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PVRC Webinar Mar 9, 2011 K9LA Selected Topics in Propagation Carl Luetzelschwab K9LA

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Presentation on theme: "PVRC Webinar Mar 9, 2011 K9LA Selected Topics in Propagation Carl Luetzelschwab K9LA"— Presentation transcript:

1 PVRC Webinar Mar 9, 2011 K9LA Selected Topics in Propagation Carl Luetzelschwab K9LA

2 PVRC Webinar Mar 9, 2011 K9LA What Well Cover in This Session An Update on Cycle 24 An Update on Cycle 24 –Will it be an underachiever? The M-Factor The M-Factor –Some theory about one of the basic parameters of the ionosphere Sunspots and Solar Flux During Cycle 23 Sunspots and Solar Flux During Cycle 23 –An interesting anomaly – not sure what it says yet Ionosphere-Ionosphere Modes Ionosphere-Ionosphere Modes –Theres more than multi-hop out there

3 PVRC Webinar Mar 9, 2011 K9LA An Update on Cycle 24

4 PVRC Webinar Mar 9, 2011 K9LA Latest Data minimum Smoothed 10.7 cm solar flux is still rising

5 PVRC Webinar Mar 9, 2011 K9LA Latest Data minimum

6 PVRC Webinar Mar 9, 2011 K9LA Review of the Predictions These are from the Solar Cycle 24 Prediction Panel (NOAA, NASA, ISES, and other personnel)

7 The Latest Prediction There may be an updated prediction (lower) from the Solar Cycle 24 Prediction Panel PVRC Webinar Mar 9, 2011 K9LA

8 Marshall Space Flight Center Similar prediction to Kane, Size of the coming solar cycle 24 based on Ohls Precursor Method, final estimate, Annales Geophysicae, July A lot of evidence pointing to small Cycle 24

9 But Not everyone agrees that Cycle 24 will be so small Recent prediction in Solar Physics – –Maximum of 131 +/- 20 – –Maximum in July /- 4 months – –From R. S. Dabas and Kavita Sharma, Prediction of Cycle 24 Using Geomagnetic Precursors: Validation and Update, Solar Physics, Vol 266 No 2, pp , July 2010 This would be good for the higher bands – and for 6m F 2 If Cycle 24 is a small one, though, 6m F 2 propagation will take the biggest hit – –Thank goodness for summer E region propagation PVRC Webinar Mar 9, 2011 K9LA

10 Predictions in General Over 60 predictions for Cycle 24 – –Maximum smoothed sunspot number from 40 to 185 Common forecasting methods – –Statistical methods: length of Cycle n correlated to maximum of Cycle n+1, maximum R 12 correlated to minimum R 12 Generally gives low Cycle 24 – –Geomagnetic precursor methods: Ap, aa, and number of magnetically disturbed days correlate to next maximum Unfortunately can give widely varied answers depending on assumptions – –Polar field precursor method: strength of Suns polar field correlates to next cycle Gives small Cycle 24 – –Solar dynamo method: the conveyor belt theory Unfortunately can give widely varied answers depending on assumptions Summary of forecasting methods from K. J. Li, et al, A brief review on the presentation of cycle 24, the first integrated solar cycle in the new millennium, Annales Geophysicae, 29, , 2011 PVRC Webinar Mar 9, 2011 K9LA

11 Recent NASA News Researchers Crack the Mystery of the Missing Sunspots Researchers Crack the Mystery of the Missing Sunspots –Solar scientists claim theyve developed a new computer model of the sun's interior that gets the physics right for all three aspects of the sunspot generation process -- the magnetic dynamo, the conveyor belt, and the buoyant evolution of sunspot magnetic fields Maybe this will help narrow down the range of the forecasted maximum smoothed sunspot number Maybe this will help narrow down the range of the forecasted maximum smoothed sunspot number PVRC Webinar Mar 9, 2011 K9LA Keep an eye on NASA Headline News, and

12 ARRL DX CW and PH PVRC Webinar Mar 9, 2011 K9LA FebMar Its headed in the right direction! ARRL DX CW ARRL DX PH

13 ARRL DX CW and PH PVRC Webinar Mar 9, 2011 K9LA Recent solar activity helped ARRL DX PH the most ARRL DX CW ARRL DX PH red line is one-day running average FebMar 28 MHz 21 MHz

14 PVRC Webinar Mar 9, 2011 K9LA The M-Factor No, not this M

15 PVRC Webinar Mar 9, 2011 K9LA What Is The M-Factor? The M-Factor (MUF factor) relates the MUF (maximum useable frequency) to the critical frequency The M-Factor (MUF factor) relates the MUF (maximum useable frequency) to the critical frequency –MUF = M-Factor x Critical Frequency –M-Factor and critical frequency (along with other parameters) are measured by ionosondes M-Factor is one over the sine of the angle between the ray and the ionosphere (also known as the secant law as 1/sine = secant) M-Factor is one over the sine of the angle between the ray and the ionosphere (also known as the secant law as 1/sine = secant) sine of this angle If the angle = 90 o (vertically incident), then the M- Factor equals 1 and the MUF = the critical frequency ionosphere

16 PVRC Webinar Mar 9, 2011 K9LA Apply It To The Ionosphere ionosphere Earth Thus the M-Factor = 1 sine (1 o ) = 57 Wow – if the critical frequency is 5 MHz, then the MUF would be 285 MHz Wow – if the critical frequency is 5 MHz, then the MUF would be 285 MHz But hold on – the Earth-ionosphere system isnt flat – its spherical But hold on – the Earth-ionosphere system isnt flat – its spherical = 1 o Ω = 1 o

17 PVRC Webinar Mar 9, 2011 K9LA The Real Earth-Ionosphere System ionosphere Earth height now matters – lets assume 300 km Now the M-Factor = 1 sine (17.5 o ) = 3.3 MUF for this F 2 region scenario is about 3 times the critical frequency = 1 o Ω = 17.5 o

18 M-Factor vs Height and Angle PVRC Webinar Mar 9, 2011 K9LA This calculation assumes specular (mirror-like) reflection over an infinitely short distance – the real-world is refraction over a spherical distance height distance ΩM-Factor 100 km0 deg2243 km 10.1 deg5.7 5 deg1389 km 11.3 deg deg 927 km 14.2 deg deg 408 km 26.8 deg km0 deg3152 km 14.2 deg4.1 5 deg2226 km 15.0 deg deg1620 km 17.3 deg deg 781 km 28.5 deg km0 deg3836 km 17.3 deg3.4 5 deg2877 km 17.9 deg deg2193 km 19.9 deg deg1124 km 30.1 deg km0 deg4401 km 19.8 deg3.0 5 deg3422 km 20.4 deg deg2687 km 22.1 deg deg1412 km 31.4 deg1.9 The higher the layer, the longer the hop distance for a given angle But the higher the layer, the lower the M-Factor (lower MUF) for a given angle

19 PVRC Webinar Mar 9, 2011 K9LA Rule of 3 and Rule of 5 For the F 2 region with low angles, the MUF is approximately 3 times the critical frequency For the F 2 region with low angles, the MUF is approximately 3 times the critical frequency –Ionosondes report the M-Factor for a 3000 km hop M(3000)F2 or M(D) where D = 3000 km M(3000)F2 or M(D) where D = 3000 km For the E region with low angles, the MUF is approximately 5 times the critical frequency For the E region with low angles, the MUF is approximately 5 times the critical frequency –Close enough for sporadic E, too Allows you to estimate the MUF only knowing the critical frequency

20 PVRC Webinar Mar 9, 2011 K9LA Sunspots and Solar Flux During Cycle 23

21 PVRC Webinar Mar 9, 2011 K9LA Why Use Smoothed Solar Indices? Reason #1: Daily data (and even monthly mean data) is spiky - hard to tell whats happening Reason #1: Daily data (and even monthly mean data) is spiky - hard to tell whats happening Reason #2: The best correlation between what the Sun is doing and what the ionosphere is doing is through a smoothed solar index - this is the basis on which the statistical model of the ionosphere for our propagation predictions was developed Reason #2: The best correlation between what the Sun is doing and what the ionosphere is doing is through a smoothed solar index - this is the basis on which the statistical model of the ionosphere for our propagation predictions was developed

22 PVRC Webinar Mar 9, 2011 K9LA Early Correlation Equation from texts on the ionosphere: SF 12 = SSN SSN 12 2 (the 12 subscript denotes smoothed values) Side note - there is very little correlation between daily 10.7 cm solar flux and daily sunspot number

23 PVRC Webinar Mar 9, 2011 K9LA More Data Some more scatter about the trend line, but still pretty good.

24 PVRC Webinar Mar 9, 2011 K9LA Include Cycle 23 In terms of smoothed sunspot number, second peak is a bit lower In terms of smoothed sunspot number, second peak is a bit lower In terms of smoothed solar flux, second peak is definitely higher In terms of smoothed solar flux, second peak is definitely higher We had much better 6m F2 propagation during the second peak We had much better 6m F2 propagation during the second peak Cycle 23 data April 2000 Nov 2001

25 PVRC Webinar Mar 9, 2011 K9LA Why The Anomaly? Dr. Leif Svalgaard (member of the Cycle 24 Prediction Panel) has several opinions Dr. Leif Svalgaard (member of the Cycle 24 Prediction Panel) has several opinions –The sunspot counting procedure or observers have changed with resulting artificial changes of the sunspot number (as they have in the past) –There are changes in the Suns corona or chromosphere accounting for additional 10.7 cm emission –Penn and Livingstons observations (Penn, M. J. and W. Livingston, Temporal Changes in Sunspot Umbral Magnetic Fields and Temperatures, The Astrophysical Journal, 649, L45-L48, 2006 September 20) suggest that sunspots have been getting warmer during the last decade, leading to a decreased contrast with the surrounding photosphere and hence lessened visibility, possibly resulting in an undercount of sunspots No definite answer (yet!) No definite answer (yet!) Visit and select item 1020 for details Visit and select item 1020 for details Check out my Propagation columns in the forthcoming May 2011 and June 2011 issues of WorldRadio Online for more on this Check out my Propagation columns in the forthcoming May 2011 and June 2011 issues of WorldRadio Online for more on this –http://www.worldradiomagazine.com/WRO is free !

26 PVRC Webinar Mar 9, 2011 K9LA Ionosphere-Ionosphere Modes

27 PVRC Webinar Mar 9, 2011 K9LA Multi-Hop Can Have Limits On the lower bands there may be too much absorption for multi-hop – the signal is too weak On the lower bands there may be too much absorption for multi-hop – the signal is too weak On the higher bands the MUF may not be high enough to refract the ray back to Earth for multi-hop – the ray goes out into space On the higher bands the MUF may not be high enough to refract the ray back to Earth for multi-hop – the ray goes out into space ionosphere Earth

28 PVRC Webinar Mar 9, 2011 K9LA Higher MUF & Less Absorption Are there modes that could give a higher MUF and/or lesser absorption? Are there modes that could give a higher MUF and/or lesser absorption? Yes - there appear to be three of them Yes - there appear to be three of them –Chordal hop –Duct –Pedersen Ray chordal hopunaffected by the ionosphere in between refraction points ductconsecutive refractions between E and F regions Pedersen Rayhigh angle ray, close to MUF, parallels the Earth

29 PVRC Webinar Mar 9, 2011 K9LA Chordal Hop Example – TEP (trans-equatorial propagation) Example – TEP (trans-equatorial propagation) K6QXY to ZL on 6m Ray trace from Proplab Pro monthly median results High density of electrons on either side of geomagnetic equator High density of electrons on either side of geomagnetic equator Extremely long hop – approximately twice a normal hop Extremely long hop – approximately twice a normal hop Only two transits through the absorbing region Only two transits through the absorbing region No ground reflections No ground reflections Literature says MUF is approximately 1.5 times normal F2 hop Literature says MUF is approximately 1.5 times normal F2 hop refraction helps MUF and absorption area of higher electron density

30 PVRC Webinar Mar 9, 2011 K9LA Duct Requires upper and lower boundary for successive refractions Requires upper and lower boundary for successive refractions Need entry and exit criteria - small range of angles Need entry and exit criteria - small range of angles No transits through the absorbing region No transits through the absorbing region No ground reflections No ground reflections Low grazing angles with ionosphere – higher MUF Low grazing angles with ionosphere – higher MUF Believed to allow extremely long distance QSOs on 160m Believed to allow extremely long distance QSOs on 160m helps MUF and absorption

31 PVRC Webinar Mar 9, 2011 K9LA Pedersen Ray Not a lot in the literature on the Pedersen Ray Not a lot in the literature on the Pedersen Ray Comment from Ionospheric Radio (Davies, 1990) Comment from Ionospheric Radio (Davies, 1990) –Across the North Atlantic, occurrence tends to peak near noon at the midpoint One would surmise that the ionosphere needs to be very stable for a ray to exactly parallel the Earth for long distances One would surmise that the ionosphere needs to be very stable for a ray to exactly parallel the Earth for long distances Probably no help with MUF – biggest advantage appears to be with lower absorption due to less transits of the absorbing region and no ground reflection losses Probably no help with MUF – biggest advantage appears to be with lower absorption due to less transits of the absorbing region and no ground reflection losses helps absorption 1 and 2 are low-angle paths 1 and 2 are low-angle paths 3 is medium-angle path 3 is medium-angle path 4 and 5 are high-angle Pedersen Ray paths 4 and 5 are high-angle Pedersen Ray paths 6 goes thru the ionosphere 6 goes thru the ionosphere

32 PVRC Webinar Mar 9, 2011 K9LA A Detailed 20m Analysis K2MO (AA2AE at the time) to ZS5BBO on July 5, 2003 at 1230 UTC on 20m SSB via long path K2MO (AA2AE at the time) to ZS5BBO on July 5, 2003 at 1230 UTC on 20m SSB via long path K2MO reported that ZS5BBOs signal was around S7 (~ -83 dBm) K2MO reported that ZS5BBOs signal was around S7 (~ -83 dBm) Long path from W2 starts off in daylight, goes into darkness, and ends in daylight Short path has high MUF but marginal signal strength due to absorption Long path signal strength from ZS predicted to be -125 dBm Long path signal strength from ZS predicted to be -125 dBm –About 40 dB shy of S7 Short path 12,700 km Long path 27,300 km

33 PVRC Webinar Mar 9, 2011 K9LA The Ionosphere Along the LP Note the tilts in the ionosphere at dawn (W2 end) and at dusk (ZS end) Note the tilts in the ionosphere at dawn (W2 end) and at dusk (ZS end) Tilt can refract the ray so that it encounters the ionosphere at more of a grazing angle (i.e., a higher MUF) Tilt can refract the ray so that it encounters the ionosphere at more of a grazing angle (i.e., a higher MUF) Good entry/exit criteria for duct Good entry/exit criteria for duct VK5

34 PVRC Webinar Mar 9, 2011 K9LA Ray Trace from W2 End Proplab Pro can only ray trace out to 20,000 km (half way around) Proplab Pro can only ray trace out to 20,000 km (half way around) Do two ray traces Do two ray traces –One from W2 end (pictured) –One from ZS end (not pictured) Ray trace from ZS end shows similar ducting Ray trace from ZS end shows similar ducting Signal strength now estimated to be -89 dBm Signal strength now estimated to be -89 dBm –Close to observed -83 dBm

35 PVRC Webinar Mar 9, 2011 K9LA The Big Picture My crude picture on the left shows chordal hops as the ionosphere-ionosphere mode My crude picture on the left shows chordal hops as the ionosphere-ionosphere mode Proplab Pro data indicates the K2MO-to-ZS5BBO QSO was ducting Proplab Pro data indicates the K2MO-to-ZS5BBO QSO was ducting Easier to draw chordal hops! Easier to draw chordal hops! Youve probably seen a similar picture in the propagation literature. Youve probably seen a similar picture in the propagation literature. Ionosphere-ionosphere modes are our friends

36 PVRC Webinar Mar 9, 2011 K9LA Summary I hope you learned something I hope you learned something This webinar will be on the PVRC web site This webinar will be on the PVRC web site –http://www.pvrc.org/webinar/webinars.htm –The slides will also be at Follow-up webinars: More Selected Topics in Propagation Follow-up webinars: More Selected Topics in Propagation –Such as noise, 10m long path, effect of the Moon on HF propagation, trans-equatorial propagation me if you have a specific topic me if you have a specific topic –Also visit Thanks to Ken K4ZW and to the PVRC Thanks to Ken K4ZW and to the PVRC And now Q/A And now Q/A


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