A wideband reflective polarization rotator featuring a single layer and vialess design is proposed in this letter. The curved bowtie resonator is employed to accomplish wideband performance. Two notch resonators are etched at both terminals of the bowtie resonator to widen the operating bandwidth. Perforated air holes are utilized to improve the polarization conversion ratio at the high-frequency band. The proposed design exhibits four resonant frequencies at 17.3, 26.4, 44.4, and 56.2 GHz with polarization conversion ratio above 89% from 16.2 to 57 GHz, which represents 111.5% operational bandwidth. The structure thickness is 0.085 λ max , where λ max is the free-space wavelength at the lowest operating frequency. The development process of the unit cell is illustrated originating from the simplest resonator shape, strip resonator. To verify the simulated results, a prototype is fabricated and measured.