<p>Efficiency limitations of flat reflector antennas designed using quasi-conformal transformation optics are examined along with mechanisms to improve performance over wide bandwidths (&gt; 2.5:1). Specifically, the aperture efficiency constraints are shown to be a result of phase aberrations induced by the approximate nature of the quasi-conformal transformation used to create an isotropic, non-magnetic structure. The aberrations are drastically reduced by introducing a simple curved surface into the domain prior to the transformation. This technique noticeably improves performance without increasing the size of the resulting device. Ultimately, this methodology allows for flat reflectors designed via quasi-conformal transformation optics to operate over wider bandwidths (up to 10:1) than with standard transformations.</p>