Its really challenging to characterize sessions like this one. Propagation wasn’t poor but, at least at my station, the WSPR decode count was down significantly from the previous session. Even with reduced spots, the path to KH6 has opened again from my station, if only briefly. Band activity is actually a little better than it was this time last year which seems to see a Spring decrease before stabilizing and returning to nominal levels through the Summer in previous years. So this was another weird one and I am sure that everyone has their own way of describing their own band conditions from their station. We are fortunate to have many active stations that permit us to make these observations.
Geomagnetic conditions continue at quiet levels. The Bz was mostly stable, averaging near 0 nT through the session. Solar wind velocities have returned to low levels, below 400 km/s. Protons were elevated through a few reporting periods prior to sunset in North America.
Ken, K5DNL / WG2XXM, reports that persistent storms have kept him off air recently but he is using the time to rebuild the shack after his recently lightning event.
Phil, VE3CIQ, reports that he was decoded by seven unique stations during this session in addition to hearing WH2XGP and WH2XZO during the session.
Doug, K4LY / WH2XZO, reports that his on going antenna work has resulted in about 30 foot of top loading being removed to manage sagging in his newly implemented rotating support on a tower that also holds his VHF and UHF arrays.
Wolf, DF2PY, reports that he was QRV on 472.5 kHz CW starting at 1910z. This activity has been on-going so listen for his signal or look for him on DK7FC’s MF grabber.
Neil, W0YSE/7 / WG2XSV, reports that the path to KL7 is working well and notes a few problems with WSPRnet:
N9APL was receiving and reporting WSPR during the session from Colorado. Roy has possibly been QRV in the past but I could not find him on any of my lists which are a disorganized mess of sticky notes. Welcome aboard!
During the morning’s CW sked I experienced a significant change in keying with the bug. It seems the dit contact spring doesn’t faithfully return to its original shape during keying. I find myself compressing it and resetting the contact spacing during the QSO to maintain dits that seem to get shorter and shorter while operating. It may be time to talk to Vibroplex about this problem. Receiving started out as a challenge but the broadside rotatable loop did a nice job nulling storms in Oklahoma and allowing the QSO to commence.
Regional and continental WSPR breakdowns follow:
There were no reports from the trans-Atlantic or trans-African paths. UA0SNV was present but no reports have been posted for this session.
Eden, ZF1EJ, continues to report WH2XZO and WG2XIQ from Cayman Island.
Laurence, KL7L / WE2XPQ, received reports from WH2XGP in Washington state and WH2XCR in Hawaii and decoded those same stations in addition to WG2XSV twice in the 1000z hour.
In Hawaii, Merv, K9FD/KH6 / WH2XCR, saw the path to the south central US open again with a couple reports of my station. The path has been missing for several weeks now so hopefully reports will continue. The path to the West coast and Pacific Northwest was also represented in addition to Alaska. VK4YB continues to share two-way reports with Merv and VK2XGJ provided a few reports as well.
Jim, W5EST, presents “PART 3: NOISE CANCELLING, PRELIMINARY CONSIDERATIONS”:
“Reception of MF/LF radio signals is hampered by the presence of noise from a variety of local and distant sources. When a radio receiver apparatus has sufficient gain in its amplifiers to adjust the received signal to a desired level, the noise is likely also increased along with the signal. Accordingly, signal-to-noise ratio (SNR) is a better measure of reception quality than mere receiver gain.
Let’s start by improving signal S in the signal to noise ratio S/N (SNR) picture. After that, we can start talking about band noise reduction. I’m assuming that one has already put up the antenna(s) in a reasonably low-noise location and eliminated local QRN or rejected noise and common-mode through antenna and ATU/coupler construction and careful grounding practices.
One achieves adequate total radiated power at the outset with a vertical antenna establishing favorably-high degree-amperes by both a tall height of the vertical and RF current uniformity due to a top hat (this blog April 2, 3, 4). Degree-amperes strongly affect the radiation resistance and the radiated power level.
Unfortunately, even with adequate radiated power, if the RF is mostly being launched at angles exceeding 10° elevation, then very little of the radiated power will be coupled into long paths. For long path transmission, the issue of low-angle elevation pattern importantly confronts us (May 7, 9, 10, 13 this blog).
The low-angle elevation performance of an electrically-short vertical that you see on the FF Plot feature of EZNEC Demo depends mostly on the quality of the grounding system and hardly at all on the height of the typical MF/LF electrically-short vertical. You can satisfy yourself of this, as I did, by antenna modeling different examples of verticals and ground parameters.
So a good radial system contributes quite significantly to long path performance, not to mention overall antenna/grounding system efficiency. If either the TX vertical itself or a separate RX vertical (or E-probe) is used for reception, good grounding and radials likewise contribute to long path reception performance by improving the signal S in signal to noise ratio S/N (SNR).
Effective solid-angle A “area” of antenna pattern lobes in steradians at a specified number of dB down can also be a helpful indicator of antenna reception capability for signals in the direction of a lobe. https://en.wikipedia.org/wiki/Steradian The solid angle of a whole sphere is 4π steradians, so the half-sphere above the horizon subtends 2π steradians.
A Beamwidth Figure of Merit 2π/A at, say, 3dB down can describe the ability of an antenna to reject band noise from directions other than the lobes.
EZNEC Demo reports an elevation beamwidth angle WELEV on the FF plot at 3dB down. For instance, an electrically-short vertical has an elevation beamwidth WELEV of about 50° elevation and an azimuth beamwidth WAZ of 360° (full circle).
You can use the Azimuth plot selection of FF Plot to see the beamwidth WAZ in azimuth degrees. For a vertical antenna WAZ = 360° is obvious without Azimuth FF Plot, of course. But for a bidirectional or unidirectional loop you probably would want to use Azimuth FF Plot. To get a useful Azimuth plot, first select an elevation angle ϕ (phi) measured upward from the horizon to the middle of a lobe found from the FF Plot elevation pattern. For a loop, estimate the total steradians for all strong lobes.
Approximate Solid angle A ~= (WAZWELEV cosϕ)/57.32
One electrically short vertical antenna example subtends an angle A where
A~= (50° x 360° cos(50°/2))/57.32 = 4.97 steradians.
Beamwidth Figure of Merit 2π/A for the example vertical is about 1.3 (not very much). As you can see, a vertical does not reject much band noise except at very high elevation angles.
In a further blog post let’s consider another hypothetical antenna system and investigate what band noise cancelling capability it might offer.”
Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD gmail dot (com)!