Abstract: The transmit/receive antenna has an active element with a two-dimensional conductor pattern formed on the surface of a dielectric substrate, surface-surface mounted to a PC board, and forming plural distribution paths of mutually different length. Antenna current is copied into a ground conductor such that the antenna element defines a linear main radiator, having a feeding end and an open end, forming a first distribution path, and a linear short-circuiting branching T-conductor, forming a second distribution path. A third distribution path is formed across the main radiation conductor leading to the ground conductor. This configuration produces two resonance frequency bands, exclusive of harmonics. The main radiation conductor and the feeding conductor are formed by conductor patterns on the dielectric substrate and the short-circuiting conductor is formed by a conductor pattern over the upper surface and side surface of the dielectric.