An end effector assembly includes a pair of opposing jaw members movable from a first position in spaced relation relative to one another to at least one subsequent position wherein the jaw members cooperate to grasp tissue therebetween. Each of the jaw members includes a microwave antenna assembly and a shielding member including a metallic plate coupled to ground and a dielectric material. The end effector assembly also includes a splitter configured to receive an active signal from a source of microwave energy and split the active signal into a first signal transmitted to the microwave antenna assembly in one of the jaw members and a second signal transmitted in the microwave antenna assembly in the other jaw member.