34 
P(x0, Yo, Zo) 
v(7,@) 
Figure 11. Source and a circular disk. 
Let the disk have radius a; then 
a et 
Re J Vat, y) jexpjkLr {cosg(cosa- cosa ) 
r=0 g=0 
+sing(cos8-cos8o )}+p(7r, g (cosy (7, )-1)] | rarda @ 
Let D>», and A(x, y) = 1, then 
oH Bh | 
Pe | I Jexnsrf const cosa- coms )+sing(cosB- cosBo ) ] rare 
r=0 g=0 
The integral becomes 
a 
R= an | ro (rd (cosa- cosco )? +(cos8- cosBo aa 
O 
Applying the identity 
| set (x)dc = xJy (x)* 
*Reference 1, page 119 
