Dual-Resonance mmWave Antenna Matching Network Comprised of Separated Ground Layers and Via Posts for Adjustable Return Current Path Modification

This paper proposes a dual-resonance antenna matching network consisting of the separated ground layers and connecting via posts. These distributed elements modify the return current path length, enabling independent adjustment of the resonance frequencies while maintaining nearly-identical radiation patterns at both frequencies. The proposed matching network is exemplified for millimeter-wave mobile devices. The designed dual-resonance antenna exhibits impedance bandwidths of 0.9 GHz (27.6–28.5 GHz) and 2.0 GHz (38.6–40.6 GHz), satisfying the 3GPP FR2 channel bandwidth requirements. The proposed dual-resonance antenna is fabricated using a low-temperature co-fired ceramic process and expanded to 1×4 phased array for evaluating beamforming performances. The measured results verify dual-resonance operations at 28.0 GHz and 39.0 GHz, achieving beam scanning capabilities. This investigation can be extended to lower and higher frequency spectrums under low-profile and volume-limited constraints.