This session was characterized by lower noise than seen in the last few nights as most storms were located further away from major population centers. Activity was down a bit but that’s not surprising for this time of year. Propagation was pretty good for these short nights, evidenced by some of the longer-haul reports experienced by stations overnight. WG2XJM reported my WSPR signal at or near CW levels very early in the session and reports from WA3TTS were not far behind. We are being teased about the very good band conditions to come in a few months.
Geomagnetic activity continues at quiet levels while the Bz pointed slightly to the South. Solar wind velocities are lower than in the previous session, averaging 480 km/s this morning. The significant variations between the Kyoto DST and the Australian DST are interesting but may just be the result of variations in the scaling:
Rick, W7RNB / WI2XJQ, continues station improvements, increasing his CW output to 900 mW ERP. Receive station noise levels in the Pacific Northwest / British Columbia area hampered any solid evaluation of the improvements during this session, however.
Phil, VE3CIQ, reports that he decoded three WSPR stations and was decoded by five unique stations, spanning much of the East coast of North America.
Steve, VE7SL, decoded four WSPR stations and was decoded by eight unique stations in British Columbia. Steve notes that conditions that far North were poor due to the limited number of stations that were decoded.
Ken, K5DNL / WG2XXM, reported that he decoded three WSPR stations and was decoded by eighteen unique stations.
Neil, W0YSE/7 / WG2XSV, reports that he decoded WH2XCR once during this session where Neil was receive-only.
Mike, WA3TTS, reported that he decoded WH2XGP at -29 dB S/N at 0822z.
Larry, W7IUV / WH2XGP, decoded three WSPR stations and was decoded by fifteen unique stations, including ZF1EJ, who has not decoded Larry in what seems like months.
Brian Justin, WA1ZMS, submitted an application for a new license for 483-515 kHz. Brian has previously operated on 477 kHz so it seems Brian may be relocating himself ahead of amateur status between s72-479 kHz. I am conjecturing on this but it seems logical until I have further information.
Regional and continental WSPR breakdowns follow:
There were no reports from the trans-African, trans-Atlantic, or trans-Equitorial paths. UA0SNV was present but no reports have been filed at this time.
In the Caribbean, Eden, ZF1EJ, reported WH2XGP, WG2XXM, and WG2XIQ:
Laurence, KL7L / WE2XPQ, decoded VE7SL, WH2XCR, and WH2XGP:
Merv, K9FD/KH6 / WH2XCR,received reports from a few more stations along with West coast in addition to the usual suspects in Australia:
Jim, W5EST, presents ‘“YOUR” IONOSPHERE AT WORK!’:
“Different electron concentration contours in the ionosphere reflect radio waves depending on their radio frequency. The electric field in a low frequency radio wave when near its peak intensity lasts longer than a high frequency wave of the same amplitude (and therefore same power). That’s because the time interval for a whole cycle period at low frequency is longer. That means the low frequency RF wave’s electric field has time to accelerate free electrons in its vicinity to higher speeds and move them around more than a higher frequency RF wave’s electric field can.
To reflect all the energy in an RF wave the electrons, which each have a truly minutely tiny but non-negligible mass, get speedy enough so they turn the RF energy briefly into energy of their motion and simultaneously reradiate it downward as reflected RF energy. So higher RF signal frequencies need more electron concentration to absorb and reradiate their energy down than the lower RF frequencies do.
If you think of free electron motion in terms of electric current in nanoamperes, then regardless of frequency you need the same nanoamperes at altitude to reradiate a given amount of RF energy. The same nanoamperes result from a few electrons moving at high speed as from a lot of electrons moving at low speed. Since lower frequency RF waves can impel electrons to move at higher speeds, LF/MF can get along with fewer electrons (lower electron concentration) to accomplish reflection than HF requires.
The critical frequency is the highest frequency vertical-incidence wave (one going straight up and back down) that an ionospheric region can reflect. Roughly speaking, the critical frequency corresponds to the highest electron concentration of any approximately horizontal surface contour that maps a value of electron concentration in that ionospheric region. Lower frequencies would also be reflected from that contour if it were the lowest in altitude. But generally, electron concentration increases with altitude up to a maximum and decreases above that. So some lower-altitude contour below the one with maximum electron concentration in that region has an electron concentration just sufficient to reflect a given lower frequency than critical frequency.
For RF signals transmitted straight up from the ground and reflected back down, the contours of electron concentration at increasing heights up to the maximum electron concentration level are the pertinent ones because they reflect corresponding frequencies from the given region of the ionosphere. That’s why ionograms for some regions curve upward with frequency and then stop at its critical frequency.
The maximum usable frequency (MUF) is the highest frequency of an oblique-incidence wave like hams send and that an ionospheric region can reflect. The angle of reflection depends on the length of the path. The MUF is, more or less, roughly three times higher than the critical frequency because the oblique-incidence wave reaches the ionosphere at a glancing angle.
An ionogram shows the MUF for a very low takeoff angle toward the horizon and may additionally list several one-hop distances and their corresponding MUF values. The MUF values for short distances approximate the critical frequency since the paths go more nearly straight up and down. The MUF values progressively increase with distance and reach the MUF value for the longest distance tabulated on the ionogram at http://www.kolumbus.fi/oh5iy/back/MOF.html (scroll 2/3)
The E-region generally has a lower critical frequency than the higher altitude F-region (or daytime F1 & F2 regions). 630/2200m waves generally are reflected from the E-region because 630m/2200m frequencies likely to be less than the E-region critical frequency. Since 630/2200m waves get reflected from the E-region, they can’t generally pass through it to reach the F-region for reflection. On the other hand 40, 20, 17, 15, 12 and 10 meter signals often exceed the E-region critical frequency and do reach the high altitude F-region. That’s why those HF bands are likely to reflect from the F-region when MUF permits, and can reach farther than the lower bands.
MUF suggests a reason (beyond antenna size and noise) why LF/MF/lower HF aren’t used for earth-to-ground satellite communications. The F layer and E layerwould often be likely to reflect hypothetical satellite signals back out to space if transmitted at LF/MF/lower HF. Conversely, the E and F layers would likely reflect hypothetical earth station signals back to earth if at LF/MF/lower HF. Amateur radio satellite communications such as with ISS (international space station) generally are at VHF/UHF–and at HF at least exceed the MUF for the angle of transmission to earth. http://www.amsat.org/amsat/intro/sats_faq.html#RTFToC17
Solar radiation ionizes the ionospheric regions more fully in the daytime because the sun’s radiation frees electrons from atoms and molecules that thereby become oppositely charged ions. The ionization declines at night by recombination to make neutral atoms. At night, the E-region that way loses many of its free electrons, so the lower HF ham band signals reflect from the F-region and go farther at night.
From an HF perspective, you may see it said that the E-region “disappears” at night. Ionosonde data below 1MHz is scarcer than for HF, which also contributes to the idea that the E-region “disappears” at night. However, the 2200m and 630m bands are so low in frequency that the relatively little free electron concentration in the E-region is still likely to be sufficient to reflect MF/LF signals. There can be exceptions, and there’s still a lot for amateurs and experimenters to learn about E-region reflection or lack thereof at night.
As to the D-region, that big subject can await another blog post.
I’ve tried to boil down complicated electromagnetic equations and ionosphere geophysics to ordinary English, to best of my understanding. If you have better wisdom about E/F regions or more to say about them, let us know. It’s appreciated!”
Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD gmail dot (com)!