In the case of the FPC antenna with the uniform superstrate, the maximum gain and 3-dB radiation bandwidth are about 15.9 dB and 25 MHz (1.1%), respectively. Considering that those of the proposed antenna are about 15.95 dB and 95 MHz (4.1%), it is worth noting that the proposed simple tapering method applied to superstrate cells is fairly effective for widening the antenna bandwidth without a large sacrifice in antenna gain. It is also worth mentioning that we have used the realized gain reflecting the total amount of efficiency to show the overall performance of our antenna. Therefore, it can be said that the influence of the return loss shown in Figure 7(a) is already considered in Figure 7(b).Finally, the measured radiation patterns in the E-and H-planes are compared with the simulation data in Figure 8. Owing to the rectangular-shaped aperture geometry, the 3-dB beam widths in the elevational and azimuthal directions are about 14 and 62 , which are appropriate for WiBro base station application. The maximum side lobe level is about À25 dB, and the measured front-to-back ratio (FBR) is larger than 35 dB. On the whole, the measured radiation behaviors agree well with our prediction.