矩形脉冲信号 E(≤5) f(t)= (|>) z/2 F() O t dt =2 sin( ot) SIn ET Sa() Et sa(ot 2 (a)=0 (4x<ol<21x) 2(2n+1)x << 4(n+1)丌     = 0 ( ) ( ) ( ) 2 2   t E t f t ( ) sin( ) ( ) sin( ) 2 2 2 2 2 / 2 / 2            E E Sa F Ee dt j t E =         = = = − − ( ) ( ) 2  F  = E Sa         = + + + ( ) 0 ( ) ( ) 2(2 1) 4( 1) 4 2(2 1)              n n n n 矩形脉冲信号