| 摘要 |
PROBLEM TO BE SOLVED: To suppress the influence on a simultaneous transmission and reception discriminating function by increasing the effective resistance values of transformers for conversion and cancellation and reducing the influence due to the variance of the lead wire resistance value. SOLUTION: An impedance element is used as a receiving coil K2 on the side of the transformer T1 for conversion and connected to a 3rd transformer T3 in a cross state. Further, the secondary coil K4 on the side of the transformer T2 for cancellation is connected to the 3rd transformer T3 is parallel. Here, the resistance value of the 3rd transformer T3 can be set up to 300Ω, if resistance values of both the transformers T1 and T2 are set to 100Ωand the variance of the resistance value of a lead wire is set to 20Ω, the effective resistance value of both the transformers T1 and T2 become 400Ω. Therefore, the degree of influence due to the 20Ωvariance of the resistance value of the lead wire becomes 5%, or a quarter as large as that of conventional technology. Thus, the effective resistance values of the transformer for conversion and transformer for cancellation are increased to greatly decrease the degree of influence even if there is the variance of the resistance value of the lead wire, thereby greatly suppressing the influence on the simultaneous transmission and reception discriminating function.
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