The AIPS++ mathematics and GUI tools present an interesting environment for developing and publishing instrumentation design tools. This article describes an example of an array feed design tool that I am in the process of building. The tool is written entirely in glish using the matrix.g, logger.g, and pgplotwidget.g AIPS++ modules. At some point I will probably move a few calculations to special clients written in C++ for better speed, but the array operations of glish are quite respectable in most cases.
The main panal for the Array Feed Design Tool looks like the figure below:
The tool has an interactive flavor so that the user can play with array configurations and excitation parameters to see how the array's far field pattern changes. One can see how these parameters affect the aperture efficiency and other performance parameters when the array is combined with a reflector antenna. The problem can also be turned around by computing the electric field amplitude in the region of focal region of the reflector, given a selected aperture illumination.
The 'Plot' and 'Calculate' menu pulldowns present the selections for computing and displaying various array properties.
If any additional information is required for the plot or calculation, a pop-up window appears to show the current values and let the user set new values, if necessary.
The glish code for the GUI follows the guidelines found in the AIPS++ documentation at
http://aips2.nrao.edu/aips++/beta/docs/notes/197/node6.htmlbut I don't pretend that it is in a form that can be installed in the AIPS++ system, yet. This is very much a work-in-progress and will probably remain so for quite some time. There are many more design functions that I want to write. Adding a new function to the menu selections involves four steps:
This sort of design tool might make a useful adjunct to a course in radio astronomy instrumentation. More conventional feeds can be substituted for the array feed, but many of the computational functions would remain the same. Since the source code is available in a package that should soon be widely available in radio astronomy, students would be free to add their own antenna design ideas for class projects.
If anyone is interested in getting a copy of my glish code, I'll be happy to put a snapshot of whatever I have at the time in our FTP area.
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