Howdy:
When a 1/2 wave vertical is about 1/2 wave off the ground you get your best radiation pattern without extra lobes, but
if you were to put it on a tower, several wavelengths high, you get multiple lobes. My question is how can you
keep a clean radiation pattern when you are several wavelengths high with a 1/2 wave antenna? Can you put a ground
plane 1/2 wave below the antenna to keep the clean pattern?

--
SeeYaa Harbin Osteen KG6URO

This is YOUR futu
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You would have to create a ground plane that extends many wavelengths
from your antenna. The multiple lobe pattern is produced by reflections
from the ground which are far away -- the lower the angle, the farther
from the antenna.

Why don't you just lower the antenna to 1/2 wavelength if that's the
pattern you want? Then you'll have just the ground plane you need, the
right height below the antenna -- the ground.

Roy Lewallen, W7EL

Harbin wrote:
Howdy:
When a 1/2 wave vertical is about 1/2 wave off the ground you get
your best radiation pattern without extra lobes, but
if you were to put it on a tower, several wavelengths high, you get
multiple lobes. My question is how can you
keep a clean radiation pattern when you are several wavelengths high
with a 1/2 wave antenna? Can you put a ground
plane 1/2 wave below the antenna to keep the clean pattern?

--
SeeYaa Harbin Osteen KG6URO

On Wed, 3 May 2006 14:51:05 -0700, "Harbin"
wrote:

Howdy:
When a 1/2 wave vertical is about 1/2 wave off the ground you get your best radiation pattern without extra lobes, but
if you were to put it on a tower, several wavelengths high, you get multiple lobes. My question is how can you
keep a clean radiation pattern when you are several wavelengths high with a 1/2 wave antenna? Can you put a ground
plane 1/2 wave below the antenna to keep the clean pattern?

create a half-wave dipole and mount it vertically.

buck
n4pgw

--
73 for now
Buck
N4PGW

Myself, I wouldn't worry about the pattern too much.
The higher antenna will still beat the lower one in most
cases despite the extra lobes at higher angles.
Of course, where you are talking will make a difference too.
But you do think a 1/2 wave at 4 waves up will lose to a
1/2 wave at a halfwave up to a ground/space wave contact 30 miles
away? "10 m as an example" Better think again...
The higher antenna will likely eat the lower one for lunch.
And we are talking pretty low angles involved.
Also, on the HF bands like 20m, a higher vertical will often "open
and close" the band earlier and later than the low antenna
when talking long haul dx. But not much difference on
medium or short paths. Yes, there are often higher angle
lobes involved on real high verticals, but if you think that
ruins them, you will be in for a surprise. If I were on 10m,
and had my pick of a 1/2 wave at 25 ft, or a 1/2 wave at
120 ft, I'd take the taller one any day of the week.
I wouldn't let knowledge of theory ruin a good thing. :/
MK

"Roy Lewallen" wrote in message ...
You would have to create a ground plane that extends many wavelengths from your antenna. The multiple lobe pattern is produced by
reflections from the ground which are far away -- the lower the angle, the farther from the antenna.

Why don't you just lower the antenna to 1/2 wavelength if that's the pattern you want? Then you'll have just the ground plane you
need, the right height below the antenna -- the ground.

Roy Lewallen, W7EL


Hi Roy:
With 10 meters and above, the higher you have your antenna, the better
the local reception. I like to get above the power lines.

--
SeeYaa Harbin Osteen KG6URO

This is YOUR futu
http://halturnershow.com/aztlan_caps.wmv
http://media.putfile.com/La-Gran-Marcha
The Mexican Solution:
http://www.centerforsecuritypolicy.o...s&code=06-D_18

-

-
"Roy Lewallen" wrote in message ...
You would have to create a ground plane that extends many wavelengths from your antenna. The multiple lobe pattern is produced by
reflections from the ground which are far away -- the lower the angle, the farther from the antenna.


Ok..... this is a problem.
--
SeeYaa Harbin Osteen KG6URO

This is YOUR futu
http://halturnershow.com/aztlan_caps.wmv
http://media.putfile.com/La-Gran-Marcha
The Mexican Solution:
http://www.centerforsecuritypolicy.o...s&code=06-D_18

-