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TopBand: Why the duct?

 To: TopBand: Why the duct? w8jitom@postoffice.worldnet.att.net (w8jitom@postoffice.worldnet.att.net) Sun, 6 Jul 1997 12:09:19 +0000
 ```> From: Frank Donovan > Another example of very selective propagation is JA-to-East Coast on 160. > The window starts in New England at their sunrise and moves southwest from > there. When the W1s are working the peak of the opening we cannot hear > the JAs at all, then 10 minutes later they can be S9 (more likely S6 > tho...) > 73! > Frank > W3LPL Hi Frank, Here in Georgia I can hear and work the JA's almost anytime between their sunset and my sunrise most days, but the signals PEAK at my sunrise. At sunrise I can work the third and fourth layer stations, if they can hear me. I suspect the propagation is always there, but the sunrise enhancement really helps. The thing I don't understand or haven't heard is why the duct is a necessary part of the explanation about anything. Maybe someone can explain what propagation characteristic fits the ducting theory, since there is no way to measure it or prove its existence other than with effects we observe. 73, Tom W8JI -- FAQ on WWW: http://www.contesting.com/topband.html Submissions: topband@contesting.com Administrative requests: topband-REQUEST@contesting.com Problems: owner-topband@contesting.com ```
 Current Thread TopBand: Why is a duct?, Larry Tyree TopBand: Why is a duct?, Frank Donovan TopBand: Why the duct?, w8jitom@postoffice.worldnet.att.net <= TopBand: Re: Why the duct?, Frank Donovan TopBand: Re: Why the duct?, w8jitom@postoffice.worldnet.att.net TopBand: Re: Why the duct?, Bill Hohnstein TopBand: Why is a duct?, John Kaufmann