Pattern bandwidth improving of printed notched-monopole antenna

A printed monopole antenna of the tapered and notched radiator with the microstrip feed-line is designed. The simulated and measured results show that the printed antenna achieves a broad impedance bandwidth of 3.1-11.1 GHz for the 10-dB return loss. This antenna features the stable omni-directional radiation patterns over the impedance bandwidth. Using the current distribution modes the influence of the radiator cut on the radiation performance is analyzed. It is indicated that the notched radiator can improve the pattern bandwidth due to the enhanced standing-wave current by the cut at the high frequency. Compared with the cut depth, the cut width performs more important functions on the radiation characteristics. To maintain the similar radiating performance, the width of the residual lower-side patch of the notched radiator must be larger than one eighth of the high-frequency resonant wavelength.