Research And Design Of Ultra Wideband And High Gain Antenna Of Electronic Countermeasure

With the continuous development of electronic technology,the electronic countermeasures technology becomes more and more important in the military struggle.As the frequency range of the radar system broadens,the requirements of ultra wideband,high gain and miniaturization for antennas also increase.The planar spiral antenna is a frequency independent antenna,it can work in a wide frequency range.The miniaturization and high gain of antenna can be realized by the optimum design of balun and metal reflection back cavity.So the planar spiral antenna has wide application prospect in electronic countermeasure technology.In this paper,the application of planar spiral antenna in electronic countermeasure technology is studied and analyzed.The research and design of Archimedes spiral antenna and the composite structure spiral antenna is the main work.The frequency of the antenna is from 2GHz to 40 GHz.First,a Archimedes spiral antenna with high gain and low profile is designed.Two radiators with different impedance are designed through the study of the Archimedes spiral antenna radiation theory.When a radiator has a lower input impedance,it can reduce the balun length and the thickness of the antenna profile.Through the study of ultra wideband micro-strip balun,a short micro-strip balun with the length of 10 mm and a zigzag balun with profile of 26 mm are designed.The antenna is simulated after the connection of the radiator and balun.The results show that the antenna has good performance in voltage standing wave ratio,gain and axial ratio in the frequency range of 2~40GHz.And the zigzag balun can effectively improve the performance of the antenna in low frequency.A metal reflecting back cavity is designed for the 10 mm balun's antenna.The axial ratio and the directional map of the antenna are stabilized by the structure of the round platform and air gap.Finally,two kinds of antennas with different balun are processed and tested.The test results show that the return loss of the antenna in the 3~40GHz band is less than-10 dB,and the gain is above 5dBi.The test results have the similar performance with the simulation results in most frequency bands.The design of Archimedes spiral antennas is successful.Then,the composite structure spiral antenna with higher power capacity is designed.By studying the advantages and disadvantages of Archimedes and equiangularspiral antenna,the deformable structure of the planar spiral antenna is discussed.First,the composite structure spiral antenna radiator is designed.The return loss and standing wave ratio are far less than the Archimedes spiral radiator,and the gain is also improved.And a coaxial balun of coaxial line transition to parallel double line is designed,this structure has higher power capacity and can improve the antenna's radiation power.Finally,a metal reflecting back cavity is designed.The simulation results show that the antenna has a good performance in standing wave ratio in the whole frequency band,and the gain is above 4dBi in full frequency band and above 12 dBi in the high frequency band.The design of the composite structure spiral antenna has also been successful.