Satgen271 A Spe Experiment by GM4IHJ 4th June 94 BID of this msg is SGEN271 Please use this BID if you retransmit this msg The Northern Hemisphere Sporadic E season has started. With strong E's propagation of satellite, plus 28 Mhz and 50MHz beacons and low band TV signals on May 9,16,17,19, 21,22 and 1,2,3 June 94. This season can be expected to continue during daylight hours , with 10 to 18 SpE days per month until mid August 94. These Spe days provide a wealth of experimental data. So far there have been, HF satellite sub horizon propagation events via E layer extensions from the south, contemporary with Spanish and German HF beacons ( Dl0IGI 28.204, EA3JA 28.250 and DK0TEN 28.257 MHz 0, plus TV from Madrid and Barcelona in Spain ( 48.25 and 62.253 MHZ) and German and Austrian TV on ( 48.26 and 49.74 MHz). Whilst these events are in progress it can be very instructive to plot the great circle paths of these signals to your QTH. In the case of IHJ the signal path mid points indicated SpE overhead Nantes on the French Biscay coast , and a second patch of SpE over Holland. These patches were further delineated by using the moving 29 MHz satellite downlinks to define those places in the E layer where their signals were getting a SpE assisted extension in their range by about 1000 kms , and then later when the satellites were above the IHJ horizon, to check their 10m downlinks and or 2m up links to find those satellite locations where SpE was blocking or attenuating the satellite signal trying to pass up or down through the Spe patch and to or from the satellite. You need to be a little careful with these satellite checks . Evidence at IHJ suggests that many of the Spe patches are only 75 to 100 kms long at their greatest extent. So care is necessary because whilst using a sub horizon satellite you may plot a SpE cloud as , say, 100 kms in extent at its 90 or 100 kms altitude, whereas , when you lok for and plot SpE attenuation from a satellite above your horizon , the shadow cast by a 100 km SpE patch located at 100 kms altitude will project a shadow perhaps 1000 kms long at the satellites 1000 km altitude. Hence a satellite travelling at 7 km/sec above your horizon may have a SpE attenuated signal for 1000 kms ( far more than the length of the SpE patch itself), and be a poor signal for at least 2 or 3 minutes. Amateur Radio publications have for years been plagued by articles attempting to link low altitude weather phenomena with SpE. Try the above experiment several times this summer and you will probably find that SpE seems to locate above favourite spots, not above weather patterns which move around. This experiment should be possible this summer in Europe, temperate Asia and, North America using 10m, 6m,2m beacons and satellites and your local low band VHF TVs. 73 de GM4IHJ @ GB7SAN PS Evening Coronal hole generated plasma continues to provide trans auroral sub horizon propagation of RS10 and RS12 downlinks when the sats are sub horizon from UK to the north beyond the pole. Best results in late May were on orbits around 1930 ut. Regret it is not possible for IHJ to both watch satellites and record detailed times of auroral activity for other people. So please no more packets or mail asking for auroral dates and times. Please get on the air and get your own reports if you need them so badly.