Abstract: A circuit to test the working of antennas for a radio telephone. The antennas each have a radiator with one end that open rises up into the space. The test currents flow through antenna wires to the antennas independent of a signal current (IRF). A secondary path with an impedance that is parallel to the RF path is connected to each radiator to return the separate test currents. A voltage evaluator monitors the operating state of the antennas by comparing the test voltages induced by the test currents at the antenna connections with a reference value and generates corresponding indication signals that provide information on the operating state of the antennas.

Abstract: A temperature-compensated diode rectifier circuit is coupled to the outside of an HF amplifier (PA) to derive a rectified voltage (UD) from an HF output signal (RFOUT) with a rectifier input (IR) via a directional coupler (D-CO) with secondary connections (1, 2), and has a rectifier output (OR) for the rectified voltage (UD), a rectifier diode (D1), a charging capacitor (C1) and a ballast resistor (R2). To stabilize the rectified voltage against temperature influences, the rectifier input (IR) is connected to a d.c. input voltage (UIN), and a compensating diode (D2) is in series with the ballast resistor (R2), and a dropping resistor (R1) is in series with the rectifier diode (D1). According to the invention the rectifier diode (D1), the compensating diode (D2), the dropping resistor (R1), the ballast resistor (R2) and the directional coupler (D-CO) are connected to the d.c. input voltage (UIN) so that the voltage amplitude of the decoupled HF output signal (RFOUT) is added to the d.c. input voltage (UIN).

Abstract: A temperature-compensated diode rectifier circuit is coupled to the outside of an HF amplifier (PA) to derive a rectified voltage (UD) from an HF output signal (RFOUT) with a rectifier input (IR) via a directional coupler (D-CO) with secondary connections (1, 2), and has a rectifier output (OR) for the rectified voltage (UD), a rectifier diode (D1), a charging capacitor (C1) and a ballast resistor (R2). To stabilize the rectified voltage against temperature influences, the rectifier input (IR) is connected to a d.c. input voltage (UIN), and a compensating diode (D2) is in series with the ballast resistor (R2), and a dropping resistor (R1) is in series with the rectifier diode (D1). According to the invention the rectifier diode (D1), the compensating diode (D2), the dropping resistor (R1), the ballast resistor (R2) and the directional coupler (D-CO) are connected to the d.c. input voltage (UIN) so that the voltage amplitude of the decoupled HF output signal (RFOUT) is added to the d.c. input voltage (UIN).