  The maximum number of non-crossing straight-line perfect matchings that a set
of $n$ points in the plane can have is known to be $O(10.0438^n)$ and
$\Omega^*(3^n)$. The lower bound, due to Garc\'ia, Noy, and Tejel (2000) is
attained by the double chain, which has $\Theta(3^n n^{O(1)})$ such matchings.
We reprove this bound in a simplified way that uses the novel notion of
down-free matching, and apply this approach on several other constructions. As
a result, we improve the lower bound. First we show that double zigzag chain
with $n$ points has $\Theta^*(\lambda^n)$ such matchings with $\lambda \approx
3.0532$. Next we analyze further generalizations of double zigzag chains -
double $r$-chains. The best choice of parameters leads to a construction with
$\Theta^*(\nu^n)$ matchings, with $\nu \approx 3.0930$. The derivation of this
bound requires an analysis of a coupled dynamic-programming recursion between
two infinite vectors.
