Fishing for DX?

This isn’t really ham radio related, but it’s amusing. Can anyone out there think of a way to hack a Billy Big Mouth Bass so that it can be used in ham radio? One thought I had was to perhaps use it as a kind of “on the air” sign. Another idea might be to pipe your audio through it.

Hot for Solar Data?

We may be at the nadir of the sunspot cycle, but that doesn’t mean there’s not a lot of interest out there in solar data. If you’re hot for this kind of thing, I suggest you get the FREE Solar Data Plotting Utility.

As the website notes:

This application was written mainly for Amateur Radio Operators who are interested in the solar cycles and solar data. Tad Cook, K7RA, writes a weekly Propagation Forecast Bulletin that is transmitted by the Americal Radio Relay League on W1AW. This bulletin contains daily sun spot and 10.7mm solar flux values that can be plotted graphically to see trends in the solar cycle. This application can be used to plot the information in a graphic format on your screen.

The program runs on Windows, and there’s even a DOS version of the program. It looks like Linux and Mac users are out of luck as far as the graphing program goes, but the data file is a plain-text file that can be imported into a spreadsheet for analysis. I easily imported the data into the NeoOffice spreadsheet program.

Tx Topper Provides Pop for QRP Ops

I’ve written before about how it would be nice if QRP ops had a little more ooomph from time to time. I was thinking that 20 or 30 W would be a good figure to shoot for. That’s a little over 6 dB for a 5 W transmitter.

For even lower-power rigs, such as the DC40A that output 1 W, there is the Tx Topper. This amp, designed by Chuck, W5USJ, and Jim, K8IQY, provides about 5 W output.

Chuck and Jim have provided a nice set of documentation for this project. I may just have to build it once I’ve completed the DC40A kit I’m working on.

Tech Pursuit

For the last several months, I’ve been working with some kids at Scarlett Middle School here in Ann Arbor, teaching them about electronics and amateur radio. For a number of reasons—that I won’t go into just yet—I haven’t been as successful as I was hoping to be.

Dismayed by my lack of success, I went to talk to a friend of mine, who had been a school librarian. After listening to my tale of woe, she offered this advice, “Can you make a game out of it somehow”? That struck a chord because one of the kids is mesmerized by computer games.

To be honest, I’m not big on games myself. My wife and I have a modest selection, including Monopoly and Scrabble. In the past, however, we did play a fair amount of Trivial Pursuit. Thinking about this a bit, it hit me that I could use the board and game pieces from Trivial Pursuit for a new game I’m calling Tech Pursuit.

In Trivial Pursuit, there are six categories, each corresponding to a color: brown, pink, orange, yellow, green, and blue. Players throw a die and move around a board, landing on spaces of one color or another. An opposing player then pulls a card from the question card deck and asks a question from the appropriate category.

In Trivial Pursuit, each card has six questions, one from each category. In Tech Pursuit, however, each question card has only one question. This is necessary because the Tech exam questions are multiple-choice.

Another difference between Trivial Pursuit and Tech Pursuit is the number of categories. Because there are ten categories in the Tech question pool, I had to assign questions from two categories to a particular color. For example, in Tech Pursuit, questions from category 3 and 4 are the “green” questions.

Since there are only ten categories, I’ve only assigned five colors. Brown is unassigned and becomes a “wild card.” If a player lands on a brown space, he or she can choose a question from any category.

Other than the differences in the cards and categories, Tech Pursuit is played just like Trivial Pursuit.

Making the Cards
Making the cards was a lot of work, since each question has to be on its own card. I chose to make the cards 2.5-in. high by 3.25-in. wide. I cut and pasted each of the questions in the question pool to a word-processing template that I set up for this. Six questions fit on a 8.5 x 11-in. page.

Then, I printed the page onto card stock and then used a paper cutter to separate the individual cards. Finally, because I had only one color of card stock, I used markers of different colors to give each a color dot denoting the category.

This was a lot of work. If I had to do it over again, I’d try to find card stock that’s perforated, so that once you’ve printed the card, all you have to do is tear them apart.

At least you won’t have to cut and paste from the question pool like I did. Here is a zip file that contains all of the pages—there are 68 in all.

The kids played this game yesterday for the first time, and it was a big success. I think it would be a success with adults and mixed groups, too. I hope that if you’re teaching a Tech class that you might give it a try.

NIST Finds “Metafilms” Can Shrink Radio, Radar Devices

This is from the March 18, 2008 issue of NIST Tech Beat. It seems to me this technology could also be used at UHF, VHF, and perhaps even HF frequencies……Dan

Recent research at the National Institute of Standards and Technology (NIST) has demonstrated that thin films made of “metamaterials”—manmade composites engineered to offer strange combinations of electromagnetic properties—can reduce the size of resonating circuits that generate microwaves. The work is a step forward in the worldwide quest to further shrink electronic devices such as cell phones, radios, and radar equipment.

Metamaterials may be best known as a possible means of “cloaking” to produce an illusion of invisibility, somewhat like the low-reflectivity coatings that help stealth fighter jets evade radar. As described in a new paper,* NIST researchers and collaborators performed calculations and simulations of two-dimensional surface versions, dubbed “metafilms,” composed of metallic patches or dielectric pucks. Vibrating particles in these metafilms cause incoming electromagnetic energy to behave in unique ways.

The researcher team deduced the effects of placing a metafilm across the inside center of a common type of resonator, a cavity in which microwaves continuously ricochet back and forth. Resonant cavities are used to tune microwave systems to radiate or detect specific frequencies. To resonate, the cavity’s main dimension must be at least half the wavelength of the desired frequency, so for a mobile phone operating at a frequency of 1 gigahertz, the resonator would be about 15 centimeters long. Other research groups have shown that filling part of the cavity with bulk metamaterials allows resonators to be shrunk beyond the usual size limit. The NIST team showed the same effect can be achieved with a single metafilm, which consumes less space, thus allowing for the possibility of smaller resonators, as well as less energy loss. More sophisticated metafilm designs would enhance the effect further so that, in principle, resonators could be made as small as desired, according to the paper.

The metafilm creates an illusion that the resonator is longer than its small physical size by shifting the phase of the electromagnetic energy as it passes through the metafilm, lead author Chris Holloway explains, as if space were expanded in the middle of the cavity. This occurs because the metafilm’s scattering structures, like atoms or molecules in conventional dielectric or magnetic materials, trap electric and magnetic energy locally. The microwaves respond to this uneven energy landscape by adjusting their phases to achieve stable resonance conditions inside the cavity.

On the downside, the researchers also found that, due to losses in the metafilm, smaller resonators have a lower quality factor, or ability to store energy. Accordingly, trade-offs need to be made in device design with respect to operating frequency, resonator size and quality factor, according to the paper. The authors include two from the University of Pennsylvania and a guest researcher from the University of Colorado.

* C.L. Holloway, D.C. Love, E.F. Kuester, A. Salandrino and N. Engheta. Sub-wavelength resonators: on the use of metafilms to overcome the λ/2 size limit. IET Microwaves, Antennas & Propagation, Volume 2, Issue 2, March, 2008, p. 120-129.

My First Ham Video

Well, here’s my first attempt at video. These are clips from our operations today at the Ann Arbor Hands-On Museum.

Just to warn you, this is not the best video. Being my first, the clips jump kind of abruptly from one to another. The video quality isn’t very good, either. I produced this with iMovie on the Mac, which compressed the video to produce a .mov, and then YouTube compressed it yet again.

I think, however, that you’ll get a flavor for what we are doing at the Hands-On Museum and all the fun we are having there.

Tonight NOT “One of Those Nights”

Sometimes, ham radio can be very frustrating. There are times when it seems no one can hear me, and I swear that my antenna’s come down. Usually, I just write off this experience as it being “one of those nights.”

Fortunately, tonight wasn’t one of those nights. In fact, it was quite the opposite.

As I’ve said before, I usually try to make at least three contacts per day. I made one in the morning before work, and one just before my wife got home from work. So, after dinner, I headed down to the shack to make my third for the day.

For some reason, 40m was really busy tonight. Conditions were good, but there were also stations than usual on tonight. It took me a while to find a guy calling CQ. I had a short QSO, and then thought I’d continue working on the kit I’m building.

I signed with the fellow, and immediately got a call from W4MQC, my friend Alan, now living down in Florida. Of all the guys I’ve worked in the last five years, I’ve had the most contacts with Alan—33 in all. He’s a great operator and always has something interesting to say. We talked about his new K3 and his plans for buying a boat.

During that contact, I lost interest in working on the kit, and for some reason, decided to see what was happening up in the phone portion of 40m. Tuning around a little, I came across a QSO between KC0TPV in Minneapolis and N4SHY in South Carolina. As luck would have it, the propagation between Minnesota and South Carolina gave out, and I was able bag N4SHY and add to my collection of QSLs from stations whose callsigns spell words.

We chatted for a bit, and after he signed, KC0TPV called me. After that QSO, I was feeling lucky and called CQ. Immediately, I got a call from WD4KZK, in Roanoke, VA. Unfortunately, his signal wasn’t very strong, and I lost him. Fortunately, K4BBL, called me, and our QSO topped off a night when it seemed like I could do no wrong. I love it when that happens. :)

The More Things Change…

…the more they stay the same. Read this article, “Friends in Radioland,” from a 1961 issue of Time magazine. Here’s an excerpt:

Amateur radio operators are called hams, and it is easy to see why: talk, talk, talk—that’s all they seem to do. There are 250,000 of them in the U.S., and another estimated 100,000 elsewhere in the world, all of them chiefly bent on short-wave conversation about capacitors, resistors, transmitters, antennas, and occasionally, the weather and what is playing at the local movie house.

We still do talk a lot about our gear, but one thing certainly has changed: there are now more than 650,000 licensed radio amateurs in the U.S. and more than 2 million worldwide.

Thanks to Bill, WA6ITF, for posting this link to the ARRL PR mailing list.

HamCOW or Cash Cow?

N1JOY is putting together a really neat communications trailer lovingly called HamCOW, short for Ham Communications on Wheels. Features include:

  • Spacious – 28 feet long x 8 feet wide x 7 feet high inside.
  • 5 comfortable operating positions, each one has 2 wired Ethernet connections, 4 antenna ports wired
    to a coax patch panel, dedicated Astron 50 or 70 Amp power supply, Anderson Powerpole DC connections, a small fluorescent light, and AC outlets.
  • 3 tier radio bench for power supplies, computers, radios, & accessories.
  • 42 foot heavy duty locking pneumatic tower with redundant air compressors (120 VAC & 12 VDC). The tower guy wires use high quality Aeroquip tension adjusters for rapid deployment, and is topped off with a HAM-IV rotor and Yagi’s for 6M, 2M, 432 SSB/ATV & a tri-band 144/220/440 vertical. Tower also sports a canvas cover to keep the elements off the hardware when not in use.
  • Antennas for all bands from 160 Meters to 450 MHz, including a fully automated satellite array.

In addition, it has a kitchen, toilet, shower, and sleeping accomodations. What a great project! It’s gotta be costing a ton of money, though.

Hacking Wireless Pacemakers

My good friend and colleague, Jack Vaughan, is always keeping an eye out for the slightly off-beat. When he finds something technical in nature, he forwards me the link.

A couple of days ago, he forwarded a link to a paper that described how to hack wireless pacemakers. The paper, titled “Pacemakers and Implantable Cardiac Defibrillators: Software Radio Attacks and Zero-Power Defenses,” describes how researchers at the University of Washington and the University of Massachusetts, Amherst first reverse engineered the protocols used to communicate with the pacemakers. They describe in detail how they used a software-defined radio to figure out the protocols.

Once they figured out how to communicate with the pacemakers, they devised a series of attacks and successfully pulled off a few of them. For example, they were able to disable a pacemakers “therapies,” or actions the pacemaker is programmed to take in response to cardiac events. This attack basically disabled the pacemaker.

The paper concludes by suggesting several different ways to improve pacemaker security. If you currently have a pacemaker that is programmed with a wireless interface, you may want to take a look at this paper. Even if you don’t, it’s an interesting read.