| The antenna, as an important device of transmitting and receiving electromagnetic waves in the wireless system, has a crucial effect on the performance of the wireless communication system. Since the 1940s, Microstrip slot antennas have many advantages of low profile and easy conformal and so on. When Microstrip slot antennas are applied into the moving objects in the communication system, the advantage of easy conformal can reduce the aircraft air resistance. And antennas can be hidden and not affect the movement of objects. In addition,the bandwidth of the antenna for reconnaissance radar signal is as wide as possible in radar communication, and Ultra wideband (UWB) wireless communication technology has the advantages of high transmission speed and low error rate (BER),which has been extensively utilized and further developed in many significant domains, such as high-speed communication, radar tracking, distance measuring, and precision positioning and guiding.The development of UWB antennas have been widely since the FCC rules the UWB communication technologies in 2002.Firstly, the paper introduces the research background of microstrip slot antennas and CPW slot antennas, By learning relevant materials, although there is the microstrip antenna,which covers the C band (5.05 GHz to 5.75 GHz) in the radar communication system, but it has many disadvantages, for example, the bandwidth is narrow in the frequency about 5 GHz,which cannot completely cover c-band frequency range, and the conformal antenna is not easy to motion object, so the microstrip slot antenna are the best choice for designing the antenna, which can realize conformal between antenna and the radar jammer; In addition, the presence of the ultra-wideband antenna already solved the problem of crowded frequency resources, improved data transmission rate and the antenna can also be used for reconnaissance radar signal, which becomes a hot research topic in recent years; And using the coplanar waveguide as the antenna feed-line, makes the antenna easy integration and miniaturization and so on.Secondly, in a lot of reading and in-depth study about the basic principle and method of the microstrip slot antenna, a new microstrip slot antenna is designed used for the jamming system of the radar communication. The designed antenna works in the C band frequency about 5.05GHz to 5.75GHz, and the structure consist of the microstrip patch antenna etching a OCSRR ring gap structure,the feed-line of microstrip,1/4 impedance transformer for impedance matching. This is the improvement of microstrip slot antenna based of the microstrip patch antenna in this paper. The parameters, which consist of the size of the radiation patch of the antenna and position of the structure of the OCSRR, have influences on the antenna performance through the parameter calculation and software analysis; Finally, the optimal antenna sizes are determined, which realize the work frequency of the antenna covering C band about 5.05GHz-5.75GHz, the bandwidth reach 3.6%. In addition, an improvement design of the antenna is proposed, which add a metal board under the bottom of the antenna. Through the repeated simulation and parameter optimization using the front method, the location of metal backboard and other parameters are obtained the optimization,and the antenna gets a greater impedance bandwidth than before,reaching 8.7%,at the same time, the antenna has higher gain and radiation.Finally, after the study of coplanar waveguide, the ultra broadband and the antenna for reconnaissance radar signal, a design of CPW slot antenna is proposed for ultra-wideband.The structure of the UWB coplanar waveguide (CPW) slot antenna consist of the CPW for feed-line; the printed monopole patch as the radiation patch of the antenna; etching a L-shaped slot ,seen as symmetric oscillator respectively on the floor of two coplanar waveguides. Because a set of optimal ultra broadband parameters of the antenna can be got by adjusting the position of the L and all parameters of the structure for antenna analysis and optimization design, the working frequency of the antenna is 3.48GHz-14.18GHz, which gets a ideal impedance bandwidth and better ultra-wideband feature. |
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