The Study Of Ultra Wideband Antenna Based On Liquid Crystal Polymer

In order to save the limited space of electronic equipment, the ultra-wideband antenna is needed to cover on its surface. Liquid Crystal Polymer is a kind of flexible material. It can be bent in any way, and it has a stable dielectric constant during a very broad band. The research on ultra-wideband antenna based on the flexible material has greater significance, more broad prospects and a wider application field.Three kinds of ultra-wideband antenna based on LCP are designed according to the antenna theory: the circular monopole ultra-wideband antenna, the monopole with strip ultra-wideband antenna and the monopole ultra-wideband antenna with defected ground, which are both fed by coplanar waveguide. They are bent along their propagation direction and simulated in HFSS. The performances of antenna under different radius are mainly studied. The simulation results show that, after bent the ultra-wideband antenna not only maintains the property of planar case:-10 dB return loss during ultra-wideband frequency; stable radiation pattern, good omnidirectional characteristics; the same gain which has little relationship with bent radius; but they also have some differences: high frequency resonant point and low frequency resonant point of return loss move to low band and high band respectively. The change increases with decreasing of bent radius. This is because that the antenna is stretched, and the stretching length increases with the decreasing of bent radius; the radiation zero point deflects more with the decreasing of bent radius. And they are close to their theoretical values. This is caused by the effective axial changes after bent.The return loss and radiation pattern of the antenna under planar and bent case are both tested. Then measurement results are compared with simulation results: under both planar and bent case, measurement results have a good agreement with simulation results of return loss. But measurement results shift to high band, which is caused by the deviation of fabrication and measurement. And they also have a good omnidirectional characteristic and measurement results have a good agreement with simulation results of radiation pattern. The measurement results also have a good agreement with simulation results of gain under different radius. The design of antenna under planar and bent case is both suitable for the UWB system.