[ARC5] FCC General exam

[D C _Mac_ Macdonald]

I seem to remember having been taught in USAF electronics school (a LONG time ago) that 160, 80, and 40 work so well at night because the D-layer is activated by sunlight and absorbs those lower frequencies during the day.  

This absorption goes away after sunset, allowing that energy to actually REACH the F-layer to be refracted. 

My SWAG would be that of Carl's; right around sunset. 

* * * * * * * * * * * 
* 73 - Mac, K2GKK/5 * 
* (Since 30 Nov 53) * 
* k2gkk hotmail com * 
* Oklahoma City, OK * 
* USAF & FAA (Ret.) * 
* * * * * * * * * * * 
 



 

> From: wlfuqu00 at uky.edu
> To: geoffrey at jeremy.mv.com; arc5 at mailman.qth.net
> Date: Mon, 25 Nov 2013 02:26:16 +0000
> Subject: Re: [ARC5] FCC General exam
> 
> No, the F layer at night is the residual ionized atoms left after no Sun light is
> shining on it. That is why you get such good DX on 160 80 and 40 meters
> at night. Because the density of the atmosphere is low at higher altitudes the 
> atoms and ions are further away reducing the chance of recombination. The 
> electrons are what actually do the refraction. The interact with each other 
> like balls with springs between them trying to push them apart. They are resonant.
> This is called the plasma resonant frequency. These act sort of like the parasitic 
> reflector on a bean antenna. Very loose analogy but the simplest I can come up
> with just now. 
> An atomic physicist and I sat down at lunch one day and talked about the plasma
> resonance formula and he said it was hard to derive because it is done in 3 dimensions
> I suggested trying to derive in in one-dimension and with a couple of napkins and felt 
> point pen we came up with the same formula. This was a calculation of plasma resonance
> vs electron density. 
> 
> 73
> Bill wa4lav
> 
> 
> ________________________________________
> From: Geoff [geoffrey at jeremy.mv.com]
> Sent: Sunday, November 24, 2013 8:34 PM
> To: Fuqua, Bill L; ARC 5
> Subject: Re: [ARC5] FCC General exam
> 
> And the E layer is highest just after sunset according to what I just read.
> Without sunspot activity there is no F layer after dark.
> 
> Carl
> 
> 
> ----- Original Message -----
> From: "Fuqua, Bill L" <wlfuqu00 at uky.edu>
> To: "Geoff" <geoffrey at jeremy.mv.com>; "ARC 5" <arc5 at mailman.qth.net>
> Sent: Sunday, November 24, 2013 6:25 PM
> Subject: RE: [ARC5] FCC General exam
> 
> 
> Well, the F1 and F2 layers are at a lower altitude in the day and merge
> into
> the F layer at a much higher altitude at night.
> So the answer should be B.
> The propagation depends greatly on frequency.
> Find some reference to the ionosphere via google or book.
> 73
> Bill wa4lav
> 
> ________________________________________
> From: Geoff [geoffrey at jeremy.mv.com]
> Sent: Sunday, November 24, 2013 6:07 PM
> To: Fuqua, Bill L; ARC 5
> Subject: Re: [ARC5] FCC General exam
> 
> ----- Original Message -----
> From: "Fuqua, Bill L" <wlfuqu00 at uky.edu>
> To: "ARC 5" <arc5 at mailman.qth.net>
> Sent: Sunday, November 24, 2013 5:10 PM
> Subject: [ARC5] FCC General exam
> 
> 
> > Here is a question that I believe they have wrong on the General Exam.
> > What is the answer with out looking it up.
> >
> > G3C02 Where on the Earth do ionospheric layers reach their maximum height?
> > A. Where the Sun is overhead
> > B. Where the Sun is on the opposite side of the Earth
> > C. Where the Sun is rising
> > D. Where the Sun has just set
> 
> 
> I would choose D. Where the Sun has just set
> If discussing the E layer anyway.
> 
> Carl
> 
> 
> 
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