Reconfigurable Substrate Integrated Waveguide Circuits Using Dielectric Fluids

The impact of fluidic pockets with different dimensions and geometries on the quality factor, resonant frequency and phase shift of SIW cavities is reported. A symmetrically tapered fluidic pocket configuration implemented using discrete circular pockets with increasing radius yields a wide resonant frequency range while minimizing quality factor degradation as fluid is added to the pockets. The fluidically reconfigurable cavities are used to synthesize a frequency-reconfigurable third-order Chebyshev BPF on a Rogers 3010 substrate (ε
_r
= 10.2, tan δ = 0.0035, h = 1.27 mm). Experiments using acetone (ε
_r
= 20.7, tan δ = 0.05 at 2.4 GHz) as the dielectric fluid show that the filter's center frequency can be shifted over a range of 170 MHz using only 13 mL of liquid per cavity. Additionally, a SIW phase shifter using acetone is presented, demonstrating a maximum phase shift of 44±6° using only 56 mL of fluid.