Topband: Modeling the proverbial "vertical on a beach"

Sun Aug 10 21:08:45 EDT 2014

Tom,
I was totallly not expecting any station from that direction, just thought 
I'd work a few locals with high incident angles before Sunset here. Then I 
heard the 6Y2 guys and it was amazing. He was the only station--no KV4FZ, 
NP4A, etc and certainly no EU at our time. Made me a believer in beach 
verticals.
73 N7RT

----- Original Message ----- 
From: "Tom W8JI" <w8ji at w8ji.com>
To: "TopBand List" <topband at contesting.com>
Sent: Sunday, August 10, 2014 5:20 PM
Subject: Re: Topband: Modeling the proverbial "vertical on a beach"

> How was his signal compared to someone from a similar heading and distance 
> at the same time who was not on the beach?
>
>
> ----- Original Message ----- 
> From: "Hardy Landskov" <n7rt at cox.net>
> To: "Guy Olinger K2AV" <k2av.guy at gmail.com>; "Richard Fry" 
> <rfry at adams.net>
> Cc: "TopBand List" <topband at contesting.com>
> Sent: Sunday, August 10, 2014 7:35 PM
> Subject: Re: Topband: Modeling the proverbial "vertical on a beach"
>
>
>> Just an observation to all:
>> When Tom, N6BT went to Jaimaca and operated 6Y2J (I think was the call) 
>> with verticals on the beach I was blown away. I heard them 2 hours before 
>> Sunset here on 160....nuff said. The proof is in the pudding.
>> 73 N7RT
>>
>> ----- Original Message ----- 
>> From: "Guy Olinger K2AV" <k2av.guy at gmail.com>
>> To: "Richard Fry" <rfry at adams.net>
>> Cc: "TopBand List" <topband at contesting.com>
>> Sent: Saturday, August 09, 2014 8:35 PM
>> Subject: Re: Topband: Modeling the proverbial "vertical on a beach"
>>
>>
>>> Just to mention that the prior opinion is controversial and not 
>>> universally
>>> agreed upon. Nor to date has anyone surfaced with actual measurements 
>>> made
>>> at the distances (25 to 50 km) and with span of altitudes (0 to 10 km) 
>>> to
>>> either prove or disprove either side.
>>>
>>> It remains unproven modelling from NEC at those distances either way. 
>>> This
>>> situation may, alas, persist this way, because the precise subject
>>> resolution appears to be without benefit to any commercial interest and
>>> therefore without funds to pay for some pretty expensive experimenting
>>> involving precision measurements from aircraft.
>>>
>>> Additionally, there is considerable suspicion that moving from LF to MF 
>>> in
>>> this general subject involves a ground modal change of some sort that 
>>> would
>>> render 50x10 km measurments at 0.5 or 1 MHz unlike those at 2 MHz,
>>> rendering commercial measurements at low and possibly high BC of no 
>>> value
>>> for extrapolation to ham use.
>>>
>>> Arguments on both sides remain basically intuitive. I have "reasonable"
>>> arguments to BOTH concur with Richard AND to not. NEC near field
>>> calculations over sea water at 50 km follow Richard's assertions, and 
>>> the
>>> same over "average" ground does not. The model clearly thinks that 50 km
>>> over most types of ground slowly dissipates low angles resulting in the
>>> controversial "notch" in low angle elevation patterns.
>>>
>>> So NEC based modelling cannot be used as a proof text to decide an 
>>> argument
>>> NEC has with itself.
>>>
>>> 73, Guy K2AV.
>>>
>>>
>>> On Sat, Aug 9, 2014 at 7:23 PM, Richard Fry <rfry at adams.net> wrote:
>>>
>>>> Just to note that the low-angle radiation produced by monopoles is not
>>>> accurately shown by a NEC model/study that does not include the surface
>>>> wave, regardless of whether one or two ground-plane media are specified 
>>>> in
>>>> the model.
>>>>
>>>> Below is a link to a NEC study of the low-angle fields of a monopole
>>>> __including the surface wave__ for three values of earth conductivity
>>>> ranging from extremely good to very poor.
>>>>
>>>> The curves there all show maximum relative field in the horizontal 
>>>> plane.
>>>>
>>>> If the surface wave had not been included in these studies then all of
>>>> those fields would have a zero value in the horizontal plane, and 
>>>> reduced
>>>> fields at low angles just above the horizontal plane.
>>>>
>>>> Reality is that radiation leaving the monopole at elevation angles of 
>>>> at
>>>> least 5 degrees decays at a 1/r rate.  Therefore that radiation is a 
>>>> space
>>>> wave which propagates in a ~ straight line to reach the ionosphere, 
>>>> where
>>>> (with suitable conditions) it can return to the earth as a skywave.
>>>>
>>>> NEC analyses of a vertical monopole of 5/8-lambda and less, and not
>>>> including the fields of the NEC surface wave do not recognize the 
>>>> radiation
>>>> sector capable of producing the greatest single-hop skywave service 
>>>> range
>>>> that can be provided by that monopole.
>>>>
>>>> http://s20.postimg.org/9xqgzu9d9/Monopole_Low_Angle_Radiation.jpg
>>>>
>>>> R. Fry
>>>> _________________
>>>> Topband Reflector Archives - http://www.contesting.com/_topband
>>>>
>>> _________________
>>> Topband Reflector Archives - http://www.contesting.com/_topband
>>>
>>
>>
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>>
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>
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