Abstract: The author designed a trapezoidal double bandnotched ultrawideband planar monopole antenna, and the influence of changing the radius of Cshaped gap bandnotched structure and Lshaped gap on the antenna performance was analyzed. The antenna consisted of trapezoidal composite structure radiation unit, coplanar waveguide feeder, floor and coaxial joint. The results show that the working frequency range of the designed antenna is 2.9—11.2 GHz, the frequency range of the bandnotch is 3.28—3.79 GHz and 4.82—6.08 GHz, double bandnotched wave and radiation effect are good, which can reduce the mutual interference caused by crossoverlapping of frequency bands among wireless communication systems.

Key words: trapezoid, double bandnotched, monopole, antenna