| 摘要 |
PURPOSE:To allow a receiver which uses a loop antenna to perform electronic band switching without any deterioration in characteristics while excluding an element which causes a decrease in Q from an antenna tuning circuit, by arranging antenna coils for MW and LW in series. CONSTITUTION:A radio wave received by an AM loop antenna 1 is inputted through an input terminal 2 and a GND terminal 3 to an MW antenna coil 8, which constitutes an MW antenna circuit as a parallel circuit together with the series circuit of a varactor diode 33 and a capacitor 34; and the coil 8 is short- circuited by turning on a transistor 31 by the signal from a terminal 30 to inhibit an MW signal from being inputted. The other end of the MW antenna 8 is connected to the input terminal of an LW antenna coil 9, which constitutes an LW antenna circuit together with a coil 9 and a varactor diode 35, and a capacitor 36. Signals selected by the respective antenna circuits are supplied through capacitors 37 and 40 to a band switching buffer 41 and after band switching and impedance conversion, the resulting signal is outputted to an RF output terminal 26. |
