160m Propagation
description
Transcript of 160m Propagation
PVRC Webinar - 20Jan10 - K9LAPVRC Webinar - 20Jan10 - K9LA
160m Propagation160m Propagation
Carl Luetzelschwab Carl Luetzelschwab K9LAK9LA
[email protected]@arrl.nethttp://mysite.verizon.net/k9lahttp://mysite.verizon.net/k9la
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What We’re Going to CoverWhat We’re Going to Cover• ForewordForeword• Fundamental physical truthsFundamental physical truths• Normal propagationNormal propagation• Interesting observationsInteresting observations• 160m predictions (or lack thereof!)160m predictions (or lack thereof!)• SummarySummary
This presentation will be on the PVRC websitevisit http://www.pvrc.org/index.htmlclick on the ‘PVRC Webinars’ link at the top
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Cycle 24 Update - SunspotsCycle 24 Update - Sunspots
Cycle 24 sunspot activity appears to be increasing
Sunspots for Solar Minimum Between Cycle 23 and 24
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Cycle 24 Update - Ap Cycle 24 Update - Ap # of Days in Month With Ap < 7 vs Smoothed Sunspot Number
Cycle 21 decline through Cycle 23 decline
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ForewordForeword• There’s still a lot we don’t know about 160m There’s still a lot we don’t know about 160m
propagationpropagation• The biggest area where we lack a good of The biggest area where we lack a good of
understanding appears to be the lower understanding appears to be the lower ionosphere – i.e., the D region and lower E ionosphere – i.e., the D region and lower E regionregion– We really don’t have any day-to-day parameters We really don’t have any day-to-day parameters
tied to this area of the ionospheretied to this area of the ionosphere• Thus don’t expect this presentation to be Thus don’t expect this presentation to be
“The Secrets of 160m Revealed”“The Secrets of 160m Revealed”• Recommendation – to better “understand” Recommendation – to better “understand”
propagation on 160m, be very active on propagation on 160m, be very active on topbandtopband
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Oler and Cohen Article in CQOler and Cohen Article in CQ
• CQ, March 1998, Part CQ, March 1998, Part 1, pp 9 -141, pp 9 -14
• CQ, April 1998, Part 2, CQ, April 1998, Part 2, pp 11-16 pp 11-16
• Oler and Cohen article is highly recommended readingOler and Cohen article is highly recommended reading– Follow-up: Ducting and Spotlight Propagation on 160 Meters,
K9LA, CQ, December 2005, pp 22-29
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Fundamental Physical Fundamental Physical TruthsTruths
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What Does It Take to Make a What Does It Take to Make a QSO?QSO?
• Enough ionization to refract signal back to EarthEnough ionization to refract signal back to Earth– MUF not a problem on 1.8 MHz even in the dead of night at solar minimumMUF not a problem on 1.8 MHz even in the dead of night at solar minimum
overhead Sun
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Ray Tracing vs Elevation Ray Tracing vs Elevation AnglesAngles
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100 km
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300 km400 km
0o10o30o 20o40o
2000 km1000 km
100 km
200 km
300 km400 km
0o10o30o 20o40o
path across the northern tier of the US at solar minimum around midnight• E region still comes into play at night at low elevation anglesE region still comes into play at night at low elevation angles
– foE approximately 0.4 MHz at nightfoE approximately 0.4 MHz at night• Angles below approximately 7Angles below approximately 7o can be refracted back to Earth by the E can be refracted back to Earth by the E
regionregion
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What Does It Take to Make a What Does It Take to Make a QSO?QSO?
• Strong enough signal to be readableStrong enough signal to be readable– Ionospheric absorption on 1.8 MHz is the real problem – too much and Ionospheric absorption on 1.8 MHz is the real problem – too much and
signal is below your noise floor (which is usually not your receiver MDS)signal is below your noise floor (which is usually not your receiver MDS)
1.8 MHz
S3S5S7
S1
low noise receiving antenna are very helpful for serious DXing
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Refraction and AbsorptionRefraction and Absorption• Refraction and absorption are inversely Refraction and absorption are inversely
proportional to the square of the frequencyproportional to the square of the frequency• Thus for a given electron density profileThus for a given electron density profile
– The lower the frequency, the more the The lower the frequency, the more the refraction (bending)refraction (bending)
– The lower the frequency, the more the The lower the frequency, the more the absorptionabsorption
160m RF is bent the most and incurs the most absorption
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Ray Tracing on 28 MHzRay Tracing on 28 MHz• o-wave and x-wave o-wave and x-wave
pretty much follow pretty much follow the same paththe same path– Index of refraction Index of refraction
approximately the approximately the samesame
– X-wave bends a tiny X-wave bends a tiny bit more bit more
• o-wave and x-wave o-wave and x-wave pretty much incur the pretty much incur the same amount of losssame amount of loss– Absorption Absorption
approximately the approximately the samesame
• Apogee ~ 240 kmApogee ~ 240 km
on higher HF bands, o-wave and x-wave propagate approximately equally
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Ray Tracing on 1.8 MHzRay Tracing on 1.8 MHz• O-wave and x-wave O-wave and x-wave do do
notnot follow the same path follow the same path– Index of refraction Index of refraction
significantly differentsignificantly different– x-wave bends morex-wave bends more
• O-wave and x-wave O-wave and x-wave do do notnot incur the same incur the same amount of lossamount of loss– Absorption significantly Absorption significantly
differentdifferent– x-wave usually x-wave usually
considered to be out of considered to be out of the picture when the picture when operating frequency is operating frequency is near the electron gyro-near the electron gyro-frequencyfrequency
• ranges from .7 to 1.7 ranges from .7 to 1.7 MHz worldwideMHz worldwide
• Apogee for o-wave ~ 170 Apogee for o-wave ~ 170 kmkm– 160m wave doesn’t get 160m wave doesn’t get
as high into the as high into the ionosphereionosphere
Generally only the o-wave is useful on Generally only the o-wave is useful on 160m, and polarization at mid to high 160m, and polarization at mid to high latitudes on 160m tends towards latitudes on 160m tends towards elliptical (elliptical ( vertical) vertical)
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Multi-hop on 160mMulti-hop on 160m• Based on previous slides, multi-hop Based on previous slides, multi-hop
propagation on 160m is via hops that are propagation on 160m is via hops that are short and lossyshort and lossy– ““Short” is relative – but it’s not 3000 or 4000 km Short” is relative – but it’s not 3000 or 4000 km
hops like on the higher frequencieshops like on the higher frequencies• Per our present understanding of the lower Per our present understanding of the lower
ionosphere, at night a 1500 Watt signal with ionosphere, at night a 1500 Watt signal with quarter-wave verticals on both ends can go quarter-wave verticals on both ends can go about 10,000 km before being below the about 10,000 km before being below the noise level of our receiving system (usually noise level of our receiving system (usually limited by external noise)limited by external noise)– Daytime limit around 1000 – 1500 kmDaytime limit around 1000 – 1500 km
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This Suggests DuctingThis Suggests Ducting
STØRY to K9LAMarch 22, 20030330 UTC
Wave refracts successively between the top of the E region peak and the lower portion of the F region
STØRY to K9LAMarch 22, 20030330 UTC
Wave refracts successively between the top of the E region peak and the lower portion of the F region
STØRY
K9LA
STØRY to K9LAMarch 22, 20030330 UTC
STØRY
K9LA
STØRY to K9LAMarch 22, 20030330 UTC
STØRY to K9LAMarch 22, 20030330 UTC
Distances at and greater than 10,000 km are likely due to ducting in the electron density valley above the nighttime E region peak
Ducting does not incur loss due to multiple transits through the absorbing region and loss due to multiple ground reflections
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Normal PropagationNormal Propagation
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Common DarknessCommon Darkness• Best place for 160m RF is in the dark ionosphereBest place for 160m RF is in the dark ionosphere
– Concept of “common darkness” along a path came from W4ZV Concept of “common darkness” along a path came from W4ZV in his 1991 in his 1991 Proceedings of Fine TuningProceedings of Fine Tuning article and his 13 Jan 97 article and his 13 Jan 97 topband reflector posttopband reflector post
K9LA sunset STØ sunrise
4 hours and 25 minutes of common darkness
maps from W6ELProp
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Signal EnhancementsSignal Enhancements• Most prevalent on the western Most prevalent on the western
end of the path when the eastern end of the path when the eastern end is around sunriseend is around sunrise– can bring a signal from no copy can bring a signal from no copy
(below your noise) to perfect Q5 (below your noise) to perfect Q5 copy for tens of minutescopy for tens of minutes
• Similar enhancements reported Similar enhancements reported on the eastern end of the path on the eastern end of the path when the western end is around when the western end is around sunsetsunset
• Enhancements believed to be Enhancements believed to be tied to ductingtied to ducting
• Ducting (specifically getting out Ducting (specifically getting out of the duct) may also have a lot of the duct) may also have a lot to do with spotlight propagationto do with spotlight propagation VE7DXR recording of Meyerton
(South Africa) shortwave station showing ~13 dB enhancement
Meyerton sunrise
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Skewed PathsSkewed PathsDon’t always assume a great circle path - remember the lower the frequency, the more the wave refracts (both in the vertical plane and in the horizontal plane)
If there’s going to be a skewed path, 160m is the most likely band
The auroral oval is probably the most likely cause of skewed pathsImage from “Skewed Paths to Europe
on the Low Bands”, K9LA, CQ, August 1999
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Spike in the K IndexSpike in the K Index
• Better opportunity for ducting ???Better opportunity for ducting ???– From “A modeling study of ionospheric conductivities in the high-latitude electrojet regions”, From “A modeling study of ionospheric conductivities in the high-latitude electrojet regions”,
Zhang, et al, Journal of Geophysical Research, Vol 109, April 2004Zhang, et al, Journal of Geophysical Research, Vol 109, April 2004• Less absorption due to higher electron temperatures causing more recombination ???Less absorption due to higher electron temperatures causing more recombination ???
– From “Frictionally heated electrons in the high-latitude D region”, Brower, et al, Journal of From “Frictionally heated electrons in the high-latitude D region”, Brower, et al, Journal of Geophysical Research, Vol 114, December 2009Geophysical Research, Vol 114, December 2009
Electron Density at an E-Field of 0mv/meter
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• Many observations Many observations of enhanced of enhanced propagation across propagation across the high latitudes the high latitudes right before (or right before (or concurrent with) a concurrent with) a spike in the K indexspike in the K index
• Includes improved Includes improved propagation on the propagation on the AM broadcast bandAM broadcast band
• Mechanism may be Mechanism may be tied to an increased tied to an increased ionospheric E-fieldionospheric E-field
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Gray LineGray Line• N6FF to A61AJN6FF to A61AJ
– Nov 29, 1999 at 1455 UTC Nov 29, 1999 at 1455 UTC (N6FF sunrise)(N6FF sunrise)
• N6FF heard A61AJ best from N6FF heard A61AJ best from the southwestthe southwest– SW on sunrise end, SE on SW on sunrise end, SE on
sunset endsunset end• Suggests long path, but true Suggests long path, but true
great circle path has too great circle path has too much daylightmuch daylight
• Is it a skewed path?Is it a skewed path?– Where’s the skew point?Where’s the skew point?
• What path did the RF follow?What path did the RF follow?• Are we fooled by short path?Are we fooled by short path?
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Interesting ObservationsInteresting Observations
some of them make yousome of them make youwonder about our age-old beliefswonder about our age-old beliefs
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Propagation Along the Propagation Along the TerminatorTerminator
• 3Y0X (Feb ’06) worked 287 Zone 4 stations 3Y0X (Feb ’06) worked 287 Zone 4 stations from 0210 UTC (image on left) to 0901 UTC from 0210 UTC (image on left) to 0901 UTC (image on right)(image on right)
• Path only near terminator at 3Y0X end – and Path only near terminator at 3Y0X end – and path gets away from the terminator quicklypath gets away from the terminator quickly
Note that this is short path
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Propagation Along the Propagation Along the TerminatorTerminator
• 3Y0X worked 8 Zone 20 stations (YO, SV, LZ) 3Y0X worked 8 Zone 20 stations (YO, SV, LZ) from 00422 UTC (image on left) to 0522 UTC from 00422 UTC (image on left) to 0522 UTC (image on right)(image on right)
• Path closer to the terminator – and not Path closer to the terminator – and not perpendicularperpendicular
Note that this is short path
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Propagation Along the Propagation Along the TerminatorTerminator
• 3Y0X only worked 3Y0X only worked 1 JA at 0819 UTC1 JA at 0819 UTC
• Path pretty much Path pretty much along the along the terminatorterminator
Note that this is short path
• This data indicates that gray This data indicates that gray line propagation on 160m on line propagation on 160m on the short path is the short path is notnot efficient efficient– Our model of the ionosphere Our model of the ionosphere
agrees with this dataagrees with this data• But our model also says that But our model also says that
Marconi’s feat never should Marconi’s feat never should have happened – may be just a have happened – may be just a high latitude issuehigh latitude issue
• And that VY2ZM on PEI never And that VY2ZM on PEI never should have heard the 100 should have heard the 100 Watt GB3SSS Poldhu beacon on Watt GB3SSS Poldhu beacon on 1.96 MHz – same high latitude 1.96 MHz – same high latitude issueissue
• There’s something going on There’s something going on that we don’t understandthat we don’t understand
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Solar Max vs Solar MinSolar Max vs Solar Min• Is solar minimum really Is solar minimum really
the best time for 160m?the best time for 160m?– Geomagnetic field is Geomagnetic field is
quieterquieter• 160m appears to be 160m appears to be
best at solar minimum if best at solar minimum if your path goes through your path goes through the auroral ovalthe auroral oval
path from IV3PRK topath from IV3PRK to # of QSOs# of QSOs resultresult
North America East CoastNorth America East Coast 106106 92% of QSOs at K 92% of QSOs at K << 3 3
North America MidwestNorth America Midwest 6767 96% of QSOs at K 96% of QSOs at K << 3 3
North America West CoastNorth America West Coast 2626 100% of QSOs at K 100% of QSOs at K << 2 2
IV3PRK to North America
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W8JI at Solar MaximumW8JI at Solar Maximum• But there appears But there appears
to be a lot of DX to to be a lot of DX to be worked at solar be worked at solar maximummaximum
• W8JI from W8JI from September 1999 September 1999 through July 2002through July 2002– Cycle 23 peakCycle 23 peak– Smoothed sunspot Smoothed sunspot
number number >> 100 100• Over 5,000 DX Over 5,000 DX
QSOsQSOs– Almost 200 countriesAlmost 200 countries– All 40 CQ ZonesAll 40 CQ Zones
low latitude pathslow latitude paths mid latitude pathsmid latitude paths high latitude pathshigh latitude paths
~ 1450 QSOs~ 1450 QSOs ~ 2700 QSOs~ 2700 QSOs ~ 975 QSOs~ 975 QSOs
VK (71%), NA (13%), VK (71%), NA (13%), north SA (8%), north SA (8%),
Oceania (6%), north Oceania (6%), north AF (2%)AF (2%)
south & central EU south & central EU (87.5%), ZL (8%), (87.5%), ZL (8%), south SA (2.8%), south SA (2.8%), Mideast (1.4%), Mideast (1.4%), south AF (0.3%)south AF (0.3%)
JA (54%), north EU JA (54%), north EU (42%), Asia (42%), Asia (3%), KL7 (3%), KL7
(1%)(1%)
60% in winter 8% in summer16% in fall16% in spring
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NM7M’s Work with GCRsNM7M’s Work with GCRs• Galactic cosmic rays are mostly Galactic cosmic rays are mostly
very high energy protons coming very high energy protons coming in from all directions – day and in from all directions – day and nightnight
• Quiet magnetic field (solar min) Quiet magnetic field (solar min) lets more in – more ionization in lets more in – more ionization in the lower ionospherethe lower ionosphere
• Active magnetic field (solar max) Active magnetic field (solar max) keeps them outkeeps them out
• GCR measurement on Earth and GCR measurement on Earth and impact to ionosphere is 180impact to ionosphere is 180oo out of out of phase with solar cyclephase with solar cycle
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CGRs and the ValleyCGRs and the Valley• NM7M’s theory is that NM7M’s theory is that
galactic cosmic rays play an galactic cosmic rays play an important role in the valley important role in the valley formation, and thus ductingformation, and thus ducting
• At solar maximum, not At solar maximum, not many GCRs ionizing the many GCRs ionizing the valley – nice and deepvalley – nice and deep– Extremely long distance Extremely long distance
DXing best at solar maxDXing best at solar max– NM7M has some interesting NM7M has some interesting
plots of QSO distance vs plots of QSO distance vs GCR decrease, but there is GCR decrease, but there is conflicting dataconflicting data
• At solar minimum, too many At solar minimum, too many GCRs ionizing valley – fills GCRs ionizing valley – fills up more and all we have left up more and all we have left is lossy multi-hopis lossy multi-hop
solar min --------solar max -------
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Recent W4DR ObservationsRecent W4DR Observationspersonal e-mail, late December 2009personal e-mail, late December 2009
“ “I have been DXing on 160 since 1970, with for the most part I have been DXing on 160 since 1970, with for the most part above-average antennas.above-average antennas.
During this present sun spot minimum (the last 2 years and During this present sun spot minimum (the last 2 years and especially the last 8 weeks) I have worked more polar path especially the last 8 weeks) I have worked more polar path stations, Zones 17, 18, 19 and 23 plus some 40's than I have stations, Zones 17, 18, 19 and 23 plus some 40's than I have in the previous 37 years. This included my first ever zone 23 in the previous 37 years. This included my first ever zone 23 on Dec 12.on Dec 12.
On the other hand I have not worked any long path or bent On the other hand I have not worked any long path or bent path SE Asians in the last 4-5 years.”path SE Asians in the last 4-5 years.”
tends to confirm that 160m propagation across the poles is best at solar minimum, and long distance DXing per NM7M’s hypothesis may need a bit more geomagnetic field activity
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North Magnetic Pole is North Magnetic Pole is MovingMoving
As the north magnetic pole moves even farther north, will 160m propagation from the West Coast to Europe improve?
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160m Predictions (or lack thereof!)160m Predictions (or lack thereof!)
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PredictionsPredictions• Our propagation predictions typically cover 3 – 30 MHzOur propagation predictions typically cover 3 – 30 MHz
– There are additional variables that impact frequencies below 3 MHz There are additional variables that impact frequencies below 3 MHz (e.g., electron gyro-frequency), and I believe they are not all identified (e.g., electron gyro-frequency), and I believe they are not all identified yetyet
• Several studies in the past used 10.7 cm solar flux and the A indexSeveral studies in the past used 10.7 cm solar flux and the A index– No good daily correlation seenNo good daily correlation seen
• Bring in space weather parametersBring in space weather parameters– Do your own evaluationDo your own evaluation
• OH2BO (way up north) monitors solar wind speed and dynamic pressureOH2BO (way up north) monitors solar wind speed and dynamic pressure• NZ4O (formerly KN4LF) outlines parameters on his web siteNZ4O (formerly KN4LF) outlines parameters on his web site
– I personally believe we haven’t identified all the important parametersI personally believe we haven’t identified all the important parameters• Correlation to AM broadcast propagationCorrelation to AM broadcast propagation
– N6RK recently brought this up on the topband reflectorN6RK recently brought this up on the topband reflector– May be localized effect or may be widespread effectMay be localized effect or may be widespread effect– My analysis when we lived in Texas (1980s) didn’t show any consistent My analysis when we lived in Texas (1980s) didn’t show any consistent
resultsresults• There were days with enhanced 160m propagation but not enhanced AM There were days with enhanced 160m propagation but not enhanced AM
broadcast propagationbroadcast propagation
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Summary – Transmit & Summary – Transmit & ReceiveReceive
• TransmitTransmit– Put up the best transmit antenna you canPut up the best transmit antenna you can
• Start with inverted-vee or inverted-L or shunt-fed towerStart with inverted-vee or inverted-L or shunt-fed tower• Progress to arraysProgress to arrays
– An amplifier is very helpful on 160mAn amplifier is very helpful on 160m• Again, start small – for example, AL-811Again, start small – for example, AL-811• Move up to 1000 Watts or legal limitMove up to 1000 Watts or legal limit
• ReceiveReceive– You’ll probably start with your transmit antennaYou’ll probably start with your transmit antenna– Improve your reception ability by implementing Improve your reception ability by implementing
directional arraysdirectional arrays• Directionality is what makes them “low noise”Directionality is what makes them “low noise”
– Don’t rule out horizontally polarized antennas for receiveDon’t rule out horizontally polarized antennas for receive
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Summary - PropagationSummary - Propagation• Polar paths should generally be great now and for the next year or soPolar paths should generally be great now and for the next year or so• Extremely long-distance paths Extremely long-distance paths maymay be hurt by this deep solar be hurt by this deep solar
minimumminimum• Understand the concept of common darkness and learn how to Understand the concept of common darkness and learn how to
determine itdetermine it• Watch for signal enhancements around sunrise and sunsetWatch for signal enhancements around sunrise and sunset• Be very active to catch spotlight propagation to your areaBe very active to catch spotlight propagation to your area• In general vertical polarization will work bestIn general vertical polarization will work best
– But you can’t have too many antennas on 160m (who first stated that?)But you can’t have too many antennas on 160m (who first stated that?)• Don’t shy away from elevated K-indicesDon’t shy away from elevated K-indices
– Can provide skewed paths around the auroral zoneCan provide skewed paths around the auroral zone– Can provide enhanced paths across the high latitudesCan provide enhanced paths across the high latitudes
• Remember “southwest at sunrise” and “southeast at sunset” along Remember “southwest at sunrise” and “southeast at sunset” along the long path (even if we don’t understand it, take advantage of it)the long path (even if we don’t understand it, take advantage of it)
• Don’t shy away from solar maximumDon’t shy away from solar maximum– Even though S9+ signals on 10m are easier to deal with, be tough and Even though S9+ signals on 10m are easier to deal with, be tough and
stay on 160mstay on 160m
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CQ WW 160 CWCQ WW 160 CW• January 30 and 31January 30 and 31• Quote from WW9R on the SMC reflectorQuote from WW9R on the SMC reflector
– ““With all the low band propagation here of late, this should With all the low band propagation here of late, this should be a real barn burner... ”be a real barn burner... ”
• Keep an eye on geomagnetic field activity (thru Ap)Keep an eye on geomagnetic field activity (thru Ap)– I think a little bit can be good, but a lot can be bad I think a little bit can be good, but a lot can be bad
• It might be helpful to have low-noise receive It might be helpful to have low-noise receive capability over the polecapability over the pole
• If you have QSOs greater than 12,000 km, I’d like If you have QSOs greater than 12,000 km, I’d like to hear about them – [email protected] hear about them – [email protected]
PVRC Webinar - 20Jan10 - K9LAPVRC Webinar - 20Jan10 - K9LA
Reading MaterialReading Material• ON4UN’s propagation and receive antenna chapters in his Low-ON4UN’s propagation and receive antenna chapters in his Low-
Band DXing seriesBand DXing series– 55thth Edition should be available later this year Edition should be available later this year– Lots of practical informationLots of practical information
• Web sites with space weather info and 160m contentWeb sites with space weather info and 160m content– W8JIW8JI http://www.w8ji.comhttp://www.w8ji.com– W4ZVW4ZV http://users.vnet.net/btippett/images/W4ZV.htmhttp://users.vnet.net/btippett/images/W4ZV.htm– IV3PRKIV3PRK http://www.iv3prk.ithttp://www.iv3prk.it– NZ4ONZ4O http://www.solarcycle24.orghttp://www.solarcycle24.org– NW7USNW7US http://www.hfradio./orghttp://www.hfradio./org– K9LAK9LA http://mysite.verizon.net/k9lahttp://mysite.verizon.net/k9la– Cary OlerCary Oler http://www.spacew.com (is there still http://www.spacew.com (is there still
160m info?)160m info?)
Apologies to any I missed !
PVRC Webinar - 20Jan10 - K9LAPVRC Webinar - 20Jan10 - K9LA
Q & AQ & AThis PowerPoint file will be at This PowerPoint file will be at http://mysite.verizon.net/k9lahttp://mysite.verizon.net/k9la