A Compact Ultra-Wideband mmWave Antenna for 5G Wearable Applications

This paper presents a compact ultra-wideband millimeter wave antenna fed by coplanar waveguide (CPW). The proposed antenna integrates a circular radiating patch with an arc-shaped slot and a dumbbell-shaped defected ground structure (DGS), enhanced by optimized F-shaped tuning stubs. Fabricated on a flexible polyethylene terephthalate (PET) substrate, the design achieves a compact size of $6 \times 10 \times 0.127 \text{mm}^{3}$. The results indicate that the antenna has a bandwidth of 26.40 − 51.59 GHz, which covers the Ka-band and 3GPP n257/n259/n260/n261 5G NR bands. The radiation efficiency is stable from 84.6 % to 96.6 %, and the peak gain reaches 4.85 dBi. Its broadband performance, miniaturized dimensions, and mechanical flexibility render it suitable for integration into 5G wearable communication systems.