Patent ID: 7994875
Filing Date: 2011-08-09
Classification: H01P

Abstract:
1. A tri-frequency duplexer circuit, comprising: a microstrip line circuit, comprising a first Input/Output (I/O) port, a second I/O port, a third I/O port and a fourth I/O port; two first mushrooms with a first Electromagnetic Band Gap (EBG) frequency, respectively disposed at a transmission line path between the first I/O port and the second I/O port and a transmission line path between the first I/O port and the third I/O port; two second mushrooms with a second EBG frequency, respectively disposed at the transmission line path between the first I/O port and the second I/O port and a transmission line path between the first I/O port and the fourth I/O port; two third mushrooms with a third EBG frequency, respectively disposed at the transmission line path between the first I/O port and the third I/O port and the transmission line path between the first I/O port and the fourth I/O port; and a first substrate and a second substrate with an air layer being defined between the first substrate and the second substrate, the microstrip line circuit being disposed on the first substrate, and the two first mushrooms, the two second mushrooms and the two third mushrooms being disposed within the second substrate; wherein the first EBG frequency, the second EBG frequency, and the third EBG frequency differ from each other.