Active frequency diplexer

摘要

The invention is based on the object of developing known active frequency diplexers further in such a manner that an amplifer for a higher frequency range with as large a series capacitance as possible can be coupled in without this resulting in greater impairment for the frequencies of a lower frequency range. Furthermore, large-signal distortions which are produced by simultaneous contribution of signals from the lower and upper frequency ranges should be negligibly small. In addition, the circuit complexity required for implementing the active frequency diplexer should be as little as possible. The solution of the present object consists in that the base point of the antenna (A) is connected to the input of the FM amplifier (V1) by a series circuit of three capacitors (C1, C2, C3). In addition, the base point is connected to the gate electrode (G) of a field-effect transistor (FET) by the first capacitor (C1) and a first inductance (L1) connected in series therewith. Finally, the base point is also connected to the source electrode (S) of the field-effect transistor via the first and second capacitors (C1, C2) and a second inductance (L2) connected in series therewith and to the input of the LMS amplifier (V2) and via a resistor (R2) to earth. A preferred field of application for the active frequency diplexer according to the invention are active antennas for motor vehicles. The drawing shows a circuit diagram of the... Original abstract incomplete. <IMAGE>