Topband: Monopole Elev Pattern w.r.t. Earth Conductivity

[Paul Christensen]

Tom,

As I recall, HFTA software has an ionospheric module that calculates the 
predictability of arrival angle as a function of frequency, time of day, 
season, etc.  Learning that program has been on my "to do" list for a long 
time.  Perhaps others here can comment on whether the arrival angle 
information goes down to 160m in that program.  I believe the program was 
designed for elevated antennas and hence the need to analyze terrain.  So, 
in addition to 160m relevance, I'm not sure it applies to base-fed 
monopoles.

I think the important "take away" in these discussions is that the far field 
pattern alone is not enough to show the real vertical profile from a 
vertical monopole.  The significance of the ionospheric element is another 
issue altogether.

Paul, W9AC

----- Original Message ----- 
From: "Tom W8JI" <w8ji at w8ji.com>
To: "Richard Fry" <rfry at adams.net>; <topband at contesting.com>
Sent: Wednesday, October 24, 2012 2:39 PM
Subject: Re: Topband: Monopole Elev Pattern w.r.t. Earth Conductivity


> ----- Original Message ----- 
> From: "Richard Fry" <rfry at adams.net>
> To: <topband at contesting.com>
> Sent: Wednesday, October 24, 2012 2:23 PM
> Subject: Re: Topband: Monopole Elev Pattern w.r.t. Earth Conductivity
>
> from [Tom W8JI]:
>>The issue here is one of measurement distance and the assumed flat earth, 
>>and how much the ground wave contributes to low angle radiation. We 
>>obviously know radiation at zero degrees is not zero, as distant models 
>>show.
>
> <As to measured data, below with his permission is a quote from a 
> broadcast
> consultant acquaintance of mine who has made helicopter measurements of 
> the
> elevation patterns of MW monopoles.>
>
> My point is that does not tell us what happens at the ionosphere.
>
> If I just take a simple program like EZNEC, and use a small sense antenna 
> out in the distance, the results follow the trend you posted from the 
> helicopter. I certainly am not disputing that data, because it seems 
> reasonable.
>
> AFAIK, we do not have measurements of arrival angles useful for long 
> distances or how lower angles from verticals might apply to that. All we 
> really know is using simple programs, low angle patterns are misleading.
>
> 73 Tom
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