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Homepage Archive - December 2023 (page 2)

See Page 1 | 2 | 3 | 4 | of the December 2023 homepage archives.

Wednesday the 14th

"Printed" Radio Circuits

"Printed" Radio Circuits, July 1946 Popular Mechanics - RF CafePrinted circuits were originally printed on onto a substrate material - thus the name "printed." It can be considered an early form of additive manufacturing, similar to printed 3−D objects nowadays. the opposite of additive manufacturing is, of course, subtractive manufacturing. Modern printed circuit boards (PCBs) have metal removed during the etching process, hence, subtractive. When a metal ingot or casting is machined and material is removed, that is subtractive manufacturing. Prior to 3−D printers, had you ever heard of additive manufacturing. Me neither, and for that matter, nobody ever spoke of subtractive manufacturing. But I digress. The early printed circuits like the one featured here in this 1946 issue of Popular Mechanics magazine still used vacuum tubes. In this case the full-size tubes were replaced by peanut tubes, but there were plenty of PCBs that had standard tube sockets mounted to them. Eliminating the time-consuming and error-prone point-to-point wiring in a cramped chassis was worth the extra expense. It paved the way for more extensive use of printed circuits so that the technology was maturing by the time semiconductors came along a decade later...

Butterworth Highpass, Bandpass, & Bandstop Filter Gain, Phase, & Group Delay

Butterworth Highpass, Bandpass, and Bandstop Filter Gain, Phase, and Group Delay Equations and Plots - RF CafeA few days ago I posted a webpage detailing my work to generate equations for gain, phase, and group delay for a Butterworth lowpass filter, using the basic polynomials. I could not find them anywhere on the Web or in filter design books I own. The only difference between calculating Butterworth lowpass, highpass, bandpass, and bandstop filter values for gain, phase, and group delay is how the relative frequency is defined. Simply substitute the following for ω in any of the equations for gain, phase, or group delay. It's that simple. Graphs are published below. Frequency units cancel out, so a 1 Hz cutoff plots the same as a 1 kHz cutoff or a 1 GHz cutoff for gain and phase. The group delay scale needs to be divided by a factor equal to the frequency units (÷103 for kHz, ÷106 for MHz, etc.)...

The G-Engines Are Coming!

The G-Engines Are Coming!, November 1956 Young Men • Hobbies • Aviation • Careers - Airplanes and RocketsAccording to what I have found during Internet searches, this "The G-Engines Are Coming" article is a much-sought-after story. It appeared in the November 1956 issue of Young Men magazine (a 13-month-long title existing between Air Trails and American Modeler). An article in the October 1958 issue of American Modeler titled "Anti-Grav" referenced this story. Until Mr. Bob Balsie scanned the pages from his rare copy of the original magazine, it was available nowhere. Science fiction writers are fascinated with the concept of anti-gravitational devices. More than one false premise forms the basis of this article, the most notable of which is a claim of the existence of a "g-particle" (that which is responsible for the gravitational force). Although the postulated possibilities for exploiting the misconception are fantastic, we now know that only extragalactic beings possess such knowledge. Do they walk among us?

Ganged Switching Quiz

Ganged Switching Quiz, April 1972 Popular Electronics - RF CafeRobert Balin created many quizzes for Popular Electronics magazine over his years with the magazine. This Ganged Switching Quiz challenges your ability to trace out connections without getting confused by crossovers - which is easy to do. Each of the six-position switches illuminate a different combination of lamps. Your job, if you accept it, is to figure out which lamps light for positions 1 through 6. Non-nodal crossing lines are not typically shown broken as they are here, so don't misinterpret them as open circuits. A huge list of electronics quizzes is posted near the bottom of the page...

RF Cascade Workbook

RF Cascade Workbook - RF Cafe RF Cascade Workbook is the next phase in the evolution of RF Cafe's long-running series, RF Cascade Workbook. Chances are you have never used a spreadsheet quite like this (click here for screen capture). 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...

Tuesday the 13th

Thordarson Christmas Advertisement

Thordarson Christmas Advertisement, December 1929 QST - RF CafeThis advertisement from Thordarson is from one of my oldest editions of the American Radio Relay League's QST magazine - December 1929. Thordarson Electric Manufacturing Company was founded in Chicago, Illinois, by Chester H. Thordarson in 1895. He was the first producer of industrial and commercial transformers. They are still in business today. Thordarson patented more than 30 inventions for transformer design and manufacturing back in its early days, including the still most popular form of laminations, the scrapless "E and I." Many discussions are available on various transformer lamination configurations, including the very common "E and I" types...

Budget Standoff for Space Development Agency

Budget Standoff for Space Development Agency - RF Cafe"The head of the Space Development Agency said delays to fiscal 2024 funding and the possibility of an across-the-board budget cut would be 'a big deal' for his organization's acquisition plans in the coming year. SDA Director Derek Tournear said Dec. 7, the agency has already put some projects on hold due to the ongoing continuing resolution, which pauses spending at fiscal 2023 levels. 'It's just too much uncertainty,' Tournear said during a National Security Space Association webinar. 'The biggest thing that we could ask for is predictability in the budget, passing a budget, so that we can continue to move fast. Right now, we can move as fast as we can but uncertainty in funding will put a break on everything. So, it's a big problem.' The agency was established in 2019 to quickly field a constellation of hundreds of data transport and advanced missile tracking satellites in low Earth orbit, about 1,200 miles above the Earth's atmosphere. Those spacecraft will augment existing fleets of large satellites and the plan is for SDA to upgrade its capabilities on a two-year cycle. The agency began launching its first batch of satellites, dubbed Tranche 0, in April and September and will finalize that tranche with a third mission early next year...

Butterworth Lowpass Filter Gain, Phase, and Group Delay Equations

Butterworth Lowpass Filter Gain, Phase, and Group Delay Equations - RF CafeThis may be the only place you will ever find the explicit formulas for Butterworth lowpass filter gain, phase, and group delay (until someone copies my work and doesn't give credit*). Hoping to avoid having to do the messy math of complex numbers requiring separating out the real and imaginary parts to obtain phase (θ) - and then to get the first derivative for group delay (τd) - I searched high and low, far and wide for closed form equations. All I could ever find was instruction to apply arg{H(ω)} for phase (θ) and -dθ/dω for group delay -- pretty useless if you want to plug an equation into a spreadsheet or software. Finally, I decided if I wanted the solutions, I would have to slog through all the equations myself. Here is the result. The basic steps are as follow: Simplify the polynomial factors by multiplying out the parenthetical quantities. Substitute jω (or iω, but engineers use jω) for each "s," where ω is the frequency (ωn) being evaluated divided by the cutoff frequency (ωco); hence, jω = jωn/ωco. Since j2 = -1 by definition, all even powers of j result in "real" parts and all odd powers of j result in "imaginary" parts. E.g., for 3rd-order:H(s) = (s + 1)(s2 + s + 1) =Re{H(jω)} =  1 - 2ω2  (parts  w/o j), and Im{H(jω)} = 2ω - ω3 (parts w/j). Gain is G(ω) = sqrt [Re{H(jω)2 + Im{H(jω)2]...

Noise of Thermal Agitation

Noise of Thermal Agitation, November 1944 Radio News - RF CafeAdmittedly, I did not do any follow-up research on this, but there is reason to believe that prior to this 1944 Radio News magazine article, there was not a general agreement on what formula to use for thermal noise in an electrical system. Here is a statement made by author S.J. Mallory, "At first, however, there was no general agreement concerning the magnitude of this basic Johnson noise power level. Some engineers used the quantity KTB, others used 2KTB and still others used 4KTB." We of course all use KTB nowadays for thermal noise power - aka Johnson noise. It's a good read on the subject of sources that determine the noise floor of a system. There's also this kind of Johnson noise...

Promote Your Company on RF Cafe

Sponsor RF Cafe for as Little as $40 per Month - RF CafeBanner Ads are rotated in all locations on the page! RF Cafe typically receives 8,000-15,000 visits each weekday. RF Cafe is a favorite of engineers, technicians, hobbyists, and students all over the world. With more than 17,000 pages in the Google search index, RF Cafe returns in favorable positions on many types of key searches, both for text and images. Your Banner Ads are displayed on average 280,000 times per year! 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. If you need your company news to be seen, RF Cafe is the place to be...

Monday the 12th

Buyer's Guide to Shortwave Receivers

Buyer's Guide to Shortwave Receivers, February 1965 Popular Mechanics - RF CafeIn 1965 when this "Buyer's Guide to Shortwave Receivers" article appeared in Popular Mechanics magazine, radio was a big deal. Transmitting required a license of some sort, but anyone could buy a receiver and listen. It was decades before the Internet and cellphones (which are radios) would make anytime, anywhere communications possible. News services still reported breaking stories via "wire" or "wireless." Only big media organizations and local newspaper offices had access to worldwide happenings. Many people used shortwave radio broadcasts to listen in on news from across the state, country, and world. Of course a lot of it was in a foreign language, but many countries also broadcast in English. Three-letter government agencies also listened in to receive reports from inside Communist countries where some oppressed citizens managed to operate bootleg transmitters. Listening for coded messages from secret agents was good sport; there were groups who traded information on them - much to the consternation of the government. Believe it or not, there is still today a cadre of shortwave listeners who maintain websites for assisting and trading info with the brethren...

Unitrode's Fully Encapsulated Diode Package

Unitrode's Fully Encapsulated Diode Package, May 4, 1964 Electronics Magazine - RF CafeWe really have it good today compared to the early days of the semiconductor revolution. Most of the most difficult problems were solved long ago. Point contact devices were still fairly commonplace even in 1964 when this ad appeared in Electronics magazine. Recall that the very first manufactured solid state diodes and transistors were the point contact type that were encapsulated in glass with a space gap where the contact was made. That left the device vulnerable to vibration and impact damage and to contamination if the hermetic seal failed between the metal lead and the junction(s). Unitrode claims to have been the first to eliminate that issue with essentially a fully bonded package. Keep in mind, however, that even the early semiconductor device packaging was no worse than the vacuum tubes that they replaced, since the tubes also suffered from the same vulnerabilities due to their construction. In fact, the process used with the early solid state device packaging descended directly from vacuum tube construction...

S-, h-, T-, Y-, Z-, ABCD- Parameter Conversions

s- to h- T- Y- Z- Parameter Conversion - RF CafeConversion formulas between various forms of 2-port network electrical parameters is difficult to find, so once I finally located the paper that included them, I felt it was my duty to publish it for public access. The paper is available on the IEEE website by subscribers only. None that I found also include the correction paper published a year later that addresses some of the technicalities of the S− and T−parameter translations when complex impedance reference planes are used. In order to avoid those sticky issues, I have reproduced only the sets of translations that are unaffected. Many thanks to Mr. Frickey for his unique work. Recently, two RF Cafe visitors wrote to comment on the conversions. You can read their contributions here...

YL News and Views

YL News and Views, December 1953 QST - RF CafeMagazines of yore were chock full of Christmas stories, holiday themes on the front cover, and advertisements with both religious and secular messages as part of the sales pitch. Take a look at the December editions of any of the vintage magazines hyperlinked in the upper right part of the RF Cafe header area to see what I mean. The December issues of QST typically featured a Christmas theme on the cover and Christmas themes in many vendor ads. Same goes for my model airplane and amateur astronomy magazines. This 1953 QST edition has a radio fax printout of a Christmas tree on the cover - in full black and white :-). In 2019 when I originally posted this "YL News and Views" column from the December 1953 issue of QST, there had been a noticeable increase in Christmas decorations and even utterances of "Merry Christmas" from checkout line clerks in the local stores. Inflation and interest rates were low and attitudes were good...

Many Thanks to Axiom Test Equipment for Continued Support!

Axiom Test Equipment - RF CafeAxiom Test Equipment allows you to rent or buy test equipment, repair test equipment, or sell or trade test equipment. They are committed to providing superior customer service and high quality electronic test equipment. Axiom offers customers several practical, efficient, and cost effective solutions for their projects' TE needs and is committed to providing superior customer service and high quality electronic test equipment. For anyone seeking a way to offload surplus or obsolete equipment, they offer a trade-in program or they will buy the equipment from you. Some vintage items are available fully calibrated. Please check out Axiom Test Equipment today - and don't miss the blog articles!

Sunday the 11th

Electronics Theme Crossword for December 11th

Electronics Theme Crossword Puzzle for December 11th, 2023 - RF CafeThis week's crossword puzzle for December 11th sports an electronics theme. This being the eleventh day of the month, many of the words begin and/or end with and/or contain the letter "K" (denoted by an asterisk). All RF Cafe crossword puzzles are custom made by me, Kirt Blattenberger, and have only words and clues related to RF, microwave, and mm-wave engineering, optics, mathematics, chemistry, physics, and other technical subjects. As always, this crossword contains no names of politicians, mountain ranges, exotic foods or plants, movie stars, or anything of the sort unless it/he/she is related to this puzzle's technology theme (e.g., Reginald Denny, Hedy Lamarr, or the Tunguska event in Siberia). The technically inclined cruciverbalists amongst us will appreciate the effort. Enjoy!

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, Baseball Caps, and more, all sporting my amazingly clever "RF Engineers - We Are the World's Matchmakers" Smith chart design. These would make excellent gifts for husbands, wives, kids, significant others, and for handing out at company events or as rewards for excellent service. My graphic has been ripped off by other people and used on their products, so please be sure to purchase only official RF Cafe gear. I only make a couple bucks on each sale - the rest goes to Cafe Press. It's a great way to help support RF Cafe. Thanks...

Friday the 8th

Radio Corporation of America Radiograms

Radio Corporation of America Radiograms, June 1947 Popular Science - RF CafeLong distance radio communications made significant advances during World War II. It had to. With as widespread and intense as fighting was, war rooms needed as much and as accurate information as possible from land, sea, and air forces. Satellite systems were more than a decade away when this news item on RCA Radiograms appeared in a 1947 issue of Popular Science magazine. While improved transmitters, receivers, and antennas were extremely important, perhaps the most significant factor in achieving reliable, predictable long distance communications was a better understanding of the Earth's upper atmosphere and how it affected the transmission of electromagnetic waves. No direct measurements of ionospheric heights and conduction levels had been made at the time, so it was a combination of theoretical and operational experience that determined parameters necessary for success. After the war, when some strategic secrets were divulged to the public, businesses and even private citizens were able to enjoy the newfound benefits. Many of the companies that helped develop the wartime technology were able to exploit that effort afterward...

The Coming Boom in Rare Earths

The Coming Boom in Rare Earths - RF Cafe"It would be an overstatement to say that the modern world runs on rare-earth elements. But as overstatements go, that one has more than a grain of truth. Because of their unique luminescent, electrochemical, and magnetocrystalline properties, rare-earth elements are essential to some of the most important and fastest-growing tech-based industries. They're used in the phosphors that make white-light and other LEDs possible, and they're in compounds used to purify key semiconductor materials such as silicon carbide and gallium nitride, to indicate just a couple of their scores of applications in technology. Perhaps most importantly, though, they're essential components of the permanent magnets used in the motors of most electric vehicles and many appliances, and also in the generators in most wind turbines. As much as 90 percent of processed rare-earth elements come from China, a supply-chain dependence that spooks Western executives and, especially, defense officials. That critical importance of rare-earths in so many tech industries is of mounting concern in many Western countries. As much as 90 percent of processed rare-earth elements come from China, a supply-chain dependence that spooks Western executives and, especially, defense officials. Rare earths are vital to countless military applications, including night-vision goggles, laser-targeting..."

Grounding & Line Fluxuations

Editorial Comment: Grounding & Line Fluxuations, March 9th The Wireless World Article - RF CafeAs radio equipment builders and operators, we still battle two fundamental issues that have been around since the beginning of time (well, from Marconi's time, anyway) - grounding and power supply fluxuations. Both topics are addressed briefly here in this editorial column from a 1932 The Wireless World magazine. Back in the day, grounding was referred to as "earthing," and was/is essential to optimal wireless and wired performance. Line voltage "fluxuations" (fluctuations) are generally much less severe today than in the 1930s thanks to better transformers, automated monitoring and adjusting of line voltages, and better distribution designs. The worst type of power line fluxuation - a lightning-induced surge - has been greatly reduced thanks to superior engineering, primarily by the simple running of a grounded neutral "static" wire running at the top of all the lines below it on utility poles and transmission towers...

1st Complete Memristor-Based Bayesian Neural Network Implementation

1st Complete Memristor-Based Bayesian Neural Network Implementation - RF CafeConsidering medical-diagnosis and other safety-critical, sensory-processing applications that require accurate decisions based on a small amount of noisy input data, the study notes that while Bayesian neural networks excel at such tasks because they provide predictive uncertainty assessment, their probabilistic nature requires increased use of energy and computation. The increase is caused by the fact that implementing the networks in hardware requires a random number generator to store the probability distributions, i.e. synaptic weights. "Our paper presents, for the first time, a complete hardware implementation of a Bayesian neural network utilizing the intrinsic variability of memristors to store these probability distributions," said Elisa Vianello, CEA-Leti chief scientist. "We exploited the intrinsic variability of memristors to store these probability distributions, instead of using random number generators." A team comprising CEA-Leti, CEA-List and two CNRS laboratories...

Hughes Aircraft Company Space Engineering

Hughes Aircraft Company Space Engineering, October 18, 1965 Electronics Magazine - RF CafeHughes Aerospace has many openings for qualified design engineers in Culver City, California. High power airborne transmitters, low noise receivers using parametric amplifiers, solid state maser component development, radar processing systems, crystal oscillators, telemetering, and high efficiency spaceborne power supplies are among the kinds of specialties needed by Hughes to support military and civilian projects. If you have been looking for just such an opportunity, then the wait is finally over... provided you happened to see this advertisement in Electronics magazine back in the fall of 1965. Quiz question: What is the difference between a geosynchronous orbit and a geostationary orbit?

How to Target RFCafe.com for Your Google Ads

Google AdSense - it makes good sense - RF CafeOne aspect of advertising on the RF Cafe website I have not covered is using Google AdSense. The reason is that I never took the time to explore how - or even whether it is possible - to target a specific website for displaying your banner ads. A couple display opportunities have always been provided for Google Ads to display, but the vast majority of advertising on RF Cafe is done via private advertisers. That is, companies deal with me directly and I handle inserting their banner ads into the html page code that randomly selects and displays them. My advertising scheme is what the industry refers to as a "Tenancy Campaign," whereby a flat price per month is paid regardless of number of impressions or clicks. It is the simplest format and has seemed to work well for many companies. With nearly 4 million pageviews per year for RFCafe.com, the average impression rate per banner ad is about 280,000 per year (in eight locations on each page, with >17,000 pages). That's pretty good exposure for $300 per month. Some companies have expressed an interest in being able to manage their advertising accounts themselves a la the Google AdSense program...

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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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