| 摘要 |
PURPOSE: A circuit for isolating frequency of a duplexer is provided to improve the response characteristic of transmitting frequency at band pass by increasing input impedance of a receiving unit. CONSTITUTION: A transmission filter(10) filters a frequency of a transmitting band. A receiving filter(12) filters a frequency of a receiving band. An antenna is connected to the transmission filter(10) and the receiving filter(12). A shield plate shields the frequency of the transmission and receiving filters(10,12). A line inductor(16) is connected to the antenna and is formed with a pattern on a plate surface of the shield plate. The line inductor(16) increases an input impedance so as not to be interfered with the receiving filter(12).
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