Characteristic Mode Analysis based Circularly Polarized Quad-Slot Circular Patch with Annular Ring Antenna Design for MM-Wave Communication Applications

In this paper, a Characteristic Mode Analysis based Circularly Polarized Quad-Slot Circular Patch with Annular Ring Antenna Design for MM-Wave Communication Applications is proposed for 5G NR (FR-2) operation in the 24–40 GHz frequency range. Five characteristic modes dominate the behavior of the structure, and exciting them correctly can generate orthogonal current distributions over a wide frequency range, resulting in an impedance bandwidth of 16 GHz and an axial-ratio bandwidth of about 26–34 GHz. The measured performance of the single-element prototype shows a peak gain of 8.46 dBi and an efficiency of 89.8%, while in a 2×2 MIMO array, the array achieves a higher gain of 11.94 dBi, maintains efficiency above 90%, and provides good port isolation greater than − 20 dB and low ECC values less than 0.0013. The CMA study also gives insight into the manner in which the slots and the surrounding ring interact; the slots shift and separate modal resonances, while the ring stabilizes the modal behavior, thereby enhancing both the bandwidth and the circular-polarization characteristics. The resulting design stays small and single-layer with no added structures such as DGS or EBG. These features are in line with the requirements for 5G NR bands n257, n258, and n260.