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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Atlanta Communications Needs
RF System Technician
Atlanta Communications Company is seeking a mature, experience person with a dynamic personality and a STRONG RF & IT background. The job opening involves daily service of large Motorola Fix Network Systems. The ideal candidate will have a FCC license, ETA , MCSE, CISCO certifications, and have recent work experience with SMARTNET, SMARTZONE, ASTRO P25 Trunking Systems or equivalent technologies. This includes all ancillary equipment associated with large public safety trunked radio systems (console work stations, data, servers, routers, switches, etc.).
Thanks Once Again to
Comdel for Support
Comdel designs and manufactures RF and DC power supplies and process instruments for the semiconductor, solar cell/photovoltaics, flat panel, and industrial heating industries. Comdel products are in use worldwide by the industry’s major equipment and IC fab manufacturers.
Relative Traffic Standings
We take wireless communications for granted. Just as people my age thought pocket-size transistor radios that ran on 9V batteries were always available, today's kids give no thought to whether there was a time when everyone did not carry a cellphone around. FM radio, if listened to at all nowadays, is likely either via an Internet connection or via an embedded FM radio IC in his/her phone, with ear bud wires acting as an antenna. It is obviously no big deal, since it always was so. In the early part of the last century most people did not own any sort of radio - even a commercial AM broadcast receiver. Having something as mysterious as a shortwave 'rig' was an indication of technical prowess since many operators built their own equipment from kits or schematics. Participation in amateur worldwide was huge at the time, which is amazing given the amount of work required to set up even a relatively simple CW (Morse code) setup...
Spartan Model 60 Short-Wave
Not everyone is into radio history, so items like this advertisement for Spartan Radio's Model 60 Short-Wave Receiver (April 1932 QST) will not invoke much or any interest. On the other hand, there is a large contingent of hobbyists and professionals who enjoy seeing these snapshots of the places from whence we have come technically. Products like radios, kitchen appliances, automobiles, etc., were constructed very robustly with metal, wood, and fabric. No cheap plastic will be found anywhere, but maybe not for the reason you think - plastic as we know it today had not entered the commercial marketplace yet. In fact, many 'modern' plastic formulas and processes were a closely held military secrets until the end of World War II.
Rationalizing the Autodyne
Although written in 1933 (era of the Great Depression), this article on the autodyne receiver has a good discussion of noise sources and how to trade off amplification for signal intelligibility. It originally used the De Forest Audion vacuum tube amplifier. Noise figure and noise temperature were not commonly used at the time, but the concept is encompassed in the treatment. So, what is an autodyne? It is a form of regenerative circuit that, rather than being tuned right at the signal of interest, is tuned slightly off center. It functions as a sort of combined local oscillator and amplifier for demodulating CW (Morse code) signals. Technical writing styles have not changed much over the decades, even as the terminology has.
HD Moore Pings the
I like these kinds of charts. In this case it is a map of all the Internet connected devices in the world, or at least per the 2.7 billion IP addresses (310 million replies) that computer security guru HD Moore pinged to get data for his map. On his off time as a researcher at Rapid7, he uses an arsenal of computers at home to run such experiments. Says Moore, "I have a lot of cooling equipment to make sure my house doesn't catch on fire." Part of the goal was to determine how many people never changed the default password for their modems and other gateway devices. It was a lot. Although everything he did was legal, he did get complaints from some of the pinged. Do you still have the default password on your wireless router? I just checked a few of my neighbors' WiFi connections and didn't find any with 'default' as the password.
Samsung’s GALAXY S 4
Skyworks Solutions today announced it is supporting Samsung's GALAXY S 4 smartphone platforms with multiple high-performance analog and front-end solutions. “Skyworks is delighted to be supporting Samsung's flagship GALAXY S 4 smartphone platform,” said Liam K. Griffin, executive vice president and corporate general manager at Skyworks. "Given our broad product portfolio and system-level expertise, we have expanded our partnership with Samsung beyond delivering traditional power amplifiers to providing an entire suite of solutions for an unprecedented level of analog and RF integration"
Klystron: Tube for Outer Space
If you have been in the RF and microwaves business for any length of time, you are probably familiar with a company named Varian. In the days before you did your parts shopping online, Varian catalogs populated the desks and bookshelves of many RF engineers who worked in the radar field, including mine. Did you know that it is named after the brothers Russell and Sigurd Varian, who started the business in 1948 to market their high power klystron tubes? Following a number of reorganizations, it was purchased by Agilent technologies in 2010. This story from Radio Electronics magazine does a real nice job explaining the workings of a klystron without getting too deep into the gory theoretical detail.
Thanks to Pulsar Microwave
for Long-Time Support
Pulsar Microwave is celebrating its 26th anniversary as a valued supplier of passive microwave components covering the frequency range of 10 kHz to 40 GHz with both narrow band and ultra-broadband products for the wireless communications markets. Power dividers, couplers, attenuators, phase shifters, switches, and more.
Rohde & Schwarz Intros
O-scopes w/Logic Analysis
With the introduction of the new R&S RTM series, Rohde & Schwarz has expanded the functional range of its bench oscilloscopes. The key upgrades are a 20 Msample deep memory and a logic analysis option with 16 digital channels. The smart operating concept of the new R&S RTM models ensures extreme ease of use. The R&S RTM provides time domain, logic, protocol and frequency analysis functions in a single box, making it the ideal instrument for the testing and development of electronic circuits
"As your company grows, you'll progress through the three phases of Internet customer feedback: 1. not enough; 2. just the right amount; and 3. way, way too much. I'm joking, of course. There is no Phase Two." - Phil Libin, co-founder and CEO of evernote.
PMI Intros 300 MHz to 2.5 GHz
PMI Model No. is a limiting amplifier that operates over the frequency range of 300 MHz to 2.5 GHz. This model provides a gain of 85 dB typically and a limited output of +15dBm ± 2.5 dBm. The typical noise figure is 5 dB and a maximum VSWR of 2.0:1 is maintained under all operating conditions into a 50 ohm impedance. The operating voltage is +12 VDC and the amplifier is reverse voltage protected. The DC current is 485 mA typically.
George R. Wilmer Seeking
George Wilmer is a radio frequency (RF), electromagnetic compatibility (EMC), and systems engineer experienced in design, integration, test, and board level to system level architecture. Staff engineering positions and independent contracting with some of the country's largest technology corporations have provided valuable insight into a variety of challenges and hands-on opportunities to resolve complex issues. Please contact George if you have need of such a fellow.
A Few Good Articles
Microwave Product Digest
Here are a few great articles that might interest you. They all appeared in Microwave Product Digest.
- RF Beamforming Techniques Improve TD-LTE Cell-Edge Performance, by Craig Grimley
- Frequency Multiplication Techniques, by Ramon Cerda
- Another Sad Moment for the FCC, by Barry Manz
Engineering Crossword Puzzle
for April 28, 2013
Take a break from the drudgery by trying your hand at some of these goodies. Every word in the RF Cafe crossword puzzles is specifically related to engineering, mathematics, and science. There are no generic backfill words like many other puzzles give you, so you'll never see a clue asking for the name of a movie star or a mountain on the Russia-China border.
Sunspot Group via
Celestron CPC800 Deluxe
The sky finally cleared and the wind finally calmed down enough to try out my new solar filter on my Celestron CPC800 Deluxe telescope ...by the time the sky cleared the sun was only about 30 degrees above the western horizon, so the seeing quality was not so great. Still, the view through the eyepiece was awesome when the atmosphere steadied occasionally for a split second. It was good enough to prompt me to go ahead and hook up the Celestron NexImage 5 camera. ...The large image of the entire solar disk was made by simply holding a point-and-shoot type camera up to the 32 mm eyepiece ...I figured the best chance of obtaining a good image was to use the video function of the NexImage 5 and run the results through RegiStax software...
Agent Smith Sells GE
Life was good as Elrond, Lord of
Rivendell, but ever since being defeated by Neo, Agent Smith has evidently been having a hard time finding work. Now reduced
to doing a gig pitching medical equipment for GE, maybe Agent Smith has had a change of heart from when he believed, "Human
beings are a disease, a cancer of this planet. You're a plague and we are the cure." It's a great commercial...
Another Great Intel Video: Our
Parties Aren't Like Your Parties
You might remember a few years back when Intel started producing commercials for geeks. The first was "Our Rock Stars Aren't Like Your Rock Stars," featuring USB co-inventor Ajay Bhatt. Not all of their videos have been spectacular, but this newer one is titled "Our Parties Aren't Like Your Parties" had me ROTFLMAO.
S. Korea Issues Touchscreen
As an erstwhile avid philatelist, I am always pleased to see countries issue postage stamps that commemorate advances in technology and the people who play key roles in that advancement. South Korea recently announced a set of four stamp designs that feature touchscreen smartphones. It was part of their April 22, 2013 Information and Communication Day celebration. Here is a page I created for stamps featuring radio and radar.
Worldwide Wired vs. Wireless
Scientific American consistently has some of the best graphs and illustrations of any technical magazine, but this new one from IEEE Spectrum that displays broadband data connectivity for wired vs. wireless is right up there in quality IMHO. What distinguishes a good chart from a bad chart? Assuming that all pertinent data is presented, the most important feature is eye catchiness. If an audience is not attracted to your information, you have wasted time. Sure, science purists will argue that a B&W line graph is all that is required to convey important results, but in today's world expectations are higher than, say, in 1879 when Thomas Edison might have been giving a lecture on the performance of various compositions of lamp filaments. Cluttering a chart with superfluous information such as background photos is not only unnecessary but potentially damaging; however, judicial use of color, line styles, and font faces can make the difference between success and failure.
What's Fair About an
Internet Sales Tax?
You have probably heard and/or seen the scuttlebutt about Congress trying to push through an Internet sales tax, ostensibly in order to level the playing field for brick and mortar businesses versus online businesses. You can be sure the effort has nothing to do with fairness and everything to do with politicians' insatiable appetite for tax money. They have been salivating over the possibility of reaping that new revenue source for years. The plan is to require online sales from out-of-state buyers to have sales tax collected and remitted to the appropriate state revenue department. Local businesses are per the claim disadvantaged because they must collect their home state's sales tax, which supposedly causes buyers to prefer Internet vendors in order to avoid such taxes. As one who has purchased many items over the Internet in the last 15 years, I can't think of many times when avoiding sales tax was the prime motivation for my decision. It was usually because either the item I wanted was not...
Amateur Observations During
the Total Eclipse of the Sun
Amateur radio operators, as with hobbyist participants in many other realms, historically have contributed significantly to the efforts of their professional counterparts. I have written of it often. This particular instance is where signal measurements in the Ham bands during a total eclipse of the sun were used to assist scientists debating the merits of rival theories relating to origin of ionization in the Kennelly-Heavyside Layers of the E and F regions, both of which were proposed in 1902 (yes, the Heaviside of step function fame). Long distance (DX) communications are dependent upon such ionization to reflect radio signals that would otherwise pass through the atmosphere and into space. The test at hand would settle the argument since the one should fail if ionization was unaffected during totality. Read the article (or skip to the end) to discover which gentleman's theory won the day.
Internet Sales Tax Fairness?
You have probably heard and/or seen the scuttlebutt about Congress trying to push through an Internet sales tax, ostensibly in order to level the playing field for brick and mortar businesses. You can be sure the effort has nothing to do with fairness and everything to do with politicians' insatiable appetite for tax money. The plan is to require online sales from out-of-state buyers to have sales tax collected and remitted to the appropriate state revenue department.
Alexander Graham Bell's
Voice Recording Restored
Alexander Graham Bell's voice has been heard for the first time thanks to a team of scientists that restored one of his wax-and-cardboard disc recordings from April 15, 1885. On it he speaks, "In witness whereof - hear my voice, Alexander Graham Bell."
AWR App Note: Circuit Design
DC to Microwave Frequencies
AWR's new application note titled, 'Multisim/Ultiboard for Low-Frequency Simulation and Layout' details how to complement Microwave Office® circuit design software with National Instrument's Multisim circuit simulation software and Ultiboard printed circuit board (PCB) layout software for a comprehensive design flow spanning from DC to microwave frequencies.
Optical Antennas, by Agio, Andrea Alù. This consistent and systematic review of recent advances in optical antenna theory and practice brings together leading experts in the fields of electrical engineering, nano-optics and nano-photonics, physical chemistry and nanofabrication. Fundamental concepts and functionalities relevant to optical antennas are explained, together with key principles for optical antenna modeling, design and characterisation. Recognizing the tremendous potential of this technology, practical applications are also outlined. Presenting a clear translation of the concepts of radio antenna design, near-field optics and field-enhanced spectroscopy into optical antennas, this interdisciplinary book is an indispensable resource for researchers and graduate students in engineering, optics and photonics, physics and chemistry.
Thanks to Copper Mountain
Technologies for Support
Copper Mountain Technologies makes lab-quality virtual vector network analyzers with high accuracy, wide dynamic range, a familiar UI and a broad variety of standard and customizable features in frequency ranges from 300 kHz to 8 GHz. Where did the name come from? Read here (near page bottom).
SigaTek Will Be Continuing
It is mainly advertisers that keep RF Cafe on the air, so to speak, to many thanks to SigaTek. SigaTek 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.
How Many Know -40°F = -40°C ?
Some of what you and I consider common knowledge is largely unrealized by most people. Call me a geek, but I take pleasure in pointing out to people that the Fahrenheit and Centigrade scales are equal at -40°, and I especially enjoy working out the simple proof for them. Most people appreciated the effort and are amazed, claiming to have never seen that before. When I read the following in Smithsonian magazine, "Winter temperatures here, some 250 miles northeast of St. Petersburg, sometimes plunge to minus 40 degrees Fahrenheit," I wondered whether the author knew that -40°F = -40°C. Maybe he just didn't want to confuse his readers by omitting the redundant superfluous 'F' or 'C,' and it couldn't be 'K' because there are no negative Kelvin degrees. It could also be that he knew but figured...
Z-Comm Intros 8 GHz Low
Noise Dielectric Resonator VCO
Z-Communications' new high performance DRO8000A covers 8000 MHz within a tuning voltage range of 0-12 Vdc and is ideal for the test and measurement market. Utilizing dielectric resonator technology this VCO features a typical phase noise of -103 dBc/Hz @ 10 kHz offset and an average tuning sensitivity of only 1 MHz/V.
Sherlock Ohms: What's the
Design News' 'Sherlock Ohms' mysteries are submitted by their readers. They tell stories of electronics posers and how the e-sleuths solve them. I only link to ones that RF Cafe visitors might enjoy. This one is a good reminder of unintended consequences of outdated government regulations and how fear of nonconformance can in and of itself result in nonconformance.
NuWaves Adds New England
NuWaves Engineering, an international Radio Frequency (RF) and Embedded Systems solutions provider, announced today that it has added Lighthouse Technical Sales, LLC as a representative of its commercial off-the-shelf (COTS) RF module-level products and engineering design services for the New England region of the United States. With the signing, Lighthouse brings NuWaves nearly 75 combined years of successful OEM sales in RF, interconnects, fiber optics, and other high-technology electronic products to NuWaves’ expanding domestic sales representative network.
USAF Radar Tech Manley Head
Joins Our Honored List
We welcome Manley Head as the newest addition to our ever-growing list of former USAF radar technicians. Per Manley, "I read the article about the GCA radar and it took me back to the days that I was a radar technician on the original MPN-1 GCA from about 1956-1959 in San Angelo, TX and in Harlingen, TX. The unit in the picture does not look quite like what I remember about the exterior. The antennas seem different from my ancient memory. However, the truck showing in the picture had a big 'Buddha' diesel generator in it that we had to start up once in a while. We had to bleed the fuel lines while it was running to get the air out. Odd how such such details stick in my memory."
Thanks to Vida RF
for Continued Support!
"Our goal at vidaRF is to design and manufacture a reliable and cost-effective RF / microwave component that fits each customer's individual application. We have the capability to produce large volume as well as quick turnaround for your custom designs. We will provide the highest standards of quality products, competitive prices, quick turnaround and exceptional customer service. We engineer unique simple solutions for defense, multimedia, medical, datacom, telecom, and industrial markets."
18 People You Didn't Know
EDN website's Senior Technical Editor Charles Murray posted an interesting piece on well-known people who you might not have realized were engineers. U.S. presidents Herbert Hoover and Jimmah Cahtah[sic] are amongst them. Not on the list are Rowan Atkinson and Brian May, guitarist of the band Queen, has a PhD in astrophysics (although that's not engineering).
Here is a great treatise on waveguide theory put in layman's language. Although written in 1948 at a time when microwave frequencies were just coming into common use, the language and descriptive drawings are similar to what you will find in modern textbooks. Waveguide is not practical for use at lower frequencies because the physical dimensions prohibitively large. For instance, for the FM radio band (88-108 MHz), waveguide width for a TE10 cutoff frequency at 88 MHz is around 67.5 inches. According to Wikipedia, the first waveguide was proposed by J. J. Thomson in 1893 and experimentally verified by Oliver Lodge in 1894.
How much do you pay every month for all of your personal communications? That includes, but is not limited to, smartphones with data plans, land lines, Internet, cable TV or satellite TV, wireless tablets and computers. Life in 2013 practically requires some degree of connectivity, but many people are paying for way more of it than necessary. I absolutely need a high speed Internet connection because of publishing RF Cafe (14 Mbps for $44.90 per month). Since most of my personal communications are via e-mail, phone service is not a high priority so my cell phone is a TracFone that I pay under $100 per year to use (mainly when away from home). Since there is no time for TV, any watching is done via the Internet - it doesn't matter if shows are a week or month old - so no cost there. I like using an old-fashioned telephone with a handset at home, so a landline is also used. Up until a couple months ago I was paying the local phone company $27 per month for basic local service (no long distance, caller ID, messaging, etc.)...
"David Ortiz spoke from the heart at today's Red Sox game. I stand with Big Papi and the people of Boston." - FCC Chairman Julius Genachowski tweet. So, the FCC has now endorsed dropping the F-bomb over public airwaves. You can be excused for just about anything these days if you're the right person.
Please Visit BRL Test
BRL Test is continuing its support to help deliver this website to you. Please keep them in mind when shopping for new or reconditioned test equipment. They also have a newer service specifically focusing on spectrum, network, and communication analyzer repair and calibration - BRL Test Analyzer Repair.
Free White Papers and Tech
Well, to be honest they're not completely free. You do need to fill out an application, so some of your time is required. Otherwise, though, the publishers pay the cost.
in a Multielement Quad
Multielement quad antennas are as popular today as they were in 1967 when this article appeared in the ARRL's QST magazine. That is not to say they are common. This particular design is for the 10-, 15-, and 20-meters bands, all three of which are still in use today. If you build a multielement quad as shown here, you might want to find a substitute for the bamboo frame members; aluminum tubing is pretty cheap, but if you use metal, you'll need to use insulators at the connection points. Formulas are provided for determining element lengths and director and reflector spacings if you want to design to an alternate specific frequency or band.
Resistor and Capacitor
Color Code Charts
As time marches on and electronics components get smaller and smaller, there is no just no room to apply color code markings for values, but in a lot of instances there is not even room to apply a laser alphanumerical marking (at least not one large enough to be seen with an unaided eye). This goes for common passive components like capacitors, inductors, and resistors as well as for integrated circuits, RF couplers and power dividers, diodes, and transformers. Open your cell phone and try to find a useful component designation. Only the largest parts will have anything you can look up on the Internet. There are ways to hunt down identification for some of the parts, but at least for Rs, Ls, and Cs, the only way to discover a value without the assistance of a schematic is to measure it. If you look at older electronics equipment, you will immediately notice color stripes and/or dots on many components. The tables below will help you decipher the meanings for component value, tolerance, temperature coefficients, etc. ,as applicable.
Anatech Continues Their
Many thanks to Anatech Electronics for continuing their support of RF Cafe. Anatech Electronics designs and manufactures the industry's widest range of RF and microwave filters at frequencies up to 40 GHz, as well as power dividers, directional couplers, and many other product types. Specialize in standard and custom designs for commercial wireless, public safety, satcom, and defense applications.
RF & Microwave Engineering
Crossword for 4-21-2013
Every Sunday I create a crossword puzzle using a word list that I personally created and added to during over a decade of making puzzles. All of the words are related to engineering, science, mathematics, chemistry, astronomy, etc. There are no numbnut clues about movie stars or clothing designers. Enjoy.