The band continues to produce good results with low noise levels. Its seems that normally we would be mired in persistent thunderstorms in some portion or portions of the country that would make receiving a challenge for everyone. While I feel certain that we will get to that point, we continue to enjoy the open band under quiet conditions. It didn’t hurt that 88 MF WSPR stations were observed at 0500z. As with the previous session, the geomagnetic field experienced a ping and perhaps this gave the band the spark it needed, at least at low latitudes, to be productive. None of this has proven to be an exact science.
Ward, K7PO / WH2XXP, in Arizona reported this morning that he was decoded by Roger, VK4YB. Roger has a very large antenna system and a nice location. Its great to see these long-haul seasonal transition reports. Congrats to both stations!
Doug, K4LY / WH2XZO, had a very strong session with reports from DL4RAJ and DL4RAJ/4. Clemens reported on the RSGB reflector that he is using a half-sized dipole on a sloping hill. Doug provided the following session comments:
John, WA3ETD / WG2XKA, reports that he was not transmitting during this session because of maintenance but offers this reception report:
Larry, W7IUV / WH2XGP, reports the best session in a long time, decoding thirteen stations including first time reception of WI2XFI. Larry was decoded by 45 unique stations and notes that the East / West high latitude transcontinental path was much better with an open path to New England and eastern Canadian stations. With local noise being lower, Larry used the East-facing flag receive antenna, which hurt some of the reports to the West.
Joe, NU6O / WI2XBQ, and Neil, W0YSE/7 / WG2XSV, completed a JT-9 QSO during the evening after Neil spent time running a JT-9 beacon earlier in the session.
John, VE7BDQ, reported that he decoded ten unique stations and was decoded by 27 unique stations in his 12-hours of operating, including ZF1EJ and ZF1RC.
Phil, VE3CIQ, reported an inch of “Spring snow” that resulted in the antenna tuning 17 kHz low. Phil decoded twelve and was decoded by sixteen unique stations including VE7BDQ at -24 dB S/N and VE7CNF at -26 dB S/N.
Mark, WA9ETW, reports that he heard WD2XSH/12 and WD2XSH/31 operating CW beacons.
Ken, K5DNL / WG2XXM, reports that he decoded thirteen unique stations and was decoded by 46 unique stations, including new stations KC9VVX.
Ron, NI7J / WH2XND, reports that he decoded thirteen unique stations and was decoded by 42 unique stations.
Regional and continental WSPR breakdowns follow:
There were no reports on the trans-African path, however, ZS1JEN was present during the session. UA0SNV was also present but no reports were found in the WSPRnet database.
Eden, ZF1EJ, operated two-stations once again, reporting WH2XCR in addition to others on the mainland of North America. Roger, ZF1RC, returned with solid reports during this session after an absence that was reported to be some type of upload problem with the software.
In Alaska, Laurence, KL7L / WE2XPQ, reports a problem with his WSPR uploads so there is nothing to report at this time.
In Hawaii, Merv, K9FD/KH6 / WH2XCR, reported after yesterday’s session that his terrestrial weather has manifested faster than expected and seems to have ushered the return of Japanese reports and the new Tasmanian report. Merv had a strong session with numerous reports into the eastern portions of North America for the second consecutive session. He includes a few comments below:
In Australia, Phil, VK3ELV, and Roger, VK4YB, were both reported by WH2XCR. As previously reported, Roger reported WH2XXP in Arizona during this session and Phil received reports from TNUKJPM.
Jim, W5EST, provides another very good discussion about RF current measurements entitled, “WHY DO ANTENNA RF CURRENT READINGS?”:
“The last few blog-days have featured the RF antenna current topic. I gave an example where one wants to set antenna base current to 1.50A. Why might one want to set antenna current to some particular value?
Firstly, you try to get your TX signal to cover at least some regional paths, indeed perhaps even continental and transcontinental distances as well. RF antenna current “I” generates the magnetic fields of the electromagnetic waves you transmit. The taller the vertical extent of the antenna, the better for letting longer lengths of antenna current intensify the magnetic fields that RF current makes. It helps considerably to know whether you are getting more RF current or less of it when you make antenna, grounding and tuning adjustments.
Second, national governments allocate the frequency bands for licensed operations in their countries and set power limits. On 630m and 2200m bands, EIRP, on which legal limits may be based, leads you by a division factor based on antenna type to a maximum lower amount of total radiated power (TRP) you can run.
To keep TRP from exceeding the maximum, you can determine your maximum RF antenna current using the formula
Imax = sqrt(TRPmax / Rradiation).
You take the square root of ratio of TRP divided by radiation resistance Rradiation. (Note: This does not substitute for officially-approved methods of establishing whether a legal limit is reached.) Further formulas and/or properly-written web calculators can help you estimate the value of radiation resistance. They get it from the vertical length and total top loading length for an electrically-short vertical with or without the top loading typically used on these bands.
Third, propagation studies and general information for the operator community benefit when you can state your power level fairly accurately. Also, for studying resilience of paths at low power levels, one can establish a lower TRP proportional to a higher TRP at some high TX power level TPO1 times ratio of a lower TX power level TPO2 to that higher TX power level TPO1:
TRP at TPO2 = (TRP at TPO1) x TPO2/TPO1.
EIRP = factor x TRP depending on your antenna type, about 3 for a short vertical.
WSPR software includes a dBm (dB over milliwatt) menu for you to tell estimated power. Suppose you have earlier determined your TRP, ERP and EIRP values, each in dBm. Which type of power should you report by WSPR?
The WSPR manual simply refers to “WSPR power” (at pp. 2, 7, 11-13).
Maybe “WSPR power” has already been interpreted by the WSPR community. If so let us know so we can post an additional link.
A bit of random searching shows two web sites that use EIRP for WSPR power, one at 10 meters and at 630m.
http://qsl.net/dl2wb/WSPR/wspr.htm 10 meters
Does the choice of type of power even matter for propagation studies? Perhaps not. TRP, ERP and EIRP are all within 2-5dB of each other for a short vertical, after all. But on a band where so many things are unknown, why compound the mysteries with human-made confusion over which power to state?
On top of that, note the potential for confusion and awkwardness about stations’ powers relative to legal limits. On HF, WSPR power is usually very far below the legal power limit. On LF/MF quite a few WSPR stations may be running EIRP near the legal limit, which may be quite within their equipment and antenna capabilities to exceed. On 630/2200m we probably can save confusion by stating our EIRP as the WSPR power, so no USA ham should state a WSPR EIRP as power exceeding their EIRP legal limit when USA hams get LF/MF privileges. Part 5 power limits, by contrast, are set by the terms of their individual licenses.
If we all decided to state LF/MF WSPR power as TRP instead, some folks might get confused what power level to run. The results might look puzzling and awkward to others too. In any event, we all need to be as understanding and diplomatic as possible and willing to learn. Confusion and errors may be unavoidable, especially at first, as we all find our way to do the right thing.
Antenna patterns: That said, let’s not forget that any one power number cannot describe for propagation studies the contributions of the complex 3-dimensional (3D) antenna patterns at the TX and RX end. That’s true even of a short MF/LF TX vertical situated among other real antennas and given your actual QTH neighborhood. Depending on the heading of a propagation path, and the path distance and elevation angle(s) that propagation favors to reach an RX, the dB of antenna pattern variation in azimuth and elevation can vary dramatically. The actual power densities emanating in any particular 3D direction from a TX antenna will widely differ.
Do you have an experienced opinion or further information? Let us know!”
Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD <at> gmail dot (com)!