[TowerTalk] HFTA Angles Data

[K8RI]

On 8/1/2013 12:33 PM, David Gilbert wrote:
>
> If I remember correctly, Dean Straw said that the ARRL crunched the
> numbers back in the mid-90's using a computer that took a few days,
> but I'm not sure it really matters.  We're talking optimum
> takeoff/arrival angles here, and I'm not sure that angle is a strong
> function of F-layer densities.  It would be pretty easy to check ...
> just run a few paths in VOACAP for the same hour of the day using two
> different SSNs and compare the TANGLE results for various
> frequencies.

Although layer height varies, these layers are relatively thick.  The
effective height of a layer at a given height varies with density which
is why we talk about refraction instead of reflections.

So antenna optimum antenna height does change withe the effective height
of the layer(s)

73

Roger (K8RI)

> 73, Dave   AB7E
>
>
>
> On 7/31/2013 8:42 PM, Roger wrote:
>> But is average really average.  The sunspot cycles highs and lows
>> we have recently experienced are quite different than previous
>> cycles and so far this is reportedly, the lowest in a hundred
>> years. From what cycle are the averages taken, or is the
>> information updated to reflect current cycles?
>>
>> I don't remember 40 ever being consistently as good for DX
>> throughout the nights as it was for 4 or 5 recent years.
>>
>> 73
>>
>> Roger (K8RI)
>>
>> _______________________________________________
>>
>>
>>
>> _______________________________________________ TowerTalk mailing
>> list TowerTalk at contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>>
>
> _______________________________________________
>
>
>
> _______________________________________________ TowerTalk mailing
> list TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk

I)