| 摘要 |
The transmitter (2) and receiver (3) operate on different frequencies. The circulator (4) has a common two-way port (5) to the antenna, an input port (6) from the transmitter amplifier and an output port (7) to the common input (9) of the duplexer (8). The attenuation between the input port and the common output of the circulator is about 0.8 dB. One duplexer output (16) is connected to the receiver, which includes an adaptive impedance network (23), and a low noise amplifier (24). The other (11) is connected to earth through a dissipative load resistor (12), typically 50 ohms. Interference from the circulator passes through a passband filter set to the transmission frequency to the resistor. USE/ADVANTAGE - Portable radiotelephones. Min. loss in transmitter signal, and very low intermodulation interference at receiver.
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