It was generally a slow session consistent with the season overnight in North America. This report will likely be short. Geomagnetic activity was quiet and the Bz pointed to the North for much of the session with solar wind improving to low levels, below 400 km/s.
Phil, VE3CIQ, probably had the banner night in North America, reporting that the session “Looks good, one west coast station-XGP Hearing: WG2XKA, WH2XGP, WI2XFI Heard by: SWL/K9, VE2PEP, WA3TTS/2, WA9EIC, WD2XSH/17, WE2XGR/3, WG2XJM, WG2XKA, WI2XFI.”
On the other side of the continent, Neil, W0YSE/7 / WG2XSV, reports a slow session but salt water still rules the night:
Doug, K4LY / WH2XZO, reports that he will be QRT until he is able to complete the work on his top loading.
Regional and continental WSPR breakdowns follow:
There were no reports from the trans-Atlantic or trans-African path. UA0SNV / UA0SNV-1 and ZF1EJ were present but no reports were found in the WSPRnet database.
Laurence, KL7L / WE2XPQ, reports that both stations, WE2XPQ in Alaska and KL7L/KH6 in Maui, are in receive-only mode at this time.
Merv, K9FD/KH6 / WH2XCR, continues to see a nice path into Australia with two-way exchanges with VK3ELV and VK4YB, even receiving Roger after sunrise in Hawaii. Merv also decoded VK5ABN during the session and continues to receive numerous reports from VK2DDI and VK2XGJ. The path to North America appears to only be limited by storm noise at the moment with reports at WE2XPQ and along the West coast of North America. KE7KRF, who has been away for some time, also decoded Merv during this session.
In Australia, it has been reported that additional activity from VK6 is in the works. Phil, VK3ELV, and Roger, VK4YB, continue to exchange two-way reports with WH2XCR and VK5ABN is decoded at WH2XCR. Phil also receives reports from TNUKJPM.
Jim, W5EST, goes to the mailbag for this discussion, entitled, “RAISING A TOP HAT PARTLY OFFSETS MORE ANTENNA HEIGHT”:
“Doug WH2XZO K4LY writes:
‘With the size and complexity of my 630M antenna, A/B tests (head-to-head) of antennas are not really possible on my acre lot so I do modelling. I may, however do some A/B testing of “630M antennas” scaled down to say 40M this summer.
I’ve modelled several 68′ and 82′ Inv L, T, and umbrella antennas that are closer to what I’ve used and am using. I’m getting Z= 1.308- j525 and Z= 1.587- j480 for antennas I have used and look forward to your analysis of the comparisons.
With only 20 segments, I probably can’t accurately model my present umbrella antenna with 5 top hat wires, but what I learn is probably transferable to MMANA-GAL.
Also, I’m reading antenna modeling articles at http://www.arrl.org/antenna-modeling.’
[L.B. Cebik W4RNL. A Beginner’s Guide to Modeling with NEC. Part I-4. QST 11/2000 -2/2001 pp. 34-38, 40-44, 44-48, 31-35 respectively.]
Jim W5EST reply: “Recall that radiated power is proportional to radiation resistance. Take the ratio of EZ-NEC resistances (using R in R+jX) given wire loss =0 in the modeling. See Doug’s illustrations.
1.308/1.587 = .83.
TRP with 68’ vertical is 17% down from the 82’ vertical. (100%-83% = 17%. 0.83 is -0.8dB.)
You might wonder: How can it be only 17% down if radiation resistance is proportional to square of antenna height and (68/82)^2 = .69, -1.6dB. Wouldn’t you expect TRP 31% down?
The departure involves degree-amperes. The top hat extent is physically the same in the 82′ vertical as the 68’ vertical. Both 68’ and 82’ verticals used four 80′ radials in umbrella configuration. So the top hat capacitance went down as antenna height went up. Fortunately, the increase in height helped more than the decreased capacitance hurt. So, “on net,” additional radiation resistance was achieved by increasing the height.
If the lengths of each of the four top hat conductors can get increased another 20 feet to scale up the entire 68’ antenna to an 82’ version, opportunity for more radiated power arises.
Or, if the hat wire lengths cannot be extended outward, try modeling with additional end wires connecting to and going sideways from each 80’ end.
Because the number of modeling segments available in the free EZ-NEC Demo is limited to 20, there’s appeal in free antenna modeling software that may be more powerful. Some background information on MMANA-GAL can be found at these websites: http://g0kya.blogspot.com/2012/03/using-mmana-gal-for-antenna-modelling.html
http://gal-ana.de/basicmm/en/ Tutorial. Scroll to bottom to download free basic version.”
Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD <at> gmail dot (com)!