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.
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Answering my call for entries in the new Out of Order feature on RF Cafe, Mr. Denny Condron responded with a great saga of his use of finely tuned (pun intended) use of fox hunting skills to track down and ultimately resolve a bad case of interference in the 2-meter amateur radio band. Although names are omitted to protect the innocent (and the guilty) parties, it is good to know that the offending source was remedied willingly by the owner of the equipment: a manufacturing operation. This is a fine example of the term "unintentional radiation," and why ignorance is usually only bliss, as the saying goes, for unaffected and usually oblivious parties. Denny noted separately that this tale...
Here is a story of a real feat of RF engineering where the stakes were high for determining the cause of the problem and effecting a solution. In this case Bell Telephone Laboratories was solicited to figure out why a commercial broadcast station's signal was not being received as strongly as predicted after the station had relocated its facilities specifically to address the issue. A lot of power was being pumped into the antenna, but inexplicably some relatively nearby listeners were getting lousy reception while reports were coming in of good signal strength from hundreds - even thousands - of miles away in other directions. A modern antenna design program like EZNEC...
The new TT Series Remote Control Transceiver is designed for reliable bi-directional, long-range remote control applications. The module consists of a highly optimized Frequency Hopping Spread Spectrum (FHSS) RF transceiver and integrated remote control transcoder. The FHSS system allows higher power and therefore, longer range than narrowband radios, reaching over 2 miles (3.2 kilometers) line of site in typical environments with 0 dB gain antennas. Regulations in the country of operation dictate the maximum legal output power, so the final system range may be less depending on the country of operation...
Piezoelectric material's first widespread application in electronics was in the form of quartz crystals that were cut along certain axes in order to provide resonance at specific frequencies. They are still used in modern circuits as frequency-determining devices in oscillators and as frequency-selective devices in filters. Many high Q and tailored frequency response applications are now using polycrystalline ceramics for surface acoustic wave (SAW) devices where crystals used to claim an exclusive domain. This article provides a bit of theory of operation as well as application in radio circuits using both fundamental and overtone frequencies.
You need custom-made precision metal parts - chemical etching, metal stamping, RF shielding, or any custom part made out of metal. Fotofab can help. We've been in the chemical etching, chemical machining, and metal stamping business for years, so we know how to make your custom part quickly, accurately, and affordably so you can get on with your business. Our rapid prototyping service is so efficient we can usually deliver your prototype within a few days of receiving your order, or our new Same-day delivery might be what you are looking for.
The new R&S SMW-K541 digital predistortion option from Rohde & Schwarz allows users to import predistortion coefficient tables directly into the R&S SMW200A. The signal generator uses these delta values to adjust the baseband signal in real-time. The option greatly reduces test times since predistorted waveforms no longer have to be tediously recalculated and imported into the generator. Amplifiers are most efficient when they operate near their maximum output power, which occurs in the nonlinear range. Although more power efficient...
A lot of RF Cafe visitors can't pass up an opportunity to get a peek inside vintage equipment, especially if it is something they used to work with many moons ago. Caleb Kraft of EE Times recently posted this short tour through a 1950s era Eico model 425 oscilloscope. It is surprisingly clean inside and the electronics are sparse. The chassis assembly reminds me of a single-channel, 10 MHz bandwidth kit o-scope that I built back in the 1980s. Enjoy the trip down Memory Lane.
AWR Corporation, the innovation leader in high-frequency EDA software, releases a new customer success story that prominently and proudly features how the AWR Graduate Gift Initiative played a role in helping Dr. Dominic FitzPatrick found PoweRFul Microwave, an engineering consultancy specializing in RF and microwave amplifier design. Upon graduation from Cardiff University, Cardiff, UK, Dr. FitzPatrick took advantage of AWR’s Graduate Gift Initiative program, which gifts a one-year complete AWR Design Environment™ software license to graduates...
Even in today's world with computing devices everywhere sporting simulators and component calculating programs, there are still times when having a good old fashioned nomograph or chart handy can be very useful while in sitting at a bench selecting component values for tweaking or troubleshooting a design. The advantage of such visual aids is that they provide a big picture of what's happening as frequencies, lengths, widths, core materials, etc. change - being able to see both the trees and the forest, so to speak. When you are working in bands where the component physical size is a significant portion of the wavelength, things get more complicated and a combination of trial and error and calculations...
PMI Model No. P6T-2G18G-60-T-512-SFF-LV is a single pole, six throw, absorptive, low video transient, solid state switch operating over the frequency range of 2.0 to 18.0 GHz. This model has a maximum insertion loss of 4.0dB and a minimum isolation specification of 60 dB with video transients of 2mV typically. It operates at 23 dBm CW maximum and has a survival specification of 27 dBm CW maximum and offers a typical switching speed of 30 ns...
Nova Microwave is a leader in technically differentiated electronic and radio frequency ferrite circulators and isolators that connect, protect and control critical systems for the global microwave electronics market place including commercial and military wireless telecommunications. Dedicated to R&D of standard and custom design quality Ferrite Circulators and Isolators from 380 MHz to 23.6 GHz.
Update: The February 5, 2014 edition of The Ohm is now online. The editor of Kansas State University Department of Engineering's newspaper contacted me asking permission to reprint one of my engineering-themed crossword puzzles in their monthly publication called The Ohm. You will find their alma matter's name buried in the word clues. Like always, all of the words are technology related. As time permits, I'll be glad to do a custom crossword for your school's newsletter.
Pasternack Enterprises, an industry leading manufacturer and global supplier of RF and microwave products, recently launched its new website which boasts best-in-class site search functionality, one-page checkout and an updated user friendly interface. The new 2014 Pasternack website is the first major redesign since the Company’s previous 2012 website overhaul. Most noticeable to the average user is the sites simplified, stripped down look and feel of the new homepage. Pasternack's main objective with the new site was to provide engineers and buyers
Another month has passed already, which means a whole new bunch of good tech articles are being posted on magazine website like MW&RF and T&M. If you're like me, you don't even look at the print versions anymore. Do you have an article written that you would like to have published on RF Cafe (and that has not been published elsewhere)? If so, please send it to me for review.
- GaN Enables RF
LDMOS and GaAs Can't
- Measure Small Impedances
with Rogowski Current
- Semiconductor Technology
Offers Exciting Possibilities
- SoCs Bring High-End RF
Devices from Lab to Sofa
- Current Reuse Gains UWB
LNA (Michael Hopkins at Current RF
has been into current reuse for a
The very first submission for RF Cafe's new Out of Order feature has been received from Joe Birsa. His experience is one that many of us (including me) has been bitten by at some point in our electronics and/or electrical pursuits. Unfortunately, this type of situation occurs so infrequently that by the time it happens again, we've forgotten about it and are prone to getting bitten again. Low Battery in Multimeter = High Voltage Scare, by Joe Birsa. Last year when I was adding a new accessory to my ham radio station at home, I noticed that the power supply I use for accessories was putting out 16 VDC instead of the nominal 12 volts I expected...
Immediately upon seeing the title of this newest Sherlock Ohms adventure, I thought of my own experience with a telephone dial tone problem. In A. David Boccuti's case the culprit turned out to have an entirely different cause than mine. Read about Mr. Boccuti's issue resolution here. My dial tone dilemma was caused by corrosion as well, but mine was inside the phone itself. Being a lifelong avid fan of Charles Schulz's Peanuts comic strip, I decided to purchase a 1976 vintage Snoopy and Woodstock telephone from someone on eBay. It was promoted as being in working condition, but I discovered 'working' was a subjective term in this case. Indeed, it was possible to hold a conversation, but the volume in the earpiece was very low, and the dial tone was weak and intermittent. I have a more detailed description...
"In my judgment, it will be only a few years before all police departments will be equipped with radio," Superintendent A. A. Carroll, Grand Rapids Police Department. Such a statement could have been deemed risky - or even career-ending back in the late 1920 to early 1930s when radio communications was still in its infancy. A lot of public figures denounced radio for anything other than a means of receiving entertainment at home. After all, the equipment was physically large and very power hungry. It was considered folly by many people to believe that an automobile's electrical generation capability would ever be able to power a vacuum tube receiver, much less a transmitter that would have enough range to be useful. Still, police and fire...
'Real' engineers can usually be identified by their tendency to deal with all aspects of life through a combination of pragmatism and objectivity. Every object and objective presents a challenge that requires consideration of both the initial assessment of each situation and the careful analysis of how it might be improved for personal optimization and utilization. You know the type; you probably are one of 'them' if you're reading this... one of 'us,' I probably should say. Be assured, you are among friends here. This latest installment in Joe Cahak's creative series offers a quantitative analysis of his new Ford C-Max Energi Hybrid horseless carriage, along with an in-depth accounting of his carefully-analyzed...
Microwave De-Embedding: From Theory to Applications, by Giovanni Crupi and Dominique Schreurs. This groundbreaking book is the first to give an introduction to microwave de-embedding, showing how it is the cornerstone for waveform engineering. The authors of each chapter clearly explain the theoretical concepts, providing a foundation that supports linear and non-linear measurements, modeling and circuit design. Recent developments and future trends in the field are covered throughout, including successful strategies for low-noise and power amplifier design. This book is a must-have for those wishing to understand the full potential of the microwave de-embedding concept...
"The IEEE MTT International Microwave Symposium (IMS) is the premier annual international meeting for technologists involved in all aspects of microwave theory and practice. It consists of a full week of events, including technical paper presentations, workshops, and tutorials, as well as a full set of social events. The symposium also hosts a large commercial exhibition featuring over 550 companies. The IEEE MTT-S Microwave Week has several conferences that are co-located at the same venues. Besides the flagship IMS Conference, Microwave Week also hosts the IEEE RFIC and ARFTG conferences...
Microwave Journal Editor, David Vye moderates a round table panel discussion among leading EDA vendors as they consider the state of IC design in China and the challenges for organization’s looking to develop a world-class EDA design flow infrastructure and adopt design automation tools. Panelists will discuss design entry and management, PDKs, EM simulation / modeling, various types of RF specific analyses, third party integration and the role of EDA companies in providing engineering support/training programs. Visit EDI CON 2014.
This is a fortuitous discovery. While perusing a 1930 edition of Radio News magazine, I ran across an article written by none other than Senatore Guglielmo Marconi himself - 28 years after the first transatlantic radio communication had occurred. It's hard to imagine having lived in an era when radio was looked upon with awe - and even fear - by most of humankind. Its seemingly magical operation was matched at the time only with the fledgling air travel revolution. Mr. Marconi here provides a brief history of his work in making that first radio contact between Poldhu, England, and Cape Cod, Massachusetts, with the assistance of the BBC and NBC, respectively. This is the type of resource that credible historians love since it is a first-hand account of an event...
The 1950s was a time of transition in the television watching business. Broadcasters were experimenting with pay-TV systems to replace or supplement over-the-air service. Much as people today think that everything on the Internet should be free, the same mindset prevailed then regarding television programming. Early coding and decoding schemes seem really hokey by today's standards, using computer-type punch cards. I remember the area around Annapolis, Maryland, where I grew up, had both over-the-air and cable-based subscription services in conjunction with the open broadcasts. I spent at least a little time playing with the horizontal and vertical picture sync settings on the back of the TV set that, if lucky...
This is Colossal, really, it is. That's the name of a website that features, among other things, amazing works of art with high technology themes. There are hundreds of pages containing thousands of images, so after spending an inordinate amount of time sifting through pages in an orderly manner looking for for items of interest, I finally discovered the Search box. I then spent my valuable time looking only of for topics like radio, technology, computers, etc. This first example, titled "Antenna Telescopes on the Streets of Birmingham, UK," is classified loosely as street art and was done to camouflage some satellite television dishes mounted to the side of a building. It would be interesting to see if the artist planned for the images to look right from...
This week's crossword puzzle, like last week's crossword puzzle, and all the weeks before that, was custom made by me and contains only words and clues pertaining to science and engineering. Print it out and take it to your next diversity in the workplace meeting so you can honestly say you got some mental stimulation out of it. Enjoy!
As do many of you, I enjoy and learn from reading online anecdotes submitted by engineers, technicians, and hobbyists that have faced and resolved situations which are sometimes daunting, sometimes impossible, and sometimes just ridiculous. Sherlock Ohms and Made by Monkeys from DesignNews, and Tales from the Cube from EDN are the most notable sources for such stories, but the topics cover a very wide range of subjects that are more often than not unrelated to RF and microwave. Lately, the stories have been pretty lame and uninspiring. I like tales of work and hobby related situations with a good description of the problem and its symptoms, followed by a fairly detailed explanation of the steps taken to resolve it. If you appreciate such articles and would like to make your own contribution for the edification and teaching of fellow techies, I will be glad to create an area for posting them on RF Cafe and title it "Out of Order: Tech Trials & Tribulations..."
This article on crystal filters will probably be more useful to people responsible for maintenance on old RF systems than for new designs. The technology has come a long way since 1957. Crystal filters were heralded as godsends as airwaves became more crowded and simple LC filters could not provide the required Q to prevent cross-channel interference. Of course the problem is many times worse today, but components are better now than then with low-cost integrated circuit front ends that handle a lot of the selectivity issues and SAW filters with better performance than many crystals.
1957 was part of the hey day of the newfound radio-in-your-car craze, and the public was voraciously consuming all the high tech equipment it could afford. Rock and Roll music was on every teenager's mind and many guys for the first time were able to have their own wheels and were outfitting them with sound systems that could blast the latest works of Buddy Holley, Chuck Berry, Elvis Presley, and Fats Domino. Those machines were the first babe magnets used for cruising the strip on Saturday nights. Radio stations were popping up all over the country, enabling cross-country travel with non-stop music, news, and variety show entertainment. Ford and Chevrolet were not going to miss an opportunity, so they delved into the high end mobile radio manufacturing business. As the quality of broadcasts increased, noise...
Even if you are even old enough to remember the Packard Bell line of desktop computers that appeared during the PC revolution of the late 1980s, you probably do not know that before making PCs, Packard Bell made television sets. Before that they made radios. Herb Bell and Leon Bell formed the company in 1933, then marketed their first radio model, the 35A. Packard Bell was sold to Teledyne in 1968, then in 1986, an American businessman named Beny Alagem and a group of Israeli investors bought the Packard Bell name from Teledyne. Because of a failing brand name, Packard Bell left the U.S. altogether in 2000. If you visit the Packard Bell homepage today, you will not find the U.S. or Canada...
CubeSats have been very popular as an affordable space platform for experimental electronics systems. Their small size presents an issue with signal strength both for uplink and downlink channels. Heretofore, some form of rigid dipole or even a ¼-wave stub, with 1 dB or so best-case gain and relatively low directivity (which subjects it to interference) is all that was available. MIT engineers are developing an inflatable parabolic antenna made of thin Mylar that will stow onboard in a small space and then deploy with a powered that turns into pressurized gas to form the antenna. CubeSats typically have short lifespans due to limited space and weight allowance for batteries and solar panels (and their usually lower orbits degrade in weeks to months), so the antenna does not need to have a long life expectancy.
That's hot dog, not hotdog. In this third installment in the adventures of John T. Frye's much-anticipated monthly exploits of teenage electronics investigators Carl Anderson and Jerry Bishop, pet mutt Bosco has developed a case of hot paw pads. Using a makeshift Geiger counter and a homemade radio homing device, the two boys set out to discover the source of Bosco's warmth. A buried, as-yet undiscovered lode of uranium is high on their suspect list, and visions of untold wealth dance through their heads. Read on to find out what they found out.
AWR Corporation has released a digital edition of its AWR Magazine that’s a culmination of news and events over the past year. Widely distributed at major trade shows and AWR-hosted seminars, the AWR magazine is now offered online in a new interactive format that’s PC, tablet and smartphone compatible. The digital edition of AWR Magazine, as well as previous static PDF issues, can be found on line.
If you work with oscilloscopes on a regular basis, you know know one of the first things you do (or should do) is to calibrate the frequency response of the probe by hooking it onto the squarewave port and tweaking the probe capacitor for no overshooting or undershooting at the waveform edges, and then verify that the displayed amplitude is correct. I remember being amazed during engineering courses at learning that any periodic waveform can be described mathematically as the sum of sinewaves at various frequencies, amplitudes, and phases. Knowing the theory behind those waveforms - particularly standard ones like squarewaves, trianglewaves, sawtooths, etc. - really helps...
Since 1992, Ophir RF has been designing and manufacturing RF/Microwave Amplifiers for military, T&M, EMC and scientific research applications. Products range 10 kHz to 40 GHz. Power levels 1 W to 25 kW. Ophir RF's specializes in replacing radar tube technology with solid state. Whether RF amplifier systems or modules, Ophir RF is your RF power source. Ophir RF designs and manufactures its products in the USA. We are well-known in the industry for successfully adapting our amplifiers or custom designing new solutions to meet your application requirements.
GEA Process Engineering Inc., a full service company specializing in process systems and solutions, is seeking people with the following skills. We were established in 1974 and promote an environment where all employees are valued and treated with respect.
- Process Engineer
- Sales Engineer
- Instrumentation & Controls
- Field Service Technician
- Construction Estimating
Companies like Q-Par Antennas (now owned by Steatite) underwrite the publication of RF Cafe, so if you have a need for products or services my advertisers offer, please check with them first. "Steatite Q-par Antennas designs and manufactures antennas, positioners, components and subsystems across the radio frequency spectrum, with specialisation in microwave & millimetric systems. We design, build and calibrate our products to the highest engineering standards. Custom products available."
I'm not sure when storytelling as a style of technical writing went the way of vacuum tubes (probably about the same time, come to think of it), but this article from the January 1958 edition of Radio-Electronics is a prime example of how such prose was utilized. Two characters, Red and Fuzzball, meet at a coffee counter and discuss the intricacies of color convergence in color television sets. Such issues are not a concern with today's electron-beam-less displays, but back in the day, it made the difference between an acceptable picture and frustrating images with color fringing. Maybe you remember those days. After having...
Bayesian Multiple Target Tracking, by L.D. Stone, R.L. Streit, T.L. Corwin, and K.L. Bell. This book views multiple target tracking as a Bayesian inference problem. It develops the theory of single target tracking, multiple target tracking, and likelihood ratio detection and tracking. In addition to providing a detailed description of a basic particle filter that implements the Bayesian single target recursion, this resource provides numerous examples that involve the use of particle filters. With these examples illustrating the developed concepts, algorithms, and approaches -- the book helps radar engineers track when observations are nonlinear...
There are lots of audiophiles in the RF Cafe audience who might appreciate this article on the characteristics of human hearing and ways in which stereo hi-fi equipment attempts to reproduce realistic sound, as if from a live performance. A handy-dandy chart is provided that shows the characteristics of various audible frequency ranges, and the kinds of speakers best suited for reproducing the sound. It was published in 1955, but still should be applicable today.
Aside from the photos of cool radar antennas, "Made by General Electric of Syracuse, N.Y.," caught my attention because I actually spent a couple years there (it was a different company by then) in the mid 1990s as an engineer working with a design team for a weather radar for the FAA. It was a kludge of left-over components and assemblies from other cancelled programs. The phased array antenna came from a Navy shipboard program, and the components for the RF, analog, and digital portions were cobbled together mostly from parts that were in the company stock room inventory. Very little money was budgeted for new parts or personnel. I handled all the RF and analog design and the equipment rack power supplies, plus RF plumbing out of the building and into the phased array antenna...
Student and part-time digital artist Jay Simons has created his first version of a Map of the Internet, where an attempt is made to cram in as much information as possible on most often used browsers, most often used social networks, NSA surveillance, worldwide Internet penetration, a list of Alexa's top 500 websites, a timeline Internet history, and top software companies. The base world map is done in old-world format and coloring with faux names like Sea of Archives, Ocean of Information, the country of Google and island of Bit Torrent. LinkedIn and its capital city of Hoffman (for LinkedIn's founder, Reid Hoffman) resides just south of...
Both winners of January's RF Cafe Book Drawing actually responded this month - woo-hoo! None of the four winners notified for November and December responded after three separate e-mail notifications (their loss is possibly your gain). Dean S., of Owensboro, Kentucky, selected Introduction to Modern EW Systems, by Andrea De Martino. This book was graciously provided by Artech House.
"The path to the CEO's office should not be through the CFO's office, and it should not be through the marketing department. It needs to be through engineering and design." - Elon Musk, CEO and chief product architect, Tesla Motors and SpaceX (engineering degree from U. of Penn., business degree from Wharton).
Mostafa A., of Ontario, Canada, is one winner in the January 2014 RF Cafe Book Drawing. Mostafa selected Design of CMOS Operational Amplifiers, by Rasoul Dehghani. Each month I randomly draw one or two names from my electronic hat (an Excel spreadsheet), and then mail it/them at my expense. Some months nobody responds to my e-mail notifications. I usually try 2-3 times, but give up after that. This book was graciously provided by Artech House.
USAF radar technician Jim Rice checked in today with his service record for adding to my list of honored service members who have spent time taming the often fickle beasts - both fixed and mobile ground-based units. Jim served America for 20 years and then worked for 25 years as an inspector at Boeing. Recently retired, he's enjoying life in the Robins AFB area.
The editor of Kansas State University Department of Engineering's newspaper contacted me asking permission to reprint one of my engineering-themed crossword puzzles in their monthly publication called The Ohm. You will find their alma matter's name buried in the word clues. Like always, all of the words are technology related. As time permits, I'll be glad to do a custom crossword for your school's newsletter.