Tunable-Efficient Spoof Surface Plasmon Polariton Phase Shifter for 5G and Beyond Applications

Phase shifters are key components in microwave, millimeter-wave (mm-wave), and optical systems, supporting applications such as beamforming, phased array antennas, RF front ends, and satellite communications. This article introduces a novel tunable phase shifter concept utilizing a highly localized electromagnetic (EM) field in a spoof surface plasmon polariton (SPP) transmission line (TL). Unlike electronic phase shifters, which often face limitations in power handling and insertion loss due to power flowthrough the electronic components such as diodes, or mechanical phase shifters, which typically suffer from bulkiness and higher costs, the proposed concept uniquely combines the advantages of existing technologies such as low insertion loss and high phase-shift range. The proposed design employs one or more dielectric disturbers to dynamically control phase shifts by adjusting their displacement relative to the confined EM field. These disturbers interact with specific numbers of spoof SPP cells, thereby altering the dispersion diagram’s slope. A theoretical analysis was conducted on U-shaped metallic corrugations extended infinitely along the y-axis to predict the effect of a movable dielectric disturber on the unit cell’s dispersion characteristics. This behavior was further validated using a planar L-shaped spoof SPP structure, which demonstrated a similar interaction. For instance, when five cells were covered by a movable TMM13 dielectric, a maximum phase shift of 160° was achieved at 28 GHz, with an insertion loss variation of only 0.7 dB. The experimental results confirm the validity of the proposed concept, showing strong agreement with theoretical predictions and simulations. The design’s compatibility with micro-electromechanical systems (MEMS) and piezoelectric actuators facilitates compact and scalable implementations of the proposed phase-shift concept.