Jul 202014

Heaviside's barely legible monument tilts atop the family plot where he lies with his parents in Paignton Cemetary, Torquay, Devon, UK.

He developed the theory of transmission lines, coined such terms as inductance, impedance, and admittance, and rewrote James Clerk Maxwell’s awkwardly expressed equations into the vector form familiar to any student of electromagnetics. Today, Oliver Heaviside’s neglected tombstone is barely legible and is beginning to lean.

Chris Spargo and Professor Alex Yakolev aim to restore the monument, and they could use our help.

Founders of The Heaviside Memorial Project, the two have set up a website aiming to collect £800 in donations for the £660 repair and £140 for any unexpected costs. The restoration will relevel, clean, and repair the monument. Their campaign has already raised nearly half of the required funds. Please go to their website and donate what you can to this worthy cause.

Jul 162014

Yesterday, UWB pioneer Time Domain announced their acquisition by a private equity group led by Bonaventure Capital and Fidelis Capital. Time Domain did not disclose the terms of the transaction. Additional details are available in a statement from the company and in coverage from the Huntsville Times.

Jul 032014

I’ll be presenting my short course on UWB antennas at the IEEE Antennas and Propagation Symposium (APS) in Memphis, TN on Sunday July 6. This is the first time I’ve been back to IEEE APS since 2007, and my short course includes some interesting revisions from the second edition of my book, underway. Here’s a summary.

The wide scale commercial deployment of ultra-wideband (UWB) systems has led to increased interest in UWB antenna designs. In many cases, though, investigators have unknowingly resurrected already known designs rather than developing new ones. Also, the subtleties of UWB antenna physics and design are not always obvious to those more familiar with narrowband antennas. For instance, the spectral and impedance matching properties of a UWB antenna exert a profound influence on an overall UWB system design.

This workshop will enable attendees to:

  • Understand basic antenna physics as applied to UWB antennas
  • Quickly and correctly apply UWB antennas to current projects
  • Design and analyze UWB antennas
  • Integrate these antennas in an RF system

Near-field wireless technology is an emerging area of great importance in Radio Frequency Identification (RFID). Specific applications include low frequency (LF) and high frequency (HF) RFID, Near-Field Communications (NFC), Near-Field Electromagnetic Ranging (NFER), and wireless power transfer. This talk discusses the origins of near-field wireless, surveys applications, presents near-field links laws, and reviews the properties and performance of electrically-small antennas. This March 31, 2014 presentation to the Huntsville, AL section of the IEEE previews the full three hour workshop presented April 8, 2014 at the 8th Annual IEEE International Conference on RFID held in conjunction with 2014 RFID Journal Live.

 A couple of misstatements I caught in reviewing this: first, Preece transmitted near field wireless signals across the Bristol Channel not the “British” Channel; and second, “unlike” links go as 40dB/decade, not 20dB/decade in the near-field. Prezi slides are available here: http://bit.ly/1x0FY7W if you’d like to take a closer look. In some of the views, you can’t see all the details.



James Clerk Maxwell (1831-1879) formalized a set of equations that describe the behavior and interaction of electricity and magnetism.

From Scientific Papers of James Clerk Maxwell, vol 2, LIV, p.311 (Proceedings of the Royal Institution of Great Britain, vol. VII, 1876). Emphasis added inn bold.

I HAVE no new discovery to bring before you this evening. I must ask you to go over very old ground, and to turn your attention to a question which has been raised again and again ever since men began to think. The question is that of the transmission of force. We see that two bodies at a distance from each other exert a mutual influence on each others’ motion. Does this mutual action depend on the existence of some third thing, some medium of communication, occupying the space between the bodies, or do the bodies act on each other immediately, without the intervention of anything else?The mode in which Faraday was accustomed to look at phenomena of this kind differs from that adopted by many other modem inquirers, and my special aim will be to enable you to place yourselves at Faraday’s point of view, and to point out the scientific value of that conception of lines of forcewhich, in his hands, became the key to the science of electricity.When we observe one body acting on another at a distance, before we assume that this action is direct and immediate, we generally inquire whether there is any material connection between the two bodies; and if we find strings, or rods, or mechanism of any kind, capable of accounting for the observed action between the bodies, we prefer to explain the action by means of these intermediate connections, rather than to admit the notion of direct action at a distance.Thus, when we ring a bell by means of a wire, the successive parts of the wire are first tightened and then moved, till at last the bell is rung at a distance by a process in which all the intermediate particles of the wire have taken part one after the other. We may ring a bell at a distance in other ways, as by forcing air into a long tube, at the other end of which is a cylinder with a piston which is made to fly out and strike the bell. We may also use a wire; but instead of pulling it, we may connect it at one end with a voltaic battery, and at the other with an electro-magnet, and thus ring the bell by electricity.

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Roger Bowley of the University of Nottingham demonstrates a dramatic increase in the range of your car’s ~315MHz key-fob merely by holding it to his head (H/T Glenn Wolenec).


Q-Track Corporation won the RFID Journal Live "Coolest Demo" Award for our indoor location system which tracked the real-time location of an AR parrot drone flying around the Exhibit Hall floor.

The last couple of weeks were action packed. Two weeks ago, I spoke at the Texas Wireless and Microwave Circuits and System Symposium at Baylor University in Waco (see my post “Demystifying Electromagnetic Superposition“). Last week, I joined the Q-Track team in Orlando for RFID Journal Live, our industry’s leading trade show. Q-Track came home from the show with the “Coolest Demo” award enabled by our remarkably precise NFER® indoor location system. In this post, I’ll share some of the story behind what we did and how and why it worked.

I arrived the night of Monday April 7, because I was scheduled to deliver a tutorial on Near-Field Wireless Technology to the folks at the co-located 2014 IEEE International Symposium on RFID Tuesday afternoon. That night, I got the word that the rest of the Q-Track team, our CEO Steve Werner, and our new Marketing Director, Chad Ludwig, would be delayed due to weather-related flight disruptions. They would not be able to arrive until an hour or so after the show’s opening reception, so the burden was entirely on me.

I spent Tuesday morning getting our booth set-up and our demonstration system deployed. It took me about an hour to unpack all our boxes and set up the pop-up booth backdrop. In another hour, I was able to get three receivers deployed in and around our booth and connected to the laptop computer that would be our tracking server. It took me a little more than an hour to walk around the tracking area taking calibration points to characterize the signal perturbations caused by the tracking environment – principally the building structure and the wiring. Then I confirmed that the system was working properly by walking around the tracking area with several NFER® Tag Transmitters deployed around my belt and the “history trails” function enabled to leave a trail on the screen. When one of our indoor location systems is working properly, you can see the difference in location of the “left” and “right” tags by observing the slightly offset paths in the tracking display. Everything checked out perfectly. Although the job would have been faster and easier with help, it wasn’t beyond the ability of a single person to get the Q-Track NFER® RTLS system up and running in relatively short order.

Q-Track CEO Steve Werner drives an AR Parrot Drone around the RFID Live Exhibit Hall floor while an NFER® RTLS tracks the drone's position to 40cm rms accuracy or better.

I ran off to get changed – the organizers do not turn on the AC in the Exhibit Hall until just before the show starts – I had lunch, and I presented my tutorial. Finishing a bit early, I returned to our booth in the Exhibit Hall to fire up the demonstration.

This has always been a moment of some trepidation. At the first show Q-Track attended way back in 2006, we had a beautiful demo set up and calibrated with some of our earliest prototype equipment. We shut everything down, and then turned it all back on right when the trade show opened up. The tracking showed embarrassingly large errors. I had to hurriedly recalibrate the system while my colleagues distracted our potential customers. Finally everything worked again, and we could show it off. But then a while later, tracking would deteriorate again, requiring another panicked round of recalibration. We spent half our time at the show tracking, and the other half recalibrating the system. In retrospect, we were being bit by thermal drift. Our system relies on very precise phase and amplitude measurements. Electronic circuits behave a bit differently when first turned on, i.e. cold, than they do after they’ve been running for a while, i.e. hot. Between the variations in tags and receivers, it was tough to get consistent performance for more than an hour or two at a time.

But with several generations of hardware improvements and years of additional experience under Q-Track’s collective belts, those days are behind us. When I fired up the demonstration system for the opening reception of RFID Journal Live, everything worked perfectly – exactly the same as when I’d last checked it that morning.  We advertise 40cm rms accurate tracking. Our demonstration was probably delivering even better than that, although I was too busy to perform a detailed accuracy check.

Q-Track's QT-701 Tag Transmitter weighs in at only 50 grams (~1.6 oz), yet delivers that same 40cm rms accurate indoor location capability of Q-Track's ruggedized industrial-strength NFER® RTLS tags. This photo shows one of the first prototypes.

Not long after the Opening Reception began, Steve and Chad arrived to help me handle the crush of opening night visitors interested in our demonstration and curious about our products. In fact, we were so busy that Steve didn’t get a chance to try out the drone until the next morning. The Parrot AR.Drone Quadricopter survived shipping and worked well. The control datalink for the drone requires a 2.4GHz wireless connection. With so many vendors trying out their wireless products, it was difficult getting a reliable connection. Steve’s demonstration worked best at the beginning and end of each day’s session when interference was at a minimum.

The technology that enables the The Parrot AR.Drone Quadricopter is remarkable in and of itself, but what made our demonstration really fly was Q-Track’s new, lightweight QT-701 Tag Transmitter. Weighing in at only 50 grams, the QT-701 Active Tag enables the same 40cm rms accurate tracking as our larger, more ruggedized industrial tracking tags, but in a compact form-factor suitable for everyday office use.

The other remarkable feature of our demonstration was its robustness. We were up and tracking for the entire duration of the show with no more than a momentary interruption. Naturally, that’s what you’d expect from a commercial indoor location system. But obtaining that kind of reliability is extremely difficult in the hostile RF environment of a trade show. With so many vendors operating so many devices, reliable wireless links are challenge to maintain, if they can be established at all. In fact a couple of our much larger competitors had much larger footprints and much fancier displays on the trade show floor. But neither was able or willing to try to demonstrate a working location system at the show. I think that fact was influential in the decision making behind the “Coolest Demo” Award.

Q-Track’s “Near-Field Electromagnetic Ranging” (NFER®) indoor location systems offer an effective, if unconventional, solution to many indoor location problems. My Q-Track colleague and co-founder, Bob DePierre, and I came from an ultra-wideband (UWB) RF background. We saw first-hand how UWB location systems could be quite accurate with a line-of-sight between a tag and a receiver, but as soon as the direct path was blocked, accuracy began to degrade. Try to go through a wall or two, and it becomes very difficult for a UWB system to get a good fix on your location. Short-wavelength and high-frequency microwave systems work great if you need to send lots of data, but location systems just require getting a signal through a complicated and cluttered environment with minimal distortion or degradation.

Bob and I left our then employer to pursue a different path. We reasoned that low frequencies were the way to go. Low-frequency, long-wavelength signals bend around or penetrate through obstructions much better than comparable high frequency signals. And when the wavelength is much longer than the distance of the link, you don’t get the kind of cancellation and fading you see in high frequency short wavelength signals. I discovered a variety of techniques for using “near-field” physics in localization, and Bob reduced them to practice by building the hardware to prove that my ideas would work. In a matter of a few months, we had a prototype that could track a little red wagon up and down Bob’s driveway to an accuracy of a few inches.

Today, our NFER systems operate at around 1MHz under FCC Part 15 rules for unlicensed low-power transmitters. With a wavelength of 300m, they deliver 40cm rms accurate tracking. Typical ranges are around 15-20m (45-60ft). In a particularly noisy environment (like the Exhibit Hall) range may be as short as 10m (30ft). In really quiet settings (like many retail or warehouse environments) range may be up to 30m (100ft).

The Orange County Convention Center in Orlando housed the 2014 RFID Journal Live trade show.

Below is a great screenshot of our NFER® indoor location system in action. We deployed three QT-555 Locator-Receivers and we were tracking about a 40ft x 60ft area around our 10ft x 10ft booth with the 40cm rms accuracy typical of NFER® real-time location systems. The system can accommodate up to 84 tags simultaneously at a 1Hz update rate, but we were never using more than four or five at a time. You can see solid, repeatable tracking on the inside loop of me (blue trail), Chad Ludwig (orange trail), and Steve Werner (green trail). Note the head shot “avatars.” I looped the outside edge of the tracking area – you can tell the system was having some difficulty because the update rate slowed down a bit (i.e. the space between the blue dots showing the location fixes got bigger). Finally, I walked the perimeter of three 10ft x 10ft squares and their diagonals to highlight the precision of our tracking. Ultimately, our system ran for the duration of the show with no tweaking or adjustment needed.

Screenshot of Q-Track's NFER RTLS indoor location system GUI. The colored lines show history trails as we tested the system the morning of April 10.

 In the final hours of the show, we heard an announcement that the Awards Ceremony was beginning. While we were excited about how well our location system was performing, the broader world of RFID encompasses many other interesting and useful applications. And no one from RFID Journal had been by to hint that we needed to attend. Chad and I were surprised when someone came by to tell us we’d won. By the time Chad could get to the stage, Steve, who had been walking back to us after meeting with a potential customer, arrived to collect the award. Chad captured this shot of Steve holding the award and me holding the drone.

Steve Werner (left) displays the 2014 RFID Journal Live "Coolest Demo" award. Dr. Hans Schantz (right) holds the Parrot AR.Drone Quadricopter. The QT-701 tag is mounted on top of the drone.

 The show ended at 3pm on Thursday. We broke down the tracking demonstration and the booth and flew home that night. I made it home around midnight.
Now we’re looking forward to the challenge of an even cooler demo at 2015 RFID Journal Live in San Diego. What would you propose we do with a robust accurate tracking system on the Exhibit Floor of a trade show? Leave your ideas and suggestions in the comments.
Apr 082014

The Q-Track gang is in Orlando, Florida this week  for RFID Journal-LIVE, the world’s premier conference and exhibition focused on radio frequency identification (RFID) and its many business applications. The tradeshow is underway April 8-10, 2014, at the Orange County Convention Center, located in Orlando, Florida. More about that later.

Our week kicks off with my tutorial at 1pm Tuesday, April 8 on “Near-Field Wireless Technology” at the co-located 2014 IEEE International Conference on Radio-Frequency Identification (RFID). This technical conference, sponsored by IEEE – the world’s largest professional association for the advancement of technology – highlights leading-edge advances in RFID technology. I will discuss the origins of near-field wireless, survey applications, present near-field links laws, and discuss the properties and performance of electrically-small antennas. Near-field wireless technology is an emerging area of great importance in RFID. Specific applications including low frequency (LF) and high frequency (HF) RFID, Near-Field Communications (NFC), RuBee (IEEE 1902.1), wireless power transfer, and Near-Field Electromagnetic Ranging (NFER). My tutorial will earn attendees 3 IEEE Professional Development Hours (PDHs). Lunch and coffee breaks will be provided. IEEE is charging $100 for the tutorial or $150 if you take my tutorial and one of the ones offered in the morning.

Slides for my Near-Field Wireless Technology workshop are available at the link.


The five pointed star is a symbol of Texas and the Texas Symposium adopted it as their own as well. By courtesy and permission of Jollie Primitives. Click to order your own.

This afternoon I will be presenting an invited talk at the 2014 Texas Symposium on Wireless & Microwave Circuits & Systems at Baylor University in Waco, Texas. In my talk, Demystifying Electromagnetic Superposition (slides), I will examine the interesting behavior of electromagnetic waves when they superimpose or interfere with each other. I have a paper on the subject that I will share soon.

Mar 312014

Blogging has been taking a back seat to everything else in my life, lately. This week, though, I have a variety of interesting and exciting developments to share. Today’s news is an update on the indoor location company I co-founded, Q-Track.

The good news began a few month ago in November with a favorable mention in IEEE Spectrum Magazine, the flagship publication of the Institute of Electrical and Electronics Engineers. An article surveying solutions to the challenging problem of indoor location noted:

“One company offering help with that is Q-Track, based in Huntsville, Ala., which claims its indoor radiolocation system can provide submeter accuracy. It uses frequencies of about 1 megahertz, which is considerably lower than Wi-Fi. Why? “You want to have a signal that can get through a messy propagation environment,” says Hans Schantz, cofounder of Q-Track. Low frequencies can more easily penetrate the many barriers found indoors. They diffract less around obstacles, and they don’t fall prey to the multipath phenomenon, whereby the different waves caroming around inside a building interfere with one another.

“Q-Track’s system differs from Wi-Fi localization in another fundamental way: It doesn’t use signal strength to gauge the distance between transmitter and receiver. Nor does it measure the time it takes the signal to travel from transmitter to receiver, as GPS does. Instead, it cleverly exploits the fact that at frequencies of a megahertz or so, and at building-size distances (say, up to 100 meters), the receiver operates in what radio engineers call the near field of the transmitter.

“In this special zone, the emanations from a radio antenna are rather peculiar. The electric and magnetic fields do not rise and fall in lockstep, for example, as is normally the case with radio waves. And the difference in their timing (their relative phase) is, conveniently enough, a function of the distance from the transmitting antenna.

“Q-Track uses the distance-dependent difference in phase, as well as other features found only in the near field, to calculate the location of a transmitter tag with respect to fixed receivers. Those receivers are fitted with antennas that can separately measure electric and magnetic fields. Outdoors, the system is accurate to 15 centimeters, but indoors, the structural elements of a building produce errors of as much as several meters. But by mapping out the site’s radio environment first, says Schantz, the system can locate one of its tags indoors to within 40 cm.”

The article, “New Indoor Navigation Technologies Work Where GPS Can’t,”  is available here.

All of us at Q-Track have been working diligently to increase the accuracy, performance, and reliability of Q-Track’s Near-Field Electromagnetic Ranging or “NFER®” Real-Time Location Systems (RTLS). That hard work paid off in December when Lockheed-Martin awarded Q-Track a $1.7 million contract to track soldiers in an urban operations training range:

Now, of course, we’re all having to work even harder – making sure we complete our order and deliver it on time. The increased visibility resulting from all this good news made us realize that our old website was simply not up to the demands of accurately presenting Q-Track’s product offerings and indoor location applications. This past month I undertook a complete Q-Track website renovation, including updating the website and its content to a fully responsive and adaptive WordPress template.

Finally, at lunch today I’m presenting a dry run of a workshop on Near-Field Wireless Technology, sponsored by the Huntsville Section of the IEEE. Near-field wireless technology is an emerging area of great importance in Radio Frequency Identification (RFID). Specific applications include low frequency (LF) and high frequency (HF) RFID, Near-Field Communications (NFC), and Near-Field Electromagnetic Ranging (NFER). This workshop will discuss the origins of near-field wireless, survey applications, present near-field links laws, and discuss the properties and performance of electrically- small antennas. Today’s session is a practice run for the three hour version I’ll be presenting next week at the 8th Annual IEEE International Conference on RFID.

© 2010-14 Hans Schantz except as noted. Suffusion theme by Sayontan Sinha

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