Compensated electromagnetic coupler

A communication device comprising:

• a transceiver configured to produce a transmit signal;
• an electromagnetic coupler having an input port, an output port, a coupled port, and an isolation port, the electromagnetic coupler being configured to provide a coupled signal at the coupled port responsive to receiving an input signal at the input port, an amplitude of the coupled signal being related to an amplitude of the input signal by a coupling factor, and the electromagnetic coupler including a dielectric layer having a first surface and a second surface, a first transmission line adjacent the first surface extending between the input port and the output port, a second transmission line adjacent the second surface extending between the coupled port and the isolation port, and a tuning element adjacent one of the first surface and the second surface and configured to stabilize the coupling factor over a range of variations in a thickness of the dielectric layer;
• and
• an antenna switch module connected to either the input port or the output port of the electromagnetic coupler and configured to direct the transmit signal between the electromagnetic coupler and either of the transceiver or an antenna.