To perform communications in a multilateral well, a first communication unit having an electromagnetic (EM) field generating element is provided to generate an EM field in a formation between a main bore and a lateral bore of the multilateral well. The EM field generating element includes a component creating a voltage difference along the wellbore. A second communication unit is for positioning in one of the main bore and lateral bore to receive the EM field propagated through the formation between the main bore and the lateral bore.