Research On Patterns Reconfigurable Characteristics Of Holographic Impedance Modulation Antenna

Holographic impedance modulation antenna has many advantages.For example,it has a low profile,its feeding network is simple,and it has high operability in the actual design process.However,because of its working principle that holographic impedance modulation antenna is to use the reference wave to illuminate the interference pattern to invert the target beam,the antenna radiation direction is hard to be changed if the operating frequency is fixed.This paper explored the method of reconfigure the antenna radiation pattern at a definite frequency in order to solve this problem.Based on the working mechanism of holographic impedance modulation antenna,I firstly designed the one-dimensional holographic impedance modulation antenna so that its E-plane pattern could meet the requirements of the performance index.By loading the varactor diode,the E-plane pattern could be reconfigured.Through the two-dimensional arrangement of the designed one-dimensional holographic impedance modulation antenna,the reconfigurability of the H-plane pattern could be achieved,so that the radiation index of the antenna could be used into engineering.Details are as follows:I first designed a one-dimensional holographic impedance modulation antenna with an E-plane radiation directions of ?=35°.We analyzed the relationship between the modulation depth and the gain of the antenna.And the best modulation depth is M=0.2 in this paper,with the gain up to 13.2 d B in this circumstance.Then,the 2-D holographic antenna was composed of the 1-D holographic antennas at the y-direction.and H-plane could be controlled by changing the feeding phase difference.Three dividers with different phase differences were designed to feed the antennas and then we simulated and tested the antennas.The simulation and test results were almost consistent,showing that the antenna H-plane pattern radiation directions were linearly changed with the feeding phase difference.The direction of the H-plane could scan from ?=-26° to ?=26° when it changed from ??=90° to ??=-90°.The gains could reach more than 18 d B.Finally,several varactor diodes were loaded on the cell structures,whose capacitance could change with the voltage.The surface impedance can be changed by the applied voltage to achieve the reconfigurable Characteristics of the E-plane pattern without changing the frequency.The DC-load line is designed to give each varactor diode with reverse voltage.Through the electronic regulation,the designed antenna can achieve the change of the radiation direction of the E-plane pattern is reconfigurable,with the direction from ?=35.2° to ?=74°.The scanning angle is ??=38.8°.