Abstract
This paper presents a millimeter-wave (mmWave) two-port multi-input–multi-output (MIMO) antenna designed for dual on-body and off-body communication at 28 GHz using a denim fabric substrate. The proposed antenna integrates two distinct radiating structures optimized for the respective scenarios. For on-body communication, a circular dipole-like structure is employed, while a coaxially fed circular antenna is utilized for off-body links. Simulation results demonstrate a realized gain of 6.77 dBi for the on-body element and 9.6 dBi for the off-body element. The total efficiencies are 0.83 and 0.90, respectively, with isolation better than −50 dB at 28 GHz, confirming excellent MIMO performance. The use of a textile substrate ensures flexibility and comfort, while the dual radiation patterns support reliable wireless connectivity in wearable devices. Owing to its compact design, high isolation, and stable performance, the proposed antenna is suitable for integration into clothing and other wearable devices for future mmWave 5G applications.