Thanks for the comments. They are right our of your book. On page 68 , fig: 3-15 , it looks like you do not assume a plane wave front in the nearfield. The figure shows cancelation due to ray length differences. On page 59 you say the line source is assumed to have uniform velocity. Could you comment on why the plane wave is calculated(3.7.69) as a series of point sources. Or, have I missed something.

-Thanks
Linc