50Mhz ionosphere propagation modes observed from Athens over the last three solar cycles. Costas Fimerelis, SV1DH G3WOS BBQ Aug. 2007
Abstract: An overview of the numerous 6m ionosphere propagation modes observed from Athens during the last three solar cycles (1978-2007) is presented in detail, related to the location geographical and radio noise limitations. Exotic modes like LP to Pacific and LDE to Australia, as well A and E-TEP to Africa are also discussed.
CONTENTS Geographical and radio noise location limitations Transequatorial propagation (A & E-TEP) F2 propagation (SP-LP-LDE) Scatter propagation Es propagation Mixed modes
Geographical and radio noise location limitations QTH (KM18VA) takeoff angle modest (>2deg. for >180deg. arc) due to three local mountains. Power line noise always present (~10db/th at min, >15db/th on average and >20db/th for 20% of time) due to LOS on a 20KV line at 200-400m distance. ANC-4 wide band noise canceller (using a 5 el. yagi as noise ant.) not effective most of the time, suppressing the noise of a single source only up to 20db.
Transequatorial propagation (A & E-TEP) Two distinct modes (or types) of propagation were observed on the Euroafrican sector: Afternoon mode, up to 1700z, propagating strong and clean signals up to ~70Mhz Evening mode, between 1730z and ~2200z, propagating marginal and severely distorted signals, mostly above 30Mhz and up to ~430Mhz (during cycle 21 only) No TEP propagation between the two modes
Cycle 21 world E-TEP paths Path Km Mhz Min Sa Max Kp Observ.
E-TEP Euroafrican sector waveguide geometry model
Short-Path (SP) 50Mhz propagation To all directions, except over North Pole All day long, starting at ~06z and up to ~24z Most rare area in the western Pacific (two 15 minute openings over cycle 22 only) Max distance 16600Km (5F2) Never heard ZL or VK1,2,5,7, in spite of clear takeoff to these directions
Cycle 22 50Mhz time of day probability of propagation
Cycle 23 50Mhz time of day probability of propagation
Long-Path (LP) 50Mhz propagation Limited to JA, KH6, KH8, within az 180-230 deg Openings to JA (max dist. 30900Km, LP ~25%) -main window: 2100-2430z (peak 23z) to JA1,2,3(80%) -sec. window: 1130-1300z (peak 12z) to JR6 (13%) -sole window: 0800-0900z (incl scatter) to JA1 (7%) -weak sigs, need for low noise location -first obs. on 9/10/88 (well before any SP opening) Openings to KH6 (max dist. 26600Km, no SP obs.) -main window: 0830-1030z (no AF sigs) (52%) -sec window: 1900-1930z (10%) -rare window: 1500-1900z (incl scatter over SA) (38%) -strong and clean sigs
Long-Path (LP) 50Mhz propagation, cont’ Openings to KH8 (max dist. 23000Km, no SP obs.) -sole window: 2000-2230z -marginal to strong sigs with some flutter Single opening to PJ2 (at 0845z over SE Asia incl. scatter, at a dist. of 30600Km) Single opening to ZL up to 45Mhz (video sigs at 2100-2245z)
Very low power 50 Mhz contacts With ZS6LN at 7000 Km via A-TEP using 1mW on SSB (1980) Path attenuation almost at free space value With PY5CC at 10000 Km via 3F2 (or 4F2) using 1mW on SSB (2000) Path attenuation some db above free space value
Long Delayed Echo (LDE) propagation on 50Mhz Observed once to VK8 (at 0845z on 26 Oct 2002) Single strong (s9) echo, sig delayed much more (est. 0.3~0.4 sec) then the usual HF RTW echoes Readability poor, need for VERY slow speaking No LP or Scatter path (over Indian ocean) present Echo observed also on LZ sigs only (by VK8MS) Strong Asiatic UA and 9M video sigs present Cluster report of unusual echo on 10m also No echo recording by any station…
Scatter (Sc) Propagation SCATTER TO SEASON TIME(z) QTF COMMENTS S. EU Mar &Oct 12-13 Arabic Pen. Northern TEP crest S. EU “ 14-16 NW. AF & Moderate sigs N. EU end Oct 09-10 Central AS Weak sigs N. EU “ 13-14 Caribbean “ JA Mar-Apr ~10 Arabic Pen. Very weak sigs NA&Carib. late Oct 13-20 NW. AF Weak sigs SA late Mar 19-23 SW. AF Weak&distorted
Es supported long distance propagation Mainly to Caribbean and north America, end of May to mid July, between 10-22z with medium strong signals Max distance up to 10600Km (HP, Jul 2006 and W5, June 2007, but max worldwide recorded ~13500Km) Same period to JA (and VR), between 06-16z with weak signals Once to 4S, early July at 06z, with medium strong signals On many openings presence of intermediate ground scatter points, but on some to US no EU signals or 48MHz video at all! Duration (several hours) and stability of ionized areas amazing Propagation footprint area mostly very limited and slowly drifting westward Signal strength much less then with F2 propagation
Mixed-mode Propagation Questionable identification of modes involved Some probable examples: -All skewed openings outside EU, F2+F2Sc -Openings to VK8 mid June, Es+F2 -Openings to VK9X late April, Es+TEP? -Openings to VQ9 late April, Es+TEP -Opening to VU mid Oct, Es+F2
50MHz PROPAGATION CONCLUSIONS THE GEOMAGNETIC LOCATION VERY IMPORTANT AND BEST WITHIN THE NORTHERN TEP ZONE (i.e. MEDITERRANEAN) LOW TAKEOFF ANGLE (BEST <2 DEG) ESSENTIAL, ESPECIALLY ON THE RISE AND FALL OF SOLAR CYCLE POWER LINE NOISE ON 50Mhz (>5db ABOVE RECEIVER THERMAL) LIMITS SIGNAL RECEPTION CONSIDERABLY PROPAGATION TIME OF DAY AND SEASON FAIRLY PREDICTABLE