The ability of helix arrays to filter circularly polarized light efficiently when the light propagates parallel to the helical axis has been demonstrated recently. In this Letter, we present a broadband linear-to-circular polarization transformer composed of metal microhelices. The device provides significant transformation performance combined with high transmittance over a broad infrared wave band. High performance is achieved through fine adjustment of a finite-element electromagnetic model. The array design assumes wave propagation perpendicular to the helical axis, which distinguishes it from well-studied analogous designs that filter light propagating parallel to the helical axis. To the best of our knowledge, this is the first time this scheme has been realized in the infrared range.