1. 6M Propagation during the 2018 summer season OR
WHAT JUST HAPPENED?
Lee Boulineau, KX4TT

2. 6M Propagation Six meters has elements of HF propagation
Also has similarities to 2m (Especially during solar minima)
Unique among ham bands in propagation characteristics
Polarization can be important on 6m
Horizontal versus vertical polarization

3. 6M & THE IONOSPHERE Layers (D – E – F {F₁ – F₂})
D Layer – attenuation of signals
E Layer – Sporadic E Propagation
F-Layer propagation can lead to very long QSO paths
Worthy of discussion
Did this happen during 2018 Summer?

4. Reflective AND REFRACTIVE

5. Reflective MODES BOUNCING A SIGNAL OFF OF 'SOMETHING' RELIES ON A DENSE AREA OF HIGHLY CHARGED PARTICLES OR A LARGE OBJECT

6. REFLECTIVE Sporadic-E Forward and Back Scatter
Multi-Hop is often 2-3 hops using E-skip
Forward and Back Scatter
Trans-equatorial Propagation (TEQ)
Aurora
Meteor
Thunderstorms
Aircraft
Earth-Moon-Earth

7. TROPOSPHERIC DUCTING RefRACTIVE BENDING, NOT BOUNCING
Temperature Inversion
Tends to occur in coastal areas like Florida
Some areas will have this go on for weeks or months
While it occurs on 50 Mhz, 144/220/430 all tend to see this more
If you suddenly hear FM or NOAA Weather stations that you normally don't hear, this may be the cause

8. HORIZONTAL VERSUS VERTICAL POLARIZATION
Horizontal for CW/USB/AM/RTTY/ FT8/PSK/JT Modes
Vertical or Ground Plane for FM modes
Cross-polarization penalty

9. Cross-PoLARIZATION Penalty
You see "Authoritative" statements like 20dB loss
Often presented as fact with no explanation or math to back up the statement
Not always backed up by Real-World results
So …..
TRUTH……OR BULL?!?!?

10. WELL – YES – AND NO!
Let's do the Math!!

11. 𝒅𝑩 𝑮𝒂𝒊𝒏=𝟏𝟎 𝐥𝐨𝐠₁₀ ( 𝐜𝐨𝐬 ϴ)² EqUATION
ϴ represents the angle of polarization

12. SOLVING THE EqUATION Remember, the gain is negative
−𝟐𝟎=𝟏𝟎 𝐥𝐨𝐠₁₀ ( 𝐜𝐨𝐬 ϴ)²
−𝟐= 𝐥𝐨𝐠₁₀ ( 𝐜𝐨𝐬 ϴ)²
𝟎.𝟎𝟏=(𝒄𝒐𝒔 ϴ)²
𝟎. 𝟏=𝒄𝒐𝒔 ϴ
ϴ = °
(Assumes 0-90°)

13. OK – It's Yes……But There is a major assumption BEING MADE
This assumes line-of-sight propagation
This also assumes perfectly planar transmissions
The waves are only formed in one discrete plane
Assumes perfect 2-dimensional antennas
So …..Is it YES or NO?

14. REAL-WORLD
Even a signal off a vertical antenna has some horizontal propagation
You simply don't have 2-Dimensional physical constructs in the real world.
Reflected and refracted signals aren't always reflected or refracted back in the same plane
Remember, reflectors and refractors operate in all three dimensions and may be uneven in form
Therefore, the 20dB loss should be used as a guideline when discussing line-of-sight propagation

15. SO – WHAT HAPPENED LAST SUMMER?
A quick and dirty analysis suggested that some F-skip may have occurred
I started with my contacts from EL88
I noticed that I would sometimes hear and work Eastern Europe but not Western Europe
E skip suggests I would hear Spain and then Cyprus or Crete if Spain were 2-hop and Crete 3-hop
Therefore, I suspected some F-skip
But – my sample size was not a large as I would like

16. I got a bigger sample size
Dan Street, K1TO provided me with his .adi file
Over 3000 QSOs on 6m from EL87
28 new countries worked last year (I had 24)
Multiple Japan entries
Nice Mode Breakdown
While FT8 and SSB Predominated, CW was present
SSB – only US and Canada
CW – Europe/Africa worked; not Japan
FT8 – Worldwide – Asia included (Japan/Kuwait/Cyprus)
Perfect for a quick analysis

17. Quick AnAlysis First, Remove QSOs less than 1500 miles
Could be Single-E, could be scatter
Removed ¼ of the QSOs that way
Second, Remove QSOs from the Caribbean
Especially QSOs from Hrs. Local
Possible TEQ Propagation.
About QSOs
Ended with ~2500 QSOs
Looked for patterns indicative of:
Double and Triple E-skip
Will see wide ranges around QSOs in roughly a 3:2 distance
Possible F-skip
Will not see above pattern – extremely long paths

18. RESULTS EU and AF appear to be double / triple hop E-skip
Groupings of 6-7K and 9-11K miles
Dates – 3, 4, 5, 24, 29 June
Almost 200 EU/AF QSOs daily 4 & 5 June
Examples of triple and double hops – 9K QSO then EA and CT shortly after are approximately 3:2 distance ratio
JA grouping on 29 June
Possible F-skip
Fairly tight grouping – to miles
18 QSOs

19. OTHER EXPLANATION MAY BE ARCTIC PATH DUCTING WORTHY OF FURTHER STUDY
Groupings are within a tight range
Total F2 ionization can be lower in the summer
Solar minimum suggests daytime MUF is not very high
Low MUF using VOACAP (even with W3EP suggestions)
Additional ADI file from Terry, N4TB, shows similar pattern to EU/AF
ALSO SHOWS SAME JA PATTERN ON 29 JUNE
WORTHY OF FURTHER STUDY

20. SELECT BIBLIOGRAPHY 50 MHz Long-Path Propagation
Jim Kennedy, KH6/K6MIO
50 Mhz F₂ Propagation Mechanisms
JR Kennedy, K6MIO/KH6
Elevation Angles Required for 6m Sporadic E
Carl Luetzelschwab, K9LA
How to Work 6-Meter DX
Emil Pocock, W3EP
QST, December 1998 (reprinted below with permission)
Interesting Propagation on 6 Meters: What Might Happen in the Future?
Predicting 6 Meter F2 Propagation
Predicting Transatlantic 50-MHz F-Layer Propagation
QST, March 1993, Pp
Trans-Equatorial Propagation (TEP)

21. QUESTIONS??