Topband: Modeling the proverbial "vertical on a beach"

[Chuck Hutton]

There is some published research in this area, mostly from the BBC using MW stations as the signal source. I'd start with BBC report 1968-45, now available online.
 
Chuck
 
> From: w8ji at w8ji.com
> To: topband at contesting.com
> Date: Sun, 10 Aug 2014 20:20:49 -0400
> 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
> >>>
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> >>
> >
> >
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