摘要 |
PURPOSE:To ensure the coupling over a wide range by using the dielectric substrate featuring a low dielectric constant at the center part of the coupling and also the dielectric substrate featuring a high dielectric constant at the both ends of the coupling respectively. CONSTITUTION:For the directional coupler, the coupling part between strip lines 11 and 12 is divided into center part C plus end parts E1 and E2. Part C is formed on substrate 13 featuring a low dielectric constant; while parts E1 and E2 are formed on substrate 14a and 14b each featuring a high dielectric constant. The coupling at the center part becomes dense since the number of the line of electric force going toward the lower part is decreased with increased number of the line of electric force going toward the lateral part. While for the coupling at the both ends becomes coarse since the number of the line of electric force going toward the lower part increases with decreased number of the line of electric force going toward the lateral part respectively. |