Controllable calibrated line for setting attenuation - has each attenuator composed of two circuits of high and low attenuation

摘要

The calibrated line has each attenuator composed of two attenuating circuits. One attenuating circuit has a low attenuation and the other a high attenuation. The two attenuating circuits are switched in and out. The switches are electronic switches such as field effect transistors. The attenuating circuits within any one attenuator have the same basic structure (eg T-network or pi-network) and the same wave impedance. An additional switch may shunt the transverse resistor or resistors in the attenuating circuit of low attenuation in each attenuator in order to increase the attenuation. The control electrode of the switch in the longitudinal path of the attenuating circuit of high attenuation may be grounded via a capacitor in order to increase the attenuation when the circuits are in parallel.