[alma-config] Near-in sidelobes

[Leonia Kogan]

John,

I have played a little bit with the spiral configuration you gave me a
year ago.  I would like to say since the beginning that the following
conclusions are valid only for this spiral.

So I built the two dimension beam using UVCON=>IMAGR=>KNTR.
The sinthesyse beam has elliptical shape which is rather far from circle.
The ration of the ellipse ases is ~2.

The sinthesize beam has wide wings. 




Now some comments about near side lobes.

You know of cource that the level of the near side lobes depends on the 
element density as the function of the distance from the array center.

The smoother this function goes down the lower near side lobes.

So your spiral configuration may have low near side lobes because of 
the tapering of the element density. 

It is simple to get the same result for donut type of cofiguration if the 
center of the donut will be allowed for the element placement.

But a configuration with the strong condensation of the elements at the 
center may have problems:

1. The size of the array should be bigger. 
2. The fitting to the topography can be a problem


Leonia