1996 - 2016
BSEE - KB3UON
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 Internet was still largely an unknown entity at the time and not much was available in the form of WYSIWYG ...
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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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This week's engineering crossword puzzle has a theme of radar. There are more than a dozen words and clues specifically related to radar, but all words and clues are related to engineering and science. You will need to print it out on paper for working. Good luck.
DS Instruments is dedicated to providing quality RF & microwave test equipment and specialized hardware in smaller form-factors and at lower cost than previously available. All hardware design, firmware development, and assembly is based in the USA. We pride ourselves in using genuine components from the top semiconductor manufacturers. Current offerings include tracking and microwave signal generators, microwave digital step attenuators, and in the near future a compact signal power meter and frequency counter capable of reaching nearly 8 GHz.
Today is Black Friday, which means we're only month away from beginning a new year. Sure, it's just an artificial demarcation point on the calendar, but target start dates for achieving goals are a good psychological tool that have been shown to be effective at helping attain a new and/or improved job, lifestyle, living location, family situation, etc. I can't help much with lifestyle, living location, and family situation (although I have an opinion on nearly everything*), the job thing is a place where I might do some good. Here is my latest roundup of useful career advice. Go for it.
Compliments of Microwaves & RF: Keeping track and updated on the latest frequency allocations isn't easy, so we've compiled the information into an easy-to-view poster. Get access to frequency allocations by country or scan by specific transmission bands. Download the digital version now. Plus, the first 500 engineers receive a printed copy 40" x 26". Hurry, while supplies last.
Wirewound inductors (as most are) can be mysterious entities even when you are familiar with their many interdependent physical and electrical properties. Because of interwinding capacitance and a sometimes (when a large number of turns are involved) rather significant series resistance, the equivalent circuit model gets quite complex - literally in a mathematical sense. If you have the luxury of staying far away from the self-resonant frequency (SRF) of the coil, your component will behave very much like an ideal inductor, that is, XL = 2πfL. This article delves into what causes inductors to …
Mourt's Relation: A Journal of the Pilgrims at Plymouth, 1622, Part VI, Edward Winslow, William Bradford:
"… We set the last spring some twenty acres of Indian corn, and sowed some six acres of barley and peas, and according to the manner of the Indians … God be praised, we had a good increase of Indian corn, and our barley indifferent good … Our harvest being gotten in, our governor sent four men on fowling, that so we might after have a special manner rejoice together after we had gathered the fruit of our labors … many of the Indians coming amongst us, and among the rest their greatest King Massasoit, with some ninety men, whom for three days we entertained and feasted … And although it be not always so plentiful as it was at this time with us, yet by the goodness of God, we are so far from want that we often wish you partakers of our plenty. We have found the Indians very faithful in their covenant of peace with us; very loving and ready to pleasure us; we often go to them, and they come to us … yea, it has pleased God so to possess the Indians with a fear of us, and love unto us, that not only the greatest king amongst them, called Massasoit, but also all the princes and peoples round about us, have either made suit unto us, or been glad of any occasion to make peace with us …" <Not what you were taught? Read it all>
All three of my hobbies are contained in this episode of Carl & Jerry - electronics, astronomy, and airplanes! For as clever as the two teenagers are, they sure do manage to get themselves into some sticky situations due to what can only be termed as stupidity. This is not the first time their future relied on a fairly large number of people being 'out there' who were familiar with Morse code. Supporting the claim that trends run in cycles, the ignition-type model engine common in the mid 1950s eventually gave way to glow fuel engines, but nowadays miniature electronic ignition systems have made …
This RF & Microwave Toolbox app has more than 50 calculators that includes noise figure, microstrip, filters, amplifiers, attenuators, electric fields, series & parallel RCL circuits, mixers, antennas, radar cross section, capacitance & inductance, color, baluns, voltage dividers, directional couplers, and much more.
Biographical historians spend endless hours searching old media for bits of information on their subjects. Finding useful material on more renowned personalities is not a problem, but filtering out relevant bits for a particular theme can be daunting. On the other hand, finding useful information on lesser known people can be frustrating because there is so little information readily available. Great Britain's World War II era superstar Winston Churchill undoubtedly falls into the former category. While scanning through my many vintage …
Use of load line charts is a fast way of selecting bias (operating) point and operational ranges for nonlinear devices. Notice that I didn't specifically say for transistors because this particular article deals with load lines for vacuum tubes. Almost nobody has any need for tube load line charts anymore, but the skill needed to interpret load lines for transistors is fundamentally the same as for tubes. Substitute Vce (collector-to-emitter voltage) for Plate Volts and Ic (collector current) for Plate milliamperes and you have equivalence.
This would be my dream job! All astronomy, all the time. Day or night, rain or shine, radio telescopes are on the job. Are you an experienced microwave engineer who is ready for a next challenge? Do you want to work in a dynamic international scientific environment and do you have a solid understanding of RF engineering concepts and principles? Perhaps this is the job you are looking for!
"In fifteen years, more electricity will be sold for automobiles than for light." - Thomas Alva Edison, 1910, as quoted in Science Digest in 1982. This might turn out to be correct after all, fifteen years from now.
Unlike the article on making your own foil capacitors, this one advising how to 'reactivate' leaky capacitors might be of use to a lot more people. The process is called 'reforming,' and consists of applying a DC voltage to the faulty capacitor, beginning at a very low voltage, and then slowly raising the voltage until the rated working voltage (WVDC) is reached. Doing so, if the capacitor is not beyond rehabilitation, will reconstitute the oxide layer that serves as the dielectric. This particular item was presented as the answer to a question …
Here is another instance that shows how much expectations have changed over the years. Except maybe for an experimenter or someone set on reproducing original equipment as closely as possible, nobody would even consider trying to build capacitors from scratch. Components are so inexpensive that it's just not worth the trouble. If you are one of the latter type people, then this story is for you. Come to think of it, another use for this article is to provide material for a physics class laboratory exercise where the student calculates a predicted value …
- Choosing Microwave PCB
Materials for Wireless
- For Long-Range Comms, Is
Narrowband 'It?', J-J DeLisle
- 10 More Tricks to Extend
O-scope Usefulness, A. Pini
Filter Technologies Solve
Challenges, P. Warder &
- A Guide to the Design of
Laminate PCBs at Microwave
Frequencies, L. Devlin &
- 100G and Things to COM,
Only a couple decades prior to when this article on a newfangled wireless automatic garage door opener appeared in Radio Craft magazine, there would have been no demand for such a device ... although maybe an automatic horse barn door opener would have been in demand if a battery was available on the coach. Amazingly, the system employed an early, albeit crude, form of both spread spectrum and digital communications in order to trigger the receiver for opening the door. The spread spectrum nature of the …
The 10CN600 is one model of the series of directional couplers that cover octave and multi-octave bands up to 18 GHz. These directional couplers are offered with SMA or N-female connectors in standard and custom configurations. Values of 6, 10, 20, 30 dB and between. Made in U.S.A.
Take a break and work this week's microwave engineering themed crossword puzzle. All the words are pulled from a hand-built list of terms, names, and abbreviations that have only to do with science, mathematics, and engineering. If you want a crossword with names of movie stars and obscure countries, try the local newspaper. If you want to exercise your nerd knowledge, this is the one for you.
Marc Edwards is a Data Systems and Security Engineer for a chain of retail stores, whom I was fortunate to get acquainted with via my amateur astronomy hobby. He and his teenage daughter are avid and highly capable telescope operators. During one of our conversations at the time earlier this year when a major retailer's credit card data breach was in the headlines, Marc explained how the typical point-of-sale (P.O.S.) system works in stores and why the most commonly installed type is so much more vulnerable to intrusion than the newer and much more secure system his company is implementing. It was an amazing story. Rather than my attempting to summarize Marc's explanation, I asked him to write a short …
As promised, here are the first of the 1941 Crosley 03CB electronics chassis restoration photos. It was decided from the beginning that the chassis would be stripped of all its components so that the metal box could be completely sanded and re-painted. That involved not just unsoldering all the individual components, but also drilling out the rivets that secured the tube sockets and solder terminals. My plan was/is to someday rebuild the original circuitry, but because I have so many other projects (both electronic and woodworking) in the works and in the queue, for now I am just going to re-install all the major hardware and wait until later to solder back in all the resistors, inductors, and capacitors - all of which will …
Call me a snob, but IMHO except for rare circumstances, if you expect to hold the title of 'engineer,' you really should have earned a college degree in engineering. Sure, there are talented people without an engineering degree that can do some engineering jobs more competently than some with an engineering degree; however, it certainly is not so in the majority of instances. It is foolish to look around at all the technology you share your life with and conclude that people without the benefit of a formal engineering education could turn out so much at such a fast pace. When someone learns that you are an engineer, there is an automatic assumption that …
RFMW announces design and sales support for a 50 W, surface mount, directional coupler serving 15–18.5 GHz applications. The EMC Technology DN05W20F provides a 20 dB coupling factor with only 0.6dB insertion loss. Directivity is 32 dB min from 17-18.5 GHz while the DN05W20F maintains a maximum VSWR of 1.6:1. The DN05W20F operating temperature is -55 to +85 degrees Celsius. EMC passive couplers offer highly repeatable, low loss alternatives to microstrip-on-PCB solutions and provide excellent reliability
Here is a real cornucopia of attenuator information. If you need circuits diagram and equations for "T," Bridged-T, Ladder, Pi, Balanced-H, Balanced Ladder, Potentiometer, and Balanced Potentiometer type attenuators, then you've come to the right place. A discussion is included on attenuator selection and specification for ordering rather than designing and building your own. The distinction between a 'pad' and an 'attenuator' has always been vague to me and I, like most people, use the terms interchangeably. Author Chester Scott seems to believe a 'pad' always has a fixed value whereas an attenuator can be either fixed or variable …
Advanced Test Equipment Rentals (ATEC), supplier of complete testing solutions for EMC, now offers, for rent, the recently released Instruments for Industries (IFI) S31-500-900P solid state pulsed amplifier. The S31-500-900P has a 500W continuous rating and the ability to deliver more than 900W in the pulsed peak mode. IFI is a leading instrumentation and systems developer for EMC emission and immunity testing. Optimal for use in test labs and automotive OEMs, the S31-500-900P generates 600V/m radar
Little did Hugo Gernsback know when he wrote the 1938 editorial about the potential of television just how prescient he was - particularly in the realm of eventually enabling remote commerce and banking. His vision involved having a camera-phone type device that would allow real-time interaction between shoppers and depositors, respectively, without either party needing to meet face-to-face. 76 years later we are not at that point (at least on a widespread basis); however, the advent of online shopping and banking has fully permitted the kind of impersonal transactions that Gernsback foresaw. Even with the growing popularity …
This week's collection of career-related articles and news tidbits includes a topic I've never seen before: "Been Arrested? How to Survive Background Checks and Land a Job." I suppose if you've done time in The Big House, legitimately paid your debt to society, and are truly reformed, then there's no reason you shouldn't have a fair shot (maybe poor choice of words depending on your crime) at a job you are otherwise qualified for. There's also an article on attire color choices for interviews - you might need more than a red power tie.
In the early 1990s a decent flatbed scanner from HP cost started at about a kilobuck - the price of a nicer notebook computer today. 3D printers are at that price point now, and in all likelihood will be in the $250 realm by 2020. You could easily justify the investment for company use and/or use it to provide an impetus for getting your kids interested in high tech and in using computers for something other than Facebook. The Dremel Idea Builder 3D printer is quite affordable and has the reputation of a great company to instill confidence and very high customer ratings! Software is included for designing printable items.
An innovative company located in Madrid and Guadalajara that develops and commercializes NewFASANT, a simulation software for electromagnetic fields for the study of antennas, radar cross section, radiation patterns, advanced telecommunications systems and other studies. Our multidisciplinary team of engineers is dedicated to the research and development of new software techniques that facilitate innovation and the satisfaction of our customers.
My civilian career began at Westinghouse's Oceanic Division in Annapolis, Maryland. It was long ago bought out by Northrop Grumman and re-named Undersea Systems. Their AQS-24 towed sonar system looks outwardly very much like the AQS-14 that I worked on while there in the 1980s. Our parent organization was the Westinghouse Electronics Systems Division in Baltimore, MD, adjacent to the Baltimore-Washington International Airport tarmac so that military aircraft could fly in and out to be retrofitted with radar systems. Headquarters …
Believe it or not, there are people who pay for vintage advertisements like these. eBay is chock full of auctions for original pages from the old magazines that contain ads for products and services. Often, if you know where to look, you can buy the entire magazine in which a particular ad appeared for only a little more. People sometimes frame them and either hang them for decoration or present them to a parent or grandparent as a memorial to their lives. Stranger things are done. These ads for Connecticut Telephone and Power, Detrola Radio, and Jensen Radio appeared in the January 1945 edition of Radio News …
"We learned in school today that there are sixteen ozzes in a lib." - Lucy Van Pelt to Charlie Brown, from You've Got a Friend, Charlie Brown, 1972, by Charles Schulz
A recent headline announced where a guy hacked his hearing aid to enable listening to Wi-Fi signals as he walked around town. Why would a person do that? I suppose now that the audible digital handshaking tones of telephone modems and fax machines are all but gone from everyday life, he must have really been missing the nerve-grating melodies. I don't recall ever seeing a story about anyone picking up Wi-Fi signals from a faulty metal tooth filling like used to occur occasionally in the presence of high power AM transmitter towers. This …
EMTensor GmbH is seeking to recruit an engineer with a background and preferably PhD in microwave / radiofrequency engineering. Hands on experience in engineering and R&D of modern devices and technologies in low GHz is essential. A track record in engineering solutions for electromagnetic (MW) imaging is highly desirable. EMTensor GmbH is developing a novel biomedical imaging modality using electromagnetics (microwave tomography)
A couple months ago I finally picked up on the restoration of my circa 1942 Crosley 03CB console radio. All of the hardware was removed from the wooden console in preparation for restoration. Paint stripper was used to remove the bulk of the original finish, and then sandpaper along with a lot of muscle power took care of the rough and final sanding. As can be seen on some of the "before" photos, there were many places where the walnut veneer had delaminated and other where small areas where pieces had broken off. I obtained some replacement wood from a vendor on eBay and spliced in the missing areas. A few of the wood corner gussets needed …
Stan Goldberg is a familiar name to comic book aficionados for his artistry in Spider Man, the Incredible Hulk, and the Archie series. QST magazine had him listed in the "Silent Keys" column in the November 2014 issue because he passed away in August. A Silent Key, in Hamdom, is usually a title reserved for a deceased licensed operator, but a search of the Internet and the FCC license database web page did not turn up a call sign for him. Unless his record has been dropped from the database, Mr. Goldberg might never have actually been a Ham, but earned the Silent Key acknowledgement because of his involvement in a 1986 special edition comic book titled "Archie's Ham Radio Adventure." It was quite an …
Test your vacuum tube knowledge with this week's crossword puzzle. Many of the words and clues are directly related to vacuum tubes. The rest of the words have to do with science and engineering - no numbnut movie star names or obscure species type from remote regions in Sub-Saharan Africa.