The mechanism that generates Sporadic E clouds is somewhat mysterious. In Propagation and Radio Science, Eric Nichols explains one possible mechanism is thunderstorms that are strong enough to break electrons free forming a cloud of free electrons. A good example presented itself on the evening of May 24, 2019 as documented by two maps of the United States taken simultaneously. The first is a radar map showing a line of thunderstorms along the Kansas/Missouri border. The second is a map of PSKREPORTER showing W0QL reports. W0QL is located in Colorado and the reports are located precisely on the opposite side of the thunderstorms and no where else (except local). Theorizing, the sporadic E cloud is above the thunderstorms and the signal from W0QL is bouncing off that cloud.
See Propagation and Radio Science, Exploring the Magic of Wireless Communication by Eric P. Nichols, KL7AJ, ARRL Publications, 2015.
How well our signals will emanate from this new location can be estimated by using software called HFTA (High Frequency Terrain Analysis – from any recent ARRL Antenna Book ) to produce a map of the terrain. It looks promising because we slope down toward the northeast, which is direction of Europe. This screen snap is what the terrain looks like as we look to the northeast, or 45 degrees, using a dipole on a 60 foot tower. Slopes down for 2 miles. Nice.
Next is a plot of Colorado to Europe using a dipole at 60 feet elevation. Looks good but could be better. About 5 dBi gain at the take off angle where most of the Europeans stations come in. The dipole peaks at 15 degrees, a good all around takeoff angle and very usable but not optimum for Europe. Four or five degree take off angle is perfect but not likely attainable at this installation.
This morning 20 meter European DX is rolling in like crazy but not a single station I call comes back to me. It’s not the old test tone problem because pskreporter shows stations spotting me in Europe. I can only conclude my antenna isn’t big enough. What about a hex beam? It would get out a lot better and still be a top hat for the low band vertical. The seed of thought has been planted. Maybe I could get some of this juicy DX to hear me.
Examine what was happening above a little deeper. I heard a Czech station call CQ and I called back. At the same time, another U.S. station was calling him, KD2EIP which we can see and apparently one we can’t see in Russia, RV3DBK. The Czech heard the Russian and came back to him. My signal was clobbered by a New York station and a Russian station. A bigger antenna might not have made any difference. Probably nothing I could do here could overpower two stations closer to the Czech Republic. I have to learn to think of it as a DX pileup where finesse and operating skill are the best way to beat out big gun stations (for example, “tail ending”). OK, back to the pileup. Hex beam is on hold for now. JT65 has become so popular every day seems like a weekend contest. It’s not like the early days when I once worked England with 100 mw. Here’s another example from this morning.
OZ1DSD, Denmark, calls CQ and I call back. Apparently KK5AA calls him, too, and the Denmark station comes back to KK5AA. I lose out. Next SQ5WAF, Poland, calls CQ and I call him back. So does a station in Spain, EA3ATJ, and the Polish station comes back to the station in Spain. I lose out again. Next a station in Bulgaria, LZ5UF calls CQ and I call back. And he doesn’t come back to anybody. He calls CQ again and I call and he comes back to no one. I lose again. Born to lose. But I’ll keep trying and maybe just maybe a little bigger antenna could compensate for being so far west. Sorry about the whining.
An interesting phenomenon has occurred. It appears the remote base is making contacts above the Maximum Usable Frequency. MUF is 18 MHz and the remote base just worked two different stations on 21 MHz using JT65. Refer to the screen snaps below. In the first frame notice the lines highlighted in red. Those are packet exchanges with the WOQL Remote Base. Clearly good contacts with excellent signal reports with time stamps between 2143Z and 2156Z.
Here is a screen snap of the Digisonde Ionogram at Boulder, Colorado at 2150Z, the same time as the contacts, showing the MUF is 18 MHz.
Any explanation? This needs to be dug into deeper. Is JT65 that good? Was the MUF in South America higher at the time than it was in Boulder? Does MUF need to be redefined? Is it just all magic anyway?
September, 2017 Followup: QST article calls this phenomenon “an above-the-MUF mode of propagation”. October 2017, page 46 by K9LA.
Finally the stars have aligned and we are having a happy Sunday afternoon watching the DX come in on 20 meters and seeing our signals posted over a large part of the world. This is only on 20 meters because we are still using only the PAR/LNR EF-20 end fed half wave vertical while we ponder antenna improvements.
I tried to operate from the top of a hill on the property temporarily but I could never get the test working. Meanwhile I had been wanting to perform an HFTA as described in the ARRL Antenna Book. HFTA stands for High Frequency Terrain Analysis. That software program might tell me if I should move the setup to the hill top permanently. After an evening of working with HFTA I concluded moving would not make a significant difference. In the directions of DX like Europe and Africa the terrain continues to slope down even though I’m not at the top of the hill. In fact it slopes down toward Europe for more than a mile. That sounds like a pretty good location. Here are the two terrain plots toward Europe (45 degree azimuth). Terrain drops off at a sharp angle.
Figure 1 – Terrain toward Europe as seen from hill top ( red diamond is dipole at 39′ up).
Figure 2 – Terrain toward Europe as seen from original location ( down the hill about 45′).
My conclusion: there is a downward slope toward Europe at both locations so it doesn’t matter. HFTA is a fantastic tool. I must make note of the peak at 10,000 feet out. It is much more of a concern when I am at the lower position. This concern might be a reason to go up the hill later if performance isn’t what I hope for.
Here is a screen snap showing a sample of what we’re seeing printed on JT65 at 7:30 am on 20 meters. Absolutey fabulous. Beyond my wildest dreams. I can’t wait to be able to transmit and see if I can work some of this delicious DX. All corners of the globe, Asiatic Russia, Netherlands, Germany, Sweden, Australia, and Indonesia all within the same minute. Now THIS is what I’m talking about!