| 摘要 |
PROBLEM TO BE SOLVED: To provide an input structure in which the leakage of electromagnetic waves and loss is low even if the contact of the ground surface around a pickup probe and a casing is insufficient. SOLUTION: On the casing having a waveguide input part, a circuit board 2 exists, and an input radio wave signal is fetched into the circuit board 2 and is received by the pickup probe 1 protected by an insulated body 1b through the casing from the circuit board 2. in the outer peripheral part of the pickup probe part 1 under the circuit board 2 of the casing, a cylindrical recessed part 5 is formed. The value L1 that the radius of the opening of the casing is subtracted from the radius of the cylindrical recessed part 5 is made the half of the wavelengthλg in the line of input radio waves and the depth D of the cylindrical recessed part 5 is made smaller than the wavelengthλg in the line. The equivalent circuit at the surrounding part becomes (B) and the input impedance viewing the outer peripheral part b point of the cylindrical recessed part 5 from the outer peripheral part a point of the opening part of the casing becomes equal toλg/2 line of tip short circuit and becomes a short circuit state.
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