Hi Steve,
Geomagnetic latitude isn't likely to be an issue in VK6, the geomagnetic
equator in your part of the world is about ten degrees north of the
geographic equator, it runs through the Phillipines and Viet Nam.
Your geomagnetic latitude is about the same as New York city.
But very poor ground conductivity could be a big issue for vertically
polarized antennas especially at relatively low elevation angles.
Conversely, for horizontal polarization the difference between
"perfect" ground and very poor ground is only about 2 dB
regardless of elevation angle.
73
Frank
W3LPL
----- Original Message -----
From: "Steve Ireland" <stevevk6vz@tpg.com.au>
To: topband@contesting.com
Sent: Wednesday, April 22, 2020 9:22:32 AM
Subject: Re: Topband: Inverted V vs inverted L
Hi Peter (and the reflector)
As George AA7JV/C6AGU says: 'It depends on a lot of things: ground
characteristics, number of radials, height of radials and the overall
height available.'
I'd add your geomagnetic latitude (not the same as actual latitude) may
also be a factor.
Here in south-western Australia, an inverted-V dipole at 90 feet high
will usually beat an inverted-L at the same height on 160m. This appears
to be because of the very poor ground conductivity in the far field.
Mike Bazley VK6HD (SK) was the most experienced 160m DXer in Australia
and had around 260 countries confirmed when he passed away some years
back. At his last QTH in Albany he built an inverted-L with an 80 to 90
feet vertical section and, painstakingly, over the course of a year, put
down a full size ground screen of 132 radials, each of a quarter-wave
length long.
This antenna enabled him to add about three new countries in Central
America (which could not hear him on the Inverted V dipole he also had)
but most of the time his inverted V dipole at 90 feet was up to two 'S'
points better. After a couple of years, Mike took the inverted-L down
because of its mostly poorer DX performance.
Now, this kind of result is highly unusual, but just seems to be the way
things work in VK6. I suspect that the inverted-L is going to work
better for you, but as George says, 'there is only one way to tell: try it'.
Vy 73
Steve, VK6VZ (inverted-U dipole at 60 feet - wire goes 66 feet up, 132
foot along, 66 foot down )
Date: Sun, 19 Apr 2020 13:02:26 -0400
From: GEORGE WALLNER<aa7jv@atlanticbb.net>
To:<topband@contesting.com>
Subject: Re: Topband: Inverted V vs inverted L
Message-ID:<ximss-86955041@be1.cluster1.echolabs.net>
Content-Type: text/plain;charset="utf-8"; format="flowed"
Peter,
It depends on a lot of things: ground characteristics, number of radials,
height of radials and the overall height available.
Generally, over average-to-good ground and with 32 or more radials, the
inverted L will perform better for DX at anything up 100', most of the time.
If you can put an inverted V higher than 100', you may get a better antenna,
especially if your QTH is over poor soil and you have only a few radials.
Really, there is only one way to tell: Try it.
Ultimately, having both will give you the best performance.
I know this is not very helpful, but ...
73,
George,
AA7JV/C6AGU
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