Miniaturization Of UWB Deformation TEM Horn Antenna And Array

Because of its structure characteristics, TEM horn antenna has many characters such as high power capacity, ultra wide band and good direction. It is widely used in communication radar, EMC, anti stealth, etc. Standard TEM horn antenna often has a high reflection at low frequency, which limits the application range of the TEM horn antenna, thus the improving design of TEM horn antenna mainly concentrates in reducing the low-frequency reflection in order to increase the bandwidth.Initially, based on the working principle of the standard TEM horn antenna, this paper analyses the radiation characteristics of the TEM horn antenna with exponential gradient. Then it designs three types of index gradient TEM horn antenna with the plate width linear gradient, parabolic gradient and exponential gradient. Through the comparison of VSWR and Vpp (peak to peak value of the far-field pulse in the axial direction),it is concluded that the TEM horn antenna with the plate width linear gradient has the minimum reflection and maximum Vpp.If the antenna length along the axial direction is a constant value, the antenna gets the maximum Vpp when the end port impedance is 215Ω.Secondly, this paper designs s new type of exponential gradient TEM horn antenna under the condition of the plate width with linear gradient and end port impedance with 215 Ω..Then based on the current are mainly distributed in the edge of the plate, do deformation processing for the antenna:cutting antenna with elliptic cylinder. The designed antenna’s low-frequency reflection coefficient is small and its Vpp is larger. It works at 0.23-4GHz frequency range with the VSWR<2.The final designs the UWB TEM horn antenna with medium load, the results show that the medium load is greatly decreased the low-frequency reflection coefficient of the antenna, the physical size of the antenna reduced about 30 percent.Finally, the paper analyzes the radiation of UWB TEM horn antenna array, the results showed that:the low-frequency radiation characteristics of folding shape antenna array get improved but its Vpp decreases, the low-frequency cutoff frequency of slot antenna array increases slightly but its Vpp increases. The E direction figure is only decided by the antenna unit distribution of E plane, in the same way, The H direction figure is only decided by the antenna unit distribution of H plane.The paper mainly analyses the influence of the plate width, end port impedance, plate cutting and medium load to the TEM horn antenna. On this basis, the design of UWB deformation TEM horn antenna improves the low-frequency radiation characteristic, and expands the bandwidth. And then it analyzes the radiation of antenna array and gets the relationship between the array antenna radiation characteristics and the distribution of antenna unit.