locked Re: Meteor Scatter
Frank Donovan
I've had excellent results with 6 meter antennas at a height of 50 feet (80 meters). That puts the 3 dB points of main lobe at 3 and 8 degrees corresponding to a singlehop sporadicE range of 13001900 km (8001200 miles). Its first null is at 11 degrees degrees corresponding to a relatively unimportant very closein single hop sporadicE range of 1000 km (600 miles). Doubling antenna height to 100 feet improves antenna gain by 6 dB at only single hop sporadicE distances beyond 2000 km (1250 miles) and double hop distances beyond 4000 km (2500 miles) but at the very significant cost of placing a very deep null at 4 to 6 degrees, a very important range of angles for sporadicE propagation. Tilting a single Yagi by 20 degrees reduces its gain by about 3 dB and very significantly broadens the 3 dB beamwidth of its elevation pattern by almost completely filling in its first null. This isn't very useful for sporadicE propagation except at a relatively unimportant very closein single hop sporadicE range closer than 1000 km (600 miles). 73 Frank W3LPL
From: "Palle PrebenHansen, OZ1RH" <palle@...> To: WSJTX@groups.io Sent: Wednesday, April 22, 2020 6:42:21 PM Subject: Re: [WSJTX] Meteor Scatter What is the point in tilting the antenna 15 deg up? Almost all MS QSO's requires a radiation angle less than 10 deg. Also tilting a beam does not change its radiation anglemuch as the radiation angle is determined by the antenna height above ground, see www.oz1rh.com with www.qsl.net/oz1rh/gnd_gain_eme_2002.zip Radiation angles needed. Supposing the MS reflections takes place at 110 km of height the needed radiation angle can be taken from this diagram:
As you can see angles below 10 degrees will fit a QSO distance over 1.100 km. The height of your antenna should reflect this. If you are on a hilltop or have a tall tower you could end up with too low angle of radiation for a 7001.100 km QSO. However the meteors are random and not all are burning at exactly 110 km, so do not take this curve too seriously, but try MS out and see how you do. 73, Palle, OZ1RH


