The band seems to be making incremental progress as the Kp has returned to quiet/unsettled levels with a North-pointing Bz that is tempering the persistently elevated solar wind velocities. Solar wind is currently peaking above 550km/s but is down from values in excess of 600 km/s during the evening in North America. Any improvement is improvement at this point and while the DST continues to suggest very poor conditions, it was obvious that the band could support long-haul communications during the course of the session.
John, W1TAG / WE2XGR/3, in Maine reports that he decoded Larry, W7IUV / WH2XGP, in Washington state this morning on the transcontinental path which has been quite rare in recent times.
Larry also noted that the path to ZF1EJ was open again after a relatively long hiatus.
After 0700z, the storm system that ravaged Oklahoma and North East Texas either moved on or subsided after running out of energy for the session and CW levels were noted from my station in Texas to points North like WD0AKX in Minnesota, WG2XJM and WA3TTS, both in Pennsylvania. Whether this was the result of improved propagation or lower noise levels is unclear at this time.
John, WA3ETD / WG2XKA, continues his testing of the HI-Z low noise vertical, experimenting with a different turns ratio. John reports his successes and details below:
Neil, W0YSE/7 / WG2XSV, was also performing A/B receive antenna testing and offers the following comments:
Regional and continental WSPR breakdowns follow:
There were no reportsfrom the trans-Atlantic or trans-African paths during this session. UA0SNV was present from Asiatic Russia but no reports were found in the WSPRnet database.
Eden, ZF1EJ, received stations from across the US, including WH2XGP in Washington State and WG2XKA in Vermont. These longer-haul decodes have been rare over the past month or more.
Laurence, KL7L / WE2XPQ, reports that he will be operating in a receive-only capacity for the foreseeable future. During this session he decoded WSPR signals from WH2XGP and WH2XCR.
Merv, K9FD/KH6 / WH2XCR, saw a return of better propagation, with reports from a number of stations in Australia in addition to a two-way path with VK4YB, and reception reports of my signal which has been absent for several sessions.
Jim, W5EST, continues his recent discussions with “PART 3: EFFECT OF LAUNCH ANGLE VS. DISTANCE ON RECEIVED SIGNAL”:
“How will the Launch dB graphed May 9, this blog, be received at the other end of the paths at their various great circle distances while taking a model TX antenna elevation pattern into account? Today, let’s answer this question, ignoring day-to-day propagation variations of course.
With a spreadsheet I generated and plotted dB effect of antenna pattern, inverse-squared distance, and guesstimated effect of the surface reflection and sky reflection added per hop.
The dB Loss graph illustration shows that the received signal strength compared to Launch dB is far less subject to dramatic variations due to critical distances where multi-hop mode transitions occur.
Why? The dramatic Launch dB variations are largely muffled by the increased loss due to surface and sky reflection as the signal goes to each next hop.
That graph illustration is at least plausible or “in the ballpark.” 40dBm (10 watt) station WH2XGP has been received as much as +28dB & +16 dB peak WSPR SNRs respectively at VE7SL 319km & WW6D 1070km away. 6dB adjustment can account for 500km base distance here relative to 1070km WW6D. The dB Loss graph indicates about -50dB loss relative to 500km to reach 12000km, like Australia’s VK4YB. WSPR SNR in Australia based on this graph could reach -28dB (=+16dB +6dB -50dB), which is conservative relative to -18dB peak SNR XGP-vk4yb April 3 at 12002km.
Departure of the graph from actual peak XGP performance into VK-land may be due to XGP’s actual antenna pattern compared to the model, or my possible overestimation of losses due to distance and due to reflections. Moreover, it’s possible that XGP is reaching VK not by E multihop but F hops instead, or that some exotic propagation like chordal hop or ducting is reducing the path losses XGP experiences.
As to the remaining wiggles in the graph near mode transition critical distances, such variations with distance would be easily masked by propagation variations over a night’s opportunity time window and even if the ionospheric reflection altitude were to vary up or down from night to night. As far as I know, no amateurs or experimenters with stations near mode-transition distances have reported any unusual variability that could be attributed to an effect of some critical distance and varying E-layer height.
I hope this 3-part series has provided an interesting perspective on the topic of antenna elevation patterns, launch angles and multi-hop! GL.
NOTES: My trial & error “PatterndB” curve-fit here onto the EZ-NEC elevation pattern involves elevation ANGLE as found in the May 7 blog post. Using ANGLE, do a curve-fit by:
PatterndB = 1.5 ln[10sin( 5 ANGLE/57.3°)] -3.3
The dB Loss vs. distance graph illustration is generated in Excel from:
dBLoss = PatterndB – 20log10(KM/500) – (Ehops -1)*5dB
The dBLoss accounts for the antenna pattern, the inverse-square-distance loss, and an extra ~5dB combined loss due to an additional E-layer reflection and salt water reflection on every hop beyond the first hop.
If the day ever comes when a deep null at a given distance could be identified with a multi-hop mode transition like 1E-2E on salt water, it might lead to a way of calculating E-layer height according to this formula: hE = Re[-1 + 1/cos(Max km/Ehop/(2Re))].”
Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD <at> gmail dot (com)!