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.
My Hobby Website:
The inventions and products featured on these pages were chosen either for their uniqueness in the RF engineering realm, or are simply awesome (or ridiculous) enough to warrant an appearance.
All Featured Product Archive Pages:
Vintage Technology Site is chock full of information on products from the early to mid 20th century. Wind-up
clocks, console televisions, Bakelite slide viewers, radio voltmeters, even bijou adapters are included. A lot
of the images are from magazines, but some are of the actual products and/or their original packaging. There
are also vintage technology items available for sale. You might even have something that he is willing to pay
for. A page of links to other collector websites is provided as well.
"Don't pay thousands for an old HP signal generator!" That's the admonition offered by the makers of the the Windfreak Synthesizer. It could be sound advice. Running under Windows via a USB port, for $249 you get this 137 MHz to 4.4 GHz software-tunable, PLL-synthesized RF signal generator. Some specs: Phase noise < -107 dBc at 100 kHz offset at 2 GHz, 0.4° RMS from 100 Hz to 1 MHz (good for 64PSK). Pmax into 50 Ω is 0 dBm @137.5 MHz, 0 dBm @500MHz, 1.5 dBm @1 GHz, 5 dBm @2GHz, 0 dBm @4 GHz, accuracy is based on an onboard 25 ppm 10 MHz crystal oscillator. It takes up a whole lot less space on a workbench than a 3U-high rack-mount chassis!
You have seen or used one of those plug-in OBD handheld automotive diagnostic devices that scan your vehicle's onboard computer for stored data. Police investigators use them at accident scenes to collect info on your driving history (acceleration, speed, braking) for possible use in court. Cell phones and PDAs are now being heavily used to solve crimes and prosecute criminals (and a few innocents). Portable systems like CelleBrite Mobile's forensics kit includes cables and a handheld computer that can pull pictures, videos, text messages, call logs, and other data from cellphones and PDAs at a crime scene. Laws are being placed on the books detailing how data extraction must be conducted in order to avoid tainting evidence. It is somewhat like the Heisenberg Uncertainty Principle of evidence gathering, where the act of observing the data affects the quality of the data collected.
many years I have wondered why cruise controls in vehicles did not include a braking function that would be
able to maintain speed when going downhill or being impeded by multilane traffic. Well, it appears Bosch, TRW,
Delphi, and others already thought of that and have solutions in their Adaptive Cruise Control (ACC) systems.
This particular video is of the Bosch system. A mm-wave radar unit measures distance and relative speed to
feed data to the microprocessor that determines when to apply the brakes or when to give it the gas. ACC is
smart enough to compensate for rapidly varying traffic speeds, as well as for lane changes and even going
around corners. An ability to monitor vehicles in multiple lanes is incorporated into it decision making.
High-end auto makers like Lexus, Audi, Mercedes, et al, have been offering it for a few years. The low-end
heaps I can afford are still waiting for a price reduction; I will be tapping the brakes and mashing the
Resume button myself for many more years.
Apps for phones have been around a long time, and in most realms of technology, the level of sophistication grows over time. MW Toolbox for the Android is a good example. The free Lite version includes attenuator (pi and T, reflectometer, and mismatch error limit calculators. For the über rich that can afford the €1.99 ($2.60) price tag, you also get microstrip, stripline, coplanar waveguide, power and voltage converter, field intensity and power density converter, parallel LCR impedance, series LCR impedance, inductor & capacitance impedance, Ohm's Law, and radar equation calculators. The author is taking requests for new calculators.
A new version of the wildly popular RF Stencils for Visio has finally been released. A lot of people have wanted pre-colored symbols and the addition of new symbols. Done. I also included the connector points for Visio's built-in interconnect lines that follow components as they are dragged around the drawing. Test equipment and rack stencils now have text that scales with the object as the size is changed (not a built-in Visio action). The ARRL schematic symbols are still include for the still low, low price of $15. Upgrades for v1 users are a mere $10. You would burn up that much money creating just one of these symbols on your own at an engineer's rate.
A couple weeks ago, RF Cafe visitor Patrick Stox, of LBA Technology, contacted me with a story and photos of an über triplexer project that engineers at the company had completed. The pictures alone of these huge filters are cool enough, but the location for installation is really unique. They recently shipped a specially built advanced technology medium wave (540-1700 kHz @ 100 kW) triplexer system to the Broadcasting Corporation of China for installation in Taiwan. Site limitations required that the triplexer operate into an electrically short tower in the middle of a lake, with only a small platform area 30 feet above the water available for the tower base and the triplexing equipment.
The Pocket Radar Personal Radar PR1000 can reliably measure a baseball pitch from the backstop on 90 foot baseball fields, or a car from 1/2 a mile away with accuracy of +/- 1 mph. Operating in K-band at 24.125 GHz, the Doppler algorithms measures from 7 to 375 mi/hr (11 to 600 k/hr) with an accuracy of ±1 mi/hr (±2 k/hr). Weight is just 4.5 oz. with batteries (10,000 readings on 2 "AAA" alkaline batteries). Operating temperature range is 20 to 140 °F (-6 to 60 °C) A zero IF receiver is used along with a dielectric resonator oscillator and high-gain vertically-polarized planar antenna array. The PR1000 can measure acceleration by making and storing up to 10 measurements in 0.75 sec increments - you have to do the math.
A year or so ago I posted information on AlphiMAX's web-based Point-to-Point Estimator. It is a very well-designed application for planning wireless radio links that enables you to compare equipment performance, while taking into account the 3-D terrain details of your separated network points. The program has been upgraded with significant new features that include, among others, an ability to integrate with the Google Earth database and the addition of new products operating up to 23 GHz. All of this is provided at no cost to the user; i.e., it is FREE. AlphiMAX developed the tool to facilitate their primary business of providing technical resources to system planning and implementation engineers as well as to equipment vendors.
is the name for a Japanese flowering cherry tree. It is also the name of a website that offers more than a
score of Java applets for electromagnetic calculations and accompanying dynamic plots. It is all free. Smith
charts, antenna fields, shielding effectiveness, transmission lines, standing wave visualization, and
waveguide fields are the subject of very professionally done coding.
The creators wrote a book called Fundamentals of Applied Electromagnetics that includes a CD with everything
here and more.
RF Cafe visitor Gary M. recently wrote to recommend a product called ACF-50 for corrosion control on electronic and mechanical components. It is a rust dissolver as well as a preventative coating, and is used by top aircraft manufacturers. ACF-50 is certified under Mil-PRF-81309F, and manufactured under ISO 9000 certified processes. Uses include cleaning and protection of electrical connectors, component leads, sockets, cables, and PCBs. The October 2010 edition of QST magazine has an excellent article titled, "Is Your Tower Still Safe?," that explains the corrosion process and how to deal with it through proper preparation, including sacrificial anode usage and coatings. While not specifically mentioned in the article, ACF-50 could be a suitable compound to help control such issues.
The proprietor of the Excel Hero website contacted me because of a recent addition to his large collection of unbelievably clever Excel spreadsheets. If you appreciate the power of VBA (Visual Basic for Application - I use it in the RF Cascade Workbook series), then you have to spend some time on the site. This particular spreadsheet is for a Smith Chart that is created dynamically from textbook equations. There is a very nice tutorial included. It does not have the built-in ability to plot actual impedance or admittance points, but if you want to do so, you can take a look at the equations I created in my Smith Chart for Excel file (free) and integrate them into this one.