Potentialities of Air-Filled Substrate Integrated Waveguides based on Carbon Nanotubes in E-band

This paper describes a classic architecture of a 4 × 4 Butler matrix in an innovative air-filled waveguide technology based on carbon nanotubes for beam pointing or beam tracking activities for 5G applications. The working frequencies concern particularly the E-band (71-86 GHz). The model used to simulate the waveguides, couplers and crossovers needed for the Butler matrix is presented as well as the expected results in terms of S parameters. The expected insertion loss is extremely low thanks to the considered technology, 0.02 dB/mm in E-band, making the carbon nanotubes very attractive in this context. The transitions that allow connecting the waveguides to planar transmission lines have also been developed and are introduced in this paper. Their maximum insertion losses are 0.6 dB for a matching better than 17 dB over the entire E-band.