Methods, systems, and apparatus for EM isolation structures. One of the apparatus includes a communication module, the communication module including: a printed circuit board; a plurality of integrated circuit packages, each integrated circuit package including at least one transmitter, receiver, or transceiver; and one or more metallic blocking structures configured to at least partially encircle a corresponding one of the plurality of integrated circuit packages, wherein each metallic blocking structure is configured to reduce signal leakage from the corresponding integrated circuit package.