PURPOSE: To simplify constitution, and to reduce cost, and to improve durability by providing electrode elements in both outer shells, and connecting the central conductors of both coaxial lines by forming the capacitor of nearly constant capacity by both the electrode elements even if both the outer shells are rotated relatively.

CONSTITUTION: The cores 31a, 31b of coaxial cables 12a, 12b are connected through inductance elements by patterns 30a, 30b and the capacitor 42. Besides, stray capacitors 44a, 44b are formed respectively between the pattern 30b and outer shell 4b and between the pattern 30a and the outer shell 4b as well. A band pass filter is constituted of those, and the coaxial cables 12a, 12b are connected through this filter. Here, since in the capacitor 42, the areas of parts to be the opposed electrode are nearly constant, and an interval between both is constant, the capacity of the capacitor is constant even through connection parts 2a, 2b are rotated relatively. Besides, since there is no contact part, the constitution is simple, and the cost is low, and further, the durability can be improved.