In some aspects, an apparatus includes a transformer including a first inductor, a second inductor, and a third inductor. The apparatus also includes a power amplifier coupled to the first inductor, a first antenna coupled to a first terminal of the second inductor, a second antenna coupled to a second terminal of the second inductor, a first switch coupled between the first terminal of the second inductor and a ground, a second switch coupled between the second terminal of the second inductor and the ground, and a low-noise amplifier coupled to the third inductor.