| 摘要 |
<p>A UHF variable attenuator is described. In order to prevent variations in the phase shift introduced by the attenuator according to the rate of attenuation, a novel attenuator structure is provided, wherein the attenuator comprises a 3dB hybrid coupler (10) having an input port (I1, I2) and an output port (O1, O2) which have loads (12, 14) formed as follows: each load comprises a resistive divider/combiner (16) with two ouputs having connected thereto a variable attenuation element (18) (e.g. with a PIN diode) and a phase-correcting reactive impedance (L, C), respectively. The results show excellent phase variation compensation, even when the reactive impedance is fixed.</p> |
