[mmaimcal] Text of AI on antenna quardupod design from Beasley

[Jeff Mangum]

Hi Al,

Regarding the subreflector hole issue...

Alwyn Wootten wrote:

> Folks,
>
> Here is the text of our action item and my preliminary response.  
> Comments?
>
> Action Item to the Science IPT (Al and Tom) from Tony Beasley could 
> you write me a few-paragraph response to each of these and return 
> asap? Regarding the Quadrupod position - the text you sent yesterday 
> [from the May 2003 Report to the Board] should cover it. ASAC opinions 
> the only one we respond to.
>
> (second point - question to Jeff Z- what did we do for Vertex?)
>
> Thanks... Tony
>
> Text from SS:
> > Science related:
> >
> > 1.     Quadripod position.
> > Members of ESAC/ASAC have different views on the impact of the feed leg
> > design on polarization. Instead of throwing numbers and statement on 
> how this
> > is going to affect the science of the antenna, it would be better to 
> use a program
> > (Grasp?) to quantify the effects.  It must be remembered  that the 
> beams of the antennas
> > will be different anyway. The japanese also have different feed 
> legs.   This may justify
> > or not  a request for a change the feed leg of AEM. Please pass an 
> action to Science IPT ( I will discuss it with AEM anyway)
> >
>
> > 2.      Subreflector hole diameter
> > We have specified 48 mm. In the past  I do believe I was told that 
> this should be 60 mm
> > (probably by Richard Hills?) This is something that I would like to 
> be checked by science.
> > If implemented now (on both antennas it is likely to be a minor 
> issue). If not needed
> > better so. Please pass an action to Science/SE
> >

I don't recall this issue ever being raised.  Only the subreflector 
central scattering cone design could affect this, I think.  More 
information from Antenna is required.

Cheers,

Jeff