Yokowo Co., Ltd.

Junichi Imai

Ryo Horie

Wasuke Yanagisawa

Shozaburo Kameda

Yuichi Kagoshima

Haruhisa Uchida

An antenna circuit which is improved the deterioration of amplitude characteristic in a strong electric field, an antenna circuit for AM broadcasting which can surely inhibit and damp FM-band signals in the strong electric field and amplifies to output AM-band signals, and an antenna circuit for AM/FM broadcasting in which AM-band signals are not damped by means of an FM-band filter. In the first antenna circuit, the output signal of an antenna ( ) is supplied to the base of a transistor Tr forming a current amplification type amplifier having a high-input and low-output impedance and the emitter of the transistor Tr is grounded through a coil L and connected to an FM receiver ( ) through a band-pass filter ( ). In the second antenna circuit for receiving AM broadcasting, an input terminal is connected to an AM amplifier circuit ( ) through coils (L ) and L in series and to the gate G of a field effect transistor FET. The source S of the transistor FET is grounded and the connecting point of the coils L and L is grounded through a capacitor C and a coil L in series. The second antenna circuit inhibits and damps FM-band signals in a plurality of steps. In the third antenna circuit for AM/FM broadcasting, the output signal of an antenna is divided into two parts and one part is supplied to an FM-band filter ( ) through a serial FM resonance circuit ( ) composed of capacitors and coils. The other part of the output signal is supplied to an AM-band filter ( ).

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Annaka, Japan

Junichi Imai