**7. Conclusions**

This chapter provides a thorough analysis and comparison of the fundamental properties of plane wave and OAM wave in different Tx–Rx combinations using simulation, RF path modeling, and measurement to understand OAM reception techniques. The analytical equations for the electric field, magnetic field, and other physical parameters with respect to wave propagation have been derived and studied. Moreover, a comprehensive comparison of plane wave and OAM wave is examined in theory, designed PWPA and OWPA, and their propagation and reception

mechanisms. First of all, analytical equations of OAM wave have been developed and compared with those of plane wave. It is found that all the plane wave parameters can effectively be deduced from the modeling of OAM waves, which presents an excellent insight for understanding the differences between OAM wave and plane wave. Cylindrical near-field scan shows that the pitch of plane wave becomes zero while the OAM wave exhibits nonzero pitch through a helical motion along the direction of propagation. Subsequently, the designed PWPA and OWPA characteristics comparison is discussed in detail to show and appreciate the behavior of the patch antenna for the generation of plane wave and OAM wave. Moreover, a comparison of plane wave and OAM wave propagation is discussed and demonstrated that OWPA–PWHA and OWPA (O1)–PWPA (P2)–PWPA (P3) are favorable mechanisms for the reception of OAM signals.

Nevertheless, these comparisons provide a detailed understanding of propagation behavior, theory, and modeling for plane wave and OAM wave using a simple patch antenna concept. Furthermore, OAM wave can be used for short-range radar sensing and opportune the different paradigm in vortex wave.
