We appear to be in a roller coaster pattern of geomagnetic storming followed by calm to unsettled conditions followed by storming conditions again. This session seems to have represented the quieter, calmer eye of the storm. Solarham reports that storm conditions should return in the coming days. For higher latitudes it may not matter as the slower recovery may not yield many improvements before storm conditions return.
It was a goods session nonetheless. Larry, W7IUV / WH2XGP, was once again reported in Australia by VK2DDI and VK4YB. Larry also notes that he decoded seven WSPR stations and was decoded by 44 unique stations with a rain stoppage at 1130z. While the band may not be 100% that far North, you can’t argue with a long-haul opening like that.
Geomagnetic conditions are quiet to unsettled but solar wind is currently below 400 km/s.
Warren, K2ORS, reported that he would be on the air with CW as WH2XIL, running about 60W into a 500′ dipole laying on the ground. WG2XSB was also QRV with a CW beacon about 10-miles away from Warren using an 80m delta loop fed as a top loaded vertical with 32W TPO. John, WA3ETD / WG2XKA, captured the signals with Argo and recorded audio, presented below:
John, WA3ETD / WG2XKA, has been QRT due to high winds and bizarre late-season “Winter” weather but provided reception reports, as noted above, including the following comments about my WSPR signal: “At 0706 you put a -9 in here…in that same hour several -10 to -13 spots from you…pretty strong.” John is a very long way away from Texas and its just remarkable to be receiving such reports from him in April!
Ken, K5DNL / WG2XXM, reported that he decoded 9 WSPR stations and was decoded by 44 unique stations during the session.
Neil, W0YSE/7 / WG2XSV, reported that eleven station decoded his 200 mW ERP signal during the session, with WG2XJM in western Pennsylvania being most distant.
Phil, VE3CIQ, reports that he decoded four WSPR stations and was heard by 24 unique stations, “although seems constrained to the eastern side of the continent. Nice to see VE3’s stop in for a listen.”
Doug, K4LY / WH2XZO, has been travelling recently, even getting the chance to receive from the road as K4LY/5, and provides the following comments that were sent to me and Jim, W5EST:
“Got home last night from the Mexican border.. Missed some darn good conditions. I made a last minute decision before leaving for Texas to take my Elad FDM-S2 and a 40M dipole which I got up 15-25′ in trees just off the 2nd floor condo balcony, but the laptop power supply caused over 2 S-units interference, wide spikes every few dozen kHz, one at 473 kHz and extending beyond 476 kHz. I have read an article on reducing the interference, but I’ll go another direction-So only decoded XXM and XIQ with the interference spike stronger at XIQ’s lower frequency.Using just the laptop battery was only a little better, still almost 10 dB interference from something. It made me appreciate how difficult 630M reception is! Tried my other laptop today to see if I should have taken it, but it’s almost as bad.Also did some A/B tests here today with the laptops and two of my antennas- the 630M TX antenna which picked up the laptop spikes like the dipole did, and my amplified loop which picked up very little interference from the laptops.I have an amplified Miniloop on order- http://www.ebay.com/itm/201547868317and it will be fun to see how it compares with the loop which is too big to fit in my suitcase.Looking forward to your continuing on ATUs and estimating antenna current.Doug”
“Roger VK4YB and I have been coming up on 472.5 CW at 0900 UTC nightly for a short while after which we QSY to 479 KHz LSB for a chat. Already had a QSO with Grant, VK3HP 2-way SSB QSO on 479.It would be great to hear other stations as well so please feel free to give us a shout or reception reports if heard.”
There were no trans-Atlantic or trans-African WSPR reports during this session. ZS1JEN and UA0SNV were present but no reports were found in the WSPRnet database.
Eden, ZF1EJ, and Roger, ZF1RC, were present from the Cayman Islands, providing reports to stations in North America. Eden also provided reports for WH2XCR in Hawaii.
In Alaska, Laurence, KL7L / WE2XPQ, reports poor conditions through the sessions but was successful at sending and receiving a few signals with many of the usual suspects.
In Hawaii, Merv, K9FD/KH6 / WH2XCR, continues to see two-way reports with VK4YB and has a strong presence in the eastern US. The JA path continues to be cut off.
In Australia, Phil, VK3ELV, and Roger, VK4YB, continue to receive report with WH2XCR while Roger experiences two-way reports with Merv. Phil receives reports from three stations in Japan.
Jim, W5EST, bring us the following discussion entitled, “ESTIMATE DEGREE-AMPERES FOR YOUR ANTENNA SYSTEM”:
“Recall from April 2, this blog, that degree-amperes are closely related to field strength in mV/meter at 1 kilometer. Total radiated power TRP is proportional to the square of degree amperes. That’s nice, but if you don’t know the RF antenna current averaged all way up the height of the antenna, then how can you estimate the degree-amperes?
Today let’s address that question for LF/MF using insights from a 2200m web site: http://www.strobbe.eu/on7yd/136ant/ . Scroll down to section 2.3. There you see some interesting capacitance formulas.
In a capacitance picture of the short vertical antenna and horizontal top hat conductor surfaces, numerous small capacitors with their susceptances (2πf C; 1.0/reactance) are distributed over the height of the vertical and along the length of the top hat. RF current gets diverted into these reactances and consequently diminishes as it progresses up the short vertical and out onto the top hat.
If you think of the vertical as having one overall average capacitance Cvert and the top hat having another capacitance Chat, then the RF current fraction Ihat that reaches the top hat is the same fraction that the susceptance 2πf Chat of the top hat bears to the susceptance of the whole antenna system 2πf (Chat+ Cvert). To get an RF current average value over the vertical height, then add up the 100% of the RF current that enters the base of the antenna plus the current that enters the top hat, and then divide by two.
The result for average current along the vertical height is
Iavg = Ibase [1 + 2πf Chat /(2πf(Chat+Cvert))]/2, or Ibase(Chat+ 0.5Cvert)/ (Chat+ Cvert).
Imagine a perfectly horizontal top hat and entire antenna system in the midst of a vast plain, use formulas for Cvert and Chat from the web site:
Cvert/Chat = h/L[log(4.0 h/dhat) / log(1.15 h/dvert)]
L is hat length, h is vertical system height, dhat is hat wire diameter, dvert is the vertical’s average diameter for wire, tube or cage. Multiple L by number of Marconi-T conductors in that type antenna. If the hat slants up or down, then add half the hat’s vertical rise to the vertical height h (or subtract half the hat’s descent). Likewise if the hat slants, revise the hat length L to be the sum of all actual horizontally-outward extents of its conductors. Figure Cvert/Chat and then calculate the average current Iavg.
Iavg = Ibase (1 + 0.5Cvert /Chat )/ (1+Cvert /Chat).
To get degree-amperes multiply the average current Iavg times the electrical height of the vertical in degrees:
Degree-amperes = Iavg (360° h/λ).
In the real world, you have an antenna farm and possibly a metal antenna tower, plus trees and nearby residences with their gutter systems and possibly even nearby buildings with steel structural support. You can still use the capacitance concept. You could just fudge numbers by hunch and experience.
Maybe you can even do better than that. Use an antenna analyzer or capacitance bridge or other measuring technique to measure the total capacitance CANT of the antenna system. Analyzer shows reactance XANT, and from there you get
CANT = 1/(2πf XANT) = Chat+ Cvert.
Using the capacitance formulas from the web site, estimate the capacitance Cvert or Chat of whichever vertical or hat portion of the antenna system is farther from (and/or more nearly perpendicular to) nearby structures. Suppose the vertical is farther. Then:
Iavg = Ibase (CANT-0.5Cvert)/CANT.
If the hat is farther from the structures and the vertical is closer, then see if you can adjust the capacitance Cvert from the web site by adding a capacitance calculated in light of the nearby geometry. If it’s a grounded tower, then try a capacitance formula based on parallel conductors. If the nearby structures seem too difficult to estimate on, then estimate the hat capacitance from the web site formula and use:
Iavg = Ibase 0.5 (CANT + Chat) /CANT.
If both the hat and vertical are nestled in a complicated environment and you can’t figure out how to do the estimation, then tell us about it. We care about how things really work!”
Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD <at> gmail dot (com)!