6 M PROPAGATION DURING THE 2018 SUMMER SEASON

6 M PROPAGATION DURING THE 2018 SUMMER SEASON OR WHAT JUST HAPPENED? LEE BOULINEAU, KX 4 TT

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

6 M & 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?

REFLECTIVE AND REFRACTIVE

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

REFLECTIVE • Sporadic-E • 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

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

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

CROSS-POLARIZATION PENALTY • You see "Authoritative" statements like 20 d. B 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? !? !?

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

EQUATION • ϴ represents the angle of polarization

SOLVING THE EQUATION REMEMBER, THE GAIN IS NEGATIVE

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?

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 20 d. B loss should be used as a guideline when discussing line-of-sight propagation

SO – WHAT HAPPENED LAST SUMMER? • A quick and dirty analysis suggested that some Fskip may have occurred • I started with my contacts from EL 88 • 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

I GOT A BIGGER SAMPLE SIZE • Dan Street, K 1 TO provided me with his. adi file • Over 3000 QSOs on 6 m from EL 87 • 28 new countries worked last year (I had 24) • Multiple Japan entries • Nice Mode Breakdown • While FT 8 and SSB Predominated, CW was present • SSB – only US and Canada • CW – Europe/Africa worked; not Japan • FT 8 – Worldwide – Asia included (Japan/Kuwait/Cyprus) • Perfect for a quick analysis

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 1400 -2100 Hrs. Local • Possible TEQ Propagation. • About 50 -75 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

RESULTS • EU and AF appear to be double / triple hop E-skip • Groupings of 6 -7 K and 9 -11 K miles • Dates – 3, 4, 5, 24, 29 June • Almost 200 EU/AF QSOs daily 4 & 5 June • Examples of triple and double hops – 9 K QSO then EA and CT shortly after are approximately 3: 2 distance ratio • JA grouping on 29 June • Possible F-skip • Fairly tight grouping – 11200 to 11800 miles • 18 QSOs

OTHER EXPLANATION • MAY BE ARCTIC PATH DUCTING • Groupings are within a tight range • Total F 2 ionization can be lower in the summer • Solar minimum suggests daytime MUF is not very high • Low MUF using VOACAP (even with W 3 EP suggestions) • Additional ADI file from Terry, N 4 TB, shows similar pattern to EU/AF • ALSO SHOWS SAME JA PATTERN ON 29 JUNE • WORTHY OF FURTHER STUDY

SELECT BIBLIOGRAPHY • 50 MHz Long-Path Propagation • Jim Kennedy, KH 6/K 6 MIO • https: //www. erau. ee/images/ULL/50%20 Mhz%20 Long-Path%20 Propagation%20 by%20 KH 6 -K 6 MIO. pdf • 50 Mhz F₂ Propagation Mechanisms • JR Kennedy, K 6 MIO/KH 6 • http: //www. ham-radio. com/n 6 ca/50 MHz/K 6 MIO_50 MHz_F 2 Prop. pdf • Elevation Angles Required for 6 m Sporadic E • Carl Luetzelschwab, K 9 LA • https: //k 9 la. us/Elevation_Angles_Required_for_6 m_Sporadic_E. pdf • How to Work 6 -Meter DX • Emil Pocock, W 3 EP • QST, December 1998 (reprinted below with permission) • http: //www. ham-radio. com/n 6 ca/50 MHz/6 mtrdx. html • Interesting Propagation on 6 Meters: What Might Happen in the Future? • Carl Luetzelschwab, K 9 LA • https: //www. sixmeterbbq. com/wp-content/uploads/2018/09/6 m-BBQ-K 9 LA-Austin-2018. pdf • Predicting 6 Meter F 2 Propagation • Carl Luetzelschwab, K 9 LA • http: //k 9 la. us/Predicting_6_Meter_F 2_Propagation. pdf • Predicting Transatlantic 50 -MHz F-Layer Propagation • Emil Pocock, W 3 EP • QST, March 1993, Pp. 32 -34 • Trans-Equatorial Propagation (TEP) • Carl Luetzelschwab, K 9 LA • https: //k 9 la. us/Trans-Equatorial_Propagation. pdf

QUESTIONS? ?