the Upcoming DXpeditions? Will the Sun Cooperate for Carl Luetzelschwab K9LA SEDXC Aug 2015 K9LA 1

Transcription

1 Will the Sun Cooperate for the Upcoming DXpeditions? Carl Luetzelschwab K9LA SEDXC Aug 2015 K9LA 1

2 Topics Cycle 24 and beyond Predictions for upcoming DXpeditions Bonus Trees as supports for low band Trees as supports for low band antennas Real Real-world low-noise receive antenna results Improved solar cycle predictions? SEDXC Aug 2015 K9LA 2

3 Cycle 24 and Beyond SEDXC Aug 2015 K9LA 3

4 Cycle Cycle 24 in terms of cm solar flux latest smoothed January 2015 latest monthly July cm Solar Flux Jan Jul Jan Jul Jan Jul Jan Jul Jan Jul Jan Jul Jan Jul Jan Second peak in mid 2014 was best Other cycles with two peaks: 9, 22, 23 SEDXC Aug 2015 K9LA 4

5 All Solar Cycles Dalton Minimum??? Minimum maximum smoothed sunspot number solar cycle number Three periods of higher solar activity Two periods of lower solar activity Looks like we re headed into another low period SEDXC Aug 2015 K9LA 5

6 How Low? Grand Solar Minimums Historical data suggests we re due for another GSM Will it be a Maunder GSM or a Dalton GSM? SEDXC Aug 2015 K9LA 6

7 If It s a Maunder GSM... Run VOACAP or W6ELProp with zero sunspots or a 10.7 cm solar flux of 65 Not much 15m, 12m, 10m via F Not much 15m, 12m, 10m via F 2 Still have sporadic E in the summer 17m and 20m should still offer F 2 DX openings Propagation similar to last minimum but for a couple decades! SEDXC Aug 2015 K9LA 7

8 Early Predictions for Cycle 25 Smoothed sunspot number of 7 Penn & Livingston, IAU Symposium No. Penn & Livingston, IAU Symposium No. 273, September 2010 Smoothed sunspot number of 118 Helai Helai & Galal,, IAGA-III III International Symposium, November 2011 Smoothed sunspot number somewhat lower than Cycle 24 Smoothed sunspot number somewhat Tlatov Tlatov,, Advances in Space Research, Vol 55, Issue 3, February 2015 Smoothed sunspot number of 62 +/- 12 Janardhan,, et al, JGR Space Physics, July 2015 SEDXC Aug 2015 K9LA 8 after Cycle 24 peak before Cycle 24 peak

9 Upcoming DXpeditions Chesterfield Island Oct 2015 North Korea Jan 2016 S. Sandwich & S. Georgia Feb 2016 Heard Island Mar 2016 Juan de Nova Apr 2016 Palmyra Apr 2016 Bouvet delayed to 2016/2017 season SEDXC Aug 2015 K9LA 9

10 Ever See Comments Like This? The solar flux is up today, but the bands aren t that good The solar flux is down today, but there s still lots of DX What s going on? Let s look at some data SEDXC Aug 2015 K9LA 10

11 Solar Data and Ionosonde Data cm Solar Flux November 2011, 2100 UTC Solar flux peaked around the 8th and minimized around the 26th day Boulder 3000 km MUF November 2011, 2100 UTC median MUF = 35.3 MHz 30 MHz MUF started the month very low, had a broad peak and then decreased somewhat at the end of the month day SEDXC Aug 2015 K9LA 11 solar flux

12 Daily MUF vs Daily Solar Flux Correlation Between Daily MUF and Daily Solar Flux 3000 km MUF over Boulder, November 2011, 2100 UTC 40 R 2 = daily MUF (MHz) daily solar flux Correlation is not good R-squared = SEDXC Aug 2015 K9LA 12

13 Best Correlation Correlation Between Monthly Median MUF vs Smoothed Solar Flux 3000 km MUF over Boulder, November months, 2100 UTC R 2 = monthly median MUF (MHz) smoothed solar flux This is basis for our propagation predictions Monthly median ionospheric parameters versus smoothed solar index Statistical in nature - median implies 50% SEDXC Aug 2015 K9LA 13

14 Assumptions for Predictions I used VOACAP Smoothed solar index from SWPC at ftp://ftp.swpc swpc.noaa noaa.gov gov/pub/weekly/predict.txt Predictions for 40m thru 10m 160m and 80m when path in darkness, and Predictions for 40m thru 10m 160m and 80m when path in darkness, and especially around sunrise and sunset 500 Watts Antennas Antennas Inverted Inverted vee on 40m and 30m, medium-size Yagi on 20m on 20m-10m Short path for sure, long path if usable signal level Short path for sure, long path if usable SEDXC Aug 2015 K9LA 14

15 Chesterfield Island Short Path your heading to DX Best 20m from 07-10z Other good bands and times 15m from 13-15z 15z 10m from 19-23z S9 = -103 dbw SEDXC Aug 2015 K9LA 15

16 North Korea Short Path Best 20m from 21-00z Other good bands and times 17m from 22-01z 30m from 07-15z SEDXC Aug 2015 K9LA 16

17 S. Sandwich & S. Georgia Short Path Best 20m, 17m from 22-08z 15m, 12m from 21-00z Other good bands and times 40m and 30m from 23-07z SEDXC Aug 2015 K9LA 17

18 North Korea Long Path Best 20m and 17m from 23-01z Weak signals Other bands and times 12m and 15m from 12-14z Very weak signals SEDXC Aug 2015 K9LA 18

19 Heard Island Short Path Best 20m from 03-06z 06z Other bands and times 15m and 17m from 12-13z 13z 20m from 11-13z 13z SEDXC Aug 2015 K9LA 19

20 Heard Island Long Path Best 20m from 13-15z 15z Other bands and times 20m from 00-02z 02z SEDXC Aug 2015 K9LA 20

21 Juan de Nova Short Path Best 20m, 17m, 15m from 20-02z Other bands and times 20m from 03-05z SEDXC Aug 2015 K9LA 21

22 Palmyra Short Path Best 40m, 30m, 20m from 04-12z Other bands and times 20m, 17m, 15m from 01-03z 15m and 12m from 18-00z SEDXC Aug 2015 K9LA 22

23 Palmyra Long Path Best 15m from 12-14z Very weak signals SEDXC Aug 2015 K9LA 23

24 Trees As Supports for Low Band Antennas SEDXC Aug 2015 K9LA 24

25 Trees: The Trunk 3 ft 1 ft 75m ¼-wave vertical in tall pine with 7 elevated radials Technical Correspondence, QST, Nov 1991 Z = 50 Z = 50 Ω at resonance Model says 32 Ω Moved bottom of antenna from 1 ft away to 15 ft away Moved bottom of antenna from No change Moved top of antenna from 3 ft away to 6 ft away Moved top of antenna from 3 ft Resonant freq increased 30 KHz Z = 35 Ω Concluded that high-voltage portion of antenna needs to be at least 6 ft away from trunk on 75m 6 ft on 75m = ft on 75m =.023 wavelengths SEDXC Aug 2015 K9LA 25

26 Trees: The Foliage Model of forest by Tamir My parameters Antenna height 55 ft Forest height 75 ft Forest extends about ¼ mile Conductivity is critical parameter Conductivity is critical 1E 1E-5 5 S/m for dense jungle 3E 3E-8 8 S/m for mid- latitude woods Mid-latitude woods Mid most likely are deciduous SEDXC Aug 2015 K9LA 26

27 Real-World Low-Noise Receive Antenna Results SEDXC Aug 2015 K9LA 27

28 Noise data from the 1970s Man-made noise raises the noise floor of receive system (from receiver minimum discernible signal as reported in Product Reviews) by at least 27 db on 160m!!! Need to resolve man- made noise as best as you can That leaves atmospheric noise to deal with Here s where low-noise receive antennas come into play SEDXC Aug 2015 K9LA 28

29 My QTH RBOG 160m Inv-L elevated radial X Shared Apex Loop RBOG runs under one of the 160m inv- L radials At 1 kw, +20 dbm into the shack on the RBOG coax SEDXC Aug 2015 K9LA 29 elevated radial NORTH

30 Comparison of My Antennas Shared Apex Loop (Array Solutions SAL-20) Eight directions - footprint is 40ft diameter See my product review in the April 2014 QST KD9SV RBOG (reversible ( Beverage on ground) Oriented ENE/WSW - 200ft long (need another SE/NW) See my product review in the upcoming Sep/Oct 2015 NCJ W1AW SNRs on KHz - various nights transmit inv-l SAL-20 RBOG 5 db 11 db 19 db 24 db 33 db 35 db 14 db 10 db 12 db 9 db 7 db 11 db 17 db 21 db 32 db Need to calibrate S- meter to make these measurements SEDXC Aug 2015 K9LA 30

31 Comment on RDF RDF = Receiving Directivity Factor Compares the forward- lobe gain to the average gain of the antenna in all directions (both azimuth and elevation) Assumes noise arrives from all azimuths and elevations Sunrise at W4ZV, February, 160m In the real world, atmospheric noise does not arrive from all directions It is directional in nature due to thunderstorms K7TJR and W8JI web sites have tables of RDFs for various antennas. tnx Chris VK5AHZ -151dBm/Hz = -94dBm/500Hz SEDXC Aug 2015 K9LA 31

32 Improved Solar Cycle Predictions? SEDXC Aug 2015 K9LA 32

33 One-Cell Pattern of Plasma Flow This was the hypothesis for many years Resulted in solar cycle predictions that weren t very accurate Early on NOAA carried two predictions for Cycle 24 Low 90 High -140 SEDXC Aug 2015 K9LA 33

34 Two-Cell Pattern of Plasma Flow Recently research has suggested that the plasma flow is at least a two- cell pattern Claims of much better predictions of previous solar cycles Next several cycles predicted to be low using this hypothesis SEDXC Aug 2015 K9LA 34

35 Summary Cycle 24 is the lowest in our lifetimes Data suggests the next several cycles will be low For the upcoming DXpeditions, 20m gives the best opportunity, with 17m and 15m likely, too Low latitude paths give best shot on 12m and 10m Long paths require DX end to be aware of long path! Trees are good for supporting low band antennas but don t put them too close You can never have too many low band receive antennas We may now have a better understanding of the sunspot cycle process time will tell SEDXC Aug 2015 K9LA 35