I’m still a “bench warmer” here in Texas as big overnight storms push through again. Ken, K5DNL / WG2XXM, is in the same situation, located 200-miles to the North. As feared, a repeat of last night is forecast for overnight tonight before we have a few days of clearing so it means another night of being QRT unless the forecast changes. Its a really good thing that I am busy right now or I would let all of this bother me but not like there is much I can do about it.
Geomagnetic conditions were reported as quiet and calm with a North-pointing Bz and low solar wind velocity. Its almost too quiet and while I would not wish for more active solar and geomagnetic conditions, the Australia DST experienced a sharp decrease during the session. This decrease may be related to recent solar flaring activity and subsequent elevated solar X-ray levels.
John, WA3ETD / WG2XKA, provided the following brief report. Its nice to see the persistence of the transcontinental path as the season wears on and the doldrums approach.
Phil, VE3CIQ, reports that he decoded four WSPR stations and was decoded by eleven unique stations during the session. Local noise level is increasing and Phil notes that he has to choose between the power line spurs while listening with the transmit vertical or local RFI on the E-probe receive antenna. My experience from last summer was that in spite of RFI and other local buzzing noises, the E-Probe won the ballgame when listening omni-directionally. Of course E-probes are cantankerous and finicky so this good performance may not repeat everywhere.
Mark, WA9ETW / WI2XHJ, reports that his grant came through this morning and he may be ready for some very QRP testing using the U3 sometime next week. Mark notes that his primary transmit antenna is out of service until the Fall due to shared access to his radial field with a local farmer. Congrats Mark and welcome to the family!
Steve, VE7SL, reports that he decoded seven unique WSPR stations including VK4YB three times. He notes that much of the success may be attributed to the 10-foot by 20-foot loop that was directed to VK overnight. Steve achieved the only receptions from Australia on the mainland of North America during this session with this arrangement.
Larry, W7IUV / WH2XGP, made it across the Pacific ocean as the lone station on the mainland of North America to be heard in Australia overnight.
Neil, W0YSE/7 / WG2XSV, reports that he only decoded two WSPR stations during the session, which may be the result of down activity as bad weather persists in the southern US. Neil offers these additional comments and statistics below:
Andy, KU4XR, in Tennessee, provided a report of his recent antenna work and performance testing which included the recommissioning of the famous ‘tree-tenna’. I don’t care why the tree-tenna works or why its not supposed to work – I know that it does work to significantly improve Andy’s S/N and over the last few seasons using this antenna he has provided many massive signal reports and recordings to support the performance. I look forward to receiving reports from this antenna again this summer.
Regional and continental WSPR breakdowns follow:
There were no trans-Atlantic or trans-African reports during this session. UA0SNV was present during the session but no reports were found in the WSPRnet database for Vasily’s station.
Eden, ZF1EJ, continues to listen to the band as noise levels increase, reporting WH2XZO during this session.
Laurence, KL7L / WE2XPQ, continues to operate in transceive mode from Alaska with what appears to be improved results over the previous sessions while operating receive-only from Hawaii while on a work assignment.
Merv, K9FD/KH6 / WH2XCR, received reports from numerous stations in the western portions of North America, including Alaska. The path to and from Australia continues to perform well including two-way reports with VK3ELV and VK4YB and reception reports with VK2XGJ and VK2DDI. David, VK2DDI, provided a screen capture of his WSPR console from early in the session. Also note the very numerous reports from stations in Australia.
In Australia, Phil, VK3ELV, and Roger, VK4YB, completed two-way reports with WH2XCR. Phil continues to receive reports from Japan from this session and late in the previous session.
Jim, W5EST, continues his current discussion with, “PART 2:DISPLACEMENT CURRENT IN YOUR RADIATED SIGNAL”:
“Radio waves get too far from their launching antenna to have antenna electric current make their magnetic field directly. Indeed, somewhere the radio waves are still traveling even after you stop transmitting! Because of their displacement current that goes so far, the magnetic fields in the radio wave nevertheless do arise and the radio energy propagates. It’s because the varying electric fields make varying magnetic fields and vice-versa.
From your transmitting antenna as its center, concentric layers of displacement current consecutively convey electromagnetic energy ever outward. Like layers of an onion, these layers of displacement current comprise a growing laminated shell that expands endlessly at the speed of light. https://en.wikipedia.org/wiki/Radio_wave (animation).
After launch from your antenna, each layer of displacement current is separated from its neighbor by half a wavelength—λ/2–315m at 630m, or about 1000 feet. Doesn’t that seem remarkable considering the height of your antenna is probably less than one-thirty-secondth of a wavelength (λ/32)! The layers comprise alternating directions of displacement current: one layer of displacement current arches upward, the next layer of displacement arches downward, and so on.
Magnetic lines of force, for their part, are generated by the onion-layers of displacement current and fill the spaces between those layers of displacement current like magnetism inside a coil. Resembling latitude lines on the surface of a globe, horizontally circular magnetic field lines occupy the interlayer spaces in directions first one way and then the opposite way from space to space.
I invite us to remember one number by heart: 377Ω. If air or free space be compared to a transmission line, its characteristic impedance is 377Ω. 377Ω is the ohms you get by dividing amplitude of electric field strength E in microvolts-per-meter by magnetic field strength H in amperes-per-meter that the displacement current of a propagating wave generates. Instead of characteristic impedance, it’s called intrinsic impedance, but it’s essentially the same thing. Dividing (E/H) boils down to taking the square root of the ratio of the inductive and capacitive properties of free space:
377Ω = sqrt[(1.26uH/m)/ (8.85pF/m)].
The intrinsic impedance in ionospheric regions departs from 377Ω a little. When a radio wave encounters the ionosphere, it sees what amounts to a transmission line characteristic impedance discontinuity. As a result, some of the radio wave is reflected. Also, some of it is transmitted, meaning that part travels onward even if redirected somewhat. In reality, an ionospheric region may include dissipation that saps some of the radio wave energy as well. The D-layer, for instance, may dissipate strongly some days in the daytime but allow daytime propagation other days on 630m.
Speaking of radio wave energy–at any place along their travel the radio waves have power density in microwatts/sq-meter moving at the speed of light in the direction of propagation. The power density is E xH because microvolts-per-meter times amperes-per-meter is microwatts/sq-meter.
Just remember that the power we are talking about results from the electric field E being perpendicular to and in phase with H along the wavefront plane where E and H are maximum. Displacement current is situated a quarter-wavelength displaced from both electric field E and magnetic field H. That’s because displacement current is our label for rate of change of electric field E.
The power density in your sky wave rapidly declines because the transmitter radiates a limited amount of power that spreads out over vast reaches of 630m paths in every direction. But it’s there, even when deeply buried in the noise– indeed even when so faint the WSPR decoder can’t decode it.
For 630/2200m RX station operators, the challenge is to present as best as we can the elusive signal we know is there and dig it out of the noise. Can the limitations of WSPR2 and even WSPR15 ever be transcended without demanding even slower data rates? Like breaking the old 4-minute mile that once seemed impossible, who knows what improvements lie ahead!
Can we say anything else about antennas and their radio waves? Let’s see tomorrow.”
Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD <at> gmail dot (com)!