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Homepage Archive #7


A Winding Machine for

Spaced-Turn Chokes

There are still a lot of people who wind their own coils, whether it be for an amateur radio rig or for work in the lab. I know I've wound many a coil around a drill bit or wooden dowel. This simple coil winding machine that appeared in a 1931 edition of QST magazine would be a handy addition to anyone's bag of tricks, especially if find yourself winding single-layer coils that have a fixed space between the windings. The home stores like Lowes and Home Depot sell small pieces of oak that would be perfect for this kind of project. A little stain and a coat of varnish would give it a real vintage look. Use your soldering iron to burn your name onto the base.

PMI Intros 10 GHz Integrated

Dielectric Resonator Oscillator

PMI Model No. PIA-10G-CD-1 is a 10 GHz Integrated, Dielectric Resonator Oscillator (DRO) Module with 3 outputs, each having a 0-360 degree analog controlled, variable phase shifter and 0-10 dB analog controlled, variable output control capability on each output. Provides low harmonic output of -50 dBc typical and output power of +19 dBm typical. ±15 VDC, 6.25” x 2.5” x 1.0” package. Other frequency ranges available.

Notable Quote

"So few autopsies are being done now that many medical students get out of school never having seen one." - RF Cafe"So few autopsies are being done now that many medical students get out of school never having seen one." - Gregory Davis, U. Kentucky College of Medicine, November 2012 Scientific American. That's as ridiculous as an EE student graduating without ever having to learn to troubleshoot circuits. Oh, wait...

MECA Electronics Intros Line

of Unequal Power Splitters

MECA Electronics' new line of unequal power splitters consists of six models offering a 2, 3, 4, 6, 8, or 10:1 signal-split ratio respectively, over 698-2700 MHz (Cellular, PCS, AWS, and BRS/EBS frequencies) and feature low PIM ratings – (better than -150 dBc.), with ultra-low VSWR and minimal coupling variation over the entire frequency band. They easily handle high power levels of 300 W (CW) and have an operational temperature range of -55°C to +85°C.  As with all MECA products, they are MADE IN THE USA and are offered with a standard 36 month warranty.

NuWaves Engineering Adds to

Its Int'l Reseller Network

NuWaves Engineering, a Radio Frequency (RF) and Embedded Systems solutions provider, announced today that the company has increased its international presence by adding authorized resellers in Europe, Southeast Asia, and the Middle East. These new partners will represent the company's high-performance module-level RF products and engineering design services.

Entry Level RF Applications

Engineer Wanted

Entry Level RF Applications Engineer (Nitronix LLC) - RF Cafe Employment ForumNitronex LLC has new opportunity for a junior or entry level engineer that is looking to aid in the applications engineering of discrete and MMIC RF and Microwave power products on Nitronex's unique GaN-on-Silicon process. You'll be driving the post production applications development of MMICs and discrete devices that span from UHF to X-Band. Nitronex is a quickly growing company that requires driven, talented individuals to bring new technologies to market that will enable devices to operate to X-band and as high as 65V. Candidates must hold a BSEE and a demonstrated interest in RF electronics, including hobbyist/enthusiast experience, senior design work, elective coursework etc. and a desire to work in a fast paced, startup environment. Alternatively, candidates can possess an MSEE with relevant coursework/thesis in RF and Wireless design.

Webinar: Precise Cable

and Antenna Measurements

Webinar: Techniques for Precise Cable and Antenna Measurements in the Field Date - RF CafeTechniques for Precise Cable and Antenna Measurements in the Field Date, by Agilent and TESSCO, Wednesday, October 24, 1:00 PM ET. This webcast introduces measurement and calibration techniques for cable and antenna testing (CAT) using the new Agilent FieldFox handheld microwave analyzers. We will discuss a variety of measurements such as cable insertion loss, return loss, VSWR and Distance-to-Fault (DTF) testing. Antenna measurements are also discussed and several examples of return loss and antenna-to-antenna isolation will be provided.

Les Fantômes de la

Seconde Guerre Mondiale

These photos are the result of superimposing images of scenes during World War II on top of modern images of the same locations in France today. It was a time when Americans were not asked for passports when entering the country by sea and air. Historical expert Jo Teeuwisse, from Amsterdam, began the project after finding 300 old negatives at a flea market in her home city depicting familiar places in a very different context.

Scientist Wrong = Jail

Bureaucrat Wrong = Promotion

Italian court ruling sends chill through science community - RF CafeMany of us have joked about wishing we had a job like the weatherman's since it didn't seem to mater how often or egregiously he was wrong, he got to keep his job. No hurricane forecaster ever went to jail for failing to foretell the ultimate effects of a storm system, nor an avalanche expert for not predicting exactly where and when a snow pack would leave its mountain mooring. It would be unreasonable to expect that level of prognostication from practitioners of the scientific method, right? Not anymore. A new precedent has just been set by an Italian court that found six earthquake experts guilty of manslaughter for not properly warning of the 2009 earthquake in the city of L'Aquila that killed 308 people. They can kiss freedom goodbye for 6 years (maybe less with good behavior). So, bureaucrats who routinely fail to predict untold numbers of financial and civil catastrophes that have directly or indirectly caused loss of life will continue to get promotions and pay raises while scientists who fail to predict a *&%$@ natural phenomenon now go to jail. Congratulations, Italy, you have set an example that will soon be coming to a country near the rest of us.

Copper Mountain Technologies

Featured in MW&RF

Copper Mountain Technologies' website declares, "Virtual Instruments. Real Performance. Real Value." What that means is their line of "virtual" instruments are as "real" as an all-in-one test box. CMT's network analyzers have a USB interface to your computer, where supplied software provides the user interface and number crunching power. Portability and price is a huge benefit. Their 300 kHz - 1.2 GHz model starts at just $2.5k. Going to 8 GHz costs you $17k. Microwaves & RF magazine did a nice feature article on them. The origin of the company name, detailed in the column, is kinda cool, too.

Amateur Broadcasting

- A Menace

J.K. Bach (not Johann S.) was amazingly prescient in 1944 with the specific types of RF-based devices that would come to be common place in our modern world. Dig this: "Radar can even be applied to the home, as a burglar-alarm, for example, or to detect obstructions on the cellar steps. Electronic devices will find many other uses as high-frequency paint-dryers, veneer-gluers, and even cordless permanent-waving machines for the ladies. Garage-door openers and other remote-control devices are not only possible but practical. Then there are certain to be other applications such as personal pedestrian telephones, two-way wrist-radios and nursery baby-cry announcing systems." Nostradamus' divination record might not even be that good.  His tongue-in-cheek thesis of ubiquitous RF interference due to the presence of Ham radio operators is not far off either, although the accused "menace" would have to be extended to include all the many varied emissive devices being used by tech-ladened pedestrians.

RFMD Intros Control

Components for Cable Apps

RFMD today unveiled two new CATV control components, in conjunction with the SCTE Cable-TEC Expo, in Orlando, FL. The new components include the RFSA2654, a 75-ohm broadband digital step attenuator, and the RFSW1012, a high power handling single-pole, double-throw switch (SPDT).

Microwave Office Designs

"Right the First Time"

Amplifier Technology, Ltd., (ATL) a provider of leading-edge RF power amplifiers (PAs) for defense, commercial, industrial, scientific, and medical applications, used a unique combination of AWR's Microwave Office RF/microwave design suite and AMPSA's MultiMatch Amplifier Design Wizard to design a complex multi-octave bandwidth, high power, high efficiency PA.

Please Thank Hittite

Microwave for Their Support

Hittite Microwave manufactures ICs, modules, subsystems & instrumentation for technically demanding digital, RF, microwave and millimeter wave applications covering DC to 110 GHz. The Company's standard and custom products apply analog, digital & mixed-signal semiconductor technologies, which are used in a wide variety of wireless / wired communication and sensor applications for automotive, broadband, cellular infrastructure, fiber optics, microwave & millimeter wave communications.

Analog Engineering Theme

Crossword for 10/21/2012

For the sake of avid cruciverbalists, each week I create a new crossword puzzle that has a theme related to engineering, mathematics, chemistry, physics, and other technical words. You will never be asked the name of a movie star unless he/she was involved in a technical endeavor (e.g., Hedy Lamar).

Calculus of Negligence

aka "Hand Rule"

Calculus of Negligence, The Hand Rule - RF CafeWhilst reading an article on legal liability, I ran across a reference to the Hand Rule, formulated by Judge Billings Learned Hand (yes, that was his given name). Hand, who studied both philosophy and law, was a judge credited with a keen sense of honor and fair play as applied, in conjunction with Constitutional principles, to such as patents, torts, admiralty law, and antitrust law. The Hand Rule was born out of a trial where an improperly secured barge escaped its moorings and caused damage to other boats. Per the Hand Rule:

"[T]he owner's duty, as in other similar situations, to provide against resulting injuries is a function of three variables: (1) The probability that she will break away; (2) the gravity of the resulting injury, if she does; (3) the burden of adequate precautions. In mathematical terms: B < PL, where B is the cost (burden) of taking precautions, and P is the probability of loss, and L is the gravity of loss. Simply stated, negligence is ruled if the effort required to prevent an event is less than the likelihood that the event will occur, multiplied by the severity of the loss. This, of course, is all subjective, which is why he who hires the lawyer best able to define values for B, P, and L wins the case. I propose an alternate name for it: Fuzzy Law.

RFMD Unveils GaN-Based

Amps for CATV Applications

RF Micro Devices unveiled multiple leading-edge GaN-based CATV amplifiers, in conjunction with the SCTE Cable-TEC Expo in Orlando, FL. The new CATV amplifiers include the RFPD2940 – a best-in-class, high-power GaN-based CATV power-doubler amplifier, as well as a new family of GaN-based push-pull CATV amplifiers, led by the RFPP2870 and RFCM3080.

Many Thanks to SigaTek

for Their Support

SigaTek microwave specializes in high quality, high frequency microwave communication components up to 60 GHz. As a pioneer supplier of microwave RF components, the main products include directional couplers, bias tees networks, power dividers / combiners, 3 dB hybrids 90° and 180°, microwave mixers, frequency doublers, load terminations, and coaxial connectors and adapters.

Undersampling Changes

Bandwidths, by Jon Titus

Jon Titus is a lot like Bob Pease - only without the scraggly beard - when it comes to analog circuits. Along with having a PhD and being the former editor of EDN and Test & Measurement magazines, Jon has an innate knowledge of circuit theory and is very good at presenting complex information to lesser beings like myownself[sic]. Most of us want to be like them when we grow up. One big difference between Jon and Bob, though, is that Jon does not eschew the use of computers. I think Mr. Pease might have been OK with the ENIAC, but once IBM introduced the XT, it surely dumbed down every future engineer from that point forward according to his oft-repeated denouncements of anything with a silicon-based processor. Fortunately for Bob - and for those of us to whom he addressed - he didn't need a computer for most tasks. This short column from Jon Titus titled "Undersampling Changes Bandwidths" is a great primer on how undersampling works. In a Pease-esque way, Jon uses hand-drawn sketches to illustrate the sampling phenomenon.

Quiz: LCP for Microwave

Packages and Modules

This quiz is based on the information presented in LCP for Microwave Packages and Modules, by Anh-Vu H. Pham, Morgan J. Chen, and Kunia Aihara. Note: Some of the books used for quizzes are available as prizes in the monthly RF Cafe Giveaway.

Thanks to Test Equipment

Connection for Support!

Test Equipment Connection handles sales, rentals and leasing of refurbished electronic test and measurement equipment to the R&D, manufacturing and quality assurance industries. All major lines including Agilent, Tektronix, Anritsu, Rohde & Schwarz, Advantest and Fluke.

A Surprising Message

from Scott Adams

The creator of Dilbert, Dogbert, Catbert, Wally, Alice, Asok, and the pointy-haired boss has just endorsed a presidential candidate based on a medical marijuana prosecution. Keep in mind that Scott Adams suffered a rather severe nervous system malady in the middle of the last decade. Although I cannot find anything for certain about whether he uses it himself, there is a good chance that he does. Adams, you might recall, lost his ability to speak and to draw for a couple years, then miraculously gained back most of his functionality. The Dilbert cartoon rarely ventures overtly into political themes, so it will be interesting to see if a strip on the subject appears between now and election day.

An Old Spark Soliloquizes

If it has been a while since you read a story with terms and phrases like "splinters of galena," "the day of the tuning coil that stretched from the front bedroom to the back library; or from the attic to the cellar," and "Ether God," then this article from the December 1931 edition of QST is for you. Galena, by the way, is a semiconductor with a bandgap of about 0.4 eV that was used as the crystal in crystal radio sets. It was used as a point-contact diode along with a safety pin or similar sharp wire, commonly known as a "cat's whisker".

Please Welcome DCH Systems

as a New Supporter

DCH Systems is engaged in the design and manufacture of RF power amplifiers and systems. Their mission is to provide advanced, highly linear, and efficient RF amplification solutions for customers in the aerospace / defense, telecommunications, and science communities. DCH Systems' core competency is the ability to design and manufacture RFPAs utilizing pre-distortion techniques, and possesses the expertise to implement the high-complexity analog and digital circuitry to produce user-friendly, reliable RFPA products that are suited for both low and high volume manufacture.

How to Talk to Non-Hams

How to Talk to Non-Hams, November 1961 Popular Electronics - RF CafeHere is a pretty funny story that, although it is fictional, it could easily have really happened. I'm not much of a party-goer, but base on what little experience I've had at social functions and the stereotypical behavior often portrayed in movies, the author's scenario likely actually did occur. Maybe he exaggerates just a bit, though. The follow-up situation would be a great gag to play on someone if you ever get the chance. It probably would not be hard to get people to fall for it.

Job Hunting Articles/Tips

- When a Job Offer is

  Put on Hold

- How Much is an

  Engineer Worth?

- Top 5 Personality Traits

  Employers Hire Most

- Why Engineers Need

   Critical Thinking Skills

- Everyone's an Entrepreneur!

- Do New Job Tests Foster


- 5 Threats to Your Job-

  Hunting Stamina

RFMD® Intros 915 MHz ISM

Tx/Rx Module w/Diversity Sw.

RFMD's new RFFM6901 is a single-chip front end module (FEM) for applications in the 868/915 MHz ISM Band. The RFFM6901 addresses the need for aggressive size reduction for typical portable equipment RF front end design and greatly reduces the number of components outside of the core chipset, thus minimizing the footprint and assembly cost of the overall solution.

High Frequency Electronics

October 2012 Articles

Linear Power Amplifiers

  for Point-to-Point Radio

  Applications (p.32),

  by S. Kumar, K. Story,

  R. Kielmeyer, T. Lodhi,

  and I. Hardcastle, RFMD

Successful Low Noise

  Amplifier (LNA) Design

  Using Discrete Components

  (p.22) S. Akamatsu,

  S. Muir, L. Dunleavy

Microwave Journal Articles

October 2012

Maximizing Receiver

  Dynamic Range for

  Spectrum Monitoring,

  by Brian Avenell

New Tile Structure for

  Microwave Modules Using

  Solderless Vertical

  Interconnections, by

  J. Moon, S. Yun, C. Ahn,

  S. Kim

LTE Downlink Transmitter

  Simulation Using MATLAB,

  by J. Pierzchlewski,

  T. Larsen 

Webinar: RF Recording to

Resolve Interference Problems

Webinar: Using RF Recording Techniques to Resolve Interference Problems - RF CafeUsing RF Recording Techniques to Resolve Interference Problems, Thursday, October 18, 2:00 pm EDT. This webcast discusses the problems associated with system operation in a cluttered environment, and RF recording techniques that can be used to capture minutes or hours of data for subsequent analysis.

GreenPeak ZigBee Success

Using AWR Software

Using AWR's Microwave Office/AXIEM software, GreenPeak was able to successfully perform RF board analysis, validation, and optimization for best RF performance, certification margin, and production yield, while at the same time cutting design iterations down to one or two when integrating its custom design into the ZigBee remote control device.

Notable Quote

"Men are dressing for the office far more seriously, in an effort to maintain a level of job security" - RF Cafe Notable Quote"Men are dressing for the office far more seriously, in an effort to maintain a level of job security" -- Steven Faerm, Parsons the New School for Design, in OFA

Please Welcome Mayfield

Plastics as a New Supporter!

Mayfield Plastics provides in-house thermoforming and twin sheet forming processes that can achieve the look and feel of injection molding without the expensive tooling charge. Pressure forming is able to form details normally found only in injection molding. Thermoforming has many advantages over the use of sheet metal, such as lower unit cost, lighter weight, and enhanced appearance. Radomes, device enclosures, and control panels are among possible applications.

Please Visit IPP to Thank

Them for Their Sponsorship

IPP is a manufacturer of RF passive components - 90° Couplers, directional couplers, RF resistors and terminations. Connectorized, surface mount. Custom designs are available.

Thanks to Antenna Factor

for Long-Time Support

Antenna Factor, a division of Linx Technologies, manufactures standard and custom antennas - monopole, dipole, embeddable, specialty, dualband, GPS, fixed point, Yagi, evaluation systems, custom designs. Hole-mount and magnetic bases available.

Anaconda Copper Mining

Company Advertisement

Anaconda Copper Mining Advertisement in the April 29, 1950 Saturday Evening Post - RF CafeIt's not often that you will see a full-page ad promoting a particular element in the periodic table, but in 1950 that wasn't the case. This advertisement for Anaconda Copper Mining Company promoted the virtues of element number 29 - copper (Cu , from the Latin "cuprum"). Aluminum and iron were other popular topics of advertising. If you do a search on the history of Anaconda, which is today owned by the Atlantic Richfield Company (ARCO), what dominates is the harm done to workers and to the environment. The short video below is one of the less vicious reports on the company's operations in Butte, Montana and in Chile. As with many forms of mining back in the day, miners were subject to very hazardous conditions, lived in company towns in company houses, sent their kids to company schools, and bought their groceries at company stores. It was a rough life, and we who enjoy the abundant freedoms and conveniences availed to us today owe...

GE "Black-Daylight" TV Ad

in 1950 Saturday Evening Post

General Electric Black-Daylight TV Advertisement in the April 29, 1950 Saturday Evening Post - RF CafeYou might think I tend to dwell too much on the past because of all the articles posted and references to vintage electronics companies and their employees. Maybe I do. My motivation is two-fold. First, I enjoy waxing nostalgic over the simpler, less crowded days of yore that were the 1920s through 1940s, and even into the 1950s. Things were not ideal by any means, but America was a thriving bastion of national innovation and manufacturing. A "wow" factor surrounded new discoveries and deserving heroes were created. Our friends as well as our enemies were well-defined and our schools put more effort into teaching literature, mathematics, and science than into what "rights" could be demanded without earning them. Second, which really follows from the first, is that I hope by reminding people of, or in some cases - especially younger website visitors - introducing for the first time, the fact that being a country that is fundamentally independent while at...

Amateur Radio Stations


When the caption for a photograph in a 1931 article refers to an "antiquated" motor, you can be sure you're looking at a really old motor. Indeed it does look very old. Whenever I see vintage photos or films of electrical / electronic apparati[sic] and operators, I always look for safety issues like no eye protection while soldering or when using powered tools to fabricate enclosures, lack of protective shields around electrical connections and mechanical drive mechanisms, wearing of inappropriate clothing near rotating machinery, etc. In this case you can see a very long, totally exposed drive belt running between that aforementioned antiquated motor and DC generator that it drives (to power the transmitter). The author mentions how the floor shook while it was running. I wonder if the filaments were shaken enough to introduce the vibration frequency into the audio (mircophonics)? Ah, the not quite so good old days.

AWR Announces Slate of

Activities during EuMW 2012

AWR Announces Slate of Activities during European Microwave Week 2012. Highlights Include Software Demos in Booth #416 of AWR 2011 Product Portfolio and Analyst™; AWR and Partners MicroApps; AWR/National Instruments Workshop; and Customer Appreciation Event.

SNL Skit on iPhone 5 Issues

Saturday Night Live Tech Talk Spoof on iPhone 5 Issues - RF Cafe Video for EngineersThis is a hilarious spoof that Saturday Night Live came up with for addressing the well-known issues with the new iPhone 5. Christina Applegate plays the host to a panel of tech industry gurus and a "trap" panel of Chinese iPhone 5 factory workers. "Tech Talk" faux representatives from real-life entities CNET, Wired Magazine, and Gizmodo gripe about the funky maps, "purple haze" from the camera, and how easily scratched the case is (these are the top 3 complaints by users). After smarmily registering their complaints, the hostess then presents employees from the iPhone 5 factory (Foxconn is never mentioned by name) who proceed to sarcastically address each topic with responses demonstrating how petty the whining is compared to their life's woes in China under Communist rule. I won't give any more away; you'll have to watch it to get the full effect of its humor.

Many Thanks for Backing by

Linx Technologies

Linx Technologies' RF modules, remote controls, evaluation kits and master development systems feature straightforward hardware configuration and clear documentation. Linx products make it simple for engineers and hobbyists to integrate wireless features without the hassle and expense of engineering RF functionality from scratch.

Sherlock Ohms:

These Fuses Melt in Water

Sherlock Ohms: These Fuses Melt in Water - RF CafeSherlock Ohms is a regular feature of Design News that presents submissions from readers about troubleshooting challenges and how they were solved. This one is titled "These Fuses Melt in Water."

Free IEEE-USA eBook

Writing for Success—An Engineer's Guide, Volume 1: Designing for Success. In the first book of this four-book series, award-winning author Tom Moran presents writing from an engineer's perspective: looking at comparisons between the steps that lead to good engineering practice, and those that result in writing excellence. Free download for members through October 31, 2012.

Felix Baumgartner Sets

Jump Height & Speed Record

Felix Baumgartner Sets Jump Height & Speed RecordOn Sunday, October 14, 2012, Austrian parachutist Felix Baumgartner stepped out of his balloon-borne pressurized capsule at a record-setting height of 128,000 feet and became the first man to break the sound barrier during free fall (1.24 Mach). The previous record had been set way back in 1960 by Joe Kittinger, who handled communications with Felix during his stunt. Felix missed breaking Joe's free fall duration record by a mere 6 seconds. Red Bull sponsored the Stratos project.

Please Thank Apex Wireless

for Its Continued Support

Since 1985, Apex Wireless has offered consulting, engineering, and design services focusing on high-performance, cost-optimized products that employ wireless RF transmitters, receivers, and transceivers. To complement our RF design expertise, we work with local experts in DSP, ultra low power design, packaging, certification, and manufacturing.

Thanks to Alliance Test

Equipment for Support!

Sales, rentals and leasing of refurbished electronic test and measurement equipment to the R&D, manufacturing and quality assurance industries. Alliance Test Equipment carries all major manufacturers' equipment.

Parallel Water Filters Increase

Flow Like Parallel Resistors

Parallel Water Filters Increase Flow Like Parallel Resistors - RF CafeThe municipal water supply here in Millcreek, Pennsylvania (next to Erie), leaves a bad taste in my mouth - literally. It's hard to make a good cup of coffee with bad water, so I decided to install a high quality water filter. The water pressure for the supply line is pretty good, so I figured that pressure reduction due to the filter's presence would not be too bad. I was wrong. This was no surprise since I have installed the same type of filters in other houses. After about two years of having about half the water flow from the cold water faucet as from the hot, I decided to do something about it. Changing the filter helped a bit, but not much. So, I figured it was time to test the theory of equivalency between water pressure and electromotive force pressure (voltage) when applied through parallel resistances. In this case the resistance is provided by the water filters and the pressure is provided by the town's water supply...

120,000-foot Parachute

Jump in Process Live


Watch Felix Baumgartner make his ascent in the Red Bull Stratos capsule to 23 miles above Earth, then do a free fall that could make him the first skydiver to break the sound barrier. SUCCESS!!!

About RF Cafe

Kirt Blattenberger - RF Cafe Webmaster

Copyright: 1996 - 2024


    Kirt Blattenberger,


RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

Copyright  1996 - 2026

All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.

All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.

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My Daughter's Website: EquineKingdom