NEC-LIST: Re: conical spiral: impedance convergency (Alexander Witte)

Dear Alexander,

As regards the feed, I do not see a problem with the angle (45 or 90) as
far as the highest frequency of operation is well short of the comparable
feed length at that wavelength. If feed wire length is small then the
sharpness of angle does not make it radiate more, at the corners, and
anyways the best symptom for such an anomaly would be a pattern squint.
(or polarization not being circular even at zenith).

As regards impedance convergence, do you get resonances? If yes, check if
they are at harmonics, and try to load the feed terminal appropriately to
begin with. Iteratively you may change the loading to attain perfect
match,
which will break the resonance and allow smooth energy flow.

Hope this helps a bit!

Nikhil Mehta
Visiting Student
Raman Research Institute
Sadashivnagar Bangalore 560 080

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