Design of Miniaturized K-band MIMO Antennas Based on DGS

This paper designs a miniaturized K-band Multiple Input Multiple Output (MIMO) antenna based on DGS, with an overall size of only $15 \mathrm{~mm} \times 24 \mathrm{~mm} \times 1.2 \mathrm{~mm}$. The front of the antenna is composed of a circular radiating patch combined with a trapezoidal microstrip feed line, achieving K-band operation on the basis of antenna miniaturization. The back features a Defected Ground Structure (DGS), with two semi-circular notches etched at the top of the ground plane, which achieves low coupling characteristics for the antenna. The antenna is simulated and measured using three-dimensional electromagnetic simulation software and a vector network analyzer, respectively. The results show that the antenna operates over a bandwidth of $17.98-28 \mathrm{GHz}$ (achieving a relative bandwidth of $43.6 \%$). Additionally, the coupling level remains less than -16 dB throughout the entire operating frequency range. The Envelope Correlation Coefficient (ECC) is less than 0.006. Thus, the designed antenna is not only extremely small and structurally simple, but also performs well, making it widely applicable in wireless communication systems.