A CPW-fed band notch super wideband antenna with Scale up/down Capability

In this paper, a coplanar waveguide (CPW)-fed slot super wideband (SWB) antenna with band notch characteristic is proposed. It comprises a wide rectangular slot excited by the tapered feedline. To obtain the SWB characteristic, a circular stub is added at the center of the slot. It effectively broadens the impedance bandwidth by improving the matching throughout the band. By optimizing the size and position of circular stub, the proposed antenna tenders an impedance bandwidth more than 175% with 15:1 frequency ratio (1-15 GHz). In addition, the antenna gain is improved from -2.2dBi to 6.3 dBi at 5 GHz and become almost stable in the entire frequency range. Besides, some guidelines have been prepared to scale up or down the proposed antenna structure for the desired frequency bands. To validate these design guidelines one test antenna is realized for 3 to 30 GHz frequency band. It is demonstrated that both antennas obtain more than 175% impedance bandwidth for VSWR<2. Finally, two L-shaped stubs are introduced just underneath the feed line to create band rejection between 3.1 to 4.2 GHz. It is observed that stubs efficiently reject the specific frequency band without affecting the frequency response of the proposed SWB antenna.