| 摘要 |
PURPOSE: A two-frequency band-pass filter, two-frequency branching filter and combiner are provided to be capable of decreasing oscillators and simplifying the structure of the circuit. CONSTITUTION: In the device, An antenna switch(2), which is transmission/reception switching means, is connected to an antenna(1), which is a scanning antenna. High-frequency amplifying means, comprising filters(3,5) and a high-frequency amplifier(4), is connected to a contact(2r), which is a receiving input terminal of the antenna switch(2). A converter(6), which is first received-signal conversion means, is connected to an output from the high-frequency amplifying means, the converter(6) being allowed to pass through a contact(7r) of a transmission/reception switch(7), which is first switching means which is a portion of transmission/reception switching means, and then connected to an output of a first local oscillator(8), which is first oscillation means. First intermediate frequency amplifying means, comprising a first intermediate frequency band-pass filter(9) and a first intermediate frequency amplifier(10), is connected to the output of the converter(6). A converter(11), which is second received signal conversion means, is connected to the rear end of the first intermediate frequency amplifying means. A second local oscillator(12), which is second oscillation means, is connected to the converter(11) through an n-times multiplier(14), which is n-times multiplying means. Moreover, the converter(11) is, through a second intermediate frequency band-pass filter(15), connected to a demodulator(16), which is demodulation means.
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