Patent ID: 7142836

Claim:
A microwave filter distributed on a circuit board of a wireless communication product, comprising an input terminal, a resonant chamber of double frequencies, and an output terminal of the microwave filter directly distributed on the circuit board of the wireless communication product as a plurality of microstrips by utilizing a manufacturing technique of printed circuit board, wherein a microstrip circuit of the resonant chamber of double frequencies comprises: a first microstrip circuit having one end perpendicularly coupled to one end of the input terminal; a third microstrip circuit having one end perpendicularly coupled to one end of the input terminal, the third microstrip circuit being parallel to the first microstrip circuit; a second microstrip circuit interconnected the first microstrip circuit and the third microstrip circuit in a meandering path and being perpendicular to each of the first and the third micro strip circuits; and a fourth microstrip circuit interconnected the first microstrip circuit and the third microstrip circuit and being disposed across the first and the third microstrip circuits, wherein the input terminal of the microstrip circuit, the first microstrip circuit, and the second microstrip circuit are provided at a top layer of the circuit board, the third microstrip circuit, the fourth microstrip circuit, and the output terminal of the microstrip circuit are provided at a bottom layer of the circuit board, and two through vias are provided on the circuit board for interconnecting the top and the bottom layers of the circuit board.