Hi Jim and Andy,
Thanks for your replies. I also heard from K9LA in a private message, who
specifically addressed the dip angle and how a signal couples with the
ionosphere. For a location somewhat above the equator (my scenario) working
stations to the north (US/EU/JA) should be better with a vertical. Working
east, west and south on a horizontal antenna.
The waterfront location is likely the safest place to be. The hilltop
location I'm looking at is spectacular, but there's limited room for the TX
antennas, and RX antennas will be nearly impossible.
Jim: I am intimately knowledgeable with N6BT's data regarding verticals on
a hill. In summary to those on the reflector: with a vertical on a hill,
for every 1 degree of downward slope, the lobe is tilted down 1 degree.
With enough slope, the peak gain of the vertical goes down to (and possibly
below) the horizon. In effect the pseudo Brewster angle is below the
horizon (actually Tom's data was taken at 2 wl out, and he had peak gain
all the way to the ground, so no pseudo Brewster angle was seen)
Andy: at the old K6KM (SK) hilltop location, the only antenna we ever
worked EU on was a dipole.
Thanks again, Kenny K2KW
[image: image.png]
Message: 3
Date: Mon, 20 Jan 2025 11:15:54 -0800
From: Jim Brown <jim@audiosystemsgroup.com>
To: topband@contesting.com
Subject: Re: Topband: Magnetic Dip Angle
Message-ID:
<ef17c010-9de2-434d-95ed-163cc7d4daf1@audiosystemsgroup.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
It seems to me that the question is really about two good choices. It
has been shown that both vertical and horizontally polarized antennas
benefit from a dropoff IN THE DIRECTION OF THE DROPOFF. Caps added for
emphasis. It is also known that horizontal antennas don't care about
soil/water conductivity, but do care about height, and that verticals
don't care about height, but care a LOT about soil/water conductivity.
In addition to all of the long existing work on antennas and terrain, I
suggest N6BT's recent work on verticals at a dropoff, and my work on the
characteristics of horizontally and vertically polarized antennas cited
above. My work is at k9yc.com/publish.htm It was invited by NCJ, but
ARRL rejected it because it was too much work for their graphics
department (although they had published equally complex graphics in NCJ).
And there's also the issue of how well the antenna works in other
directions. As we all know, you can never have too many antennas!
73, Jim K9YC
On 1/20/2025 10:48 AM, Andy Blank wrote:
> Hi Kenny
>
> I have a similar situation at V47T.
> The QTH is at the edge of an 1100 ft hill, sloping down around 30degs or
> more to the Atlantic.
>
> I have tried every kind of 160 antenna over the years. Finally settling on
> a horizontal dipole at 50ft right at the edge of the hill.
> It works great. The verticals (Inv L, Tee, C's, slopers) all performed
> about the same; just OK.
> The dipole doesn't need radials, a big plus for me.
> I use beverages for RX so that is not an issue.
>
> That said, there is no substitute for a vertical on the beach.
> You are the master of those!
> As you know, the proximity to salt water really makes a huge difference on
> Topband.
>
> GL!
>
> 73, Andy N2NT
>
> On Mon, Jan 20, 2025 at 12:53?PM Kenny Silverman <kenny.k2kw@gmail.com>
> wrote:
>
>> I?m scouting locations for a low-band trip and I found an interesting
>> entity that has a dip angle of 30 degrees.
>>
>> In this example, there?s a high hill overlooking the ocean, another place
>> right on the beach. With the low dip angle, does it make sense to go
>> horizontal if the horizontal polarized antenna takeoff angle is low
enough?
>>
>> 73 , Kenny K2KW
>> _________________
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>> Reflector
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