Design of a CPW-fed Dual Band-Notched Planar Wideband Antenna for UWB Applications

Since the first Report and Order by the Federal Communications Commission (FCC) authorized the unlicensed use of ultra wideband (UWB) which must meet the emission masks on February 14, 2002 [1], both industry and academia have paid much attention to R&D of commercial UWB systems. Among UWB system design, the UWB antenna is the key component. Recently, a considerable amount of researches have been devoted to the development of the UWB antenna for its enabling high data transmission rates, low power consumption and simple hardware configuration in communication applications such as radio frequency identification devices, sensor networks, radar, location tracking, etc. Nowadays, the planar printed antenna fed with a microstrip line or a coplanar waveguide (CPW) has received much attention due to its high radiation efficiency and compact size and can be easily integrated with the other circuit. However, compared to the microstrip-fed antennas, the CPW-fed antennas are very good candidates since the feed line and slots are on one side of the substrate [2]. In order to obtain ultra wideband, the different optimum metal radiation patch geometries have been developed, like fork shape [3], elliptical shape [4], square shape [5], spade shape [6], circle shape [7], or made some modifications about the radiation patch [8]. Besides, over the designated frequency band, there exist some narrow bands for other communication systems, such as WiMAX operating in the 3.3 to 3.6 GHz band, and WLAN operating in the 5.15 to 5.825 GHz. They may cause communication interference with the UWB system. To solve this problem, it is desirable to design antennas with band notched characteristics to minimise potential interference. Several UWB antennas with frequency band notched function have been reported recently. The reported antennas are generally embedded with a half-wavelength structure such as a ω-shaped slot [2], a Ushaped slot [4], a C-shaped slot [8], or a V-shaped slot [9]. But most reported antennas were designed with only one notched band, mainly discussed on WLAN frequency band 5.15 to 5.825 GHz. UWB antennas with dual notched band were recently reported. In [10], the dual notched bands were formed by two nested C-shaped slots embedded in the bevelled patch. A pair of asymmetrical spurlines on the feedline was used to achieve dual notched band in [11]. A recently reported antenna has been designed by making use of two split resonant rings (SRR) to obtain dual band-notched characteristics [12]. Nevertheless, the geometry of the SRR structure is relatively complex. In this paper, a CPW-fed novel planar ultra-wideband antenna with dual band-notched characteristics is introduced. In order to obtain ultra wideband, some modifications about