Many thanks to SWLing Post contributor, Troy Riedel, who writes:

Thomas, if I were to read this on your blog, I would not have believed the following.

I live in Virginia nearly equidistant from RIC/Richmond Int’l AP (east of Richmond) and PHF AP (in Newport News). I had a 1:40 P.M. doctor’s appt. [July 12] and I took to I-64 East en route to the doctor near Newport News. My Silverado has an XM Radio that I typically listen to, but the reception is bad in the summer because of the wooded nature of the interstate.

I hit the “FM” button and I quickly found a station at 105.7. There were two other 105.7 stations that periodically interfered, but one station was dominating/booming. After music I heard commercials about concerts in Iowa. I heard an Iowa Lottery Commercial. And a Lasik commercial – yes, all from Iowa. I heard a weather forecast that definitely wasn’t for Virginia. After 10-12 minutes I got a station I.D.. It was KSUX Sioux City, Iowa. Sioux City, Iowa is 1,332 miles away or an estimated 22-hour drive!

KSUX dominated the airwaves until I got very close to my Newport News, VA appt. By then (around 12:55 P.M.) I had picked-up one of the other two stations that were competing on 105.7. It was a station on the Outer Banks, NC (about 2.5 hours by car away).

When I went back to my Silverado at exactly 2 P.M., the KSUX was barely audible as the Outer Banks, NC station was now the most clear. I drove back towards my home on I-64 West and after a few miles (5-10 at most) the third of the three stations became clear. The third station was “Kiss 105.7” originating in Richmond, VA. That means the Sioux City, Iowa station, 1,332-miles away, had obliterated the Richmond, VA signal from 12:30 P.M. to almost 1:00 P.M. even though at this juncture of my drive Richmond was 45-55 miles away.

The KSUX Sioux City, IA station … even though weak on the drive home … still occasionally popped through the airwaves to cause interference with the Richmond, VA signal.

If I hadn’t heard it, I would have never believed it. I did a quick check and I didn’t see anything regarding closer stations possibly simulcasting the KSUX signal. It appears to be 100% legit.

I’m dumbfounded. It’s a head scratcher for sure.

Thanks for sharing your experience, Troy. You, sir, were the recipient of some excellent FM DX openings!

FM DXing conditions

There are a few conditions that make for proper FM DX:

1. Sporadic-E and tropospheric ducting (DXers often call this, “Tropo”)
2. Meteor scatter, where signals bounce off of ionized trails left by meteors
3. Also, when there is exceptionally high sunspot activity, FM signals have been known to bounce off the ionosphere (like shortwave signals)

I strongly suspect you were enjoying FM DX from sporadic E. If memory serves (and keep in mind, I’m currently vacationing in an off-grid cabin without Internet), we had a K Index of 5 or so on July 12–at least, I believe I heard a ham radio operator report this on 40 meters that day. I can confirm that the HF bands were absolutely obliterated parts of that particular day. Conditions were very unsettled for the HF (high-frequency) bands, but potentially excellent for sporadic E.

Source: Wikimedia

Fred Osterman writes about Sporadic E on DXing.com:

Sporadic-E propagation is caused by patches of intense ionization in the E-layer of the ionosphere (approximately 35 to 60 miles above the Earth’s surface). Signals on frequencies above 30 MHz normally pass through the ionosphere and into space. However, sporadic-E “clouds” are capable of refracting such signals back to Earth. The term “clouds” is an apt way to describe the patches of highly charged particles that form during a sporadic-E event. Like clouds, these patches move and are highly irregular in size and shape. It is possible to track the movement of a sporadic-E “cloud” by noting the locations of stations that fade in and out on a frequency as the cloud moves.

Sporadic-E propagation can occur any time of day or year. However, sporadic-E is most common from about mid-May to late July, with another peak a week before and after the winter solstice. Sporadic-E seems to be most common from about mid-morning to noon, local time, and again from late afternoon through the evening hours.

If you’re interested in chasing a little FM DX (’tis the season–!), read Fred’s full article about FM and TV DXing on DXing.com. What I like about Fred’s article is that it’s simple and easy to understand.

Post readers: Has anyone else enjoyed a little FM DX this summer? Please comment! This is a part of the DXing hobby that I rarely feature on the SWLing Post, but would love to highlight more often. Let me know if you’d like to write a guest post on this topic!