Development Of Compact Uwb Dual-Polarized Antenna

With the improvement of electronic device technology and the rapid development of wireless communication, ultra wideband technologies applications has begun to shift from military to civilian technology. Meanwhile, dual-polarized antenna has the advantages of polarization diversity and frequency multiplexing, which can overcome the multipath effect of signal transmission in the short-range wireless communication and obtain the polarization isolation in the satellite communication. It can also provide two mutually orthogonal polarization waves in the broadband direction finding system,so the ultra-wideband dual-polarized antennas have great potential in many areas. In this paper, two types UWB dual-polarized antennas for different applications have been designed. The main works are three parts: 1.A planar UWB dual-polarized antenna at 2.6-12GHz; 2.A compact UWB dual-polarized antenna at 2.3-12GHz with band rejection; 3.A four arms sinuous antenna at 3-12GHz has been designed and simulated.The main works of the first type antenna are as follows:1) After studying the dual-polarized antennas based on new UWB antennas, two planar UWB dual-polarized antennas have been designed. The first antenna by making improvements in the traditional single decoupling stub, three open-stubs extend from 45° axis of ground have been proposed. This method improves the isolation of the two ports and the performance of low frequency via extending the surface current path. The second antenna with quasi-self-complementary structure can obtained high isolation without any additional decoupling structure. It can also reduce the size of the antenna and achieve the goal of miniaturization design.2) The UWB from 3.1 to 10.6 GHz overlaps with the WiMax frequency band from 3.3 to 3.7 GHz and the WLAN band from 5.15 to 5.85 GHz, so an efficient way to solve this problem is to design an UWB antenna with band-notched performance. For the second antenna, the WLAN band rejection is obtained by using the mixed notch-method.By introducing two transmission poles, the notch-band has better rectangular radio,which avoids the waste of useful signals.The main works of the second type antenna are as follows:1) By analyzing the theory of sinuous antenna, the traditional planar form-arm sinuous antenna is simulated. It is found that the traditional way to reduce the dimension of antenna is to reduce the number of units of sinuous antenna. In this paper, the miniaturization technology of antenna by using both inductive and capacitive loads is studied. The method of loading two polygon rings around the sinuous arms, which attached to the top and bottom sides of substrate respectively, can realize the miniaturization of sinuous antenna. The simulation results verify the conclusion.2) In order to match the input impedance of the four-arm sinuous antenna, a dual-balun which realizes impedance transformation from 50 ohm to 200 ohm is designed. To obtain the unidirectional radiation characteristic, a metal back-cavity with absorbing material which needs to place on one side of the sinuous antenna is used in this work. Finally, a four-arm sinuous antenna with unidirectional radiation characteristic is obtained.