The details for March 11, 2016 can be viewed here.
The band was surprisingly good after several days that were hit or miss due to active geomagnetic conditions and high QRN levels. It was a noisy evening here in Texas as lightning-rich storms about 60 miles to the South pulsated without moving very far through the evening. Fortunately these storms dissipated in the late evening and overnight and QRN conditions improved a bit. Storms to the North in Oklahoma and Arkansas appeared as morning approached. It was by no means a perfect session but it was better than the previous session that was essentially a washout in the central and eastern portions of North America.
Geomagnetic conditions were quiet for the moment with a Bz that is pointing slightly but persistently to the South. Solar wind velocities have returned to low levels, averaging 385 km/s. DST values have been agitated for a number of sessions although the tendency has been toward the centerline over the past 24-hours.
Trans-Atlantic openings congregated in New England after several sessions where openings stretched down the eastern seaboard and into the Caribbean. QRN was high so reports were only one-way with two North American stations being reported in Europe. Report details can be viewed here.
WG2XPJ -> G3XKR, PA0O
WD2XSH/17 -> DJ0ABR, DK7FC/p, F1AFJ, F59706, G3XKR, LA2XPA/2, PA0O, PA0RDT, PA3ABK/2, PA7EY
Doug, K4LY / WH2XZO, reported, “Better than average conditions overcame the high QRN levels to some extent, and the 14 decoded and 52 who decoded XZO were a surprise given the static crashes. Best was two way WH2XCR.”
Rick, W7RNB / WI2XJQ, reported good propagation across North America, provided decodes for eight WSPR stations and receiving reports from 35 unique stations. Rick’s unique report details can be viewed here.
Ernie, KC4SIT / WI2XQU, has resurfaced and provided the following comments for the session:
“Spent yesterday with Doug Allen, WH2XZO, trying to work out the WI2XQU transmit problem. Picked up a transverter and Doug is coming to the QTH this month. We have a major snow event predicted to start at 7pm local time this evening. Last night I had 13 spots (plus one bogus). The storm the night before, with lightning filled skies, shut down operations.”
Neil, W0YSE/7 / WG2XSV, reported a strong session with transcontinental openings. He provided these comments and statistics:
Mike, WA3TTS, reported good openings to WH2XCR and other transcontinental destinations:
Trans-Pacific report details for this session, excluding KL7 and KH6, can be viewed here.
Roger, VK4YB, received reports fom JA1PKG, JA3TVF, VE6JY, VE6XH, VE7BDQ, VE7SL, and W7IUV. He provided reports for WH2XXP and WH2XGP. Roger continues 160/630m comparison experiments with VE6XH and provided these statistics: “160m 4 spots, best -19, 630m 11 spots, best -25.”
Larry, W7IUV / WH2XGP, provided reports for thirteen WSPR stations and was decoded by 54 unique stations including JA1NQI and VK4YB. As W7IUV, Larry provided reports for eleven WSPR stations including VK4YB.
Ward, K7PO / WH2XZO, received reports from 75 unique stations including JA1NQI, VK2XGJ and VK4YB.
It was a pretty noisy night here in Texas and after a very long week I chose to go to bed early so my activity was limited to WSPR. Domestic conditions were very good with a number of single-digit S/N reports. Transmissions reports were typical and plentiful. Receive report totals of other stations were down once again, likely due to local noise, but WG2XKA was received early in the evening in spite of QRN while using the multi-turn receive loop. Transmission report details can be viewed here and reception report details can be viewed here.
Band activity was high with 135 MF WSPR stations observed at 0200z on the WSPRnet activity page.
Regional and continental WSPR stations follow:
Eden, ZF1EJ, provided reports for ten WSPR stations and was decoded by forty unique stations including WH2XCR.
Laurence, KL7L / WE2XPQ, experienced a strong night of reports from JA stations, including 7L1RLL4, JA1NQI, JA8SCD5, JE1JDL, and JH3XCU. Laurence also shared two-way reports with WH2XCR. The path to VK was completely cutoff during this session. Report details can be viewed here.
Merv, K9FD/KH6 / WH2XCR, also experienced a strong night of openings to JA, with reports from 7L1RLL4, JA1NQI, JA3TVF, JH3XCU, JA1PKG, and JE1JDL. Many of those reports were at or even after local sunrise in KH6, Merv also received reports from VK2XGJ and shared two-way reports with VK4YB and WE2XPQ. A few late reception reports were recorded at VK4YB at or just after local sunrise. Merv provided reports for ZF1EJ but the path was not reciprocated during this session, likely due to high noise in the Caribbean. North American coverage favored the East coast once again, with two-way reports for WH2XZO and reception reports for WI2XBV, WG2XPJ, and WD2XSH/17. Merv was heard by many stations in the East. DX report details can be viewed here.
Jim, W5EST, presents, “GET A GRIP ON 630M GROUND WAVE: PART 2”:
“Part 1 plotted daytime 630m morning receptions March 6, 2017, at various distances out to 1200 km. Superimposed on SNRs was a family of theoretical TX-power-adjusted ground wave loss curves I generated. To read Part 1, just click: http://njdtechnologies.net/030717/ .
Today, let’s use FAQs to focus on RF ground wave as it encounters terrain features.
Question 1: Can ground wave jump over dips and valleys as sky wave, or does it hug the ground wherever it goes?
JH Answer: Compared to a ground wave curve of steadily declining signal strength dB on uniform-conductivity flat earth, ground wave signal strength can locally increase where ground wave RF meets a hill and then considerably decrease behind it. [I’m interpreting computer simulations by Zhou et al. (2011)*.]
At multiple wavelength distances on flat terrain beyond the backside of a hill, some but only some of the lost dB strength is restored as the declining strength curve on uniform flat earth resumes. Presumably diffraction accounts for that partial recovery. If the hill is high compared to the wavelength, the shadowing effect is greater. With multiple hills situated one after the other in the direction of ground wave propagation, the effect is replicated and involves cascaded up-down variations in dB.
From your transmitting antenna itself, the radiation divides into RF sky wave signal power and RF ground wave signal power. A valley or ridge far away would also introduce some power division between RF signal power that “hugs” the terrain and any RF signal power that diffracts or “jumps.” I wouldn’t call it sky wave. In that case, it’s diffracted ground wave RF power.
A valley or ridge varies the ground slope relative to horizontal and that way can alter the electric field orientations as the wave front travels. An altered electric field orientation relative to horizontal would be more nearly slanted towards the horizontal and there presumably increase the ground losses of whatever ground wave continues to propagate along the ground unless augmented by arriving diffracted energy.
Question 2: Does ground wave self-cancel somehow in valleys and between ridges?
JH Answer: Behind a hill, I’d call it shadowing. The Zhou et al. graphs also show partial self-canceling strength variation a few wavelengths in front of a tall hill, not behind it, due to reflection from the hill or ridge back toward the TX. I have driven up and down on local streets here in Little Rock with car radio tuned to 500m, 600KHz WREC Memphis. The station is strong some places and buried in unchanged band noise other places. This can happen even in medium size road dips and hills far less than a wavelength (500m) wide or deep. (At still other places, noise from power poles is deafening and buries the station, but that’s another story!)
Do you understand the behavior of ground wave differently or have contrary experiences of 630m ground wave reception? Share any of your ground wave reception experiences from sunup to sundown with this blog!”
*Zhou, L., Xi, X., Liu, J. and Yu, N. “LF Ground-Wave Propagation Over Irregular Terrain,” Antennas and Propagation, IEEE Transactions on, Vol. 59(4): 1254–1260, April 2011. (Unfortunately, I found no free web site and had to access the journal through a university system.)
Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD gmail dot (com).