One of my clients asked me to research really low-cost EMI antennas they could use for bench top troubleshooting radiated emissions. I wanted ones that included long coax cables and had common connectors attached. A quick search on Amazon revealed a couple affordable antennas that could be used. After ordering them, here are the results.
This one has a fixed total length of 10.5 inches (half wave), so the resonant frequency would be 565 MHz. This would still work for most emissions, so long as it was positioned close enough to the EUT. If it could be placed at least 1m away and still observe the emissions, that would be fine. There is a sticky pad on the back where you could stick the antenna to a stick or wall for support. It includes a 2m long coax cable with BNC connector.
This one is much more versatile and the telescoping elements can adjust from 14 inches to 38 inches (half wave) and resonates from 77 to 422 MHz. This would be a much better choice, given that most emissions are in the range 90 to 300 MHz. For good measure, they also included a ferrite choke on the shorter cable. The included suction cup mount doesn’t appear to be a very reliable mounting solution, so I’d recommend a full-size or table top tripod to mount it. The antenna base includes a common 1/4-inch-24 threaded socket, so is designed to fit normal tripod screws. This one comes with a shorter coax cable and SMA connector, but with a longer 2m extension cable. I had to tighten the two hinge screws in order to keep the dipole elements in place. I’d probably use this one over the BingFu model.
Because neither of these antennas have calibrated antenna factors, they would only be useful for relative troubleshooting measurements. “Are the emissions getting higher or lower?”
My September 23rd presentation in Milwaukee went well with over 80 engineers from across the region attending. My thanks to the team of Milwaukee Section, IEEE EMC Society for hosting!
I tend to present seated in front so I can annotate the slides as needed. It also makes it easy to switch between the presentation slides and live camera, spectrum analyzer or scope shots on the projection screens. Pictured is the new Micsig TO3004 300 MHz BW scope (R) and Signal Hound BB60D 6 GHz spectrum analyzer (L). I set up the experiments using a SensePeek PC board holder and probing system. All the live demos of basic EMC concepts help set my presentations apart from others.
I was also honored to provide the keynote presentation, “Arcs & Sparks – Characterizing and Troubleshooting ESD”, at the Minneapolis EMC Event, September 25th. I was also able to present “Characterizing & Troubleshooting Wireless and IoT EMI”. Thanks to Dan Hoolihan and team for hosting!
I decided to list links to all the recent EMC-related articles I’ve written in the past years in ONE PLACE! While I hope this reference will help many, I also did this for myself as well. Ha ha! Please enjoy the bed time reading. EMC engineering and related product design and test is an important field. Here are some links to my recent articles. You’ll also want to subscribe (free) to In Compliance Magazine, Interference Technology Magazine and EMC Aware.
My Amazon Author Page (U.S.), where you may purchase my “EMC Troubleshooting Trilogy”, which includes a few of the articles above. This page should be available in other Amazon country storefronts.
My interest in radios and listening to AM “medium wave” (MW) and shortwave (SW) broadcast stations started at an early age. My dad was an electronics engineer and when I was about 10 years old, he made me an excellent performing crystal radio with components built onto a piece of plywood. Connecting a “long wire” antenna to this would bring in local AM broadcast stations, such as KFI (640) and other strong stations in the Los Angeles area. I’d lay in bed listening to stations before dropping off to sleep.
Later, I was given an old GE tube-type AM radio receiver, which could pick up stations across the U.S. during nighttime propagation. I’d log these “DX” (long distance) stations while carefully tuning the bands (530 to 1605 kHz at the time).
In the late 1960s, both my dad and I got hooked on Heathkit products and one Christmas, he bought me a GR-64 AM/SW receiver, which I carefully assembled. This started me on the path of receiving and logging various shortwave stations around the world. He had hooked up a long wire antenna from the house about 100 feet long to one of the farthest power utility poles. Now 1968 was at the peak of solar cycle 20 (NOAA), so reception was extremely good with the highly ionized atmospheric layers, allowing signals to bounce a long way.
The solar cycle from 1956 to 1978. Peaks represent the best SW propagation due to strongly ionized atmospheric conditions.
Later, both my dad and I purchased the latest portable shortwave radios at the time (1980), the Sony ICF-2001, which was an early synthesizer-tuned AM/FM/SW receiver. I still have this and it still works well and has connections for an external antenna (important for best SW reception). Who can remember the powerhouse shortwave station, HCJB, broadcasting with 500kW from Quito, Ecuador? Unfortunately, the internet and satellite technology has spelled doom for many broadcasters, such as the BBC, Deutsche Wella, and VOA, who have greatly reduced their shortwave broadcasting. But there are still many more countries who continue the tradition. Gayle Van Horn’s Global Radio Guide (Kindle only, now) include up to date listings of MW and SW stations with time and frequency information.
The Sony ICF-2001 digitally-synthesized AM/FM/SW radio (circa 1980).
My interest in radios ultimately led me to amateur radio, where I was now able to communicate with other hams throughout the world using these same shortwave bands. This, in turn led me to a career in electronic engineering where I spent most of it in electromagnetic compatibility (EMC) engineering.
So, circling back to late-2020, in reorganizing my storage closet, I ran into a boxed Radio Shack AM/FM/SW portable receiver (20-125) I’d purchased years ago and had never even opened. It receives AM (530 to 1710 kHz), FM (88 to 108 MHz) and SW (2.3 to 26.1 MHz). It uses 3 AA cells.
This radio (YouTube review) was unique in that it included 10 memory buttons for each band selected. So now I have ready access to the best received stations on MW, SW and FM broadcast. I can also directly enter frequencies, which is helpful. The scanning function seems to work well in locking onto active frequencies. It also includes a dual-time clock that I set for local and UTC time. The timer will automatically turn on the radio when you want and the sleep timer will let it play for a set amount of time before turning off. While it lacks an external antenna connection for my long wire antenna, merely connecting the end of it to the built-in antenna boosts the signals a great deal. A sensitivity switch reduces sensitivity for local stations.
The Radio Shack 20-125 AM/FM/SW radio.
So tonight, located in Colorado and reliving my childhood, I’m laying in bed listening to AM stations 50kW KFI (Los Angeles), KCBS (Los Angeles), KRVN (Nebraska) and others around the country – and this with nothing more than a built-in “loopstick” ferrite core antenna! Despite the poor propagation conditions (we’re in the bottom of the sunspot cycle) I can also hear several shortwave stations – mainly religious broadcasters from the U.S.
Radio Shack no longer sells much in the way of shortwave radios, although you can still find the excellent-quality DX-150 and DX-160 tabletop AM/FM/SW receivers in the used market. If its a portable radio you want, then the best brands are Eton (who purchased the Grundig line of products a few years ago), Sangeon, Tecsun, C. Crane and Retekess. Some of the more avid AM and SW listeners have turned to software-defined radios (SDR), such as SDRplay, RTL-SDR, and Airspy HF+ Discovery. As the current sunspot cycle continues building, expect to hear a lot more worldwide shortwave stations!
I recently published the first book in a three-volume series on EMC troubleshooting and pre-compliance testing techniques that may be performed right on the workbench at your own facility.
Creating Your Own EMC Troubleshooting Kit – Essential Tools for EMC Troubleshooting
Why Read This Book? – With all the many pressures you have as a product designer, does electromagnetic compliance (EMC) always seems like a stumbling block to delaying product sales? Is your product exhibiting one of the top three failures; radiated emissions, electrostatic discharge or radiated immunity? Are you continually cycling between design/fixing – running to the compliance test lab – failing again – and back to applying more fixes? Wondering how to attack these issues earlier in the design cycle? Would you like to learn how to characterize and troubleshoot simple design issues right on your workbench? Then this is the book for you!
The purpose of this guide is to help you to duplicate and customize your own EMC troubleshooting kit. This should prove useful whether you are an “internal EMC consultant” in a larger corporation, an engineer who “wears many hats” and occasionally is forced to deal with EMC compliance or if you’re consulting in the field of EMC for other companies. Most of the content is a collection of past blog articles from EDN.com and Interference Technology Magazine. My hope is that the information within this guide will help you become more efficient and offer a more professional appearance to your managers or clients, as the case may be. Future volumes in the series will include simple ways of using these tools to perform your own in-house emissions and immunity troubleshooting and pre-compliance testing.
Hi All, just a quick update on my activities. After serving for three years as senior technical editor for Interference Technology Magazine, I decided to leave in order to better serve my existing clients. This will also give me a chance to do a little more writing.
I’m also back blogging for EDN.com for “The EMC Blog”, which I started writing six years ago. See https://www.edn.com/electronics-blogs/4376432/1/The-EMC-Blog. I’ll continue writing and blogging for Interference Technology, however.
I’m continuing to develop my seminar schedule for 2019 with plans for Santa Clara, Colorado, and Chicago areas. If you happen to reside outside the U.S., I’m also working on possible plans to hold a series of seminars in Europe.
Well, I write this on the eve of my last day with Agilent Technologies and an EMC design career spanning 21 years! Many have asked how it feels (of course, the smile keeps getting larger) and after some thought, it’s the same feeling I get when just about to embark on a major trip – a mix of anticipation and a little excitement. I certainly have mixed feelings about leaving the company early (I turn 57 this April), because I’ve enjoyed the job, enjoyed working with such talented people and have loved the challenge of helping the designers over the regulatory hurdles. On the other hand, this is the longest I’ve worked for any company and it just seems right to move on to new opportunities. Exciting times ahead, to be sure!
