Compact Bluetooth/UWB Dual-Band Planar Antenna With Quadruple Band-Notch Characteristics

A compact Bluetooth/Ultrawideband (UWB) dual- band planar antenna with quadruple band-notch characteristics is presented. The proposed structure consists of a UWB semi-elliptical planar monopole, attached to an approximate trapezoidal spiral for 2.45-GHz Bluetooth application. The proposed antenna utilizes rectangular resonant spiral structures for rejection of quadruple frequency bands, i.e., WiMAX (3.3-3.6 GHz), WLAN (5.15-5.35, 5.725-5.825 GHz), and ITU 8 GHz. These resonant spirals are capacitively coupled with the microstrip feedline. The band-notch characteristics are controlled by changing the effective length of the spirals along with coupling gaps between the feedline and the spirals. The proposed antenna also achieves sharp reduction in the gain and efficiency at all the notch frequencies. However , at the passbands, the gain and radiation efficiency are almost stable. A good agreement between the simulated and measured results shows that the proposed antenna with surface dimensions of 24 × 17 mm² is suitable for Bluetooth/UWB dual-band applications.