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 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.


In order to answer your question, one would need to know...
How accurately do you want to measure? If you want to know to tenths of
a dB, that's a very different matter from, say, to the nearest 3 dB.

In most practical field antenna installations, local conditions and
installation can result in field strength variations of +/- 3dB without
needing to come up with absurd scenarios.

This is why most commercial emergency HF comm systems rely on fairly
simple antennas which are fairly insensitive to surroundings (e.g.
loaded folded dipoles, or wires with autotuners at the feedpoint, and so
forth) and having enough RF power to accomodate the inevitable
variations in performance.

Note that this is a VERY different scenario than the typical ham setup,
where the ham wants to get the very best performance from limited power.


So, maybe your testing might be to work out the deployment details
(what's easy to put up), and just do simple RF testing to make sure that
your easy to deply scheme isn't "terrible" and is "good enough".

OTOH, if you're looking to do antenna shootouts with cases of beer
riding on the results, a whole nother measurement methodology would be
called for.

Now to practicalities...

Something like a Icom PCR1000 computer controlled HF receiver has a
pretty accurate signal strength measuring feature, certainly, it's
pretty good over small variations (10-20dB) in signal strength. You
could put it at some distance (a mile away?) with a short whip (so the
receiving antenna is nondirectional) and make your measurements. You'd
put a fixed amount of power into the test antenna (i.e. set up your rig
for, say, 10W out, and "put a brick on the key"..)

Actually, almost any receiver will do, if it has a reasonably stable way
to check if the received signal is at the same level. You put a
variable attenuator on the input, and just adjust it until the audio
output voltage is the same, or the S-meter hits the same tick mark on
the scale, etc. Since the receiver is always seeing the same level,
things like nonlinear AGC or uncalibrated meters don't make any
difference. It's all in the variable attenuator.

What's also important is making sure the transmitter power is really the
same each time. You don't much care exactly what it is, just that it's
the same. Almost any power meter can do this, as long as the system
isn't too horribly mismatched. Remember, you're looking to hit the same
mark, not have some absolute value. Big changes in mismatch mean that
the quality of the forward and reverse balance in the meter will have an
effect.

Easy way is to have
transmitter: power meter: tuner: feedline: antenna system.

Adjust the tuner for no reverse power on the meter, and there you go.
(Of course, feedline and tuner losses are now part of your measurement)


People literally spend their entire lives doing this kind of thing
professionally, so you need to take a step back and decide what level of
measurement you need. For all you know, just doing some A/B comparisons
when receiving WWV might be good enough.

Tom,

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

Larry, W0QE

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

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

"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

"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.

"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.


There is no exect answer to the question. If you are only transmitting to
one fixed station , the better types of antennas can be determined. If
transmitting to several differant stations, there is usually no one antenna
that will be the best.

Several times I and some of the local hams have been together and had mobile
rigs with the same mounts and differant antennas. Swapping antennas from
car to car, the results were differant depending on where the distance
stations are. Sometimes the 1/4 wave would be beter and on the same mount a
5/8 or longer colinear would be beter on other stations. While we could not
use it on the same mount, one ham had a 40 meter antenna on the bumper of
his car and it had a beter receive signal on one repeater than the antennas
cut for 2 meters we tried on the same car.

It is not so much as the effective radiatred power, but having both stations
in the same lobe of the power. Antennas do not really give any gain to the
signal, they just redirect the ammount you have to a differant direction.
Just as a beam will have lots of gain, if it is not pointed at or near the
desired station, they will not be heard.

On 9 Nov, 14:29, Larry Benko wrote:
Tom,

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

Larry, W0QE



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- Hide quoted text -

- Show quoted text -

He would be better off going to E ham for basic questions

Would a simple field strength meter do the trick?

Scott
N0EDV

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

--
Scott
http://corbenflyer.tripod.com/
Gotta Fly or Gonna Die
Building RV-4 (Super Slow Build Version)

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

So, given that you want an omnidirectional antenna ("flat pancake"
radiation pattern), if I were in your shoes, I'd place a field
strength meter far enough away from the point at which I'm placing
each antenna I'll test that it's well into the far field, and then
install the antennas I want to test, feed them power from the
transmitter I'll be using, and see which gives the highest indicated
field strength. Note that you can take a liberal interpretation of
"field strength meter." It might well simply be the received signal
strength indication on a receiver at one of the remote sites you want
to communicate with. Note that this is getting really close to
testing exactly the condition you want to optimize. Why do otherwise
unless you have to? Why not try to optimize the communications on the
path that's giving you the most trouble now, and then verify that all
the others still work at least that well? You asked what instruments
can be effectively applied to provide results that will be borne out
by actual performance--to me, the best is a test of the performance
itself.

Implicit in this, to me, in the name of efficiency, is that you can
try modelling some candidate antennas before building/buying physical
versions to try out.

Also, you're not the first person to have this problem, and others
have solved it various ways. You very well may be able to get
recommendations from people who have. You may be able to borrow some
of the common commercially available antennas to try, too.

Since the antenna itself is only one component of the overall
communications channel, it seems to me that it would be good for you
to step back and look too at other aspects of the channel. If you
have limited resources to put into the project, it may well do more
good to get a modest antenna up high at each site, than to put a "high
gain" antenna in a bad location (e.g. too low).

I suppose there will be several people who will disagree with this and
get into theoretical debates about why it can't be so, just as you
say. But don't let that keep you from trying real antennas and
finding out what really solves your particular problem.