We just thought we knew what unstable was when it came to the geomagnetic field. Persistent G3 storm levels continue to disrupt this band and others. Solar wind velocity continues above 600 km/s and DST measurements are as low as I can remember them being in the previous year. Merv, K9FD/KH6 / WH2XCR, reports that a scan of 20-meters yielded a wasteland with the very rare situation of no signals heard while tuning across the band. I guess I should be content with the fact that overnight storms kept my station off the air.
Then again, a few stations found success through these disturbed band conditions.
John, W1TAG / WE2XGR/3, who recently transitioned to his QTH in Maine, operated his station at 20-watts TPO using a loop with a 200-foot perimeter. John received 50 WSPR decodes from six reporting stations with the best DX at 1106 km. He also notes that the PA is capable of 150-watts but that capacitor plate spacing at the ATU necessitates lower power at this time. This leaves some room to grow as we progress further into Summer conditions.
Neil, W0YSE/7 / WG2XSV, notes that a new station near Sacramento, CA was receiving his signal and provides these session statistics:
Regional and continental WSPR breakdowns follow:
There were no WSPR reports from the Caribbean, trans-Atlantic or trans-African paths. UA0SNV was present but no reports were found in the WSPRnet database.
Laurence, KL7L / WE2XPQ, reported WH2XCR and WH2XGP through the ionic fog.
Merv, K9FD/KH6 / WH2XCR, reported VK3ELV and VK4YB during the session. The path to Australia was severely impacted during this session. The path to North America was not much better.
Jim, W5EST, continues his thought with part 2 of a discussion entitled, “EFFECT OF LAUNCH ANGLE ON RELATIVE LF/MF POWER DENSITY”:
“Launch angle (degrees) vs. great circle distance (km) follows a sawtooth-shaped relationship shown May 6, this blog, and repeated in the color inset upper right in the first illustration here. But how can we find out how much that sawtooth of launch angles affects signal strength at various distances?
Today, I start by finding the launched power density at various launch angles. Tomorrow, I’ll conclude this three-part series by analyzing relative signal strengths at various distance-established arrival angles. After all, that’s the ultimate objective of transmitting!
To get an antenna pattern, I set up EZ-NEC Demo to specify a vertical 70’ (21m) tall made of 1.5” (3.7cm o.d.) copper pipe, overtopped with 200’ (60m) total length of #12 copper wire as a symmetric top hat slanting down to ends at 40’ (13m) high. The ground conductivity is adjusted in its “High Accuracy” option to a value of 18 mS/meter to simulate some radials over a real ground.
Trial-and-error L-network modeling delivered a plausible V-shaped SWR curve reaching 1.1 : 1 at 475.5KHz. Far-field FFPlot displays the antenna elevation pattern at lower right. There, you can read off the pattern dB degree-by-degree of elevation angle by mousing the cursor along the EZ-NEC pattern plot. Compared to 0 dB elevation angles in the 12°-25° range, this antenna is -3dB, -4.5dB, -8dB down at 3°, 2°, 1° angles respectively.
The second illustration displays a graph of relative TX launch power density dB for paths in order of distance. The right inset shows 0°-30° of elevation pattern from EZ-NEC Demo translated to X-Y coordinates. “Launch dB” farther left shows the dB of EZ-NEC’s antenna elevation pattern at same scale as the inset at right. The “150Launch” angles from the inset were translated to X-axis path distances assuming ionospheric E-layer reflection at 150km E-region altitude.
Plainly, for long path purposes the model antenna launches a variety of power densities that will vary about 10 dB with launch angle as its signal rays enter corresponding paths. (Calculated dB depths of decline vary, due to 100km granularity of distance steps.) For launch angles so close to 0° that the path goes near a multihop mode-transition point, the variation in Launch dB is especially dramatic.
But how will the Launch dB be received at the other end of the paths at their various great circle distances? For the answer, join us at this blog tomorrow!”
Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD <at> gmail dot (com)!