Re: [IRCA] When is maximum D-layer absorption?

[Russ Edmunds <wb2bjh@xxxxxxxxx>]

Anywhere around the summer solstice at midday ( 1 pm Daylight time ). But because sunrise and sunset are not equidistant from noon, and the differences in length of day are minimal at that time of year, one would be safe suggesting a couple of hours around midday anytime between June 15 and June 26.


Russ Edmunds
15 mi NNW of Philadelphia  
Grid FN20id
<wb2bjh@xxxxxxxxx>
FM: Yamaha T-80 & Onkyo T-450RDS w/ APS9B @15'; Grundig G8
AM:  Modified Sony ICF 2010's barefoot


--- On Mon, 9/5/11, Stephen Airy <pianoplayer88key@xxxxxxxxx> wrote:

> From: Stephen Airy <pianoplayer88key@xxxxxxxxx>
> Subject: [IRCA] When is maximum D-layer absorption?
> To: "IRCA List" <irca@xxxxxxxxxxxxxxxx>
> Date: Monday, September 5, 2011, 7:56 PM
> ... so that absolutely NO skywave is
> possible on the AM BCB?
>  
> For example, let's say a signal on 1700 kHz is strong
> enough (as the skywave reaches the lower limit of the
> D-layer for its first hop) to spontaneously inflict severe
> enough RF burns to require immediate advanced medical
> intervention for survival.  At approximately what time of
> the day, year, solar cycle would it be absolutely impossible
> to detect any trace of that QRSS CW, PSK5 or other
> efficient-mode signal, no matter WHAT sophisticated radio +
> antenna setup you're using in an area at least 12,000 miles
> from the nearest power grid or thunderstorm activity?  Or
> if it never absorbs that much, how close does it get and
> when?
>  
> I've sometimes noticed traces of mid morning/afternoon
> skywave (at least 3 hours after sunrise / 3 hours before
> sunset) using my portable radio and loop antenna even in
> March/April and September/October or thereabouts.  I've
> especially noticed this with 1670 KHPY fading in and out,
> sometimes even within a couple hours of noon and within a
> couple months of the summer solstice.  Considering that I'd
> guess a sophisticated receiver+antenna setup is probably at
> least 100-120 dB more sensitive than my PL-606 and
> Select-A-Tenna, I wonder if they can get skywave all day
> even in summer (even if it's extremely weak)?
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