Design Of Dual Band-notched UWB Antenna And Wearable Antenna

Traditional ultra-wideband antenna have already can’t satisfy the requirement of UWB wireless communication technology at the moment, such as in UWB spectrum, and some other communication systems that already exist(3.3 to 3.6GHz WiMAX, 5.15 to 5.825 GHz WLAN), which interfere with UWB spectrum, so in this thesis we design two ultra-wideband antennas which the stopband locate at WLAN and WiMAX spectrum. Because the proposed dual stopband antenna can only be used for dual stopband once be fabricated, so a reconfigurable antenna that can work in a variety of modes according to the requirements is proposed. Our main innovations are as follows: first of all, we propose two antennas with small structure and dual band-notched, according to the input impedance of the antenna, the equivalent circuit with stopband characteristics is put forward. Second, two identical antennas are placed face to face and side to side to measure the transfer function, the magnitude of transfer function is flat in the operating band, the group delay is constant over the entire operation band as well. For reconfigurable ultra-wideband antenna, it can work in four different modes by controlling the state of the switch, which realized an antenna has four applications.The improvement of people’s life quality promotes the application of wireless network technology which take the human body as the center. Wearable antenna is an important part of this technology. So-called the wearable antenna which uses materials that are similar to clothes, and can wear it, the difficulties of the research on it has two points. First, because the wearable antenna is close to human body when working, some even paste in man’s clothes, so how to increase the body’s comfort is a factor which need to be considered in designing antenna. Second, because the antenna is close to body, so human’s irregular activities every day will affect the antenna structure. Thus, whether the distortion of the antenna structure will has great influence on frequency characteristics is the second technical difficulties. In order to solve the above problem, this thesis proposes a wearable antenna applied to 2.45 GHz. Main innovations are as follows: the soft nylon conductive fabric is used as the antenna radiating element to increase the comfort of wearable, the thin felt is used as dielectric substrate, in order to test the stability of the antenna during the human body’s unpredictable activities. In the measurement, we place the antenna on the arm and test the body’s impact on it. We constantly bend the antenna to get the bending degree of tolerance. Antenna radiating element and the ground also used the copper sheet. Comparing with conductive fabric, the result indicate the conductive fabric band is wider, copper voltage standing wave ratio is smaller.