Transmissive Polarization Converter with Eliminated Filtering Effect Based on Non‐Reciprocal Metasurface

Abstract The utilization of polarization conversion metasurfaces (PCMs) has enormously facilitated the capabilities of numerous wireless systems and optical devices. However, the cross‐polarization conversion performed by the PCM inevitably results in a parasitic filtering effect that severely hinders its capacity to receive multiple polarization waves. In this paper, a high‐efficiency transmissive PCM based on the non‐reciprocal metasurface integrated with the NPN transistors is proposed, which can convert both input x ‐ and y ‐polarized waves into the y ‐polarized transmitted wave, meanwhile, the parasitic filtering effect of the polarization converter is effectively eliminated. The total transmission efficiency of orthogonal polarizations is higher than 50% within 3.26–3.39 GHz, excluding the gain from the transistor‐based circuits, and the peak efficiency reaches 85.4% at 3.35 GHz. In addition, the proposed PCM opens up the possibilities for expanding the range of received polarization states. For the conceptual demonstration, the conversion from arbitrary linear polarizations to y ‐polarization has been achieved with the transmission coefficients higher than ‐0.66 dB at 3.35 GHz. The performances of designs have been verified by experiments and tests. These designs show potential for breaking the constraints on multiple polarization conversion and promoting the development of versatile PCMs.