[mmaimcal] Re: [Almasci] [Fwd: Antenna Differences]

[Mark Holdaway]

Richard Hills wrote

> 2) Even if there are effects due to bright sources in these sidelobes 
> it is far from clear that it is desirable for the patterns to be the 
> same.  Suppose we call the antennas V and A and that they have the 
> present designs.  A source cannot then be in the sidelobes of both 
> types of antennas.  We will have 4 sets of patterns V*V, V*A, A*V, and 
> A*A and the source can only have an effect on the interferometric map 
> via either V*V or A*A.  It seems to me that this means that it will 
> only have 1/4 of the effect on the map that it would if we have all 
> the antennas the same, although it will happen twice as often (for 
> sources at random locations).  Is this right?


Hello,

V*A and A*V are the same, right (or complex conjugates of each other)?
AND, why do you say that V*A correlations are immune to sources bubbling 
up through the
sidelobes?

There are now pretty good techniques for imaging the confusing source 
outside the main beam
with "MX" type methods.  Those techniques will probably break down when 
you get the 3
primary beam situation ---  BUT we can then make 3 different images of 
the offending source,
one for all A*A baselines, one for all A*V baselines, one for all V*V 
baselines (each image
will be quite different, depending on how the sidelobes fall on the source).

> 5) It is not obvious to me that the configuration of the legs has any 
> significant effect on the instrumental polarization within the main 
> beam.  Can anyone see a mechanism that would do that?
>
In an email which you didn't see, I argue that it doesn't matter what 
the feed legs do to the
polarization leakage beam -- We have to implement an algorithm which 
corrects for the
pol-beam-leakage for a SINGLE antenna design -- and once that is in 
place, it will be
simple to extend that to 3 different polarization patterns.


I think we need a new WBS entry:  

Write all conditional statements in software:  "if (ant1 == 'Vertex' && 
ant2 == 'Alcatel')"

     -Mark