OAM Radio Modulation for Bore-Sight Phase Singularity

The patent introduces a new dimension to the OAM phase function by adding a time-varying component. The phase function becomes φ(ρ,φ,t) = kφ + β(t), where β(t) is a time-varying phase modulation. This temporal dimension allows the OAM modes to be distinguished not only by their spatial structure (topological charge k) but also by their temporal evolution, enabling multiple OAM modes to be transmitted through the same bore-sight direction without requiring larger receiving antennas.

The patent converts the harmful phase singularity effect into a beneficial feature by using it to create orthogonal OAM modes. The phase singularity, which traditionally creates nulls at the bore-sight direction, is instead exploited to generate distinct OAM modes with different topological charges (k = 0, ±1, ±2, ...). These modes are mutually orthogonal and can be efficiently transmitted and received in the bore-sight direction, transforming the problem into a solution.

The patent applies dynamics by making the OAM phase function time-varying through the addition of β(t). This dynamic phase modulation allows the system to maintain orthogonality between multiple OAM modes even when transmitted in the same direction. The time-varying component ensures that different OAM modes can be distinguished at the receiver, maintaining reliability as the frequency reuse factor increases.