부산대학교 도서관

In this paper, in order to discard the impedance matching circuit and reduce the antenna overall size, a directional antenna integrated a low noise amplifier (LNA) with ATF-54143 transistor is designed. Two 50ohm matching networks between the antenna and the LNA can be eliminated, and the insertion loss and the space occupation of RF front-end system have also been reduced. The simulated results show that this directional antenna with input impedance of 23.1-j15.4 ohm rather than 50 ohm at 2.45GHz and has a great radiation performance. The noise figure of the integrated antenna decreases by 0.1 at 2.45GHz, in comparison with the traditional cascade circuit by designing 50ohm matching networks. It provides a useful guiding method for the design of active antennas.