60 GHz microstrip reflectarray on a benzocyclobutene dielectric substrate

Benzocyclobutene (BCB) polymer is proposed in this study as an innovative and versatile substrate material for millimetre-wave reflectarrays. The excellent material features in terms of low loss, low dielectric constant and strong dielectric stability against frequency and temperature are highlighted. The design, realisation and test of a 60 GHz reflectarray with 21 21 variable-sized patches giving a focused boresight beam pattern are fully described. The BCB thickness is chosen on the basis of a parametric analysis performed on the unit cell to optimise the performances in terms of dielectric losses and radiation bandwidth. The in-house fabrication process able to assemble multi-layered BCB substrates is described in detail. Experimental results on the radiation pattern and the boresight gain are used to validate both the synthesis and the manufacturing process.