ANTENNA STRUCTURE AND WHEEL STRUCTURE WITH A TPMS SYSTEM

A wheel unit antenna for use in a TPMS and corresponding wheel structure, in which the antenna is sized and oriented such that complete wheel structure including tire will act as a waveguide. The antenna may be non-resonant, in the form of a monopole perpendicular to a ground plane. In addition, the antenna has a length substantially shorter than a quarter wavelength, for example λ/10 or less.