Measurement and Characteristic Analysis of OAM Reflected Wavefront under Building Materials at 30 GHz

This paper investigates structural changes in the wavefront after the reflection of orbital angular momentum (OAM) waves off various materials—glass, PVC, plaster, wood, and raw stone—at 30 GHz. By employing direct wavefront measurements, the phase distributions of the OAM wavefronts for modes 1 and 3 are obtained after passing through each of the five materials. The purity of the OAM mode is used to assess the degree of damage to the OAM wavefront structures caused by different materials. The results indicate that the internal structure of the material has a greater influence on the reflected OAM wavefront than the surface roughness of the material.