Textile Folded Half-Mode Substrate-Integrated Cavity Antenna

The half-mode substrate-integrated cavity antenna is a promising candidate for wearable applications because of its planar structure and high isolation from environmental effects. However, for operation at 2.45-GHz ISM band, the cavity dimensions are relatively large. To reduce the antenna size in one of the dimensions, a folded half-mode substrate-integrated cavity antenna is proposed and designed. Furthermore, as an additional significant advantage for practical applications, the folded geometry allows a planar feeding structure using a shielded stripline. A prototype of the folded cavity antenna has been fabricated using textile materials and computerized embroidery. The measured reflection coefficient and radiation patterns of the prototype compare well with the simulation results and demonstrate the feasibility of the design.