Propagation Considerations Carl Luetzelschwab K9LA

1. Propagation Considerations Carl Luetzelschwab K9LA DXU at W9DXCC 2014 DX’ing from the Black Hole

2. Carl Luetzelschwab K9LA Carl was licensed as WN9AVT in October 1961.  He selected K9LA in 1977 when the FCC offered 1 x 2 call signs to Extra Class licensees. Carl enjoys propagation, DXing, contesting (he was the Editor of The National Contest Journal from 2002-2007), antennas and vintage rigs.  He earned a BSEE and MSEE from Purdue University, and retired in late 2013 as an RF design engineer with Motorola (from 1974-1988) and Raytheon (formerly Magnavox, from 1988-2013). Carl is a card checker for both ARRL and CQ awards, and is at the Top of the DXCC Honor Roll, WN9AVT/WA9AVT DX’ing from the Black Hole

3. What We’ll Cover – Five Issues • What do the numbers mean? • Sf (solar flux), ssn (sunspot number), K and A • When is the best time to work the DX station? • When no one else is calling, of course • Which way should I point my antenna? • Short path? Long path? Skewed path? At the moon? • What should I do when propagation is disturbed? • Read a good book? • What’s Cycle 24 Doing? • And how about the CQ WW and ARRL DX contests? DX’ing from the Black Hole

4. 10.7 cm Solar Flux • Measurement at 2800 MHz - objective • From Planck’s Law, energy of one photon at 10.7 cm is 0.0000115 eV • Need about 34 eV to ionize O (atomic oxygen) in the F2 region • Thus 10.7 cm solar flux has nothing to do with ionization • 10.7 cm solar flux is a proxy for the true ionizing radiation, which is at wavelengths from 10 – 100 nm (EUV) for the F region • Sunspots are also a proxy – and are a subjective measurement DX’ing from the Black Hole

5. 10.7 cm Solar Flux • Daily 10.7 cm solar flux does not correlate well to daily MUF • This is why our propagation predictions are statistical (probabilities) over a month’s time frame Similar plot if use daily sunspot number Similar plot if use EUV DX’ing from the Black Hole

6. 10.7 cm Solar Flux • Reiterate: no short-term (daily) correlation to daily MUF (two other parameters involved) • Excellent long-term correlation to monthly median MUF • If 10.7 cm solar flux has been high for a long time, higher bands should be better – and vice versa • Short-term variation in 10.7 cm solar flux does not necessarily indicate better or worse propagation on the higher bands • If solar flux goes up, MUF may go down • If solar flux goes down, MUF may go up Sunspot numbers behaves similarly DX’ing from the Black Hole

7. K Index • Variation of Earth’s magnetic field in a 3-hour period relative to a quiet day • Measured in nT (nanoTeslas) • Measurement of currents flowing at E region altitudes • Values from 0 (quiet) to 9 (extremely disturbed) • Plot of nT vs K is quasi-logarithmic • nT on log scale, K on linear scale each observatory has its own range of nT DX’ing from the Black Hole

8. K Index • When K is elevated • High latitude E region ionization can increase • Increased D region absorption can occur in and near auroral oval • Usually the F region ionization decreases at mid and high latitudes • The F region ionization can increase at low latitudes DX’ing from the Black Hole

9. A Index • K index is a 3-hour index • A index averages the eight 3-hour K indices to arrive at a daily index • Have to convert each quasi-log K index to a linear index (‘a’ index) • Now can average the a indices to get the daily A index • A index values from 0 (quiet) to 400 (extremely disturbed) • Plot of nT vs a is linear • nT on linear scale, a on linear scale DX’ing from the Black Hole

10. What We Desire • High bands and 6m F2 • High long-term 10.7 cm solar flux • Low K and A indices • Low bands • Low long-term 10.7 cm solar flux • But how much does it really matter since we DX on 160m in the dark ionosphere? • Low K and A indices • VHF aurora • High K and A indices DX’ing from the Black Hole

11. When Is the Best Time? • HF propagation is due to refraction in the ionosphere • The ionosphere varies considerably • Amount of ionization varies by latitude • Highest MUFs at low latitudes (around the equator) • Lowest MUFs at high latitudes (polar regions) • Most of us are in between those two extremes • Amount of ionization varies over time • Long-term – over a solar cycle • Mid-term – throughout the seasons • Short-term – throughout the day and even day-to-day • And then there are anomalies! DX’ing from the Black Hole

12. Best Time • Ionosphere varies over a solar cycle • Approximately 11 years from min to max • Higher bands (15m/12m/10m) depend on ionization (MUF) - best at solar max – where we are now – during day • Lower bands (160m/80m/40m) depend on ionospheric absorption – best at solar min – during night • Mid bands (30m/20m/17m) hold up throughout solar cycle • If you can only put up one antenna for one band, go for 20m DX’ing from the Black Hole

13. Best Time • High bands - needed ‘long-term’ solar flux or sunspot number for F2 openings • 6-Meters: sf > 200 or ssn > 100 • 10-Meters: sf > 100 or ssn > 50 • 12-Meters: sf > 75 or ssn > 35 • 15-Meters: sf > 50 or ssn > 25 • All bands - Ap index less than 7 indicates quiet geomagnetic field • Over the pole paths (high latitude) are best The Big Picture – sf, ssn, Ap http://www.solen.info/solar/ DX’ing from the Black Hole

14. Best Time • Ionosphere varies throughout the seasons • Composition of the atmosphere changes throughout the year • More F2 region ionization targets (atomic oxygen) in the fall, winter and spring months in the northern hemisphere generally results in higher MUFs in these months Fall and winter are best for QSOs in the northern hemisphere DX’ing from the Black Hole

15. Best Time • Ionosphere varies throughout the day • The MUF maximizes during the day and minimizes during the night – but not the same values on consecutive days • Anomalies in the ionosphere • For example, there are three areas in the world where the MUF maximizes during the night • Around Japan, off the northeast coast of North America and over the Weddell Sea near Antarctica • So how do you make sense of all this variability? • On the lower bands, the best times are when the path is in darkness – especially around sunrise/sunset times • On the higher bands, the best times are when the path is mostly in daylight – in other words, point your antenna towards the Sun DX’ing from the Black Hole

16. Best Time • For specific predictions, propagation prediction software packages available • For example, two free ones are • VOACAP • Voice of America’s version of IONCAP • W6ELProp • More user friendly than VOACAP • Has a very useful mapping application that includes great circle paths (and the terminator) so you can see how your RF usually gets from Point A to Point B • Tutorials for these two are available at http://k9la.us • Includes download instructions, set up instructions and interpretation of results DX’ing from the Black Hole

17. Best Time • If you don’t want to roll your own . . . • Use the predictions by N6BV • Over 240 locations worldwide • Over six phases of a solar cycle • Summary predictions to seven continental areas (EU, FE, SA, AF, AS, OC, NA) on 80m, 40m, 20m, 15m, 10m • Detailed predictions to all forty CQ zones on 160m – 10m (including 30m, 17m and 12m) • http://radio-ware.com/books/N6BV.html Predictions from any pin to any other pin DX’ing from the Black Hole

18. Which Way Should I Point Antenna? • Purpose of an antenna is to put the most energy • at the required azimuth angle (N, NE, E, etc) • at the required elevation angle (10o, 20o, etc) • with the required polarization (horizontal, vertical, something else?) • The ionosphere dictates these three parameters • Biggest misconception may be that the higher the antenna, the lower the ‘radiation angle’ and thus the better the signal strength • But the ionosphere determines the elevation angle that gets from Point A to Point B, not the antenna • At times a higher angle (lower antenna) is best DX’ing from the Black Hole

19. Which Way - Azimuth • An electromagnetic wave travels in a straight line unless it is refracted, reflected, or scattered • Shortest distance between two points on a globe is a great circle path • This is short path - airliners generally fly short great circle paths to use the minimum amount of fuel (exceptions due to storms, winds, etc) • Other way around is long path • Location on opposite side of Earth to your location is called your antipode • Short path and long path are equal – approx 20,000 km (12,500 miles) ANTIPODE Most of the time short path is best – sometimes long path is better – at other times gray line is best DX’ing from the Black Hole

20. Which Way - Azimuth • Most of the time a great circle path is dictated • Skewed paths and scatter paths sometimes available • Use W6ELProp mapping feature to see the great circle paths (and the terminator) • With respect to polarization, circular polarization is predominant on the HF bands • Horizontal or vertical equally good • Only down 3 dB if the gains are the same • My preference is horizontal antenna • Vertical antenna picks up more man-made noise and is more ground dependent DX’ing from the Black Hole

21. Which Way - Azimuth Example: W6 to EU on 75-Meter LP via gray line • Generally occurs from November thru March • Around W6 sunrise • Good signal strengths without high power levels and without big antennas • Example shown is classical “gray line” propagation Good example of the mapping application in W6ELProp DX’ing from the Black Hole

22. Which Way - Azimuth Example: 10-Meter LP for North America For W9, morning long path to SE Asia is most productive DX’ing from the Black Hole

23. Which Way - Elevation Elevation angles (N6BV data) required on 10-Meters for Indianapolis DX’ing from the Black Hole

24. Which Way - Elevation Antenna elevation patterns 5-element HyGainmonobander over average ground DX’ing from the Black Hole

25. Which Way - Elevation Superimpose required elevation angles on antenna patterns • Data available on other bands • To cover all the elevation angles, probably need stack of antennas • Tough to achieve low angle radiation on low bands • At 25 ft (red) – doesn’t cover the low angles (< 10o) very well • At 100 ft (purple) – covers the low angles, but has two nulls at 10o and 20o • At 50 ft (blue) – probably the best height overall for a single Yagi – 1.5 λ DX’ing from the Black Hole

26. Disturbances to Propagation • Review summary conditions at http://www.swpc.noaa.gov/ • G = Geomagnetic storm - disturbance in the Earth’s magnetic field caused by gusts in the solar wind that blow by Earth (CMEs and coronal holes) • S = Solar radiation storm – disturbance in the polar cap due to increased levels of energetic protons (from big solar flares) • R = Radio blackout – disturbance on the daylight side of Earth due to increased electromagnetic radiation at X-ray wavelengths (from big solar flares) • Each is on a scale of 1 (minor) to 5 (extreme) • More details at http://www.swpc.noaa.gov/NOAAscales/ DX’ing from the Black Hole

27. Disturbances Disturbances to Propagation – A Visual Picture 2) Solar radiation storm (a.k.a. PCA) – increased D region absorption in the polar cap due to energetic protons from a big solar flare 1a) Geomagnetic storm – decreased F2 region MUFs at high and mid latitudes both day and night X North magnetic pole 3) Radio blackout – increased absorption on daylight side of Earth due to extremely short wavelength electromagnetic radiation from a big solar flare 1b) Geomagnetic storm – increased auroral ionization causing increased absorption and horizontal refraction (skewed path) Solar flares and CMEs not necessarily concurrent DX’ing from the Black Hole

28. Disturbances - Mitigation • Geomagnetic storm – effect can last up to a week • Check for auroral propagation at VHF • Check for skewed paths on 160m • Move down in frequency on HF paths thru mid and high latitudes • Look for enhanced low latitude paths (e.g., southern USA to VK/ZL) • Solar radiation storm – effect can last up to several days • For paths over the poles, try long path if the short path is degraded and vice versa (since the effect is not necessarily similar in the north and south polar caps) • Radio blackout – effect can last up to several hours • Move to the higher frequencies • Use paths that are in darkness DX’ing from the Black Hole

29. Cycle 24 • We’re in the second peak • Higher bands should be good this fall/winter DX’ing from the Black Hole

30. Summary • Understand the numbers • Generally we desire high solar flux, and low K and A • When is the best time to work the DX station? • Lower bands – solar min, night, special attention around sunrise/sunset • Higher bands – solar max, path mostly in daylight (can tolerate some darkness) • Use propagation predictions to pin down more specific times DX’ing from the Black Hole

31. Summary - continued • Which way should I point my antenna? • Use propagation predictions and mapping feature to identify short path, long path and gray line path • Short great circle path best most of the time • Don’t ignore elevation angles • Polarization is an issue on 160-meters – vertical is best for mid latitude and high latitude stations in the northern hemisphere • What should I do when propagation is disturbed? • Try the suggestions on the “disturbances” slide – no guarantees! • Get on the higher bands now! • Second peak of Cycle 24 won’t last forever • Read, read, read to understand more DX’ing from the Black Hole

32. References for Your Library • Books • Robert Brown NM7M (SK) “The Little Pistol’s Guide to HF Propagation” - available at http://k9la.us – moderate reading • The NEW Short Wave Propagation Handbook (W3ASK-N4XX-K6GKU, CQ, 1995) – light reading • Radio Amateurs Guide to the Ionosphere (Leo McNamara, Krieger Publishing, 1994) – moderate reading • Ionospheric Radio (Kenneth Davies, Peter Peregrinus Ltd, 1990) – heavy reading • Visit http://k9la.us – timely topics, basic concepts, tutorials, general, 160m, HF, VHF, contesting and webinars on propagation DX’ing from the Black Hole