I am working with some guys on ambient noise measurement in a pre BPL
scenario.

They are using FSM ( http://www.vk1od.net/fsm/ ) to make field
strength measurements using a known comms receiver and a Carolina
Windom (CW).

We need to form a view on the CW antenna system losses (radiator,
ground reflection, isolator, matching unit, feedline, ATU.

Has anyone built and calibrated NEC models for the CW, or have they
measured reliably feedpoint impedance on the various bands.

This is not a troll, and I don't want to excite a war over the claimed
performance of the CW, I am not interested in anecdotal evidence or
QSO evidence as to whether they "work".

I see that there will be significant issues in modelling the "secret"
components of the CW unless someone has worked out an RF equivalent
circuit of those components (the isolator and matching unit).

Thanks...

Owen
--

"Owen Duffy" wrote in message
...

I am working with some guys on ambient noise measurement in a pre BPL
scenario.

They are using FSM ( http://www.vk1od.net/fsm/ ) to make field
strength measurements using a known comms receiver and a Carolina
Windom (CW).

We need to form a view on the CW antenna system losses (radiator,
ground reflection, isolator, matching unit, feedline, ATU.

Has anyone built and calibrated NEC models for the CW, or have they
measured reliably feedpoint impedance on the various bands.

This is not a troll, and I don't want to excite a war over the claimed
performance of the CW, I am not interested in anecdotal evidence or
QSO evidence as to whether they "work".

I see that there will be significant issues in modelling the "secret"
components of the CW unless someone has worked out an RF equivalent
circuit of those components (the isolator and matching unit).

Thanks...

Owen

Owen, I have done some tentative modelling of the CW; how valid the model
is, I am not sure. I used the "TL" card for the actual coaxial feedline,
and ran a single wire from the antenna feed point to one side of the TL
source segment. The idea was to replicate the coaxial surface current. I
don't think the balun (Isolator) will have any effect on the antenna
performance. I may even have the code saved someplace if anybody is
interested. Why would you not use a calibrated EMC monopole for HF?

Frank

On Fri, 03 Mar 2006 21:15:19 GMT, "Frank's"
wrote:



Owen, I have done some tentative modelling of the CW; how valid the model
is, I am not sure. I used the "TL" card for the actual coaxial feedline,
and ran a single wire from the antenna feed point to one side of the TL
source segment. The idea was to replicate the coaxial surface current. I
don't think the balun (Isolator) will have any effect on the antenna
performance. I may even have the code saved someplace if anybody is
interested. Why would you not use a calibrated EMC monopole for HF?

Thanks Frank. Some thoughts...

I think they call the thing at the top a matching unit, and it seems
to be a 4:1 transformer, but I have no idea of its common mode
impedance that is relevant to the model.

Similarly the common mode impedance of the lower unit (Isolator) is
relevant to the model, and of course the treatment of the main
feedline (routing, where it is earthed).

The loss in the vertical coax is probably relevant, and not adequately
modelled in NEC.

The loss in the main feedline and ATU are also relevant, and can be
calculated from the feedpoint Z.

If I were building a model, I would be thinking of the assymetric
dipole with the generator at the "upper" feedpoint, a vertical wire to
ground loaded where the matching unit and isolator are located, and
loaded for an underground coax feed (as is the case in this
installation).

But, the model will depend heavily on the common mode impedance of the
two proprietary boxes. Unless someone has measured these, or
calibrated a model, the model results will be of limited value.

Perhaps Roy will comment on the above.

Owen
--

On Fri, 03 Mar 2006 20:59:01 GMT, Owen Duffy wrote:


I am working with some guys on ambient noise measurement in a pre BPL
scenario.

They are using FSM ( http://www.vk1od.net/fsm/ ) to make field
strength measurements using a known comms receiver and a Carolina
Windom (CW).

We need to form a view on the CW antenna system losses (radiator,
ground reflection, isolator, matching unit, feedline, ATU.

Has anyone built and calibrated NEC models for the CW, or have they
measured reliably feedpoint impedance on the various bands.

This is not a troll, and I don't want to excite a war over the claimed
performance of the CW, I am not interested in anecdotal evidence or
QSO evidence as to whether they "work".

I see that there will be significant issues in modelling the "secret"
components of the CW unless someone has worked out an RF equivalent
circuit of those components (the isolator and matching unit).

Thanks...

Owen

Their catalog shows modelled patterns. Might be some NEC models
available at the Radio Works web site.

bob
k5qwg

On Sat, 04 Mar 2006 04:11:07 GMT, Bob Miller
wrote:


Their catalog shows modelled patterns. Might be some NEC models
available at the Radio Works web site.

Bob, I saw that, but did not find links to model files.

Owen
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