A key fob includes a power amplifier including an output having an output impedance. A radio frequency antenna connected to the power amplifier output represents a first load impedance to the power amplifier output in a space substantially free of interference for radio frequency transmissions, and a second load impedance to the power amplifier output when a hand of a user is capacitively coupled to the antenna. The difference between the second load impedance and the output impedance of the power amplifier is less than the difference between the first load impedance and the output impedance.