Is it possible to ask questions here?
 

"Ralph Mowery" wrote in message
...

"Jerry Martes" wrote in message
news:ydoZi.102$RR1.77@trnddc02...

"Tom Horne" wrote in message
For 2 meter antennas, the 137 MHz from the NOAA satellites is probably
close enough. That would require making some test antennas about 5%
bigger than the 2meter antennas.

If you E-mail me I can show you some radiation patterns I have plotted
from NOAA satellites. My plots of actual measured signal strength make
me more and more confident that EZNEC is accurate.

Jerry

With all the OSCAR satellites up there is no need to do go to the NOAA in
the 137 mhz range. The two meter sats will do just fine.

Just because an antenna works well on a sat is no reason to assume it will
work well on signals from the ground. I have not used one , but the old
Ringo antenna sent most of its signal up at an angle. It would probably
make a good sat antenna, but a poor antenna for ground work.

People in this thread are making way too much out of it. In most cases
the longer/bigger the antenna is , the more gain it will have. Just put
up the biggest one of good quality you can and don't worry about it.
There will be enough differance in the lay of the land to make differant
antennnas work beter in differant directions unless you are on a very flat
land.


Hi Ralph

I missed being able to be clear in my "other" post. If there is a Beacon
signal available from a POE satellite at 2meters there is an Excellent
2Meter source of signal with which a person can use to Very Accurately
record the radiation pattern from horizon to horizon at all azimuth angles.
That radiation pattern will be the pattern of the Ground antenna, not the
satellite antenna. We have to assume the satellite radiates equal in all
directions.

The strength of the received signal is recorded into some program like
Excel as a function of time. The actual Az-El to the satellite is
published, or can be computed. So, it becomes fairly easy to record the
actual (ground based) antenna's radiation pattern which includes all the
environmental effects like trees and neighbors's houses.

Jerry KD6JDJ

Is it possible to ask questions here?
 

"Jerry Martes" wrote in message
news:m4qZi.419$763.177@trnddc07...

I missed being able to be clear in my "other" post. If there is a
Beacon signal available from a POE satellite at 2meters there is an
Excellent 2Meter source of signal with which a person can use to Very
Accurately record the radiation pattern from horizon to horizon at all
azimuth angles. That radiation pattern will be the pattern of the Ground
antenna, not the satellite antenna. We have to assume the satellite
radiates equal in all directions.

The strength of the received signal is recorded into some program like
Excel as a function of time. The actual Az-El to the satellite is
published, or can be computed. So, it becomes fairly easy to record the
actual (ground based) antenna's radiation pattern which includes all the
environmental effects like trees and neighbors's houses.

Jerry KD6JDJ
Jerry you were clear to me. There are several things wrong trying to use
the sat to determine the patern of the antenna on the ground at other than
the specific pass. Low orbiting sats will start at a great distance as they
come over the horizon and get to with in a few hundred miles as they go over
head. The squnit angle of the sat antenna will change so the sat antenna is
not always pointing at the ground antenna. The apparent polarity will
change and that can make a big differance.

I have the KLM circular beam pair for 2 meters and 435 mhz on an az/el setup
and computer control. Also can switch from left to right circular and have
monitored the sats go over and sometimes have to switch left to right as
they pass for the best signal.

I have not tried it on a sat but for the Icoms ( it might work on others)
there is a program that will record the s-meter and draw a plot on the
screen . I have done it looking at repeaters and it does seem to work ok
for drawing paterns.

Is it possible to ask questions here?
 

"Ralph Mowery" wrote in message
...

"Jerry Martes" wrote in message
news:m4qZi.419$763.177@trnddc07...

I missed being able to be clear in my "other" post. If there is a
Beacon signal available from a POE satellite at 2meters there is an
Excellent 2Meter source of signal with which a person can use to Very
Accurately record the radiation pattern from horizon to horizon at all
azimuth angles. That radiation pattern will be the pattern of the Ground
antenna, not the satellite antenna. We have to assume the satellite
radiates equal in all directions.

The strength of the received signal is recorded into some program like
Excel as a function of time. The actual Az-El to the satellite is
published, or can be computed. So, it becomes fairly easy to record the
actual (ground based) antenna's radiation pattern which includes all the
environmental effects like trees and neighbors's houses.

Jerry KD6JDJ
Jerry you were clear to me. There are several things wrong trying to use
the sat to determine the patern of the antenna on the ground at other than
the specific pass. Low orbiting sats will start at a great distance as
they come over the horizon and get to with in a few hundred miles as they
go over head. The squnit angle of the sat antenna will change so the sat
antenna is not always pointing at the ground antenna. The apparent
polarity will change and that can make a big differance.

I have the KLM circular beam pair for 2 meters and 435 mhz on an az/el
setup and computer control. Also can switch from left to right circular
and have monitored the sats go over and sometimes have to switch left to
right as they pass for the best signal.

I have not tried it on a sat but for the Icoms ( it might work on others)
there is a program that will record the s-meter and draw a plot on the
screen . I have done it looking at repeaters and it does seem to work ok
for drawing paterns.

Hi Ralph

Although I disagree with your premise about "great distance and a few
hundred miles", I must admit that I lack knowledge of the satellites other
than the few NOAA satellites. The NOAA satellites are about 4 time more
distant at the horizon than overhead. That results about 12 dB less signal
at the low elevation angle. The 12 dB is fairly easy to put back in the
plot.
The guys at NASA/NOAA did an excellent job of tailoring the NOAA satellite
pattern shape so it is close to equal over the entire pass. I'd have
expected the "OSCAR" guys to have done the same and shaped their satellite
antenna beams to be essentially equal level over the angle at which the
Earth intercepts the satellite beam.
I'd like to know more about a 2Meter beacon satellite. Can you point me
to a site where I can learn about 2Meter beacon satellites? I have a
friend who will write me a program to plot signal strength as a function of
angle on a polar plot. He made me one for the NOAA (137 MHz) satellites.
I like modeling antennas at 2Meters and have an Icom PCR1000 that I'd like
to get some use out of.

Jerry KD6JDJ

Is it possible to ask questions here?
 

"Jerry Martes" wrote in message
news:%dsZi.2897$CI1.289@trnddc03...
Although I disagree with your premise about "great distance and a few
hundred miles", I must admit that I lack knowledge of the satellites other
than the few NOAA satellites. The NOAA satellites are about 4 time more
distant at the horizon than overhead. That results about 12 dB less
signal at the low elevation angle. The 12 dB is fairly easy to put back
in the plot.
The guys at NASA/NOAA did an excellent job of tailoring the NOAA
satellite pattern shape so it is close to equal over the entire pass.
I'd have expected the "OSCAR" guys to have done the same and shaped their
satellite antenna beams to be essentially equal level over the angle at
which the Earth intercepts the satellite beam.
I'd like to know more about a 2Meter beacon satellite. Can you point me
to a site where I can learn about 2Meter beacon satellites? I have a


Jerry you can find information on the ham sats at www.amsat.org.

I guess the great distances I was thinking about was from about 200 miles to
around 1000 or so. As you said that is getting close to 10 to 12 db
differant. In one way that is not really that much differance in signal,
but the types of antennas we have been talking about would have from 0 db to
about 6 db of gain. Most would have just one or two db worth of differance
in the best direction.

Is it possible to ask questions here?
 

"Ralph Mowery" wrote in message
...

"Jerry Martes" wrote in message
news:%dsZi.2897$CI1.289@trnddc03...
Although I disagree with your premise about "great distance and a few
hundred miles", I must admit that I lack knowledge of the satellites
other than the few NOAA satellites. The NOAA satellites are about 4
time more distant at the horizon than overhead. That results about 12 dB
less signal at the low elevation angle. The 12 dB is fairly easy to put
back in the plot.
The guys at NASA/NOAA did an excellent job of tailoring the NOAA
satellite pattern shape so it is close to equal over the entire pass. I'd
have expected the "OSCAR" guys to have done the same and shaped their
satellite antenna beams to be essentially equal level over the angle at
which the Earth intercepts the satellite beam.
I'd like to know more about a 2Meter beacon satellite. Can you point
me to a site where I can learn about 2Meter beacon satellites? I have a


Jerry you can find information on the ham sats at www.amsat.org.

I guess the great distances I was thinking about was from about 200 miles
to around 1000 or so. As you said that is getting close to 10 to 12 db
differant. In one way that is not really that much differance in signal,
but the types of antennas we have been talking about would have from 0 db
to about 6 db of gain. Most would have just one or two db worth of
differance in the best direction.

Hi Ralph

I would sincerely like to know where to find that 2Meter beacon from a
satellite. I have searched a little. Since you have knowledge of the
satellite with the 2Meter beacon, I'd appreciate any link to it. I have
some AMSAT journals but I havent recognized which satellite transmits that 2
Meter beacon.
Your posts show clearly that you question the accuracy of the radiation
pattern measurement of an antenna when the satellite is used for the
illuminator. I submit to you that you wont find a better way to record the
actual radiation pattern. I can measure an antenna's pattern with close to
20 dB dynamic range. It is unclear to me why you doubt the accuracy of
patterns I record.
One of the benefits of using 137 MHz is the ease with which a person is
able to find programs that tell the exact location (Az - El) to the
satellite. You can se an example of the radiation pattern at Patrik Tast's
site http://www.poes-weather.com/. The pattern is in the section
"antennas".
I sure will appreciate any information you can give me related to 2Meter
beacon satellites. I'm trying to make a program (free) that amateurs can
use to record 2Meter antenna radiation patterns. I am very pleased with
the program Patrik made for me using the 137 MHz satellites.

Thanks for your help
Jerry

Is it possible to ask questions here?
 

"Jerry Martes" wrote in message
news:rDGZi.171$RR1.12@trnddc02...
entire pass. I'd
have expected the "OSCAR" guys to have done the same and shaped their
satellite antenna beams to be essentially equal level over the angle at
which the Earth intercepts the satellite beam.
I'd like to know more about a 2Meter beacon satellite. Can you point
me to a site where I can learn about 2Meter beacon satellites? I have
a


Most of the ham sats are simple as far as that can be. The antennas on them
are not really made to point that accurate.

Here are some sats that have beacons near 145 mhz.

http://www.amsat.org/amsat-new/satel...tes/status.php

Is it possible to ask questions here?
 

"Ralph Mowery" wrote in message
...

"Jerry Martes" wrote in message
news:rDGZi.171$RR1.12@trnddc02...
entire pass. I'd
have expected the "OSCAR" guys to have done the same and shaped their
satellite antenna beams to be essentially equal level over the angle at
which the Earth intercepts the satellite beam.
I'd like to know more about a 2Meter beacon satellite. Can you point
me to a site where I can learn about 2Meter beacon satellites? I have
a


Most of the ham sats are simple as far as that can be. The antennas on
them are not really made to point that accurate.

Here are some sats that have beacons near 145 mhz.

http://www.amsat.org/amsat-new/satel...tes/status.php


Thanks Ralph

I found the staellite and will set up my receiver to learn more about that
2Meter beacon from VO-52. I sure appreciate your help.

Jerry

Is it possible to ask questions here?
 

What's the easiest method of determining which antenna works the best
for a particular situation? Simplest answer is to try it and see
(experience). Then again, what happens when that 'situation'
changes? Hmm, try something else? Great answer, isn't it? Very
helpful, right?
There is no 'best' answer for all situations unless you do some very
comprehensive testing, with some very expensive equipment, done by
people who know what they are doing. That 'best' answer is still a
'maybe'.
So. A "Can you hear me now?" tends to work well. Accept the fact
that there are always going to be times when everybody isn't gonna
hear you. That's what relays are for (the 'INFO' line on a message
header?). For almost any range, but especially for VHF/UHF, higher is
usually better. Produces more usable range than the antenna design
(within reason!).
Everybody wants the 'best'! Very few, except in particular instances,
ever get it.
- 'Doc


(Don't you just hate answers like that?)

Is it possible to ask questions here?
 

wrote:
What's the easiest method of determining which antenna works the best
for a particular situation? Simplest answer is to try it and see
(experience).

There is lots of experience on this newsgroup from
which to draw. Most of us can predict that someone
will not be satisfied with a CB whip and autotuner
on 75m, for instance.
--
73, Cecil http://www.w5dxp.com

Is it possible to ask questions here?
 

Tom Horne wrote:

Mike
I already own the J pole I mentioned and an Isopole for two meters. I
expect to have a third two meter omni to cover APRS, Packet, and voice.
I can see me throwing up each of these antennas in turn in a shopping
center parking lot on a Saturday night when all the cars are gone and
doing some measurements. I cannot see me rigging each in turn to the
eve brackets on my house while my victims, I er mean buddies or at least
they would be at first, cool their collective heals waiting for each
successive test. Then there is the possibility that we may need to
pre-install some sort of dual or mono band antenna at each of thirty
plus fire stations and you can see why we might want to know which of
the designs we can build or buy will put out the strongest signal.

I would venture to guess that any of the popular designs will be within
a dB or so of each other. Your bigger concern will be system issues
like cost, feedline losses, construction time, etc.

You might look into some form of collinear array (multiple half waves
stacked on top of each other) because you'll get more gain at the
horizon and still have an easy install. There's lots of these in all
the commercial catalogs (e.g. Tessco), and there's a few in the ARRL
antenna book if you want to build something.



If I
test at my home I will know which antenna works here but I'm unlikely to
be called on to provide emergency communications from my home. I'd like
to find out in as objective way as possible which antenna has the best
chance in terms of power out to get the signal through in conditions
that cannot be known in advance.
--
Tom Horne
--
Tom