| 摘要 |
PURPOSE:To improve the mounting efficiency by adopting hollow structure for the microstrip line side of a through hole provided to a metallic case pedestal so as to minimize the occupied area on a flat circuit. CONSTITUTION:The through hole 10b provided to a metallic case pedestal 10a is of the two stage constitution comprising a large diameter part 10b1 (diameter R1) and a small diameter part 10b2 (diameter R3), a coaxial conductor dielectric substance 4 is inserted to the larger diameter part 10b1 only and the small diameter part 10b2 remains hollow. Since the specific dielectric constant epsilonr of air is the unity, the characteristic impedance of the coaxial line comprising a metallic case 10 and an inner conductor 2 in the small diameter part 10b2 is equal to the characteristic impedance ZO of the coaxial line in the larger diameter part 10b1. The contact with a ground conductor 7 is ensured by decreasing the size of the metallic case pedestal 10a. Since the end of the dielectric substance of the coaxial conductor is inserted to the larger diameter part 10b1 of through hole, the relative position between the inner conductor 2 and the inner face of the through hole 10b of the metallic case 10 being the outer conductor over the entire length of the through hole 10b is kept constant. |
