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 ...
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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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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Skyworks Intros High Iso SP4T
Absorptive Switch w/Decoder
Skyworks Solutions has introduced a new 0.02 – 4 GHz, high isolation, single pole four throw absorptive switch with 50 Ω terminations and excellent isolation performance. The symmetrical SKY13392-359LF is ideal for military communications, test and measurement and GSM/CDMA/WDCMA/LTE cellular infrastructure applications requiring feedback, channel and filter-bank switching where very high isolation (>50 dB) and low loss (1 dB) are needed. The device contains integrated logic.
Florida Man Cited by FCC
for Noisy Well Pump
Here is an interesting story where the FCC issued a citation of violation for incidental radiation due to a malfunctioning well pump. The noise was evidently being generated by the motor and radiated from the AC power wires. The interference was affecting local MF and HF amateur radio operation. FCC investigators used direction finding equipment to locate the source ('fox hunting' in Ham terms). The owner was threatened with a $16,000 fine unless corrected immediately, with up to $112,500 levied if he screwed around. Replacing the AC line filter did not solve the problem, so he probably ended up replacing the entire pump. Being in Florida where the water tables are typically near the surface, it was likely not a submersible type pump, so the entire assembly would have had the opportunity to radiate. Submersible pumps use brushless induction motors deep within the metal casing lining the well hole (a nearly ideal RF shield), but depending on the vintage of the resident's above-ground pump it could be brushed, with arcing causing the problem.
June Magazine Articles
Here are a few recent articles from our industry's leading magazines that you might find useful.
Thank to Linx Technologies
for Long-Time Support
Linx Technologies' RF modules, remote controls, evaluation kits and master development systems feature straightforward hardware configuration and clear documentation, making it simple for engineers and hobbyists to integrate wireless features without the hassle and expense of engineering RF functionality from scratch. They also offer design services including board layout assistance, programming, certification advice and packaging design. "Wireless Made Simple"
June 30, 2013 Wireless
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.
Please Visit Apex Wireless
in Appreciation of 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. Consumer, defense, aerospace, power, transportation, industrial, sports, and other industries served.
The NASA-136 Nuvistor-
Powered Satellite Receiver
Have you ever heard of a 'nuvistor?' It didn't seem familiar to me right away until after I looked it up. Nuvistors were high mu (high gain) tubes, manufactured originally by RCA, used in sensitive receiver front ends. They came in about a dozen different varieties. This particular NASA-136 receiver for satellite reception uses a 6CW4 triode. Per Wikipedia, "Most nuvistors are basically thimble-shaped, but somewhat smaller than a thimble, and much smaller than conventional tubes of the day. Triodes and a few tetrodes were made. The tube is made entirely of metal and ceramic. Making nuvistors requires special equipment, since there is no intubation to pump gases out of the envelope. Instead, the entire structure is assembled, inserted into its metal envelope, sealed...
Many times I have extolled the high quality of QST authors' knowledge and writing skills. H. Ward Silver writes the "Hands-On Radio" column which usually features circuit and system design and theory topics. It often includes, gasp, mathematics. His July 2013 article is titled "Phasors, Part One." It promises to be a good series. The last paragraph says, "There is a final way to describe the signal - the exponential form in which it is represented as V ejΘ. This form comes from the mathematics behind Euler's equation in which the coordinates of our points are miraculously shown to be equivalent to ejΘ=cosΘ +j sinΘ. The serious and beautiful math behind this equation lies at the heart of much electrical engineering and leads to the jaw-dropping Euler's identity: ejπ = -1 which unites the two most widely used transcendental number (e and π), imaginary numbers (j), negation and unity. Not bad for a moving point in a simple circle, huh?" Beautiful. After reading it Melanie asked why my eyes were suddenly red. "Allergies," I explained.
PMI Intros 8-Bit 0.5-2.0 GHz
Digital Control Phase Shifter
PMI Model No. PS-500M2G-8B-SFF is a Stare-of-the-Art, 8-Bit Digitally Controlled Phase Shifter that operates over the 500 MHz to 2.0 GHz frequency range. This model has a typical insertion loss of 10dB and offers 360 degrees of phase shift via 8-Bit TTL control. The phase shift error is less than ±10 degrees and the amplitude error is less than ±1 dB. The switching speed is 500 nsec maximum.
Linx Intros SMA and Reverse
Polarity SMA Connectors
Linx Technologies' new low-cost gold plated connectors are now available from Linx, adding new options to our already diverse connector line. The gold jacks are available in SMA and Reverse Polarity SMA styles in straight or right-angle versions. In addition, the 50-ohm connectors are available as PCB mount or surface mount components offering a variety of mounting options for your design.
Wear Part of Bletchley Park
on Your Wrist
By the time you read this it will probably be too late to be an original owner of this very limited edition 'Codebreaker' watch, made by the prestigious UK Bremont Watch Company. Each Codebreaker watch will incorporate a piece of pine wood from the iconic Hut 6 and numbers from some rare, original punch cards used in wartime machines that carried out rapid analysis of encrypted message systems to assist the Codebreakers. Each watch will also have incorporated into its rotor, material from an original Enigma machine rotor. Speaking of Bletchley Park news, the WWII era Electronic Delay Storage Automatic Calculator (Edsac) restoration project recently reached a key milestone. Edsac is built of 3,000 valves (vacuum tubes) spread across 140 separate shelves.
Say You Saw It in QST- It
Identifies You and Helps QST
In the early 1930s, QST magazine (ARRL's monthly publication) usually ran a line at the bottom of every page in the back half of each issue that said, "Say You Saw It in QST - It Identifies You and Helps QST." They even got the capitalization correct (all lower case short prepositions and conjunctions, but I digress). The December 1933 edition was a bit different, however, in that all the left-hand pages had the message translated into one of fourteen different languages while the right-hand pages used English. I deemed that discovery cool enough to scan and post here. Since the only languages I speak with any fluency are English and Pig Latin, I took the trouble of entering the English sentences into the Google Translator engine for each language...
The 1933 World's Fair
Radio Amateur Exhibit
The 1933 "Century of Progress" World's Fair, held in Chicago, was a big deal on many fronts. Life in America and around the world was changing rapidly due to the widespread introduction into homes a decade earlier of electrical and telephone service, indoor plumbing, and associated appliances. The state of the art was a modern wonder. Transportation had been made affordable to many families, and leisure time was becoming more abundant. If it were not for the advent of the stock market crash in 1929, economies would be thriving because there was so much cool stuff to be had. Many people had taken up the hobby and/or profession of wireless communications, so a display was included on the fairgrounds for the craft. An interesting consequence of a combination of noisy (electrically) electromechanical wonders being promoted and the desire to demonstrate working amateur radio equipment was a necessity to locate the two as far apart as possible...
RF Cafe Poll
Started June 26, 2013
Linx Intros DTS & EUR Series
RF Xcvr MPMP Modules Control
The DTS Series and EUR Series RF transceiver modules combine a low power wireless transceiver with a powerful multipoint-to-multipoint protocol controller to form an effective UART-to-antenna wireless communication solution. The modules use a wide band digital modulation technique known as Digital Transmission System (DTS) and are capable of replacing wires in almost any RS-232/422/485 application. This system has a higher output power, giving it a range of up to 1 mile / 1.6 km line of sight without having to limit duty cycle, hop channels or the expense of a DSSS system.
Atomichron - World's Most
The National Company, of Malden, MA, which made this cesium-based Atomichron in the mid-to-late 1950s, began life as a toy manufacturer. It had an output frequency at the nominal resonance frequency of cesium - 9192.631830 MHz - and was accurate to better than a second in 600 years. The unit was 7 feet tall and weighed 500 pounds. Modern cesium standards are more stable and are portable. As of January 2013, the NIST-F1 cesium fountain primary frequency standard is accurate to within one second every 100 million years!
PMI Intros 2 MHz to 18 GHz
PMI Model CDT-2M18-30-BB Options DE, D is a threshold detector that operates over the 2 MHz to 18 GHz frequency range. This model has a low insertion loss of 2.5 dB maximum and operates over an input power range of -30 to 0 dBm. The threshold level is adjustable and the output signal is TTL positive logic. In addition to the threshold detector, this unit offers an analog detected output voltage of 0 to 2.5 VDC.
Scientists Use Electron 'Ink'
to Write on Graphene 'Paper'
This new technology could be a relatively simple and inexpensive method of creating permanent, high density records storage. Using an electron beam, the planar hexagonal carbon matrix of graphene (2-dimensional by definition) is disturbed and replaced by a 3D clump of carbon atoms that provide a discernable relief easily recognized as printing under a microscope. While the print could be similar to a normal printed page, it might be more useful to encode the information in some other form that will require decryption to read. Magnetic and optical digital storage media is notoriously non-permanent due to cold flow and migration of localized storage domains. This process eliminates that problem.
Geak Unveils NFC Smart Watch
and Contactless Ring
You have probably heard proposals for 'smart guns' that will only fire when owners wearing special rings are in possession. Here is a near field communications (NFC) ring that permits only its wearer to use a cellphone, tablet, or other NFC-enabled device linked to its code. Doing so eliminates the need to enter a password for access. According to an NFC World report, the ring contains an IC that can store personal contact information as well allowing the wearer to voluntarily "share" certain details about him/herself (why would you do that?) simply via proximity contact. Initially, the ring will only work with Geak's devices, but plans are in the works for more widespread adoption.
AWR / Prof. Keith Kikkert to
Offer eBook on RF Design
AWR Corporation announces a new eBook, RF Electronics: Design and Simulation, which is available free of charge to students, graduates, professors and industry professionals through AWR’s new Professors in Partnership™ web portal. Developed by adjunct associate professor C. J. (Keith) Kikkert of James Cook University School of Engineering and Physical Sciences, Townsville, Queensland, Australia, the book describes the use of AWR's Microwave Office® and AXIEM® software to design RF electronic devices for applications such as amplifiers, radar, mobile phones, Bluetooth, and WLAN.
High Power Crystal Set
Most regular RF Cafe visitors will probably not be too interested in this article, but there are a lot of people who build and/or repair vintage radio gear and search the Internet for helpful information. Having built a couple crystal radio sets as a kid, I've always been amazed at how a few picowatts of RF energy can be received, processed, and heard through an ear plug without the need for external power from a battery. Speaking of crystal radios, I remember one time while working as an electrician in Annapolis, MD, (prior to entering electronics) I had a telephone handset for use in communicating with other electricians in a building I was wiring, and it picked up the local AM radio station. A pair of the old style handsets...
Notable Tech Quote
"It's stupidity. It's worse than stupidity: it's a marketing hype campaign." - GNU founder Richard Stallman on embracing Cloud Computing for its ostensibly "free" data storage on uncontrolled servers rather than on your local machine.
Phase Matrix Intros QuickSyn
10 GHz Frequency Synthesizer
Phase Matrix's newest addition to the QuickSyn® line of microwave frequency synthesizers is a 10 GHz synthesizer housed in a very compact package, only 4 x 4 x 0.8 inches. The new synthesizer, model FSL-0010, employs the revolutionary phase-refining QuickSyn® technology. The new Quicksyn® Lite synthesizer is less than half the size of the full featured 10 GHz and 20 GHz QuickSyn® synthesizers, yet it performs with wide coverage (0.65 to 10 GHz), fine resolution (0.001 Hz resolution), fast frequency switching (100 μs), and exhibits instrument-grade spectral purity.
Free White Papers
The folks at Rev Response have a pretty big collection of white papers on a very wide range of subjects that are free for downloading. Well, not quite free - they do require you to sign in, but no $$$ is involved. I make a few pennies on each download, so you're helping to support RF Cafe if you participate. Here are a few of the newer ones that might interest you:
- 2012 Laptop Buying Guide
for June 23, 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.
Crosley 03CB Console Radio
After searching occasionally for many years for another Crosley 03CB radio in a location close enough to drive for pick-up, I finally saw one on Craigslist in Harrisburg, PA, about 300 miles from my home in Erie, PA. Melanie and I picked it up yesterday. It needs - and will receive - a total restoration for both the cabinet and the electronics, but it appears to be in better condition that my first pre-restored Crosley 03CB. This radio is Chassis #95. If you look at the photo of the first radio , you will notice that the tuning dial has no cover over it. I never knew there was supposed to be a glass bezel in front of the dial...
$86 Million in Tax Refunds
Sent to Just 10 Addresses
Think the illegal alien problem is just made up? Here is the IRS's own 2012 fraud report showing more than $86 million sent to just 10 addresses. See Figure 5 on page 17. In Atlanta alone, a single address for 23,994 'Unauthorized' (aka Illegal) Aliens received payments totaling $46M. This crap is costing our economy jobs by requiring working citizens to pay the tab for this. It also feeds into the massive fraudulent voting scheme for one party and suppression of voting by the other party. We now have a politico-economic oligarchy, folks. Congratulations.
Tech Employment News
Here are a few more useful stories on the tech job market and job hunting. Enjoy.
** Notice **
I will be travelling on Friday with limited e-mail access. Responses will probably be delayed for a few hours. I apologize for any inconvenience.
Quiz on AC Circuit Theory
Here is a fairly simple quiz on AC circuit analysis. If you are not already comfortable with adding series and parallel circuits containing resistors, capacitors, and inductors, you will appreciate the simple formula presented that will keep the sweat level down ;-) OK, pick up you pencils... now.
Crystal Photocell Circuits
Electronics hobbyists are always anxious to hear the announcement of a new device that is forecast to revolutionize the tech world. In the late 1950s something as relatively tame as a crystal photocell satisfied that urge. Today it takes something like a negative refractive index metamaterial to invoke the same sense of awe and wonder. Those were simpler times, but then again even today's beginners in the world of electronics circuit designing and building have to start somewhere, and these types of circuits are as good as any place.
for the TV Industry
I wasn't able to verify Dr. Baker's (VP of GE) prediction in 1957 of what the state of the television industry would be by 1960. He said 10 million sets would be sold in 1960 vs. 7.5 million in 1957. Some recent sources claim there were as many as 52 million TV sets total by 1960, so he might have been right. Transoceanic scattering techniques were thought to be the method of choice for television broadcasts, but we know that ultimately relay satellites would win out. It wasn't until 1962 that the Telstar bird carried the first TV signals, however. "Truly portable" transistorized TVs would be appearing...
An Intrstng Exprmnt in Spch
Here is a little insight into early speech processing research by the Bell Telephone Laboratories. 1957 was the early era of real-time digital processing where the need to cram more calls into less signal space (bandwidth) led to sampled systems - 1:6 in the case of this advertisement from Bell that appeared in Radio & Television News. Engineers of the day would be amazed at how the state of the art has advanced since then, both in mathematical techniques and in miniaturized hardware.
Job Hunting Tips
from IEEE's JobSite
AWR Wins 1st Annual Best of
MW & RF 2013 Survey Awards
AWR has won in two categories in the first annual Microwaves & RF magazine "Best of Microwaves & RF" awards. The company won the Best Training and Education category and was first runner up in the Best Supplier Industry Blog category. The winners were determined through a recent survey that went out to readers of Microwaves & RF magazine inquiring about their favorite online tools for keeping up to date within the microwave/RF industry.
Thank Again to RFtronics
for Long-Time Support
RFtronics develops both turnkey and custom solutions for the RF telecom equipment designers and manufacturers. Currently, our product line includes high power couplers, splitters / combiners and filters between 1 MHz and 3 GHz. They have more than 20 years experience in the RF/microwave design and manufacture, with the agility of a small company and the production capabilities of a larger-sized, high-volume manufacture. RFtronics will usually deliver prototype quantities (less than 50 pcs) directly and for larger orders the design will be transferred to our manufacturing partner.
Intern Bill of Rights: Unintended
Consequences to Follow?
A recent NY Times article reported on a court ruling in favor of a couple interns who claimed they were not fairly paid for their work. Author Steve Greenhouse points out that while it could be a victory for the litigants, ultimately it could bode poorly for internship programs. Legal precedence is widely referenced and applied by legal teams, and is notoriously difficult to overturn. This particular internship involved work on a movie production set, but expect the decision to ripple through to even engineering and science business programs. An estimated 1,000,000 internships are hosted each year in America, a significant portion of which could be eliminated out of an abundance of caution and fear of being sued. Is this another "careful what you wish for, you might just get it" scenario?
Please Support RF Cafe!
Microstrip Lines and Slotlines, by Ramesh Garg, Inder Bahl, and Maurizio Bozzi. Planar transmission line technology has progressed considerably due to developments in UWB communications, imaging, and RFID applications. In addition, the simultaneous demands for compactness of wireless electronic devices while meeting improved performance requirements, necessitates increased use of computer-aided design, simulation, and analysis by microwave engineers. This book is written to help engineers successfully meet these challenges. This book was used as the basis for RF Cafe Quiz #50.
The Great Patent Race
You might have read about the recent U.S. Patent and Trademark Office (USPTO) law that changes policy from a 'first to invent' to a 'first to file' system. It was meant to reduce the amount of work required by patent examiners and to reduce litigation by eliminating the heretofore potentially subjective nature of determining who was the 'real' inventor of an idea. Previously, if a person could prove via formal dated notes, witnesses, etc., that he was the first to manifest an idea in the form of a working model, there was a good chance that an existing patent could be reassigned. Now, it is almost purely a matter of who gets the earliest timestamp for having been received at the USPTO. This short piece in Inc magazine discusses the new patent filing issue.
Please Visit 3Gmetalworx
in Appreciation of Support
Since 1994, leading wireless electronics companies have relied on 3Gmetalworx to deliver cutting edge solutions for advanced RF/EMI PCB-level shielding requirements. From prototyping and design services to JIT manufacturing supply, our clients depend on us to provide a seamless service pathway supporting entire product lifecycle. All shields can incorporate these features, as well as your custom needs:▪Engagement tabs, trace/component relief, tuning/access openings, thermal relief.
Contributing to Science
Larry Wolfgang has a good article in the May 2013 edition of QST titled "Contributing to Science." In it he recalls a few examples of how amateurs have helped professional scientists and engineers advance the state of the art in wireless communications. For instance Pat Dyer, WA5IYX, conducted an 11-year study of mid-latitude sporadic E, and Dave Olean, K1WHS, built a magnetometer to predict aurora to aid in 144 MHz DX. Hams also discovered trans-equatorial propagation. Mr. Wolfgang suggests that pursuing a meaningful scientific investigation of your own or maybe by your club would be a worthwhile and satisfying endeavor. BTW, while writing this I happened upon a resource for current QST articles on EBSCO Host website, which is significant because non-members of ARRL cannot access their online editions.
RF Cafe Poll
Started June 18, 2013