| 摘要 |
PROBLEM TO BE SOLVED: To obtain a compact radar receiver where test adjustment is easy and does not require much time by using a capacitance-variable-type capacitor as a circuit component and varying a pass bandwidth within a fixed range. SOLUTION: In aΔch-side intermediate frequency band pass bandwidth variable bandpass filter 36, a capacitance-veriable-type capacitor is used for a capacitor that is inserted in series with a signal path out of its circuit components. By changing the value of the capacitance-variable-type capacitor, the pass bandwidth can be changed. In general, a bandpass filter has characteristics where the amount of attenuation in a passband also changes by L0±ΔL when a pass bandwidth BW0 is changed by BW0±ΔBW. By using the characteristics and hence varying the capacity of the capacity-variable-type capacitor in aΔch-side intermediate frequency band pass bandwidth variable type bandpass filter 36, the amount of attenuation in the passband of theΔch- side intermediate frequency band pass bandwidth variable type bandpass filter 36 can be changed and hence the relative amplitude balance betweenΣch andΔch can be adjusted.
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