RF Cafe Software
About RF Cafe
1996 - 2022
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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There are 1,000s of Pages Indexed on RF Cafe !
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.
Homepage Archive Pages
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2013: Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec
Here is page 2 of the March 2015 homepage archive.
How to Use Grid Dip Meters
(aka Grid Dip Oscillators)
Grid dip meters, aka grid dip oscillators (GDO in this article), are extremely useful for determining when a circuit is functioning at resonance. In the words of Sherlock Holmes, "It is simplicity in itself" the way a GDO operates. The grid dip oscillator emits power at a calibrated frequency which is absorbed (or not) to a degree depending on how close to resonance the external circuit under test is to that frequency. The nice thing about this type of instrument is that it does not need a wired or other type of physical connection to the circuit. Of course modern day GDOs do not use vacuum tubes with grids that register relative current levels as an indication of resonance, but the nomenclature has persisted …
Skyworks Intros Step-Down
Converter for Multiple Apps
Skyworks introduces a step-down, DC-DC converter for automotive, distributed power, industrial, and medical applications. The 28 V, 3 A, non-synchronous SKY87608-11-577LF is also applicable for general purpose, point-of-load, 16 V, 20 V, and 28 V voltage regulators. The converter offers prime thermal performance and space savings in addition to addressing the green-power initiative in the non-portable markets. The competitively priced high-performance solution comes in a SOP-8L, EP, 5 x 6 x 1.55 …
Radio Wave Curvature
Early investigations into RF signal atmospheric 'ducting' was reported in this 1956-era article in Popular Electronics. Ducting effects were first noticed during World War II when Nazi broadcasts from occupied Paris were received occasionally in London. Scientists discovered that a small change in the humidity of the air near the surface has the effect of trapping radio waves, a trapping process dubbed "ducting." These waves are conducted as if they were inside of a metallic waveguide. Research by the U.S. Army Signal Corps determined a sudden temperature rise of around 50 to 200 feet above the surface appears …
from 1963 Electronics World
Research has shown over and over again that engaging in mental exercise is a good way to stave off senility in old age. Playing musical instruments, writing software, working crossword puzzles, and other types of activities that require logic, physical dexterity, and memory recall are often cited as examples. There is no guarantee these things will prevent or even delay cerebral atrophy, but why take a chance? Work this crossword just to make sure. Disclaimer: I am not a doctor and am not prescribing this challenge as a remedy for potential future imbecility, daftness, tendency to dodder, mental infirmness, or senescent gray matter accumulation, nor do I suggest that starting now will reverse …
R&S SMW200A Creates Signals
for Complex A&D and 5G Apps
Rohde & Schwarz now offers three new options for its R&S SMW200A high end vector signal generator with microwave frequency ranges from 100 kHz to 12.75 GHz, 100 kHz to 31.8 GHz and 100 kHz to 40 GHz. An option covering the range between 100 kHz and 20 GHz has been available since the summer of 2014. The R&S SMW200A is the only microwave signal generator on the market to combine a baseband generator and RF generator with fading, AWGN and MIMO capabilities in a single box. As a result, it supports numerous challenging aerospace and defense and wireless communications applications …
KR Intros 10 MHz Bidirectional
Absorptive Notch Filter
KR Electronics part number 3230 is a 10 MHz bi-direction absorptive notch filter. The filter maintains excellent forward and reverse return loss even throughout the notch frequency. The filter has a typical 3 dB bandwidth of 1.66 MHz and 60 dB bandwidth of 577 kHz. The filter is supplied with SMA connectors. Other frequencies and bandwidths are available.
Ripple Filter Design Chart
Even in this age of a prodigious supply of computer programs and mobile device apps (OK, apps are also computer programs) to calculate circuit component values and responses, having a cool graph to look at can take a lot of mystery out of the results. Depending on the sophistication of your software, calculated values can be unrealizable in real life (size, power handling, standard values, Q, operational frequency, etc.), or maybe you have a box full of parts you want to use and the suggested value is not readily available. In those instances and others, being able to grab a handy-dandy design chart to see where component values lie with respect to all design parameters, in this case load impedance, desired power supply ripple, inductance and …
Why FR-4 Is Often Inadequate
for RF Design
Ed Troy, owner of Aerospace Consulting, LLC, was kind enough to offer a few of his articles for posting on RF Cafe. With more than 30 years in the electronics communications design field, Ed has a lot of valuable knowledge to impart to us mortals ;-) This second paper discusses why using a less expensive substrate material for a production printed filter design can be much more costly in the long run. As the old says goes, a picture (in this case a screen capture) is worth a thousand words. He's a highly rated airplane pilot as well, which counts for something in my book. Stay tuned for others...
MFJ-969 300W 6-160M Deluxe HF
Antenna Tuner w/4:1 Balun
As with most other types of commercial electronics products, Ham radio equipment is sold by many distributors at prices discounted below MSRP (manufacturer's suggested retail price). Manufacturers usually have sales agreements with distributors that they (the manufacturers) will not offer lower prices for current products in order to not compete with their distributors. When shopping for deals, be sure to consider return policies and shipping costs (inc'l for returns). Amazon, while sometimes not the lowest posted price, is very good in customer service and free shipping, often making them my choice; I buy almost everything online through them. If you plan to buy via Amazon, please start your shopping with a link from RF Cafe since I make a few ¢ commission on the sale and it doesn't cost you extra. Thanks.
Resistance of a Ground
For some reason the subject of grounding has been very prominent in my reading in the last few days. The chapter I just finished reading in one of David Herres' books on the National Electric Code (NEC) covering grounding of commercial and residential services, an article by H. Ward Silver in QST titled, "Grounding and Bonding Systems," and now this article by John T. Frye (of Carl and Jerry fame) on grounding, makes for a wealth of knowledge. Mr. Frye takes a unique approach at teaching by exploiting his gift for story-telling. In this article, electronics repair shop owner Mac give technician Barney a nice bit of tutelage on what constitutes a good Earth ground and what does not. In some …
Maiden Flight of My 105%
Airtronics Aquila Sailplane
There are some RF Cafe visitors who are into model building and operation, so this might be of interest. Radio control systems these days use a combination of DSSS and FHSS modulation on the 2.4 GHz ISM band, while the brushless motors and LiPo batteries used are state-of-the-art. Back in the late 1970s I built an Aquila sailplane from plans that appeared in RC Modeler magazine, then I built another Aquila in the early 1980s from a kit. Both are long gone. About 6 months ago while waxing nostalgic about the Aquila, I decided to build another, but this time I had the plans enlarged to 105% to get the wingspan over 100" while not having to change airframe component sizes. This version has a 0.10 size electric motor for power. I wanted to determine the amount of down-thrust needed to prevent a nose-high climb prior to final nose shaping and canopy installation. For this maiden flight, there was about 8°, which was not enough. It really needs about 12° …
Eagle Comtronics Intros
Blockband Tunable Satellite Filter
Eagle Comtronics Model NF-1110-TUNABLE passes the entire satellite block band from DC to 2500 MHz. The tunable notch filter is preset to a center frequency of 1110 MHz and tunable ±40 MHz with a passband loss less than 1.0 dB (0.5dB typical). Factory set notch depth is 15 dB with a 3 dB bandwidth of 3 MHz. Power capability is 1 A at 20 VDC. Connectors are 75 ohm type “F” female/female and the unit measures 8.5” X 1.75” X 2.5” approx. Unit is designed for indoors use. 30 dB and 40 dB models also available. For different frequencies, connectors and …
Radar Reaches the Moon
"These pulses speed toward the moon at the fantastic speed of light… through the ionosphere and on into the unknown void surrounding the earth's atmosphere [emphasis added]." Hard as it might be to imagine nowadays, in 1946 there was no empirical data regarding the Earth's upper atmosphere other than the few instrumented sounding rockets that had been launched for studies. Orbiting man-made communications satellites were still a decade away when engineers at the Evans Signal Corps Engineering Laboratory in New Jersey made the first Earth-Moon-Earth (EME, aka 'moon bounce') signal bounce using a massive radar and antenna that blasted 10 MW EIRP pulse at the lunar surface. It was a big deal then; it's no big deal today. Amateur radio hobbyists routinely conduct EME …
Anatech Electronics Intros
3 New Filter Designs
Anatech Electronics offers the industry's largest portfolio of high-performance standard and customized RF and microwave filters and filter-related products for military, commercial, aerospace and defense, and industrial applications up to 40 GHz. Anatech has released three new filter designs: a 90-1100 MHz connectorized highpass filter, a 100-1250 MHz surface mount LC lowpass filter, and a 2574 MHz connectorized highpass filter. All can be ordered directly through their AMCrf web store.
Notable Tech Quote
"The explanation for the occurrence of power amplification in the junction transistor is somewhat less complicated than is the case with the pint-contact transistor, but it is still too abstruse to attempt here except to say again that two junction areas interact. A more thorough explanation calls for the use of the concept of conduction by 'holes' in addition to conduction by electrons. Holes are places in the germanium crystal atomic structure where electrons could be but are not. Although this sounds ridiculous it has considerable foundation in fact. These holes do enter into the conduction process and behave as if they were positive electrons. There is no …
Free Engineering White Papers
& Books for March 2015
The free whitepapers, pamphlets, books, and chapter examples listed here are a small sample of a lot of new items that are offered for FREE through TradePub. The publishers make them available to qualifying people as a promotional campaign for their full line of offerings. You might want to take a couple minutes to see what's new there. They are all free downloads.
What is Q?
'Q' is an often used term to describe the electrical 'quality' of a circuit or component, and for the most part anyone engaged in the conversation (verbally or via reading) understands the concept. However, having a firm grasp on the technical ramifications is required if you happen to be a circuit or system designer and need to conform to certain specifications. 'Q' can be good or bad, depending on your needs. If, for example, you need a narrowband receiver to reject adjacent signals or you are designing a high stability and spectrally clean oscillator, then you want all the 'Q' you can get. On the other hand, if your goal is to receive a spread spectrum signal or generate white noise across some bandwidth, then a lower 'Q' is what you want. This article provides a brief look at …
New Version of NI AWR Design
Environment Now Available
NI (formerly AWR Corporation) announces the immediate availability of the 11.03/.04 release of NI AWR Design Environment™ high-frequency software, inclusive of Microwave Office, Analog Office, Visual System Simulator™ (VSS), Analyst™ and AXIEM for the design of MMICs, RF PCBs, RFICs, microwave modules, communication systems, radar systems, antennas and more. More than 100 improvements, enhancements and user interface changes are contained within this release …
Send Me Your Company's
Job Opening Announcements!
If your company has a current opening for an engineer, technician, manager, salesman, or other relevant position, you might want to let the appropriate HR people there know that they can have those job opportunities posted at no charge on RF Cafe. More than 8,000 of the very type people you are seeking visit RF Cafe on a typical weekday, so don't miss the opportunity. Only offers from direct hire employers are accepted - no recruiters. It could be a good way to filter out a lot of worthless resumes because let's face it, RF Cafe visitors are the kinds of people you want to hire :-)
Career and Job Hunting Advice
Oddly, most of this roundup of career and job hunting articles have titles asking questions, as opposed to the typical counted ones that have '5 ways' to do this or '7 things' not to do. The most interesting article, IMHO, is Alan Murray's piece on what Millennials are looking for in terms of opportunity, stability, situation, etc. Not too surprisingly, according to Mr. Murray the 'Me' generation seems to be comfortable with big government programs with its accompanying social program safety nets, and are largely compliant and willing to be fit into a mold as long as their network of 'friends' (real-life and online) is not compromised. Be sure to see the Pew Research Center study that he cites. This situation most likely does not apply as much to RF Cafe visitors, who are …
Send Me Your Company's
Since deciding to discontinue the hosting of private advertising on RF Cafe, I have had many requests to resume the program. Serving between 7,000 and 9,000 pages each weekday provides a valuable amount of exposure to people like you - serious engineers, technicians, students, and hobbyists. While I do not plan to reconstitute private advertising anytime soon, there remains a very easy - and FREE - way for you to get your company's products and services in front of RF Cafe visitors: Press Releases. If your company makes products that I deem relevant to my readership, I will gladly post your press release, company news, product announcements, etc. Please send the information, along with …
Pasternack Releases Broadband,
High Power Coaxial Limiters
Pasternack, a leading manufacturer and supplier of RF, microwave and millimeter wave products, debuts their new broadband, high power coaxial limiters which help protect sensitive low power RF receivers and other microwave circuits in close proximity to high power signals. Common applications for these RF limiters include electronic warfare, instrumentation, fiber optic communication systems, military communications, radar, SATCOM, point-to-point radio, telecom, data links and R&D. Pasternack’s latest release of high power limiters consists …
Daylight Saving Time
This week's Daylight Saving Time crossword puzzle has a few special words and clues related to our biannual timekeeping shift. All the rest of the words and clues are engineering and science related - no movie star names or clothing designers.
R&S Unique 2 GHz Analysis BW
in FSW High End Signal Analyzer
Rohde & Schwarz is expanding the analysis bandwidth of its R&S FSW high end signal and spectrum analyzer to 2 GHz by introducing the new R&S FSW-B2000 hardware option. This test solution enables R&D users to demodulate extremely wideband signals and analyze them in detail. There is no other instrument on the market that combines such a large analysis bandwidth with a frequency range up to 67 GHz, and it opens up numerous applications. For example, users can measure the EVM values of communications signals or the chirp rate on chirped radar systems …
Heaviside Orbital Step Function
Occurs This Weekend
Twice each year the Earth undergoes the first of two annual Heaviside step functions in its orbit around the sun. Earth is the only celestial body known to be subject to such a phenomenon. The Bible says God stopped the Earth it in its tracks one time, but that is nothing compared to what truly omnipotent kings, politicians, and bureaucrats have decreed to occur since the early part of the last century. Those megalomaniacs instituted Daylight Saving Time here in the U.S. and most other parts of the world with a scheme which each year causes clocks to be advanced by one hour near the vernal equinox and to be retarded one hour around the autumnal equinox. Experts disagree on who was the first person to propose our inconvenient timekeeping shift; some credit (or blame) a New Zealander named George …
LinkedIn, Twitter, and Facebook
Are 'Write-Only' Venues
If you have ever sent me a message via LinkedIn, Twitter, or Facebook and I have not responded, please know that it is not because I elected to ignore your message. Rather, it is because I use those three venues in a 'write-only' manner. My trusty secretary, Melanie, posts the items for me on LinkedIn, and then LinkedIn has a feature where it automatically broadcasts the same message on both Twitter and Facebook. So, I typically do not see or read messages from social media users. If you want to contact me for any reason, please send an e-mail to email@example.com. I always respond to e-mails from legitimate senders; i.e., those not from the widows of Algerian princes or from Chinese aluminum window blind manufacturers …
Congrats to February Book
Winner Stephen B. !!!
Congratulations to Stephen B., of Georgetown, TX, for being selected as one of the February 2015 RF Cafe Book Drawing winners! Stephen opted to receive Aviation Security Engineering: A Holistic Approach, by Rainer Kolle, Alex Tarter (graciously provided by Artech House). Two other people have been notified for having been selected, so check your e-mail if you either bought a software item from me or submitted an entry in the month of February.
Using Simulation Tools to
Troubleshoot an LC Filter Design
Ed Troy, owner of Aerospace Consulting, LLC, was kind enough to offer a few of his articles for posting on RF Cafe. With more than 30 years in the electronics communications design field, Ed has a lot of valuable knowledge to impart to us mortals ;-) This first paper discusses a method for accommodating real-world stray capacitances in the simulation model for helping to assure first-pass success on LC filter designs. He's a highly rated airplane pilot as well, which counts for something in my book. Stay tuned for others …
Carl & Jerry:
Extra Sensory Perception
Carl and Jerry were early adopters of the near field communications (NFC) craze that is going full-swing today. The often harmlessly mischievous teenage duo used their combined grasp of modern electronics to pull off gags on unsuspecting friends... and sometime adversaries. In this episode, a near-field transmitter and receiver pair is designed to help Carl bedazzle a scientist who was attempting to disprove the ability to use extrasensory perception (ESP) to determining what another person was thinking about. In this case it was detecting which playing card was being displayed on an overhead projector. Of course Carl didn't really have 'the gift,' but relied on his co-conspirator, Jerry …
Pilotless Plane Run by Radio
News reports are full of features about the wave of radio controlled (R/C) 'drones' terrorizing citizens with their often inexperienced pilots navigating their camera-laden craft to peer into bedroom windows, obtain 'birds-eye' views of sporting events, and to be a general pain in the posterior to people trying to enjoy their right to privacy and safety (except, of course, unless it is the Government choosing to violate them). Incredible advances in radio, navigation, and sensor systems has facilitated a wide variety of very affordable multirotor (the correct term, not 'drone') aircraft that can literally fly themselves. For under $500 you can buy a GPS-guided multirotor that can be programmed to fly to one or more waypoints and return to the launch location, with range and flight duration limited …
Werbel Microwave Intros 4-Way
Splitter for 2-18 GHz
Werbel Microwave expands its series of 2-18 GHz coverage with the new, model 4PA1000 four-way SMA splitter. Can be optimized using our trade techniques to meet strict amplitude and phase balance per customer requirements. High isolation, typically 22 dB or more between all branches. Great for lab test setups, made in USA.
Frequency & Time Standards
It was not until 1963 that the International Committee of Weights and Measures (CIPM) adopted the cesium clock as the world scientific community's standard time reference. It boasted an accuracy that kept it within 1.1 parts in 100 billion, meaning it would not gain or lose more than a second in 3 thousand years. To show how far technology has advanced since 1963, in April of 2014 the National Institute of Standards and Technology (NIST) launched a new atomic clock called NIST-F2 (also cesium-based) to serve as a new U.S. civilian time and frequency standard. NIST-F2 would neither gain nor lose one second in about 300 million years - a factor of 10 thousand. According to the U.S. Navy's official Time.Gov website, the Internet time reported on my computer was 1 minute and …
Coaxial Cable Advertisement
Amphenol has been around since 1932, when founder Arthur Schmitt offered sockets for vacuum tubes. Now headquartered in Wallingford, CT, the company began life in Chicago, Illinois. Amphenol was a major supplier of coaxial cable in the days when most of the cable Americans used was produced in the country. Alpha Wire, Amphenol, Carol Cable (now part of General Cable), and General Cable are the names that come to mind that were around in the 1970s when I entered the radio-electronics realm. The radar system I worked on in the USAF, and all of the defense electronics electronics systems I worked on as a technician and engineer, used those four brands. Today, of course, there is a seemingly unlimited number of coaxial cable …
Poll: Which OS Does
Your Phone Use?
Terahertz Metrology, by Mira Naftaly. "This new book describes modern terahertz systems and devices and presents practical techniques for accurate measurement with an emphasis on evaluating uncertainties and identifying sources of error. This is the first THz book on the market to address measurement methodologies and issues - perfect for practitioners and aspiring practitioners wishing to learn good measurement practice and avoid pitfalls. This book provides a brief review of different THz systems and devices, followed by chapters detailing the measurement issues encountered in using each of the main types of THz systems, and a guide to performing measurements rigorously. Particular attention is given to evaluating …
Training with Visual Aids
Long before there was Power Point (OpenOffice's Impress is the free equivalent), presentations at training seminars were conducted using overhead projectors and larger-than-life props of the devices being taught. The U.S. Navy, during World War II, set up a special facility called the Visual Aid Model Shop located at Radio Chicago, Chicago, Illinois. Its charter was to design and build very large scale models of equipment and tools that service personnel used while performing their duties. It is kind of funny to look at the sizes of some of the items, like the 8x size radio chassis assembly shown in this article's main photograph. As a life-long model builder myself, I would have loved to work in a shop …
RFMW SM Iso-Attenuator for
High Power Circuit Protection
RFMW announces design and sales support for the Iso-Attenuator model RFSL2308-A30 from RF Circulator Isolator (RFCI). RFCI Iso-Attenuators combine protection for active components from distortion or potentially damaging reflected power with a convenient, attenuated port for monitoring RF power or providing a feedback loop. The RFSL2308-A30 is capable of handling 1000 W peak / 200 W average forward power and 100 W CW reverse power into the on-board, 30 dB attenuator. Spanning 2200 to 2400 MHz, the RFCI RFSL2308-A30 provides >25 dB typical port-to-port isolation …
Notable Tech Quote:
- Marshall McLuhana
"Xerography is bringing a reign of terror into the world of publishing, because it means that every reader can become both author and publisher." - Marshall McLuhana, 1966, from March 2005 Smithsonian magazine. An unregulated Internet provided the next step in that freedom. On February 26, 2015, the FCC adopted "Net Neutrality," giving the Federal government control over the Internet under the guise of protecting little 'ol you. Be sure to thank the people you know who voted for the people who passed this. If you think you're being spied on now, you ain't seen nothin' yet.
NI AWR Design Environment
Application Note Now Available
NI (formerly AWR Corporation) released a new NI AWR Design Environment application note, “Improving the Second-harmonic Pass Band Rejection of Microstrip Side-coupled Filters.” Because of their low cost and easy manufacturability, side-coupled filters constructed from printed-circuit board-based microstrip are widely used throughout the industry. One of the main drawbacks of the side-coupled filter is its limited rejection of the second harmonic. This application note demonstrates a solution that mitigates this problem through the introduction of notch-filter elements that improve the overall rejection of side-coupled filters at the second harmonic without significantly affecting the filter passband behavior …
February 2015 Book Drawing
Winners Have New Selection
Thanks to Qorvo's Jeff Cameron, Sr. Manager, Product Marketing, Filter Solution, for providing this very high quality polo / golf shirt (made by the Pebble Beach brand) with a Qorvo company logo embroidered on the front. It is being offered as a prize selection in the monthly RF Cafe Book Drawing. I knew Jeff back in the early / mid 2000s when I worked for RF Micro Devices in Greensboro, NC. As you probably know, RFMD merged with TriQuint last year and became Qorvo. Both of February's winners have been notified, but I haven't heard back yet from either. The shirt might be gone before the March drawing occurs.
and Mixed Applications
Synergy Microwave currently has an opening for an Intermediate Engineer: Embedded Hardware/Software and Mixed Applications. A very exciting opportunity to join a strong engineering team dedicated to developing radio frequency products for the microwave communication, microwave instrumentation, radar and defense applications. You will have extremely deep resources and guidance for modern radio product development using mixed signal and digital radio techniques. Qualifications include experience in radio frequency applications, modulation algorithms, signal detection, leveling and control …
See The Full-Page Splash Ad
You've Been Missing on RF Cafe
Are you kidding me ?!?!?! Why in the world would you WANT to see a full-screen splash ad when you visit any website? I absolutely detest those things. When I visit a website, I want the first thing I am presented with to be the content of the site, NOT a full-page advertisement with some lame message like, "Please wait while your page is loading," or "Welcome Screen," or some other annoying and/or disingenuous text. Do the webmasters really think visitors are stupid enough to believe that the website's real content is loading behind the advertising screen, and that they are doing visitors a favor by providing …
Radar Engineering Crossword
Puzzle for March 1, 2015
I stopped creating the RF Cafe engineering and science themed crossword puzzles at the end of January in order to test the interest in them. As of today, on March 1st, I will resume creating them every couple weeks. It takes up to an hour to make each crossword. Enjoy this radar engineering themed puzzle.