Mechanically Flexible Dielectric Waveguides and Bandstop Filters in Glass Technology at G-band

A novel mechanically flexible filter integrated in a glass dielectric waveguide is presented for sensor applications at G-band (140–220 GHz). The use of laser-induced deep etching (LIDE) technology enables the production of via holes and thus the local modulation of the effective permittivity in a dielectric waveguide. This approach enables the implementation of a filter without the use of metal structures. In addition, extraordinary mechanical flexibility is achieved through meandering slots, which simultaneously perform the permittivity modulation. The RF performance was studied in full-wave simulations and validated by measurements of the manufactured bandstop prototypes. The experimental results of the implemented filter element show good agreement with the simulated values. At the center frequency of 156 GHz a notch depth below −14 dB in the measured stop band is achieved. Additional measurements show a stable filter characteristic at up to 8◦ bend angle applicable for the use as a low-loss waveguide under harsh environmental conditions
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