| 摘要 |
A radio link with two communicating transceivers each having a system for isolating incoming and outgoing radio signals to permit simultaneous transmit and receive by each transceiver on the same frequency or in the same frequency range. This is done so that in-coming receive signals received by each of the transceivers from the other transceiver is much stronger than the portion of its own transmitted signal that is coupled back into its antenna. The invention uses a special electronic circuit, termed the iso-circulator, to couple the antenna to both the co-located receiver and the transmitter. The iso-circulator circuit includes a simulated antenna load with an impedance matched to the antenna impedance. The circuit also includes a transformer with its primary side fed asymmetrically by the antenna so that it can pass the desired receive signal with minimum attenuation. The transformer's primary is on the other hand fed symmetrically from both sides by equally small portions of the transmit power from the co-site transmitter, but these signals are 180 degrees out of phase and cancel almost completely in the transformer.
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