A new type of fractal-shaped microstrip patch antenna for ultra-wideband (UWB) applications and with sufficient rejection in the WLAN band is presented. The radiating patch is placed on a 1.6 mm thick low-cost FR-4 epoxy substrate and is fed using a symmetric coplanar waveguide. The size of the proposed antenna in terms of wavelength is 0.189λ 0 × 0.197λ 0 . A sectorial-circular slot in the patch is used to create WLAN band notch. An impedance bandwidth of 11.76 GHz (from 2.19 to 13.95 GHz) is achieved, along with achieving WLAN band rejection from 4.67 to 6.21 GHz. Nearly omnidirectional radiation pattern with the maximum gain of 5 dB in the passband is achieved. In the rejection band, the gain drops to −3 dB. The simulated results are verified against experimental data and a good agreement between the two sets of data is seen. The proposed antenna covers both the unlicensed 2.4 GHz band and the UWB. K E Y W O R D S coplanar waveguide (CPW) feed, fractal design, ultra-wideband (UWB), WLAN band notch

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A coplanar waveguide fed asymmetric rectangular antenna with sufficient WLAN bandrejection is presented for ultra-wideband applications. The antenna uses an asymmetric rectangular patch, modified feedline, and defected coplanar ground plane for obtaining ultra-wideband performance. An inverted-L shaped slit in the radiating patch is used for realizing the WLAN band-rejection. The antenna is designed on a 1.6 mm thick FR-4 substrate having an area of 12×16 mm 2 (0.169λ L ×0.225λ L). An impedance bandwidth of 11.49 GHz with a WLAN band-notch from 5.15-5.86 GHz is achieved. In addition to this, desirable radiation characteristics in terms of stable radiation patterns, peak realized gain of 4.5 dBi, and maximum total efficiency of 81% are achieved in the pass-band. In the notchedband, the peak gain and total efficiency reduce to −1.3 dB and 40%, respectively. Measured results agree well with simulated results. This antenna structure has fractional bandwidth of 115.18% and a bandwidth dimension ratio of 3029, which is comparable or better than that of similar structures available in the literature. The proposed antenna has desirable time-domain performance in terms of fidelity factor, group delay, isolation, and S 21 phase.

A new miniaturized ultra‐wideband antenna with sufficient dual‐band rejection in WiMAX and WLAN bands is reported. The antenna uses the conventional rectangular patch radiator with built‐in sectorial and Inverted‐U slots to achieve the required dual‐band rejections. A coplanar waveguide feed line has been used to achieve the ultra‐wideband operation. The design has been implemented on 1.6 mm thick FR‐4 substrate. The design size is 20 × 26 mm2 (0.16 λL × 0.208 λL in terms of wavelength). An impedance bandwidth of 2.4 GHz to 10.5 GHz has been achieved. Pass‐band gain of 7 dBi and stop‐band gain of −4 dBi have been achieved. Experimental results agree well with simulated results.