Patent ID: 7747227

Claim:
A transmission module comprising: a power amplifier amplifies power of a radio frequency signal that is to be transmitted via an antenna; a duplexer that allows the transmitted signal to travel from the power amplifier to the antenna, allows a received signal to travel from the antenna to a radio frequency receiver side, and prevents the received signal from traveling to the power amplifier, the received signal being received by the antenna and having a different frequency from the transmitted signal; a coupler that allows the transmitted signal from the power amplifier to travel toward the duplexer, prevents a part of power of the received signal being leaked from the antenna via the duplexer from traveling to the power amplifier, and causes the part of power of the received signal to flow to ground, the coupler being provided between the power amplifier and the duplexer; a detector detecting part of the transmitted signal branched into the detector by the coupler; a controller controlling the power amplifier based on the part of the transmitted signal detected by the detector; and a substrate provided with the power amplifier, the coupler, the duplexer, the detector and the controller, wherein the substrate includes a first dielectric layer, a core layer and a second dielectric layer, which layers are laminated; the coupler includes multiple striplines respectively provided on two opposing surfaces of the core layer; a region defined by the projecting one of the multiple striplines onto another of the multiple striplines is smaller than said another of the multiple striplines and is included in said another of the multiple striplines.