on Rockwell Collins and now Collins Aerospace) has been around since 1933. Like the vast majority of U.S. companies during the World War II era, they - management and employees - took great pride in doing their part for the war effort. Unlike today, when a relatively few people actually know someone on active duty in the armed forces, workers were very likely to have a brother, son, father, or husband in the service. Here is an advertisement that I scanned out of my copy of the April 1945 QST magazine. It mentions that many of the employees are amateur radio operators. During the war, a call went out for surplus equipment from all sources, including amateurs, so some sacrificed their personal equipment for the good ...

Modeling Micro-Doppler Effects

Algorithms to Antenna: Modeling Micro-Doppler Effects - RF CafeIn another installment in their "Algorithms to Antenna" series in Microwaves & RF magazine, Rick Gentile and Honglei Chen discuss micro-Doppler effects. "Micro-Doppler effects are a result of motion with respect to platform motion. This post investigates these effects, using pedestrian identification and helicopter-blade-speed estimation as examples. We have described radar modeling in past blogs. Now, we want to dig a little deeper in terms of modeling objects and targets that a radar may see in its field of view. The most common technique is to define targets using radar cross-section (RCS) profiles that may vary with aspect angle ...

Thermal Testing Goals Reached Faster with Potential of Differential

Cascade Temperature Algorithm Demonstrates Thermal Testing Goals Reached Faster with the Potential of Differential - RF CafeJohn Booher, of TotalTemp Technologies, has published a new Blog topic titled, "Cascade Temperature Algorithm Demonstrates Thermal Testing Goals Reached Faster with the Potential of Differential." Per John's post: "Having a specific requirement to test a product to a given temperature profile, how does one show that the actual temperature requirements are being achieved? Many times, there are parts of a device to be tested that have different heat capacities and also possible active load heat sources. A single point temperature control algorithm can have trouble effectively dealing with these variables. Additionally, while it may be tempting to say that a temperature setpoint has been achieved ..."

Selecting Frequency and Time Standards

Selecting Frequency and Time Standards, May 1967 Electronics World - RF CafeThis article from the May 1967 edition of Electronics World shows you just how long the Frequency Electronics company has been around! In fact, here is an excerpt from their website: "Frequency Electronics, Inc. was founded in 1962 and is now a well-established public company in Long Island, New York, and trades on the NASDAQ Stock Exchange under the symbol FEIM." Mr. Irwin Math, the project engineer at Frequency electronics who wrote the article, has surely retired by now. The discussion on short- and long-term stability is as relevant today as it was 45 years ago. Interestingly, the term "phase noise" is nowhere to be found. Neither is "digital," which might explain the absence of the former ...

Cubesat Carries 1st 3D-Printed Space Antenna

Cubesat Carries 1st 3D-Printed Space Antenna - RF Cafe"A CubeSat containing the first commercial microwave radiometer and 3D-printed antenna for space has launched from the US. Dubbed IOD-1 GEMS, the miniaturised weather observing and forecasting technology is the first of the Satellite Applications Catapult's In-Orbit Demonstration (IOD) Programme, which is funded by Innovate UK. It is also the first satellite in Orbital Micro Systems' (OMS) Global Environmental Monitoring System (GEMS) constellation. 'Through the support and collaboration with Satellite Applications Catapult and other IOD team members, OMS is now positioned to be a market leader in gathering and delivering actionable ..."

Anatech Electronics: Off-the-Shelf and Custom RF & Microwave Filters

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. Sam Benzacar's monthly newsletters address contemporary wireless subjects. Please visit Anatech today to see how they can help your project succeed ... 

Sunday 28

Engineering & Science Crossword Puzzle for April 28

Engineering & Science Crossword Puzzle April 28, 2019 - RF CafeSince 2000, I have been creating custom science and technology-themed crossword puzzles for the brain-exercising benefit and pleasure of RF Cafe visitors who are fellow cruciverbalists. The jury is out on whether or not this type of mental challenge helps keep your gray matter from atrophying in old age, but it certainly helps maintain your vocabulary and cognitive skills at all ages. A database of thousands of words has been built up over the years and contains only clues and terms associated with engineering, science, physical, astronomy, mathematics, chemistry, etc. 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 ...