Well, i've never used Excel for vector algebra.

It's certainly nowhere near as clean as, e.g., Matlab or MathCAD, but it can
certainly do it. Look up the 'COMPLEX' function; it'll tell you you need to
install the 'Analysis ToolPak add-in' and under 'see also' point you to the
functions you'll need (e.g., IMSUM for complex arithmetic, etc.)

As i understand the Z11 formula
i stated, you will still get a vector
solution, so in essence the Z11 will
be a gamma reflection coefficient, or magnitude
(from 0 to 1) with an angle.

Right, or... just a regular old complex number. You can use IMABS and
IMARGUMENT to obtain the maginutde and angle of your complex number.

---Joel