Setting coupling coefficient pass and filtering device

The utility model relates to a double-group hollow coil which is a fixed value coupling coefficient filter electronic element with the surface affixed with SMD structure device. According to the theory that two hollow coils can produce different coupling coefficients because of the change of the parameters such as distance between coils, the circle quantity, the size of the inner diameter, the thickness of the lead, the medium coefficient and so on; the proper coil coupling distance is derived; and then proper shell fixing manner or injecting manner is utilized to fix the two coils according to the derived distance by fixing glue with given medium coefficient.