| 摘要 |
PURPOSE:To improve the matching of a mixer diode by providing an intermediate frequency blocking circuit showing a high impedance to an intermediate frequency signal between a mixer diode and a 3dB directional coupler so as to prevent the deterioration in the frequency characteristic. CONSTITUTION:The 3dB directional coupler 3 and the mixer diode 6 are separated in terms of the intermediate frequency by providing the intermediate frequency blocking circuit 10 showing a high impedance to the intermediate frequency signal in series to a line between the 3dB directional coupler 3 and the mixer diode 6. Thus, in making a length l42 of a line 42 to a length over at least lambda/4 and adding a stub or the like to the line 42 as required, the mixer diode 6 is matched to a high frequency. It is not required to make adjustment in this case, taking a circuit or the like connected to terminals 1, 2 of the coupler 3 into account. Thus, the leakage to the high frequency side at the intermediate frequency is reduced in this way, no dip is generated in the frequency characteristic of the frequency converter and the mixer diode is matched easily to high frequencies. |
