1. DX University Visalia California – 2015

2. DX University – Visalia 2015DX University – Visalia 2 What We’ve Learned from DXpeditions Carl Luetzelschwab K9LA

3. DX University – Visalia 2015DX University – Visalia 2 Carl Luetzelschwab K9LA First licensed in 1961, began DXing in 1977. Enjoys propagation, DXing, contesting, antennas and vintage equipment. Top of the Honor Roll, 5BDXCC, 160m DXCC, need 6 zones on 80m for 5BWAZ. DXpeditions: YK9A in February 2001, OJ0/K9LA in July 2002, many operations from ZF as ZF2LA and ZF1A. President of the Fort Wayne DX Association (FWDXA), retired RF design engineer for Motorola and Raytheon (formerly Magnavox). You can contact Carl at k9la@arrl.net

4. DX University – Visalia 2015DX University – Visalia 2 Topics VK0IR (1997): Wedge of daylight on the low bands STØRY (2003): Ducting on 160-Meters 3Y0X (2006): Short path gray line on 160-Meters? FT5ZM (2014): Skewed paths on 10-Meters FT5ZM (2014): Arrival direction on 160-Meters Two short subjects DXpeditions provide a valuable source of data for understanding propagation

5. DX University – Visalia 2015DX University – Visalia 2 VK0IR (1997) – Wedge of Daylight on the Low Bands Image from the book “VK0IR: The 1997 Heard Island Expedition” by Robert Schmieder KK6EK January 1997 There was a large area of the US that pretty much had no propagation to VK0IR on the low bands It never got dark in the area with the non-smiley face I should have inverted the colors – it looks like a wedge of darkness!

6. DX University – Visalia 2015DX University – Visalia 2 How to Make That Map Generate a map (using W6ELProp or DX Atlas, for example) when the target location is at sunrise Generate another map when the target location is at sunset Overlay the two maps (print the second one on top of the first one) FT5ZM This one from DX Atlas for the FT5ZM DXpedition in 2014

7. DX University – Visalia 2015DX University – Visalia 2 VK0EK Forthcoming DXpedition to Heard Island If you’re a low band enthusiast and live in the wedge of daylight, what are you going to do? Accept the fact that you’re in the wrong place and not work them on the low bands? Operate from a QTH that is not in the wedge of daylight? Use a remote station that is not in the wedge of daylight?

8. DX University – Visalia 2015DX University – Visalia 2 STØRY (2003) – Ducting on 160-Meters Why do we need to invoke ducting? What’s wrong with multi-hop? Physics says absorption is inversely proportional to the square of the frequency The lower the frequency, the more the absorption Absorption moves up from the D region during the day to the lower E region during the night Due to absorption being the product of electron density and electron-neutral collision frequency Electron density increases as altitude increases Collision frequency decreases as altitude increases

9. DX University – Visalia 2015DX University – Visalia 2 Multi-hop on 160-Meters At night one hop still incurs about 10 dB of absorption Assume 1000 Watts to ¼ λ verticals over avg gnd Assume 2000 km hops Amount of refraction inversely proportional to the square of the frequency The lower the frequency, the more the bending – shorter hops Assume 3 dB loss per ground reflection Assume quiet rural noise at -103 dBm/Hz Use P rcv = P xmt – FSPL + Gain ant1 + Gain ant2 – absorption – gnd refl loss

10. DX University – Visalia 2015DX University – Visalia 2 Limit for Multi-hop on 160-Meters With 4-Squares on both ends, 10,000 km is about the limit for multi-hop on 160-Meters How do we have QSOs beyond 10,000 km? Distance (km)P xmt (dBm) FSPL (dB) free space path loss Abs (dB)Gnd refl (dB)P rcv 2000 ( 1 hop )+60-103.6100-53.6 4000 ( 2 hops )+60-109.6203-72.6 6000 ( 3 hops )+60-113.2306-89.2 8000 ( 4 hops )+60-115.7409-104.7 10,000 ( 5 hops )+60-117.65012-119.6

11. DX University – Visalia 2015DX University – Visalia 2 Natural Ducting Mechanism in the Dark Ionosphere Successive refractions between top of E region and lower F region Electron density profile at midpoint of STØRY to K9LA path

12. DX University – Visalia 2015DX University – Visalia 2 Ray Trace Shows Ducting Go through the absorbing region only twice No ground reflection losses Need stable ionosphere to maintain the duct Get out of duct by irregularity or tilted ionosphere at sr or ss Could be responsible for spotlight propagation My sunset 2354 UTC STØRY sunrise 0400 UTC On several nights they came up well out of the noise around 0320 UTC and went back in the noise around 0340 UTC I didn’t work them 

13. DX University – Visalia 2015DX University – Visalia 2 3Y0X (2006) - Short path gray line? My earlier session wondered about short path gray line enhancements G0YKA didn’t see any significant enhancements on a G-to-VP8 path 3Y0X gave us a great example of short path gray line to JA Only 2 Asia QSOs on 160-Meters Why not?

14. DX University – Visalia 2015DX University – Visalia 2 3Y0X to NA on 160-Meters 774 NA stations between 0210 and 0901 UTC Path is away from the terminator in the dark ionosphere Made 486 QSOs on 160-Meters with EU through dark ionosphere Supports earlier conclusion that propagation along terminator is not efficient

15. DX University – Visalia 2015DX University – Visalia 2 FT5ZM (2014) – Skewed Paths on 10-Meters After the DXpedition, I received an e-mail from N4II saying he and several others in FL worked FT5ZM on 10-Meters on headings from 60 o to 75 o His true great circle short path is to the SE I worked FT5ZM on 10-Meters to the East My true great circle path is to the East I read that AA7XT worked FT5ZM on 10-Meters on a NE heading His true great circle path is to the West

16. DX University – Visalia 2015DX University – Visalia 2 Great Circle Paths Out of FT5ZM If you’re east of the FT5ZM antipode, short path is to the East If you’re west of the FT5ZM antipode, short path is to the West N4II noted best heading was to ENE K9LA noted best heading to E AA7XT noted best heading to NE We all worked FT5ZM on the same day around the same time

17. DX University – Visalia 2015DX University – Visalia 2 Worldwide MUF Map with True GCPs Red circles are 2000 km radius N4II to FT5ZM – N4II end ok, FT5ZM end not ok K9LA to FT5ZM – K9LA end ok, FT5ZM end ok AA7XT to FT5ZM – neither end ok

18. DX University – Visalia 2015DX University – Visalia 2 Same Worldwide MUF Map with Actual Headings Great circle paths that can support 28 MHz intersect over northern Africa This intersection is in the equatorial ionosphere – where the highest MUFs occur

19. DX University – Visalia 2015DX University – Visalia 2 We’ve Answered Three Questions Why weren’t the true great circles path available? MUFs too low at one end or both ends What enabled the reported paths? High enough MUFs on these headings But requires skew point (or skew area) to knock RF off one great circle path onto another great circle path Where is the skew area? Likely in the equatorial ionosphere with the highest MUFs in the world Bottom line – turn your antenna – you may be pleasantly surprised

20. DX University – Visalia 2015DX University – Visalia 2 FT5ZM (2014) – Arrival Direction on 160-Meters For me and many others, FT5ZM was surprisingly easy to work on 160-Meters They had a great 160-Meter set-up, dedicated low band ops, and the ionosphere cooperated After the DXpedition I posted a message to the topband reflector requesting direction information for those who worked or heard FT5ZM on 160-Meters Received 77 reports

21. DX University – Visalia 2015DX University – Visalia 2 Map of the Data 49 reports of great circle path propagation 28 reports of non-great circle path propagation But watch it – I believe our antennas can fool us For example, we likely optimize SNR (not signal) when using our low-noise receive antennas Bottom line – always check other directions Solid lines are great circle paths out of FT5ZM x is FT5ZM antipode

22. DX University – Visalia 2015DX University – Visalia 2 Short Subject #1 – Propagation Predictions In my earlier session, I mentioned that our propagation predictions are statistical over a month’s time frame Correlation is between smoothed solar index and monthly median results We saw data for August 2009 - here’s another month/year Shows why we don’t have daily predictions Shows how the daily MUF varies about the monthly median value – our predictions don’t tell us which days might be better and which days might be worse

23. DX University – Visalia 2015DX University – Visalia 2 Real-Time Assessment Listen to the IARU/NCDXF beacons on 20m, 17m, 15m, 12m and 10m Or use SSNe (effective sunspot number) in your favorite propagation prediction program The concept behind SSNe is to vary the sunspot number in the model to force the output to agree with real-time ionosonde data For example, on October 15 the actual MUF at 1700 UTC was 35.71 MHz so SSNe at 1700 UTC would be higher than the normally-inputted smoothed sunspot number Likewise, on October 5 the actual MUF at 1700 UTC was 28.96 MHz so SSNe at 1700 UTC would be lower than the normally- inputted smoothed sunspot number Where do you get SSNe? http://spawx.nwra.com/spawx/ssne24.html

24. DX University – Visalia 2015DX University – Visalia 2 Short Subject #2 – Sunrise and Sunset Sunrise and sunset at your QTH and at the DX QTH are good reference points for low band propagation Often QSOs are reported after sunrise and before sunset What’s important are the conditions where the RF encounters the ionosphere – not the conditions at our QTH or at the DX QTH

25. DX University – Visalia 2015DX University – Visalia 2 An Example March 21 K9LA sunset is 2348 UTC At 2328 UTC, the terminator is 335 km to the east That’s where RF at an elevation angle of 15 o out of K9LA would encounter the absorbing region of the ionosphere 20 minutes before my sunset Modified a bit by the month due to the terminator being slanted on other dates K9LA

26. DX University – Visalia 2015DX University – Visalia 2 Another Example Higher frequencies tolerate more daylight (due to less absorption) I heard EP6T on 80m CW at 2202 UTC on January 20, 2015 40 minutes before my sunset But I couldn’t work them as they were working JA And if RF comes out of a duct at a high angle Gets through the absorbing region very quickly Can probably withstand even more daylight Even earlier time before sunset Even later time after sunrise Bottom line – on 160-Meters, good idea to hang around for about 30 minutes after your sunrise and be there about 30 minutes before your sunset

27. DX University – Visalia 2015DX University – Visalia 2 Summary DXpeditions provide a valuable source of data for understanding propagation Thanks to the DXpeditions that have given me access to their logs Beware the wedge of daylight for low band operation When the DX station comes out of the noise, it may be due to ducting If you ever hear a significant short path gray line enhancement on the low bands, let me know! Always check other directions with your antennas – you may be pleasantly surprised On the low bands, be there after sunrise and before sunset Rough guide – 30 min on 160m, 1 hr on 80m There are some pretty interesting “exceptions” to this