Abstract: A dual-band bandpass filter with stepped-impedance resonators uses only one circuit to generate dual-band effect. It adopts the principle of stepped-impedance resonator, which contains a connecting section and two coupling sections. The impedance and electrical length of the connecting section and coupling sections conforms to a selected condition to generate two passbands at desired frequencies. A multi-layer broadside-coupled parallel lines structure may be applied to increase coupling-amount between the parallel lines so that the dual-band bandpass filters have broader bandwidth and less loss.

Abstract: The present invention discloses a filter using multilayer ceramic technology. The filter comprises an input port, an output port, a first lumped resonator and a first step-impedance resonator connected to the input port, a second lumped resonator and a second step-impedance resonator connected to the output port, a coupling capacitor used for the coupling of the first lumped resonator and the first step-impedance resonator to the second lumped resonator and the second step-impedance resonator. The filter according to the present invention can provide the multi-transmission zeros in the stopband to isolate the adjacent channel and suppress the harmonics, and provide the transmission poles in the passband to have lower insertion loss. In addition, a manufacturing method for the filter using multilayer ceramic technology is also disclosed.

Abstract: A communication network switch system, comprising: a first phone number database accessed by a cable telephony network service provider; a second phone number database accessed by an internet service provider; a plurality of communication network switch devices conducting audio and/or data communications therebetween through a cable telephony network or an internet, the communication network switch devices switching audio and/or data communications between the cable telephony network or an internet telephony system and a short-range wireless communication network; and a plurality of mobile communication devices each of which including a long-range wireless network system transceiver module, a short-range wireless network system transceiver module and a switch device module.