OPEN TYPE COAXIAL CABLE

PURPOSE:To reduce transmission loss and to increase the intensity of a radiation electromagnetic field by forming a circuit with lower coupling impedance between an internal conductor and an internal-layer external conductor than between an external-layer external conductor and the ground. CONSTITUTION:An open type coaxial cable consists of the internal conductor 1, insulator 2, internal-layer external conductor 3, and external-layer external conductor 6. The insulator 5 is interposed between the internal-layer external conductor 3 and external-layer external conductor 6 to obtain mutual insulation between the both. The opening width of an opening part 4 and the winding pitch of the external-layer external conductor 6 of a metallic tape are selected adequately to form one circuit having 10-100OMEGA/km coupling impedance between the internal conductor 1 and internal-layer external conductor 3 and the other circuit with 100-1,000OMEGA/km coupling impedance between the external-layer external conductor 6 and ground. Consequently, transmission loss is reduced and an intense electromagnetic field is established.