(Seize the Day!)
My USAF radar shop
Airplanes and Rockets:
My personal hobby website
My daughter Sally's horse riding website
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 Google Search box at the top of every page.
Homepage Archive Pages
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2015: Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec
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2013: Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec
2012: Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec
2011: Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec
2010: Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec
2009: Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec
AWR White Paper: Design
Flow for PA MMIC Design
A new white paper from AWR, "RF/Microwave EDA Software Design Flow Considerations for PA MMIC Design," examines a gallium arsenide (GaAs) pseudomorphic high electron mobility transistor (pHEMT) power amplifier (PA) design approach from a systems perspective. The design flow and its essential features for most PA design projects is illustrated through the design of a simple, Class A GaAs pHEMT monolithic microwave integrated circuit (MMIC) PA using AWR’s Microwave Office® high-frequency design software.
IEEE USA: Today's Engineer
Hiram Percy Maxim's Gravesite
in Hagerstown, Maryland
Isaac Newton famously said, "If I have seen farther it is from standing on the shoulders of giants." His statement was figurative, of course, but I can now say literally that I have stood on the shoulders of a giant. Somewhere recently, I don't recall where, I read that although American Radio Relay League (ARRL) founder Hiram Percy Maxim was born in New York and spent most of his adult life in Connecticut, he was buried in Rose Hill Cemetery located in Hagerstown, Maryland. That just happens to be where Melanie and I stop a couple times each year to visit her mother. We lived there ourselves for about three years in the early 1990s. That day, I surely stood if not exactly atop Mr. Maxim's shoulders, then very nearly so as I maneuvered to take this picture of his grave marker. Why is he buried in Maryland, you might ask? That is where his...
More Good Stuff
Here a few new headlines for you from LinkedIn, in case you don't receive their weekly update. They usually have some pretty good stuff. I'm not big into the social media scene, but LinkedIn is kind of like Facebook with a brain required for participation.
Upskilling for Career
- Who's Your New Mobile
Carrier? How 'Bout Wi-Fi?
- 5 Things You Have to
Unlearn to Succeed at Work
- Every Step You Take,
Every Move You Make
- You've Got the Degree,
Now Get out the Passport
Thanks to Electro-Photonics
for Continued Support!
Electro-Photonics LLC is a global supplier of RF & Microwave components. Their products include SMT hybrid couplers, wire bondable passive components, coaxial products, test fixtures and very useful test boards for evaluating components. The Electro-Photonics team can support your small R&D design requirements with RF & Microwave test fixtures and save you valuable design and characterization time.
Get in the Scrap!
An extraterrestrial threat to existence, be it an impending asteroid strike or an intelligent being's announced intention to do harm to the earth, would probably be required these days to invoke the sort of voluntary personal sacrifices of today's average citizen that was exhibited in the enthusiastic, patriotic response by Americans to the 'V' for Victory campaign during World War II. You no doubt have seen pictures of kids pulling wagons filled with metal scrap, rubber tires, and glass milk and pop bottles collected for the war effort, and pickup trucks piled high with sections of pipe, car parts, and retired furnaces. Resources were relatively scarce at the time, and material was being consumed very quickly in the effort beat back the aggressive advances of Axis forces throughout Europe, northern Africa, and the South Pacific. This article from a 1942 edition of Radio Retailing Today encouraged radio repairmen to check with customers during service calls...
Advertisement circa 1942
Triplett is a well-know name amongst electronics technicians and engineers who have been in the business for any length of time. Triplett meter movements (aka panel meters) were considered to be top-of-the-line product in the days before digital meters and displays. They were used in industrial instrumentation, in military equipment, and in amateur radio gear. Triplett is still in business today but it appears they no longer sell just meter movements, although there is a large supply (new and used) available on eBay and Ham radio websites and swap meets. This advertisement for Triplett Thin-Line Instruments appeared in the September 1942 edition of Radio Retailing Today magazine.
Skyworks Solutions, Inc. unveils a new device for cellular infrastructure, VHF/UHF military and public safety radios. The SKY12408-321LF is a 50-600 MHz, 6 dB differential attenuator that is pin-for-pin compatible with its 12 dB SKY12407-321LF attenuator, but ideal for IF radio applications requiring lower overall attenuation and gain control. The new solution also offers a novel differential I/O design and fast settling time for applications that down convert to a low Intermediate frequency.
From Whence Came the Term
'Bug?' You'll Be Surprised, Too
It was one of those, "Well, huh!," moments for me when I read in a story from the IEEE that claims the first recorded use of the term 'bug' in reference to a problem in hardware was not by U.S. Navy Admiral Grace Hopper and her colleagues, as popular belief (including mine) goes. Their finding of a dead moth - a 'bug' - in a Harvard University computer is legend, but evidently was not the first known instance. Instead, it was none other than Thomas Edison who may have originally used the term. Before you go accusing the respected Institution of waging a War on Women (a popular indictment of convenience these days) for denying credit where credit is due, nobody is implying that she purloined Mr. Edison's term. According to researcher Dr. Paul Israel, editor of the The Papers of Thomas A. Edison, and the IEEE History Center, Edison regularly referred to technical problems as bugs. "In 1873 Edison first confronted what he later called a bug when he began developing a quadruplex telegraph...
Electro-Photonics Intros HP
2-Way SMD Divider/Combiner
Electro-Photonics LLC announces the availability of Y2D-900R, a high power 2-way SMD power divider / combiner. Our new Y2D-900R power divider/combiner operates from 700-1000 MHz and can dissipate up to 350 W in a small 480 mil x 650 mil package. This power divider offers excellent isolation, low insertion loss, and good phase balance for most critical applications. The Y2D-900R requires an external 100 ohm resistor for operation. Power will only be limited by the size and power ratings of the chosen resistor.
Please Thank Colby
Instruments for Support
Colby Instruments designs and manufactures the world's finest high-precision Programmable Delay Line (PDL) instruments and modules. All instruments are fully programmable via GPIB interface, and are suitable for use in high frequency RF signal applications as phase shifters or where an extremely high precision and accurate amount of delay is required. Colby Instruments has been helping deliver RF Cafe since 2009.
TPN-19 Radar Photos &
MPN-13 Radar Model
USAF radar technician Elbert Cook just sent some photos of the TPN-19 radar units that were based with him at the 3rd Combat Communications Group (aka 3rd MOB, aka 3CCG) at Tinker AFB, Oklahoma. He also sent the first couple pictures of a scale model of the MPN-13 radar unit that he has begun. Stay tuned for project updates.
VidaRF Intros High Power
30 dB Coupler for 2 to 4 GHz
VidaRF has introduced a high power 30 dB coupler with a 2-4 GHz frequency range (other coupling values available). Average power is 500 W, with a Peak of 8 kW. Loss is 0.25 dB (excluding coupled power), directivity is 18 dB, and VSWR is 1.30:1. Connector type is "N" Female on all ports. Custom designs available upon request. VidaRF offers a wide selection of Directional Couplers, Dual Directional Couplers and Hybrid Couplers, designed to cover 0.1 GHz to 20 GHz.
Fortune Telling & Reliability?
An Expert Testimony Enigma
A fair number of people who visit RF Cafe have at some point been involved as an Expert Witness for a court case involving product liability and/or IP ownership or infringement. They quickly learn how important it is to have competent and renowned legal representation. IMS ExpertServices is a law firm specializing in expert witness cases. Every month or so they send me an article about specific court cases that could be of interest to RF Cafe visitors. This particular article is titled "Fortune Telling & Reliability? An Expert Testimony Enigma." It illustrates how dicey the process of selecting appropriate Expert Witnesses can be for legal teams - especially given the subjective nature of judges who decide on admissibility of evidence.
DongJin Intros Composite
DIN 7/16 Connector
DongJin Technology Innovation announces the immediate availability of very affordable composite DIN 7/16 connectors. The body material is a composite plastic black with silver-plated bronze contacts, as opposed to a standard brass body and beryllium-copper (Be-Cu) contacts. This newly developed 7/16 connector is seeing a steep increase in use in leading countries like Japan, Germany, and the USA.
Please Welcome Parsec
Technologies as a Sponsor
A former comrade contacted me recently to say he, too, had moved on from where we used to work. He is a very capable RF engineer and is now retired from his 20+-year stint as a communications officer in the Air National Guard. Parsec Technologies is now the beneficiary of his know-how. He recommended that they try advertising on RF Cafe and the result is this announcement. Thanks Conrad! Parsec's LNAs have been designed to optimize GaAs for the ultimate combination of noise figure, gain, and IP3. We are redefining what high performance amplifiers are in today's market for low voltage, low power amplifiers with low noise, high gain and high IP3 normally found on amplifiers that consume much more power.
A 1955 Portable Phone
- the 'Portaphone'
Sending texts must have been a real challenge on this early portable phone. Aside from having to type out your message on a standard telephone keypad (oh, the humanity), the baud rate must have been snail-like. The article doesn't mention whether dropped calls were a big issue and whether there was a massive marketing plan with a bespectacled "Can You Hear Me now?" guy. I'm just kidding, of course. This news item appeared in a 1955 edition of Air Trails: Hobbies for Young Men. Before you laugh at the Portaphone's dipole antenna and carrying case, consider that it was only a little over two decades ago that Motorola debuted its famous M800 'Bag Phone.' From the magazine: "Portable two-way radio phone...
Please Visit Z-Comm in
Appreciation of Their Support
Z-Communications is a world leader in the design and development of surface mount VCO modules & PLL frequency synthesizers for the commercial microwave/RF wireless market. RoHS compliant signal source products currently range from 40 MHz to 13.5 GHz bands. PLLs available in integer, fractional-N and single frequency models. VCOs feature coaxial resonator based and high-Q distributed resonator construction.
Troubleshooting & Repairing
Commercial Electrical Equip.
Troubleshooting and Repairing Commercial Electrical Equipment, by David Herres, is another in a series where he has leveraged his many years working as a Master Electrician. It is his first work that offers a practical approach to diagnosing and repairing commercial / industrial electrical equipment – covering everything from motors, computers, elevators, and fire alarm systems to heavy-duty ovens and audio equipment. This one-of-a-kind guide can help you become more competent in your profession. Inside you'll find ways to become faster, more efficient, and able to achieve a much higher success rate in restoring large electrical equipment without damaging it, introducing an additional defect, or creating a hazard.
Tales from the Cube:
There don't seem to be many electronic products these days without some form of software in them (EEPROMs, ASICs, μProcessors, FPGAs, etc.); indeed, many electrical engineers also wear a software engineer's hat. Two consultants that advertise on RF Cafe, Lance Lascari (RF Dude) and Joe Cahak (Sunshine Design) come to mind, along with many others known during my career. I've even done a bit of software and FPGA programming myself. This installment of EDN's "Tales from the Cube" series involves an engineer who needed to live in both worlds in order to solve his problem with a meter designed by someone long gone from the company. Mihaela Costin applied a bit of ingenuity to make the best of a bad situation...
everything RF Intros
New Cable Builder App
The New Cable Assembly Builder tool on everything RF lets you specify your cable assembly requirements in a form and on submission directs it to over 20 companies that can manufacturer it. Your query will be directed to the leading cable assembly manufacturers – Aeroflex, Emerson, Amphenol, San-tron, RF Industries, VidaRF, Pasternack, SV Microwave and many others. You no longer need to send out individual request to each manufacturer - everything RF does that for you. The tool has been optimized for Desktops, Tablets and Mobiles so you can use it from anywhere on any device.
Anatech Electronics Intros
New Combiner and Duplexers
Anatech Electronics has released new designs for a 710-716 MHz / 740-746 MHz bandpass combiner , 779 MHz / 749 MHz ceramic duplexer , and a 1710-1755 MHz / 2110-2155 MHz cavity duplexer. All can be ordered directly through their AMCrf web store.
National Radio Institute Home
Study Radio Course c.1948
Bob Davis sent me a link to Mike Yancey's (KM5Z) website where there is a scanned version of the 1948 National Radio Institute (NRI) home study course for radio technicians. It is a very extensive collection of 55 volumes (PDF format) covering topics like Simple Radio Circuits and Meters, Radio Coils and How They Work, How Detectors Work in Radio and Television Receivers, Current, Voltage and Resistance Measurements, and How to Eliminate Man-Made Interference. KM5Z also has some other good content that you might be interested in while you're there like a 1958 edition the RCA Radio & TV Course, online calculators for toroids, inductor Q, voltage dividers, and antenna field strength, and radio restoration projects.
Many Thanks to IPP
for Continued Support!
Innovative Power Products, Inc. has more than 25 years of experience designing and manufacturing RF Passive Components. Our couplers, combiners, resistors, and terminations incorporate the latest technology in materials available, which equates to unrivaled product performance. IPP has been with RF Cafe since early 2008.
New Articles from
Microwave Product Digest
Product Digest just posted articles from their August edition.
Lots of good stuff there, as usual.
- How to Calculate Peak
Uncertainties, Sook H. Wong
- Considerations When
Conducting Noise Figure
Measurements, Sean Flavin
- EMC Test Equipment and
Services Market – Another
Opportunity in China,
- USB Brings Portability and
Flexibility to MW Test Bench
– Wherever it May Be,
- Building Low PIM Coax
Assemblies with Consistent
The Twittertape Machine
Something old, something new, something borrowed, something... brown. My paraphrasing (lamely) of the old saying for bringing good luck to a bride aptly describes Adam Vaughan's effort in building his 'Twittertape Machine.' Adam's machine prints out Twitter messages on a paper tape in the manner of early stock market tickers. "This astounding device will print a permanent copy of all Tweets yet requires no ink or computer." So says a proclamation in vintage serif font and decorative trimmings on the website's homepage. Indeed it does. The prototype uses two wall wart AC/DC adapters, an Arduino-style microcontroller with an Ethernet interface, a Bell jar, a thermal printer, and miscellaneous clock parts. Full details of the design and operation are provided, including a video. It checks for and prints out available Tweets every 30 seconds. Before you get upset about altering historic relics...
"If you think it's expensive to hire a professional for a job, wait until you hire an amateur." - Red Adair, famous global firefighter. Red Adair is the guy who put out all the Kuwait oil well fires after Hussein's troops ignited them while retreating from occupied territory. Television 'experts' said those fires would burn for decades. They were out in months.
Crossword for 8/25/2013
Take a break and work this week's wireless 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.
PMI Intros 30 MHz to 26.5 GHz
Low Noise Amplifier
PMI Model No. PEC3-40-30M26R5G-6R0-12-12-SFF is a 30 MHz to 26.5 GHz Low Noise Amplifier that provides greater than 35 dB of gain while maintaining a maximum gain flatness of ±3.5 dB maximum over the operating frequency. The noise figure is 6.0 dB typical and offers an OP1dB of +12 dBm minimum. The operating voltage is +12 to 15 VDC and the current draw is 700 mA maximum.
Sherlock Ohms: The Case
of the Oblivian Customer
You're going to love this installment of Sherlock Ohms. Even if you have never had to deal directly with customers for a product performance issue, you will easily empathize with engineer Jonathan Eckrich in "The Case of the Confused Customer." The incident reminds me of a story I read years ago by an engineer who worked on development of one of the early computer languages - I think it was FORTRAN. The user called to complain that a section of code was failing and demanded assistance because in his opinion, the language kernel was faulty. The caller's name was not disclosed, but the engineer said he was a notable figure. After listening to the problem, the cause seemed obvious, so the engineer (wish I could remember his name) instructed the guy to make sure he was using the "less than" symbol, to which the guy responded that he is no idiot and the problem must be something else...
Mathematics in Radio Calculus
and its Application in Radio
I challenge you to find a calculus lesson in a modern-day electronics magazine. In 1932, not all that long after Isaac Newton developed differential calculus (that's a joke), Radio News magazine ran a series of "Mathematics in Radio" articles that included, among other topics, a few lessons in calculus. Anyone who has taken college-level science or engineering courses knows how indispensible calculus is in working out many circuit, physics, and chemistry problems. My appreciation for calculus came when I realized that it actually allowed me to derive the kinds of standard equations that are commonly seen in lower level applications. For instance, if you needed to know the volume of a sphere, you could look up the familiar Volume = 4/3 π r3 formula, or you could write the equation...
AWR Awards Prizes to IMS2013
Student Design Winners
AWR Corporation, the innovation leader in high-frequency EDA software, gifted its software to the winners of the High Efficiency Power Amplifier (HEPA) and Software Defined Radio (SDR) Student Design Contests offered at the 2013 IMS MTT-S conference. The gifts are part of the AWR University Program, which sponsors student design contests throughout the world to encourage students to become involved in the dynamic profession of microwave and RF engineering and to apply their knowledge to practical designs using the highly efficient AWR design methodology.
Career News from the
Slideshow: Special Report:
Silicon Valley's Dirty Secret
- Age Bias (it ain't just in SV)
- Layoff Taboo: Japan's
- 5 Global Recruiting Trends
to Help You Land Your
- Does Your Entry-Level Job
Have Growth Potential?
Here are a couple more I found while looking around:
Many Thanks to Dong Jinr>Technology Innovation!
Dong Jin Technology Innovations helps to deliver RF Cafe through their advertising, which was just renewed for another term. Dong Jin designs, manufactures, and assembles RF connectors, cable assemblies and components. Competitive price, on-time delivery and best quality. No minimum order size. One-day delivery. ISO9001, ISO14001, RoHS certified.
Sherlock Ohms: Earth Station
Stopped by Lightning
This is another great RF troubleshooting saga; in fact, it would make a good short action film. Designing and implementing proper lightning protection can be a real challenge - and quite expensive. Lightning has a nasty habit of seeking out and exploiting weaknesses. Author Rod Hine doesn't cite improper protection as the culprit for causing his woes in his telling of, The Case of the "Earth Station Stopped by Lightning." A couple decades ago I worked with a team that designed a prototype weather radar system with cobbled-together parts that included a surplus military phased array antenna. After doing all the initial design, build and test at our facility, everything was moved to an open air site that sat at the top of a ridge which was known to attract lightning like trailer parks attract tornadoes. A fair amount of effort went into lightning mitigation over the years, so we felt comfortable hooking into the existing system. All went fine for the remaining time I was there. About a year later...
Cognitive Radio, HDTV, and SDR
Vendor Pages Added
After being contacted by a friend of mine who works for Parsec Technologies about adding their company to my categorical Manufacturers and Services pages, I realized that I blinked and missed the need to add resources for the relatively new fields of Software Defined Radio, Cognitive Radio, White Space, and Mobile HDTV. Having just awoken, there are now the beginnings of pages for them. In searching for companies to include it quickly became apparent that most of what is available to fill the need is re-purposed ICs and hardware, but as the technologies mature and standards are established there will be more specialty products. Parsec Technologies is one of those companies working now to fill the need.
Vida RF Intros Low Loss
VidaRF has introduced a low loss Waveguide Isolator, model VDWR42-2021-A, with a frequency range from 20.2-21.2 GHz. The isolator offers 0.1 dB loss, isolation 28 dB, VSWR of 1.11:1. Forward power handling is 3 watts with operating temperature -40 to +80 C. Pressure sealed to 10 psi.
Low Plate-Potential Tubes
Once radios in the family car became a standard accessory, a push ensued to make them cheaper, more reliable, and service-free. A major Achilles' Heel was the high voltage power supply required to energize vacuum tubes. Known as vibrator power supplies due to using an oscillator to convert the battery's 12 DC supply (some autos still used 6 V systems) into AC that could be transformed up to the 300 volts used by most tubes of the day, most early failures were attributed to the circuits. They also caused annoying noise in the audio output if careful filtering and installation was not performed. Having been invented only a couple years earlier, transistors were being designed into the power supplies, but low-voltage tubes were still needed for the electronics. In response to the demand, low-voltage tubes were created to fill the gap until acceptable transistors became available for a fully solid-state radio. This article discusses some of the problems with low voltage tube design and methods employed to overcome them.
Waveform Design for
Active Sensing Systems
Waveform Design for Active Sensing Systems: A Computational Approach, by Hao He Hao He, Jian Li, and Petre Stoica, is my Featured Book for this week. With a focus on developing computational algorithms for examining waveform design in diverse active sensing applications, this guide is ideal for researchers and practitioners in the field. The three parts conveniently correspond to the three categories of desirable waveform properties: good aperiodic correlations, good periodic correlations and beam pattern matching. In addition to numerical results, the authors present theoretical analyses describing lower bounds or limitations of performance. Cambridge University Press.
Does Marketing Matter?
OK, so now I have read about someone who credits social media - LinkedIn specifically - for success. Judy Warner, of Transline Technology, responded to the "Fake Twitter Follower Factory" commentary that I posted on LinkedIn to say she has had an overwhelmingly good response from reaching out to and engaging the LinkedIn community of engineers. In fact, Judy's experience was so spectacular that in a few short years she went from being a connectionless marketing exec re-entering the PCB marketing realm after a decade-long hiatus, to being a sought-after expert in her field. Read her short article "Does Marketing Matter?" in the April 2013 edition of the pcb magazine (page 62). Maybe Judy's feedback to my LinkedIn post means I, too, can now claim social media success!
Fake Twitter Follower Factory
I've always been a bit dubious about the whole social media thing. Yes, it can be a great medium for connecting with old friends and maybe getting some breaking news, but otherwise services like Twitter seem to mostly be a time-wasting enabler for people with too little meaningful purpose in their lives. Achieving the largest number of 'Followers' is now a lifetime goal in order to assert and prove popularity and dominance in society. Catering to vanity is big business so as you might expect, there is a plethora of opportunists who offer to inflate the Followership of gullible Twits. A recent story in Inc magazine, one of many such stories in many news reports, illustrated just how easy it is given even a modest cash outlay to buy Followers - some charge as little as a penny apiece. If you are thinking of starting a Twitter Follower business of your own, businesses will also sell you 'verified' e-mails address batches, Captcha defeaters, and HideMyAss.com will...
Have I mentioned how much I appreciate good graphs and illustrations for conveying information? Yeah, I guess I have... often. The adage about a picture being worth a thousand words certainly holds true - even if the thousand words inadvertently describes the artist's crappy attempt to get his/her message across. This particular graphic presents information on some of the vast resources of [mostly] free online educational sources for engineering and related topics. Massive Open Online Courses (MOOC) was launched in 2008 at the University of Winnipeg and is credited with birthing the idea (at least for being the first to successfully implement it). There are, of course even more courses in other areas of interest. Flight vehicle aerodynamics, astronomy, solar energy, physics, numerical statistics, even sci-fi and creative writing, all useful in a well rounded engineering experience, are among the listed types...
Good Articles from T&M World
writers at Test & Measurement magazine hit a high note
this month with articles. Enjoy.
- Ensure Magnetic
Components Meet Specs
by Jeffrey Dierker
- Solve MOSFET
and Reliability Degradation
Issues, by T. Nishimura
- Improve Wireless Testing
of Sensitive Devices,
by Per Nielsen
Please Welcome Analyzer
Repair as a New Advertiser!
Analyzer Repair is based in Cocoa, Florida, and focuses on servicing spectrum analyzers and network analyzers. "All of our technicians are military PMEL graduates." After their tenure, they spent time in R&D labs, USAF PMEL labs, and commercial calibration labs. Repair calibration services for new equipment & extend life of obsolete high performance analyzers.
"An acquisition is the end of a dream." - Jake Lodwick, co-founder of Vimeo. This quote appeared in the July/August 2013 Inc magazine, where Mr. Lodwick describes the Heck he went through with his company. He further states, "If you truly believe in the potential of your company to change the world for the better, there's no excuse for settling for an acquisition."
for August 18, 2013
Take a break and work this week's 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.
Project West Ford: Earth's
Saturn-Like Ring of Dipoles
What do you think of the USAF's plan to deploy a band of millions of tiny dipole antennas into orbit around Earth for communications support? Because over-the-horizon (OTH) radio communications rely on the upper atmosphere being conductive to reflect radio waves, it is essential that there always be something for bending signals back to Earth rather than allowing them to escape into space. The ionosphere has many identified regions that do a good job of reflecting signals of certain wavelengths during particular times of day and under special atmospheric conditions cause by solar activity. There are times when reliable OTH communications are not possible because of severe coronal mass ejections (CMEs), high meteoric activity, and even terrestrial events like major volcanic eruptions. Even predictable variation in ionosphere characteristics like the diurnal blending of the F1 and F2 layers into a single F layer complicates emergency and strategic communications planning...
Thanks to BRL Test Analyzer
Repair for Continued Support
Both BRL Test and their Analyzer Repair division are helping to deliver RF Cafe by advertising. BRL Test Analyzer Repair specializes in the repair of spectrum and network analyzers. They are a leading dealer of new and reconditioned test and measurement equipment. They buy, sell, rent, lease, repair and calibrate all types of general purpose test and measurement equipment.
Can Expert Statements
Inadvertently Waive Protection?
Expert witnesses play a big role in most of the court cases that get reported here. IMS ExpertServices is a law firm specializing in expert witnesses. Every month or so they send me an article about specific court cases that could be of interest to RF Cafe visitors. This particular article is titled "Can Expert Statements Inadvertently Waive Protection?" It the case, an expert witness used by Company A to compel Company B to submit to claims was not intended to be used in court and so per Company A, he/she should not be able to be deposed during the discovery phase of the lawsuit (it involved faulty materials in a transmission). The expert witness' opinion was quoted but not declared as evidence. The laws pertaining to testifying and non-testifying experts are, as you might imagine, complex and prone to the subjective whims of courts even though most might consider the codified law to be quite clear. The lesson here is to be careful how expert witnesses are handled, even if you have no intention of using their opinions in court.