[evlatests] ea05 P-band beam cuts

[Barry Clark]

Radial phase dependence = out-of-focus, which I think we knew.

On 05/06/2014 11:40 AM, Rick Perley wrote:
> I took two beam cuts of the the VLA antennas at P-band yesterday.
> Attached are the results for ea05, in both power and phase. Note the
> power plot is in dB.
>
> The previous noted 'shoulder' is easily seen. Now that (think) we know
> which labeled output (R,L) is which polarization (H,V), it can now be
> stated that the elliptical 'shoulder' is oriented orthogonally to the
> polarization. Thus, for the 'H' polarization, the shoulder is vertical,
> for the 'V' polarization, it is horizontal. A physical explanation is
> still wanting ...
>
> The phase plots show an interesting feature, previous unknown to me:
> There is a radial phase gradient in the primary beam, slightly steeper
> in the directions of the shoulder. The phase becomes opposite at about
> where the first null would be (if there were one ...), and stays near
> -180 degrees as far as the raster cuts went (about 15 degrees).
>
> These plots are of one antenna (hopefully typical), and at one
> frequency. I know from 'SPFLG' plots that the beam and sidelobes obey
> the law of diffraction (more or less). But some more work to check for
> details would be useful. (Any volunteer?)
>
> It would also be really interesting to do a full holography (say, 41 x
> 41) to determine the full electrical weighting.
>
> Rick
>
>
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