Antenna Pattern Shaping

J

Jim Thompson

Guest
I have a 1086-1094MHz monopole antenna mounted on a small ground
plane.

I would like to modify the ground plane so that it sees only signals
in a cone from 45° above horizon and upwards.

I'm clueless in this antenna world.

How should I do this?

Thanks!

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
"Jim Thompson" <Jim-T@golana-will-get-you.com> wrote in message
news:63gumv8lvegv2665en9k7nirsai7sjpia4@4ax.com...
I have a 1086-1094MHz monopole antenna mounted on a small ground
plane.

I would like to modify the ground plane so that it sees only signals
in a cone from 45° above horizon and upwards.

I'm clueless in this antenna world.

How should I do this?

Thanks!

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
Click to expand...
See if I have this straight, you have a small linear antenna on a printed
circute card you'd like to limit it so it receives only signals that fall
from *above* the board such as might occure in radio signals from satalite
communications? possibly a very small parabolic or hemispherical dish? or
leaves of reflector material around the antenna at 45 degree angle to cut
the strength of the side signals?

Charles
 
On Mon, 22 Sep 2003 19:43:23 GMT, "Charles W. Johnson Jr."
<qrus19@oneimage.com> wrote:

"Jim Thompson" <Jim-T@golana-will-get-you.com> wrote in message
news:63gumv8lvegv2665en9k7nirsai7sjpia4@4ax.com...
I have a 1086-1094MHz monopole antenna mounted on a small ground
plane.

I would like to modify the ground plane so that it sees only signals
in a cone from 45° above horizon and upwards.

I'm clueless in this antenna world.

How should I do this?

Thanks!

...Jim Thompson
[snip]

See if I have this straight, you have a small linear antenna on a printed
circute card you'd like to limit it so it receives only signals that fall
from *above* the board such as might occure in radio signals from satalite
communications? possibly a very small parabolic or hemispherical dish? or
leaves of reflector material around the antenna at 45 degree angle to cut
the strength of the side signals?

Charles
Click to expand...
It's actually a "rubber ducky" vertical-stub antenna attached to a BNC
connector on a circular ground-plane.

It receives signals from aircraft flying overhead. I just want to
limit the reception to those in a 45° cone overhead, but kill the
horizon response.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
Jim Thompson wrote:
I have a 1086-1094MHz monopole antenna mounted on a small ground
plane.

I would like to modify the ground plane so that it sees only signals
in a cone from 45° above horizon and upwards.

I'm clueless in this antenna world.

How should I do this?

Thanks!

...Jim Thompson
--
Click to expand...
Talk to the guys at:
news:rec.radio.amateur.antenna
news:rec.radio.amateur.homebrew
--


Michael A. Terrell
Central Florida
 
It's actually a "rubber ducky" vertical-stub antenna attached to a BNC
connector on a circular ground-plane.

It receives signals from aircraft flying overhead. I just want to
limit the reception to those in a 45° cone overhead, but kill the
horizon response.
Click to expand...
If you would like to experiment, drill a hole in the side of a coffee can
that will allow you to insert the ducky. The hole should be about a quarter
wavelength from the bottom of the can. Face the open end of the can
straight up Have fun.
 
On Mon, 22 Sep 2003 16:12:36 -0400, "Charles Schuler"
<charleschuler@comcast.net> wrote:

It's actually a "rubber ducky" vertical-stub antenna attached to a BNC
connector on a circular ground-plane.

It receives signals from aircraft flying overhead. I just want to
limit the reception to those in a 45° cone overhead, but kill the
horizon response.

If you would like to experiment, drill a hole in the side of a coffee can
that will allow you to insert the ducky. The hole should be about a quarter
wavelength from the bottom of the can. Face the open end of the can
straight up Have fun.
Click to expand...
Good idea!

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
Corner reflector Jim.

--
Gregg
*It's probably useful, even if it can't be SPICE'd*
http://geek.scorpiorising.ca
 
Antenna height determines the vertical radiation patern lobes. Your probably looking at 0.64
wavelength above the ground plane. But there is still a ground lobe present for a vertical.
A horizontal dipole will give better results because of the ground reflections in the horizontal
mode. And if set up as a corner refletor (as pointed out) it will work better.

Cheers

"Jim Thompson" <Jim-T@golana-will-get-you.com> wrote in message
news:63gumv8lvegv2665en9k7nirsai7sjpia4@4ax.com...
I have a 1086-1094MHz monopole antenna mounted on a small ground
plane.

I would like to modify the ground plane so that it sees only signals
in a cone from 45° above horizon and upwards.

I'm clueless in this antenna world.

How should I do this?

Thanks!

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
Click to expand...
 
On Mon, 22 Sep 2003 11:36:59 -0700, Jim Thompson <Jim-T@golana-will-get-you.com>
wroth:

I have a 1086-1094MHz monopole antenna mounted on a small ground
plane.

I would like to modify the ground plane so that it sees only signals
in a cone from 45° above horizon and upwards.

How should I do this?
Click to expand...
Lengthen the antenna in stages. At some point between 1/4 wave in
length where it is now and 1/2 wave, you will get a null in the horizontal
direction. You'll also get approximately 45 degree lobes both up and down, but
the ground plane, if it's area is large enough, will reflect the downward 45
degree lobe upward.

Jim
 
Question?

It's difficult enough receiving SSR transponder blibs on 1090MHZ with a
vertical mounted on the roof, why limit it to 45deg Up and over?


"Jim Thompson" <Jim-T@golana-will-get-you.com> wrote in message
news:63gumv8lvegv2665en9k7nirsai7sjpia4@4ax.com...
I have a 1086-1094MHz monopole antenna mounted on a small ground
plane.

I would like to modify the ground plane so that it sees only signals
in a cone from 45° above horizon and upwards.

I'm clueless in this antenna world.

How should I do this?

Thanks!

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
Click to expand...
 
Drill hole in centre bottom of can that is about the width of your
ground plane, stick rubber ducky through hole, grounding the can and
adjust height of can sides to suit. It seems can height should be around
a 45 degree angle from the antenna base, but practically this doesn't
quite work. Can width will also make a difference, but it doesn't work
out as some recognisable fraction of a wavelength (or didn't for me anyway).

Al

Jim Thompson wrote:

I have a 1086-1094MHz monopole antenna mounted on a small ground
plane.

I would like to modify the ground plane so that it sees only signals
in a cone from 45° above horizon and upwards.

I'm clueless in this antenna world.

How should I do this?

Thanks!

...Jim Thompson
Click to expand...
--
Please remove capitalised letters to reply
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Blame it on the morons that spam the net
 
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