Pairs of (a, b)-Gabor dual frames for \(L^2(\mathbb {R})\) have been extensively studied in the classical “painless-expansion” region with \(ab\le \frac{1}{2}\) . Beyond these regions, this paper considers \(ab\in (\frac{1}{2},\frac{2}{3}]\) with the normalized translation parameter \(a=1\) and modulation parameter \(b\in (\frac{1}{2},\frac{2}{3}]\) . For any given primal window g supported inside \([-1,1]\) , we characterize all pairs (g, h) of compactly supported Gabor dual frames for \(L^2(\mathbb {R})\) with the dual windows h having explicit parametric expressions. We further characterize these dual windows having continuity, high smoothness, and symmetry. Based on our characterizations, we present several examples of pairs (g, h) of Gabor dual frames such that the dual windows h have small supports and several desired properties such as high smoothness, symmetry, and small condition numbers, which are nearly optimal with respect to the primal window g and exhibit excellent stability and strong robustness. In particular, by employing smoothing techniques, we construct a family of pairs of smooth Gabor dual frames with the near smallest optimal condition number such that both primal and dual Gabor frames are very close to Gabor tight frames for \(L^2(\mathbb {R})\) .
