Modeling Radiation Patterns
of Whip Antennas
Computer modeling of antenna radiation patterns has evolved from a relatively simple electric field equation that diminishes as the inverse of the distance from the source, to exotic, highly sophisticated numerical methods that account for conducting and dielectric surfaces and volumes. A spreadsheet can be built rather quickly to calculate and graph the free-space azimuth and elevation e-field patterns for a 1/4-wave whip or a dipole antenna using textbook formulas, but building a model for displaying the 3D radiation patterns of a cellphone placed next to a human head, or a UHF radio antenna on top of an aircraft takes some pretty serious computing power. In large part we owe a debt of gratitude to the Ph.D. types who have labored hard to make such tools...
Anatech Intros Duplexer, BPF,
Isolator, & Directional Coupler
Anatech Electronics has released new designs for a 902 to 928 MHz cavity bandpass filter, a 1850 to 1910 MHz/1930 to 1990 MHz cavity duplexer, a 840 to 960 MHz circulator , and a 5 to 18 GHz 8-way power divider. All can be ordered directly through their AMCrf web store.
Please Thank Nova Microwave
for Their Support
Nova Microwave is a leader in technically differentiated electronic and radio frequency Ferrite Circulators and Isolators that connect, protect and control critical systems for the global microwave electronics market place including commercial and military wireless telecommunications. Dedicated to R&D of standard and custom design quality Ferrite Circulators and Isolators from 380 MHz to 23.6 GHz.
Coil Function Quiz
Here is a quick, 10-question quiz about coils (inductors). It appeared in the June 1962 edition of Popular Electronics magazine. Don't be scared off by the vacuum tubes that appear in three drawings. Just pretend they are transistors - it won't affect your answers. One of the coil applications is almost obsolete for most people as the nature of computer monitors and TV screens has changed significantly in the last decade.
Selected Job Tips from IEEE
Here are this week's suggestions, plus a couple others I found as well.
- 6 Memorable Engineering
- 7 Missed Opportunities
That Can Cost You That
- Can You Make a Workplace
U-Turn? (leave, then go back)
- How's the Engineering Job
Market? Depends on Whom
- Engineering the Perfect
- U. of Maryland School of
Engineering job Search Tips
Thanks to Windfreak
Technologies for Support!
Windfreak Tech designs, manufactures, tests and sells high value radio frequency products such as RF Signal Generators & Synthesizers, RF Power Detectors, RF Mixers, RF Upconverters and RF downconverters. We develop high quality, reliable, low cost products to make your life easier. Windfreak Tech is developing high quality, low cost products to make life easier for RF Engineers and hobbyist. Future products will be more synthesizers, transmitters, receivers and test equipment. All at low cost.
The Future of Mobile
Forrester Research Report: The Future of Mobile Application Development. This report, which is the vision report of the mobile app development playbook for Application Development and Delivery professionals, focuses on the changes application developers need to understand if they want to build modern applications that deliver contextual customer experiences. With more than 1 billion smartphones worldwide, and tablets numbering in the hundreds of millions, the scope of the mobile revolution rivals that of the move from monolithic systems to client/server computing in the 1990s...
Baluns: What They Do
and How They Do It
Baluns are not devices familiar to most engineers even if they have been in the RF business for many years. Most have heard of them but few probably really know what a balun is, how it works, and how it is used. Admittedly, it wasn't until maybe a decade ago that I ever even came into contact with one - at least that I was aware of. Having spent most of my career connecting cables and waveguide to pre-designed, pre-packaged components, there was never a need to convert between balanced and unbalanced transmission lines. The many analog circuits that I did always used ICs that had single- or double-ended inputs and/or outputs so it was never necessary to be concerned with the details. Now that I have been reading the ARRL's QST magazine monthly for the last few years, an appreciation for...
What is a Servomechanism?
Servomechanisms are all around us in the form of electronically actuated controls for our cars, stepper motors in our ink jet printers, overhead garage door openers, and anywhere else you can identify where a combination of electricity and mechanics operates with some form of positional sensing and feedback. The author of this article in one instance declares a control circuit with a human operator as part of the operation as being "open loop," but I contend that the human element is part of the loop and therefore constitutes a component in the effectively "closed" loop, albeit not strictly a pure electromechanical system. Those of us who operate radio-controlled model airplanes, boats, cars, etc., are very familiar with servos for moving control surfaces as commanded by the transmitter's joystick position.
How to Break into
the Aviation Radio Game
Yes, this is another article that will probably appeal to a small percentage of RF Cafe visitors, but please countenance my indulgence in things aeronautical as well as things electrical. The early 1930s was a time when both airplanes and electronics were a wonder and a mystery to most of the public worldwide. Of course today both are still a mystery to the public but the wonder is gone - it's merely taken for granted. Many idiosyncrasies of airborne electronic communications were encountered for the first time, like the need for proper grounding and static electricity dissipation. Ruggedization of chassis assemblies in terms of mechanical vibration and shock as well as for temperature extremes...
- Gift Suggestions -
Your New Job Title Is "Accomplice," by Scott Adams. If you are looking for a gift for your engineer spouse, friend, son, or daughter, then what could be better than the latest collection of Dilbert comics? Both traditional paperback and newfangled Kindle versions are available. Not the reading type? How about a Dilbert 2014 Calendar? Seriously, if you are buying the calendar because your engineer is not a reader, then he/she would be better served with Learn to Read, by Zac the Rat (the name doesn't really rhyme, BTW).
Does Anyone Still Make
Does anyone still manufacture new vacuum tubes? The simple answer is yes if you are referring to the kind used in household radio and television sets, but don't expect to find a full line of replacements. Also, don't expect them to be made anywhere other than places like China and Russia. China does it because mainly to service the rest of the world's demand for restoring and maintaining vintage equipment. Russia probably does it to supply its own military and civilian populace which largely still hasn't heard of transistorized electronics (just joking, kinda). Three of the most widely available newly produced vacuum tubes are made by JJ Electronics, Valve Art, and Ruby Tubes. They are all over Amazon.com and eBay at reasonable prices. If you are in the market for vacuum tubes and prefer to buy...
Please Thank Reactel
for Helping Deliver RF Cafe
Established in 1979, Reactel is an industry leader in the design and manufacture of RF and Microwave filters, diplexers, and sub-assemblies. We offer a line of filters covering DC-50 GHz. The latest in CAD/CAM methods and equipment in all of our design and manufacturing processes are used. We feature a modern, well-equipped machine shop complete with multiple CNCs, which gives us the ability to produce long production runs quickly and economically. Our testing department is equipped with the latest in Agilent Technologies Network Analyzers offering quick, dependable, and accurate measurements.
Sagetech Announces Principal
Development Engineer Position
This is one of the best job descriptions I have ever seen. It reads like it was written by real engineers who need a really good person to work with the team. To wit:
EE UAV Avionics Design and Certification
"Unmanned Aerial Vehicles (UAVs) in civil airspace are the next big thing. Sagetech is a leader in UAV avionics and has exciting projects starting now in FAA / military UAV design and certification. We are building a kick-ass team. You might fit if this grabs you: We seek highly talented, disciplined, imaginative engineers (RF design, embedded, or FPGA programmers) who love creating novel and highly efficient solutions in a requirements-based design environment. That’s not easy. We seek team members who are like us, who are energized by challenge."
Mary Burke, W3CUL Wins
1956 Edison Award
$5,000 in 1956 currency is equivalent to about $43,000 in 2013, per the U.S. Bureau of Labor Statistics' "Inflation Calculator." That is the value of the amateur radio equipment used by Mrs. Mary Burke in her work handling "an average of 3000 messages per month, principally for service personnel overseas." For her tireless efforts, she was the first woman to win the coveted Edison Award Cup (sponsored by General Electric). Most of Mrs. Burke's communications was via Morse code, where she restrained herself to "about 30 words a minute to maintain accuracy". Way to go, Mary!
New Life for Old Computers
Remember the old adage about not throwing away that wide tie because someday it will be back in style? Well, the good folks at Neverware have built a business model and product that exploits that concept. "Neverware installs powerful software on schools' existing computers, taking over the 'heavy lifting' and allowing the computers to run like new. Neverware's servers can supercharge any PC - even if it's ten years old and missing its hard drive." Those of us who have been using computers since the 1970s ['78 for me] know this system as a network with dumb terminals. The main difference between then and now is wireless connectivity rather than copper cables. Calling the server a "Juicebox" helps the sales pitch and with cinching the deal - it sounds trendy. I have long predicted that the "personal" computer in business and other large networks like in schools and government offices would eventually come full circle...
Notable Tech Quote
"Twitter is the only place where you're thrilled when a complete stranger starts following you." - Anon
PMI Intros PIN Diode Transfer
Switch for 0.5 to 18 GHz
PMI Model No. SWN-2181-TRA is a pin diode transfer switch that operates over a frequency range of 0.5 to 18.0 GHz. It has 60 dB min of isolation, max insertion loss of 3.5 dB and a max input power of +10 dBm CW. This model incorporates a TTL compatible driver for easy system integration and is supplied with removable 2.92 mm (F) connectors in a housing that measures 1.0" x 1.0" x 0.25"
The Swiss Quad Antenna
This design for a "Swiss Quad" antenna appeared in the September 1967 edition of QST magazine. One of its touted strong points is not needing spreaders or a boom. I am not an antenna design guy, so I can't comment on its usefulness. No gain measurement was provided by the author. The article states that the antenna had not yet enjoyed widespread adaptation in the U.S. at the time of the writing. A Google search for Swiss Quad antennas turns up a handful of modern examples. I could not locate an example of a computer-generated gain plot (radiation pattern) for the Swiss Quad, so if you know where one exists, please let me know so I can post a hyperlink. Maybe you own a copy of EZNEC and can model it?
for December 1, 2013
This is a BIG crossword puzzle so be prepared to spend some time on it. In fact, if you find yourself being dragged along for a major Christmas shopping jaunt, then you might print it out and take it with you to be entertained whilst sitting on the mall bench. As always, this puzzle contains only science, engineer, and mathematics type words - no numbnut movie star names or obscure mountain peak names.