Design On The Feed System Of X-Band And Ku-Band Multi-Unit Radial Line Array Antenna

Vigorously develop of high-power microwave technology, driving people to the study of high power microwave antenna technology which as the terminal of high power microwave technology. Due to the high power microwave with a special high-power feature, in addition to meet the high power microwave antenna’s radiation indicators, also need to implement include high power capacity, miniaturization, light-duty, and other special requirements. As a kind of planar array antenna with special feeder structure form, radial line spiral antenna array get more and more attention because of the high utilization structure, high radiation efficiency, feeder structure is easy to implement and other advantages.In recent years, great progress has been made in the research of high power radial line helical array antenna, through the single and double spiral ring radial line array analysis, it made clear in the reliability for the miniaturization, high efficiency; through the increase the number of units of the single sub-array to reduce the number of combinations between sub-array cascade, thus achieved in improving high-gain antenna array at the same time can lower insertion loss value goal; through a rectangular grid, triangular lattice unit layout research contrast, acquire the method of saving the cost of system; by coupling probe and choke structure of collaborative design, realized the radial line of high efficiency transmission design. On the basis of such technology, this type of antenna to a higher frequency of development has become possible. This paper will be of high power radial line spiral antenna array in the application and performance optimization of X-band and Ku-band are studied.Firstly, we learned and summarized the basic theory in the study which involved to the rectangular planar array antenna, the radial line frequency characteristic, principle of coupling probe and so on. At the same time, we also analyzed the difficulties of the high-power radial line spiral antenna array when used at high frequency applications, how to restrain neglected amplitude in the condition of multi-mode coaxial transmission and how to miniaturization design choke structure.Then carried on the preliminary design of the X-band unit 58 triangular grid radial sub-array feed system, analyzed and determined the use of a cylindrical base plus ring coupling probe, by introducing metal plate to changes of the microwave phase distribution in radial line achieved the uniform distribution of microwave in radial line optimization. Thus achieved a substantially equal width output feed with port 58 road in the center frequency at 9.3 GHz, combined with experimental tests to verify the feeding system design. The design success makes the X-band high-power radial line spiral antenna array element number by 32 units extend to 58 units.Next, in order to improve performance of the X-band unit 58 sub-array radial line, its amplitude-frequency characteristics and power capacity is optimized. Using the way of add metal plate on the radial line edge to improve the coupling method of probe, has optimized the amplitude-frequency characteristic of the feed system, by increase the input coaxial size and optimize neglect reflection increased the power capacity of the feed system. The simulation results show that, the port coupling imbalance under center frequency 9.3 GHz decreased from 2.14 dB to 1.41 dB, and within the 9.2 GHz-9.4 GHz frequency range, coupled imbalance decreased from 4.34 dB to 2.99 dB; a single array power capacity increased from 15.3 MW to 29.4 MW. Finally, the helical unit sub array radiation characteristic simulation results show that the center frequency array VSWR of 1.09, the radiation gain is 24.98 dB, axial ratio is 0.89 dB, proved the feasibility of the optimization program.Finally, in order to continue explore in high-frequency band, this paper studies a Ku-band multi-cell rectangular radial line sub-array feed system. In order to meet the coupling target of outer radial line probe, proposed and designed a new type of coupling probe, this cascading probe can be extracted coupling energy more effectively; at the same time, designed a miniaturized choke structure which could applied to Ku-band sub-array radial line feed system, implement the feed system design of 28-units sub-array rectangular grid radial line. Approximate continuous output in the center frequency of 12.5 GHz, VSWR of 1.03, unbalanced coupling degree is 1.27 dB; a single sub-array feed system power capacity of 15.36 MW. And experiment have been carried out to test the radiation characteristics of the 112-units sub-array, the results show that, an array VSWR in center frequency of 1.18, the axial radiation gain of 25.17 dB, axial ratio is 1.25 dB, can be achieved microwave directional circularly polarized radiation, proved the feasibility of the optimization program.