A BPF 20, which is a filter circuit, is formed by arranging a plurality of wiring patterns 21a, 21b and 22a to 22c on a substrate 10. Also, a freely movable impedance control rod 26 is formed so as to interfere with characteristics of the wiring patterns 21a, 21b and 22a to 22c of the BPF 20 without touching them. Interfering with the characteristics means cutting the passage of the frequency at the BPF 20, so that switching depends on whether the frequency is passed or cut.