| 摘要 |
PURPOSE:To improve isolation characteristics by providing a conductor layer to the coupling part of a distribution coupling type directional coupler consisting of slot lines with an insulator layer between. CONSTITUTION:The 1st and the 2nd slot lines 2 and 3 are formed on the top surface of a substrated 1 made of a semi-insulating semiconductor, and part of them are made adjacent to each other in every section to form a coupling line part 4. The insulating film 12 is formed on the top surface of the coupling line part 4 and the conductor layer 13 is formed thereupon. Consequently, an elctromagnetic field produced at the coupling line 4 is confined principally in the dielectric substrate 1 and slightly at the part of the insulating film 12, but no electromagnetic field leaks in free space by the conductor layer 13. Therefore, there is no difference between the phase constants of an odd and an even mode due to the difference in dielectric constant between the free space and dielectric substrate and deterioration in isolation characteristics is prevented. |
