Hi Graham, I think if you are hoping to get a handle on the effect of an
elevated loading coil you are in for a disappointment, you can calculate the
(small) increase in Rrad this gives. The problem is the one illuminated by
Jim's recent experiments....the effect of the surrounding environment. As I
understand it an elevated loading coil would give no real advantages in
Jim's open field situation. However its effect is to change the current
distribution on the radiating section, and this is the bit where any
coupling to surrounding "environment" leads to big losses. The effect of the
elevated coil is to reduce the voltage on the radiating section thus
reducing the current diverted throught the couple capacitance into the lossy
surroundings (voltage times loss reactance....reducing the voltage, reduces
the current diverted from flowing through all the distributed Rrad).
Sadly, like the effect of the top capacitance reducing the ground loss,
these environmental effects are not modelled.....and a simulator is only as
good as the model and the equations used. Hint for a mathematically minded
amateur !!
As an aside Jim's measurements disprove my idea that the "shortfall" in
measured ERP over the calculated value, was due to poor ground causing more
radiation of the signal upward from a "small" aerial (HFC 2007). It would
seem from Jim's tests that it is purely an "environment loss thing". An
ounce of measurement is worth a ton of theory (half baked or otherwise !)
Cheers and HNY de Alan G3NYK
----- Original Message -----
From: "Graham" <[email protected]>
To: <[email protected]>
Sent: Friday, December 28, 2007 6:45 PM
Subject: Re: LF: -HELP- MMANA-GAL Antenna analyzer .... can anyone'code' an
array ?
> Ok Thanks for that Rik,
>
> Thats the basic layout , ive only 2 top wires , but thats the layout .. I
> see you have a load defined in the geometry listing , but where on the ae
is
> it located ? , I found one post on the user group , where a element could
> be given a short lenght and have inductance added to it .. that way you
> could control where the coil was placed
>
> My ae has the 'coil' at the 90 deg bend , top of the vertical section , if
i
> could work out how to add that, I would be half way there ! the earth
> system would be the other half hihi
>
> Tnx
>
> Graham ..
>
>
>
>
> ----- Original Message -----
> From: "Rik Strobbe" <[email protected]>
> To: <[email protected]>
> Sent: Friday, December 28, 2007 5:49 PM
> Subject: Re: LF: -HELP- MMANA-GAL Antenna analyzer .... can anyone'code'
an
> array ?
>
>
> > Graham,
> >
> > attached a MMANA-GAL file that simulates my 136kHz antenna when
> > adapted for 500kHz.
> > Maybe that will be of some help.
> >
> > 73, Rik ON7YD
> >
> > Quoting Graham <[email protected]>:
> >
> >> -HELP- MMANA-GAL Antenna analyzer .... can anyone 'code' an array ?
> >>
> >>
> >>
> >> After several attempts .. and getting no-where fast , Is there anyone
> >> who can code a top loaded antenna array ? the array is in the shape of
> >> a inverted L . with top loading coil and 2 wire capacity section
> >>
> >>
> >>
> >> I can find some similar files , but can I add to them .... not as yet
!
> >>
> >>
> >>
> >> It 'works' up to about 5 mhz , then falls over , I have a feeling
> >> the earth system is playing a part in this ... also how do you code a
> >> parallel 2 wire section ?
> >>
> >>
> >>
> >> Any help would be appreciated ,
> >>
> >>
> >>
> >> Tnx
> >>
> >>
> >>
> >> Graham
> >>
> >>
> >>
> >> G0NBD
> >
> >
> >
> >
> > Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm
> >
> >
>
>
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>
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