| Recently,RF communication technology is in rapid development,its application fields are also covers many aspects of our social life.The RF communication system continuously towards ultra-wideband,compact,low cost,which makes the study of the antenna of the radio frequency communication system work exists both opportunities and challenges.Wideband balanced antenna is one kind of planar antennas which is commonly used in the RF front-end systems.This paper chooses Vivaldi antenna as an example to discuss the design of ultra-wideband balanced antennas.The antenna feeding network has much effect on characteristics of antenna,such as impedance bandwidth,radiation characteristics and so on.In order to avoid this phenomenon,this paper adopts the method of analyzing the radiation part of the antennas singly.Comparison of different types of improvement way,this paper puts forward a better terminal loading form,which could broaden the impedance bandwidth of the Vivaldi antenna obviously.This method could provide guidance for future Vivaldi antenna design.In this paper,the balun feeding network has been chosen for feeding the radiation patches of the Vivaldi antenna.A new type of ultra-wideband balun based on broadband transition structure has been presented in this paper.Furthermore,the working process and realization principle of balun have been introduced in detail through the analysis of the electric field distribution method.The simulation results show that an ultra-wide bandwidth with excellent amplitude imbalance and phase imbalance.A new ultra-wideband Vivaldi antenna feeding by balun is presented in this paper.By using EM simulation software ANSOFT HFSS 13,the antenna is simulated.Bisides,it has been fabricated and tested.The simulated and measured results show that the Vivaldi antenna integrated with balun can work from 0.9 to 6 GHz with good radiation performance.The minimum gain of the antenna is 4.7 dB at 1.25 GHz,while the maximum gain is 8.1 dB at 6 GHz.This shows that the balun does little influence on the performance of the antenna.In addition,the size of the antenna to 133 mm × 117.5 mm.comparing with the tradition Vivaldi antenna,the size of the proposed antenna decreases greatly.Thus,the design method of Vivaldi antenna proposed in this paper has practical value for research and engineering application. |
