Highly-miniaturized microfluidically-based frequency reconfigurable antenna diplexer employing half-mode SIRW

This article introduces a super-miniaturized frequency reconfigurable antenna diplexer based on microfluidic techniques. The proposed structure is developed using a half-mode substrate-integrated rectangular waveguide (HMSIRW). The antenna architecture consists of two HMSIRW cavities loaded with L-shaped slots, which are excited by two microstrip feedlines to realize two distinct radiating frequency bands. The footprint of the antenna diplexer is miniaturized by using the half-mode cavities. Further size reduction is achieved by the capacitive loading of the slots. The design evaluation, radiation mechanism, parametric analysis, and equivalent circuit model are discussed in detail. The empty fluidic vias are drilled on the bottom plane of the cavities and poured with various dielectric liquids to obtain independent frequency reconfigurability at two operating bands. For validation, a frequency reconfigurable antenna diplexer is designed, manufactured, and demonstrated experimentally. The measured results show that the return loss, isolation, and realized gains are greater than −20 dB, 28 dB, and 3.3 dBi, respectively, while ensuring small footprint of only 0.071λ_g². The fabricated diplexer exhibits a frequency reconfiguration range greater than 17 % at both frequency bands.