Hi Tom

Direct field strength measurement at the "normal" coverage distances,
calibrated and compared against a known/real world system is IMO the
best choice. I was involved in a VHF paging project that used a laptop,
GPS and measuring receiver for the job. The laptop had a A/D converter
attached to the parallel port. This gave coverage results that were
compared against a modeled prediction, but there is no reason you
couldn't set it up to compare a "new" system to an existing/real one.
One of the beauties of sampling over some time/distance is that small
positional errors with nulls/peaks evident on VHF/UHF can be averaged or
even studied as a distribution. The system I worked with you could even
see Raleigh fading on, but for us it wasn't a useful output!

Biggest hurdle is the RX. You need some kind of Volts per dBm signal
output. You could of course take an S meter output and calibrate it.

If you want a rough answer it may even be worthwhile attaching a laptop
line input to an RX audio out and doing a visual/waterfall analysis of
the level of (FM) quieting present with different antenna systems. You
could of course also calibrate this system.

If you don't want to travel to the limits of the coverage area you can
always do the tests at a lesser distance and then extrapolate with some
RF coverage software.

Hope you find this helpful. Your comments on theoretical debates are
noted, but the best you can do is to just not read them.

Bob VK2YQA

Tom Horne wrote:
My question, again, is what measuring instruments can be effectively
applied to the comparison to provide results that will be born out by
real world performance.

"Hal Rosser" wrote in message
...

"Tom Horne" wrote in message
news:Md4Zi.36$WN2.29@trnddc08...
Is it possible to ask questions here without triggering an arcane debate
about competing views of theory. I'm about to find out. I asked earlier
in another thread what measuring instruments I would need to have the use
of in order to compare the effective radiated power of different
antennas. As near as I can tell there was no answer.
Tom Horne, W3TDH

A Field strength meter can be used to compare relative output of antennas.

Well, in addition to a field strength meter, some low low power source
hooked onto to your antenna may help so you don't have to drive all over the
country side. I used an MFJ antenna Analyzer, some string, and a tape
measure, to 'map-out' on a graph locations of equal field strength.
Just have to watch out for your body affecting the signal pattern.

Tom Horne wrote:
Is it possible to ask questions here without triggering an arcane
debate about competing views of theory. I'm about to find out. I
asked earlier in another thread what measuring instruments I would
need to have the use of in order to compare the effective radiated
power of different antennas. As near as I can tell there was no answer.

I built a collinear J pole using copper tubing. I'd like to know if
it is more or less effective at radiating whatever works to the
stations I'd like to be able to talk to under conditions of emergency
operation then say a collinear ground plane or any other omni
directional antenna.

I would like to deploy the most effective practical antennas that
field testing can devise and not have to wait until the next
breakthrough in physics to be able to get my local governments Email
out to my county's government, the state government and the responding
relief forces.

My question, again, is what measuring instruments can be effectively
applied to the comparison to provide results that will be born out by
real world performance. I have to admit that I find the endless
theoretical debate wearying. As long as it continuous then the
newsgroup will be useless to newer licensees, like my self, who would
like to get some "patient council to the beginner" from those of you
who have been there and done that. Before I have to go there and do
that would be soon enough.
--
Tom Horne, W3TDH
Larry Benko wrote:
Tom,

I tried to reply to you directly but you posted a bogus email address
the email bounced.

Larry, W0QE

Larry
I apologize for not checking the Verizon default newsgroup settings.
Try hornetd via gmail com. And thank you for taking that time to try to
answer.
--
Tom Horne, W3TDH

wrote:
On Nov 9, 1:23 pm, Tom Horne wrote:
Is it possible to ask questions here without triggering an arcane debate
about competing views of theory. I'm about to find out. I asked
earlier in another thread what measuring instruments I would need to
have the use of in order to compare the effective radiated power of
different antennas. As near as I can tell there was no answer.

I built a collinear J pole using copper tubing. I'd like to know if it
is more or less effective at radiating whatever works to the stations
I'd like to be able to talk to under conditions of emergency operation
then say a collinear ground plane or any other omni directional antenna.

I would like to deploy the most effective practical antennas that field
testing can devise and not have to wait until the next breakthrough in
physics to be able to get my local governments Email out to my county's
government, the state government and the responding relief forces.

My question, again, is what measuring instruments can be effectively
applied to the comparison to provide results that will be born out by
real world performance. I have to admit that I find the endless
theoretical debate wearying. As long as it continuous then the
newsgroup will be useless to newer licensees, like my self, who would
like to get some "patient council to the beginner" from those of you who
have been there and done that. Before I have to go there and do that
would be soon enough.
--
Tom Horne, W3TDH

All things being equal, a simple field strength meter will let you
compare different antennas. Those things needing to be equal a all
the test antennas are all vertical or all are horizontal. The distance
from the radiating element to the pickup antenna on the FSM is always
the same, the power to the antenna is the same, perhaps others, as
well.

Any help?
Paul, KD7HB


How basic? Dare I ask for some examples of available models that might
yield acceptable results.
--
Tom Horne, W3TDH

Mike Kaliski wrote:
"Tom Horne" wrote in message
news:Md4Zi.36$WN2.29@trnddc08...
Is it possible to ask questions here without triggering an arcane
debate about competing views of theory. I'm about to find out. I
asked earlier in another thread what measuring instruments I would
need to have the use of in order to compare the effective radiated
power of different antennas. As near as I can tell there was no answer.

I built a collinear J pole using copper tubing. I'd like to know if
it is more or less effective at radiating whatever works to the
stations I'd like to be able to talk to under conditions of emergency
operation then say a collinear ground plane or any other omni
directional antenna.

I would like to deploy the most effective practical antennas that
field testing can devise and not have to wait until the next
breakthrough in physics to be able to get my local governments Email
out to my county's government, the state government and the responding
relief forces.

My question, again, is what measuring instruments can be effectively
applied to the comparison to provide results that will be born out by
real world performance. I have to admit that I find the endless
theoretical debate wearying. As long as it continuous then the
newsgroup will be useless to newer licensees, like my self, who would
like to get some "patient council to the beginner" from those of you
who have been there and done that. Before I have to go there and do
that would be soon enough.
--
Tom Horne, W3TDH

Tom

Get together with some friends and have them drive out and assess your
signal under real life conditions. Make a day of it and all get together
in the evening for a social gathering and to compare notes. You really
need to know whether it works okay or not, not what the 'S' meter is
reading.

Mike G0ULI

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. 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

In news wrote:

I tried to reply to you directly but you posted a bogus email address
the email bounced.

Why not follow up in the newsgroup so that others might benefit from the
exchange?

--
Bert Hyman St. Paul, MN

Hal Rosser wrote:
"Hal Rosser" wrote in message
...
"Tom Horne" wrote in message
news:Md4Zi.36$WN2.29@trnddc08...
Is it possible to ask questions here without triggering an arcane debate
about competing views of theory. I'm about to find out. I asked earlier
in another thread what measuring instruments I would need to have the use
of in order to compare the effective radiated power of different
antennas. As near as I can tell there was no answer.
Tom Horne, W3TDH
A Field strength meter can be used to compare relative output of antennas.

Well, in addition to a field strength meter, some low low power source
hooked onto to your antenna may help so you don't have to drive all over the
country side. I used an MFJ antenna Analyzer, some string, and a tape
measure, to 'map-out' on a graph locations of equal field strength.
Just have to watch out for your body affecting the signal pattern.


Please guys
Without going to war with each other over the answer and leaving me not
knowing who to believe, is an MFJ analyzer a good choice in the under
five hundred dollar range? Would using one of the one watt HTs do for a
signal source or is that still to high.
--
Tom Horne

Tom Horne wrote:
My question, again, is what measuring instruments can be effectively
applied to the comparison to provide results that will be born out by
real world performance.

Bob Bob wrote:
Hi Tom

Direct field strength measurement at the "normal" coverage distances,
calibrated and compared against a known/real world system is IMO the
best choice. I was involved in a VHF paging project that used a laptop,
GPS and measuring receiver for the job. The laptop had a A/D converter
attached to the parallel port. This gave coverage results that were
compared against a modeled prediction, but there is no reason you
couldn't set it up to compare a "new" system to an existing/real one.
One of the beauties of sampling over some time/distance is that small
positional errors with nulls/peaks evident on VHF/UHF can be averaged or
even studied as a distribution. The system I worked with you could even
see Raleigh fading on, but for us it wasn't a useful output!

Biggest hurdle is the RX. You need some kind of Volts per dBm signal
output. You could of course take an S meter output and calibrate it.

If you want a rough answer it may even be worthwhile attaching a laptop
line input to an RX audio out and doing a visual/waterfall analysis of
the level of (FM) quieting present with different antenna systems. You
could of course also calibrate this system.

If you don't want to travel to the limits of the coverage area you can
always do the tests at a lesser distance and then extrapolate with some
RF coverage software.

Hope you find this helpful. Your comments on theoretical debates are
noted, but the best you can do is to just not read them.

Bob VK2YQA

Bob
As you can see from some of the replies I gave to others I'm trying to
devise a way of practically comparing antennas available because in
emergency service communications support we have no way of knowing were
we will need to set up. Hence the desire to set up some sort of antenna
experiment that will allow us to compare the antennas against each other.

Just for the sake of my education is it likely to be true that the
antenna that puts out the most effective radiated power will be a bad
choice in a large percentage of possible sites?
--
Tom Horne, W3TDH

"Tom Horne" wrote in message
news:0Z9Zi.79$Y32.0@trnddc04...
Mike Kaliski wrote:
"Tom Horne" wrote in message
news:Md4Zi.36$WN2.29@trnddc08...
Is it possible to ask questions here without triggering an arcane debate
about competing views of theory. I'm about to find out. I asked
earlier in another thread what measuring instruments I would need to
have the use of in order to compare the effective radiated power of
different antennas. As near as I can tell there was no answer.

I built a collinear J pole using copper tubing. I'd like to know if it
is more or less effective at radiating whatever works to the stations
I'd like to be able to talk to under conditions of emergency operation
then say a collinear ground plane or any other omni directional antenna.

I would like to deploy the most effective practical antennas that field
testing can devise and not have to wait until the next breakthrough in
physics to be able to get my local governments Email out to my county's
government, the state government and the responding relief forces.

My question, again, is what measuring instruments can be effectively
applied to the comparison to provide results that will be born out by
real world performance. I have to admit that I find the endless
theoretical debate wearying. As long as it continuous then the
newsgroup will be useless to newer licensees, like my self, who would
like to get some "patient council to the beginner" from those of you who
have been there and done that. Before I have to go there and do that
would be soon enough.
--
Tom Horne, W3TDH

Tom

Get together with some friends and have them drive out and assess your
signal under real life conditions. Make a day of it and all get together
in the evening for a social gathering and to compare notes. You really
need to know whether it works okay or not, not what the 'S' meter is
reading.

Mike G0ULI

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. 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

Hi Tom

That's a very fair comment under the circumstances. That sounds like a
pretty big project you are planning. Setting up an antenna farm in a big
field or car park and plotting the antenna patterns with a field strength
meter, or hooking up an Icom scanner to a PC and recording the results seem
like the best suggestions so far.

Do remember that each site where you eventually install the antennas will
have it's own characteristics. One design may not be suitable for
everywhere. I personally have had very good results with a semi commercial
5/8 over 5/8 co-linear design with 6 x 24" horizontal radials at the base.
The antenna is cut and tuned for the 2 metre band, but also works well on 70
Cm. Range fully quietening around 40 miles on only 5W on 2m across flat
terrain with the base of the antenna 20 feet above ground. This is the most
effective design I have come across for omni-directional working. The whole
thing is built in a seamless fibre glass tube with the radials screwed into
a ring bonded at the base of the antenna.

Good luck with the project

Mike G0ULI

"Tom Horne" wrote in message
news:j1aZi.80$Y32.72@trnddc04...
Hal Rosser wrote:
"Hal Rosser" wrote in message
...
"Tom Horne" wrote in message
news:Md4Zi.36$WN2.29@trnddc08...
Is it possible to ask questions here without triggering an arcane
debate about competing views of theory. I'm about to find out. I
asked earlier in another thread what measuring instruments I would need
to have the use of in order to compare the effective radiated power of
different antennas. As near as I can tell there was no answer.
Tom Horne, W3TDH
A Field strength meter can be used to compare relative output of
antennas.

Well, in addition to a field strength meter, some low low power source
hooked onto to your antenna may help so you don't have to drive all over
the country side. I used an MFJ antenna Analyzer, some string, and a tape
measure, to 'map-out' on a graph locations of equal field strength.
Just have to watch out for your body affecting the signal pattern.


Please guys
Without going to war with each other over the answer and leaving me not
knowing who to believe, is an MFJ analyzer a good choice in the under five
hundred dollar range? Would using one of the one watt HTs do for a signal
source or is that still to high.
--
Tom Horne

Tom,

A one watt HT will do fine, but the signal will still be too strong close in
to work with. You need to get the power down to perhaps one milliwatt or
less to plot the antenna pattern in a field or car park. You can make up an
attenuator to reduce the power from the HT. Just making up a patch lead
between the HT and the antenna with a 50 ohm, 1 watt resistor shorting the
core and outer will probably reduce the signal to something you can work
with while still giving the transmitter a load to work into. (You can make
up exactly 50 ohms using two 100 ohm, 1/2 watt resistors). Or make up a
simple single transistor 'bug' transmitter from a handful of components.
Plenty of designs available through Google No need to spend more than a
couple of dollars. The 9v battery is likely to be the most expensive bit.

Mike G0ULI