//chapter 2
//may june 2009
printf("\n");
n=10;
d=0.25;
lamda=1;//assume
Gdmax=4*((n*d)/lamda);
printf("\nthe maximum directive gain is %g",Gdmax);
Gdmaxdb=10*log10(Gdmax);
printf("\nthe maximum directive gain in db is %gdb",Gdmaxdb);