A line of length nλ/4 (n is integer) in short circuited

A line of length nλ/4 (n is integer) in short circuited at the far end. The input impedance is—

For the line of shorted and multiple of λ/4. Input impedance is given by
Z = j Z_d tan βd
so for

d =	nλ
	4

β =	2∏	we get '∞' impedance.
	λ