UWB 통신을 위한 CPW 급전 디스크 섹터 안테나 설계 및 제작

Abstract

Technology of ultra-wide band(UWB) communications for the next generation is a radio transmission technology that consumes a very low electric power and transmits digital data on the free space using by Gaussian monocycle pulse. The wireless UWB system is utilized in the frequency ranges from 3.1 GHz to 10.6 GHz. The goal of the UWB antenna design is to make an antenna with small size, simple structure that produces low distortions but can provide a wide bandwidth and omni-directional pattern. In this paper, we design and fabricate disk sector antenna fed by CPW for UWB communications. Also, we insert a rectangular slit on the arc-edge, or fan-shaped slit on the side edge of disk sector antenna. Then, the antenna has either directivity of E-plane or band stop characteristics. In order to antenna design, input impedance is matched with the feed line of 50 Ω varying parameters that compose of the antenna. These parameters are the radius, flare angle of disk sector, length of ground and length of ground corner near by feed line. In case that there is a rectangular slit on the arc-edge of disc sector antenna, impedance bandwidth is only a little changed. However, the disc sector antenna has directivity to opposite of direction with a rectangular slit. Because a rectangular slit is inserted along direction of electric current at the position whose surface current intensity is not strong. On the other hand, radiation pattern of the antenna does not change in case that there are two fan-shaped slits on the side edges of disk sector antenna. However, the antenna has characteristics that band stop frequency is controlled as the length of fan-shaped slit. Because surface current intensity of fan-shaped slit inserted on the side edge is strong. Dimension of the antenna designed for UWB communication is 72mm?26mm, and impedance bandwidth through computer simulation is 3∼13 GHz in VSWR≤2. From results in measurements, impedance bandwidth is 1.98～11 GHz. When the results in measurements are compared with simulation results, the phenomenon of frequency shift has a little effect on the left side over the operating frequency of UWB system. Because the effect on ground plane of fabricated antenna is weaker than that of simulation result. Return loss and gain of fabricated antenna are -50.38 dB, 1.34 dBi at 3.5 GHz, -12.27 dB, 3.35 dBi at 5.5 GHz, -23.2 dB, 3.8 dBi at 8 GHz and -16.17 dB, 5.2 dBi at 10 GHz, respectively.