A compact four‐element mmWave MIMO antenna designed using characteristics mode analysis (CMA) with wideband performance and high isolation is presented. The antenna is realized on a 0.254‐mm Rogers RO5880 substrate with meandered conductive strips arranged in a window‐shaped configuration and a partially truncated ground‐plane notch. CMA is employed to observe the modal behavior of the structure, revealing that Mode 1 is the dominant radiating mode, while Modes 2 and 3 contribute to resonance formation and bandwidth enhancement. The single antenna element occupies a compact size of 12 × 14 mm 2 (0.1305 λ 0 × 0.1119 λ 0 , where λ 0 is the wavelength at 28 GHz), whereas the four‐port MIMO configuration measures 24 × 32 mm 2 (0.224 λ 0 × 0.229 λ 0 ). A decoupling structure is introduced to suppress mutual coupling, achieving interelement isolation better than 20 dB. The proposed MIMO antenna operates over a wide impedance bandwidth from 24.5 to 33.5 GHz and exhibits a peak realized gain of 6.2 dBi. Due to its symmetric layout, the design is inherently scalable to higher order MIMO systems. Experimental results obtained from a fabricated prototype show good agreement with simulations, validating key MIMO performance metrics, including ECC, MEG, CCL, and DG, confirming the suitability of the proposed antenna for mmWave RF applications.
Kiani et al. (Thu,) studied this question.