                Support for Directional Couplers. 
		--------------------------------
This realse 4.0.1 is just a few  minor changes from 4.0.1. Mainly corrected spellings, although programmes rect_in_rect, circ_in_circ etc shouludd be more 
consistant on each different machine they are run on. 

I suspct this will be the last 4.x.y release. The next version will be 
5.0.0, which will support a GUI for the first fime. 

Release 4.0.0 was the first release of atlc that supported directional
couplers. Although at present the software only reports on the
odd and even mode impedance Zodd and Zeven, it is possible to calculate
the properties of a coupler with such mode impedances quite easily. 

The coupler support is not complete, but it is there for vacuum
dielectrics and calculations against an exact model for thin stripline
couplers indicates an rms error of around 0.6 %. 

Some software will be written later to produce plots of coupling vs.
impedances, but for now you will have to do it on external software such
as Spice, Puff or similar. See the documentation on couplers for more
information. 

Dr. David Kirkby, 11/4/02.

