Ultrawideband Strip-Loaded Circular Slot Antenna With Improved Radiation Patterns

An ultrawideband strip-loaded circular slot antenna is proposed in this Communication, which presents a measured impedance bandwidth of 144.8% , much stable radiation patterns and small dimensions. The loading strip is used for redistributing the electric field within the slot to achieve stable radiation patterns across a wide frequency band, and it is optimized to influence on the impedance bandwidth as slightly as possible. For clarity, the simulated three-dimension (3-D) radiation patterns are given and compared with those of a conventional circular slot antenna without strip loading. The measured gain of the proposed antenna in the broadside direction is over 0 dBi from 2.4 to 11 GHz. The measured and simulated return losses and radiation patterns of the proposed antenna are given, and finally, parametric studies are performed for practical applications.