| 摘要 |
PURPOSE:To obtain the filter having sufficient attenuation by arranging plural half wavelength resonance electrodes on the surface of a dielectric base and approaching the earth potential of the upper and lower case via plural through holes provided around the electrodes. CONSTITUTION:The rear face of the dielectric base 1 is used as a lower face earth electrode 4, the half wavelength resonance electrodes 2a-2e and the upper face earth electrode 3 are formed on the surface and the electrodes 3,4 are conducted by a through hole 5. The base 1 is inserted to the lower case 6 while the electrode 4 is brought into contact and the upper case 7 is brought into contact with the electrode 3. A metallic wall 9 of the channel structure is provided to the case 7 and the lateral size is selected as the cut-off frequency in the waveguide mode being sufficiently higher than the pass frequency of the microstrip line filter. Thus, the earth potential of the cases 6,7 is made close together via the through hole 5, then the earth of the base 1 is fixed stable, the undesired radio wave irradiation is reduced in space and the filter characteristic with excellent attenuation is attained.
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