| 摘要 |
PURPOSE:To make a reception frequency characteristic flat by applying an induced voltage of a main coil wound on a ferrite core between a gate and source of an FET so as to connect a drain of the FET to a load through a negative feedback coil. CONSTITUTION:A hot potential side of a main coil L1 of a bar antenna 1 is connected to a gate of an FET3 and its cold potential side and a source of the FET3 are grounded. A negative feedback coil L2 is wound to the antenna 1, a drain of the FET3 is connected to a power supply VDD via an input coil L3 of an inter-stage transformer 7 being a load through the coil L2 and a mixer circuit 4 is connected to an output coil L4 of the transformer 7. A voltage induced in the coil L1 is amplifier by the FET3, a drain current flows to the coil L2, a negative feedback is applied to the input side of the FET3 by selecting the polarity of the coil L2, the frequency characteristic is a flat characteristic without any peak and the difference in the sensitivity depending on reception frequencies is eliminated.
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