Generation of Multifrequency Multimode Vortex Waves With Multiring Nested Microstrip Patch

Here, we introduce the concept of multiring nested circularly polarized patch antenna for the creation of vortex waves at the same frequency with multiple modes, and at multiple frequencies with the same mode, thereby achieving both orbital angular momentum (OAM) mode and frequency diversity. We explore the radiation process of these vortex waves by comparing it to the mechanisms of circular patch antennas. To validate our theory, a prototype antenna with three nested rings and circular polarization is developed. Both simulation and experimental results confirm that this antenna can produce vortex waves with OAM modes of 0, −2, and 4 at a frequency of 2.5 GHz. Furthermore, it successfully generates the −2 mode at frequencies of 1.5 GHz, 2.5 GHz, and 6.75 GHz simultaneously. The combination of OAM mode diversity with frequency diversity shows promise for use both in communication and sensing systems.