I don't have a scientific calculator to hand Mike, but those '200 ft hills are
what 18 degs? 100' is 9degs? The latter is going to be fine for EU on the
high bands in good times, but if you're really talking verts on the beach, then
that whole saltwater scenario is what is going to count. The Fresnel zone will
be out to 10 wavelengths at least so 1000 feet is going to be fine down to 30
metres (10Mhz). On 40m, that's likely to be a little less than ideal, but the
improved ground conductivity in the very near field will likely begin to play
into your hands at that frequency and in particular below as Ed says. Some of
those places in VE1 that you describe are up creeks and might be just brackish
rather than pure seawater at the 'beach' of course. Good luck!
Al G0XBV
-----Original Message-----
From: Jim Brown <k9yc@audiosystemsgroup.com>
To: cq-contest <cq-contest@contesting.com>
Sent: Thu, 13 Aug 2015 18:09
Subject: Re: [CQ-Contest] Verticals on the beach (AGAIN)
The best place to study this is in the early chapters of the ON4UN book,
where
he talks about situations like this.
Someone suggested HFTA. HFTA applies
ONLY to horizontally polarized
antennas.
David is right -- NEC does allow
two ground models. It would be tricky
though -- the key here is the sea water
ending in the range of 1,000 ft.
So the model would have to start with sea
water out to 1,000 ft, then
shift to land for the second media. That would
yield an overly
optimistic view of ground losses, but would take the limited
sea water
into account.
73, Jim K9YC
On Wed,8/12/2015 7:33 PM, David
Gilbert wrote:
>
>
> I don't remember for sure off the top of my head, but I
think that
> EZNEC+ has the capability of specifying two different areas of
ground
> conductivity surrounding the antenna. You could rather easily see
the
> impact of the nearby salt water if I'm correct.
>
> Dave
AB7E
>
>
>
> On 8/12/2015 1:19 PM, Mike Smith VE9AA wrote:
>> As we
continue to look for land around the Maritimes for a small weekend
>> cottage
we occasionally come upon a location that has shorefront on
>> saltwater, which
really is not completely open water all the way to
>> EU or
>> USA, so it's
not ideal. The south coasts of VO1, VY2, VE9 and VE1
>> all kinda
>> point
S/SE
>>
>>
>> I have found a couple with a clear shot to the Caribbean or
Africa,
>> but with
>> so few contest stations there, it's really not very
important, except
>> perhaps for that rare LP to JA...
>>
>>
>> A few spots
have open salt water towards EU of around 1000', before
>> it hits
>> land
again (opposite side of the harbour) then gently sloping up past
>> that.
>>
(0-100/200 feet)
>>
>>
>> So my question is really, does 1000' of salt water
make any
>> difference at
>> all, or not enough to make any difference and
the 200' hills on the
>> other
>> side of the harbour would be more hindrance
than the salt water would be
>> helping?
>>
>>
>> There must be stations all
over the world with a short salt water
>> takeoff
>> who could
comment?
>>
>>
>> Has anyone done any A/B comparisons or proof at
all?
>>
>>
>> I have read N6LF's and K2KW's and most related stuff on the
Internet,
>> but it
>> generally references DXpeditions in the Pacific or
Caribbean with
>> completely
>> open water as far as the eye can see. I am
just wanting to know about a
>> 1000' salt water runway, then low land
again.
>>
>>
>> Thanks,
>>
>>
>> Mike
VE9AA/VE1TTT/VO1TTT/VO2DX
>>
>>
>> Mike, Coreen & Corey
>>
>> Keswick
Ridge, NB
>>
>>
>> _______________________________________________
>>
CQ-Contest mailing list
>> CQ-Contest@contesting.com
>>
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>>
>
>
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