In four microstriplines (2, 3, 4, 5) disposed close such that they are coupled with each other, the left-hand end of the third microstripline (4) serves as an input (6), the left-hand ends of the first and second microstriplines (2, 3) and the right-hand ends of the first and fourth microstriplines (2, 5) serve as outputs (7, 8, 9, 10), and the right-hand end of the second microstripline (3) and the left-hand end of the fourth microstripline (5) are grounded.