On q-analog Steiner systems of rank metric codes

In this paper we prove that rank metric codes with special properties imply the existence of $q$-analogs of suitable designs. More precisely, we show that the minimum weight vectors of a $[2d,d,d]$ dually almost MRD code $C\leq \mathbb{F}_{q^m}^n$ which has no code words of rank weight $d+1$ form a $q$-analog Steiner system $S_q(d-1,d,2d)$. In particular, $d+1$ must be a prime.