An ultra-wide band antenna design with two inverted L slots for U-NII band rejection

In this paper, a novel rectangular planar ultra-wide band antenna (UWB) with band-notched characteristics is presented. The proposed design has two level stepped corners (lower) at the radiating patch along with two inverted L shaped slots on the two non-radiating edges of the microstrip patch antenna. The dimensions of the two L slots are optimized so as to achieve the U-NII band rejection (5.15 GHz to 5.825 GHz). The proposed antenna is designed and simulated using Computer Simulation Technology Microwave Studio (CST-MWS). This antenna operates in a frequency band ranging from 2.79 to 11.03 GHz with a band rejection from 4.88 to 5.94 GHz. The dimension of the proposed design is 27.00 mm (L), 32.42 mm (W) and 1.7 mm (H). The VSWR is less than 2 for entire operating frequency range. The impedance bandwidth of the proposed design is nearly 7.18 GHz with band rejection. This antenna can be used in various applications in 3.5 GHz WiMAX, 4 GHz C band and lower frequencies of X band without interference from U-NII (Unlicensed National Information Infrastructure) band. The effect of the partial ground plane and the dimensions of stepped corners with two inverted L slots are optimized for better return loss, whose parametric study is discussed in detail.