Patent ID: 7221240

Claim:
A narrow bandpass filter installed on a circuit board for suppressing a high-frequency harmonic wave, using a printed circuit board manufacturing technology for manufacturing a circuit board of a wireless communication product by means of a metal microstrip method of directly building a microstrip circuit corresponding to a narrow bandpass filter on a side of said circuit board; wherein said microstrip circuit comprises a capacitor microstrip and using an interdigital finger method to lay said microstrip circuit on said circuit board, wherein said capacitor microstrip uses one end as an input end of said bandpass filter and the other end for perpendicularly coupling to a first inductor microstrip, wherein said first inductor microstrip is substantially in the shape of a meander line, having an end perpendicularly coupled to an end of a second inductor microstrip and the other end perpendicularly coupled to an end of a third inductor microstrip, and wherein an end where said third inductor microstrip and said first inductor microstrip are connected serves as an output end of said bandpass filter.