A novel compact antenna for ultra-wideband application is investigated and presented. The proposed structure consists of a modified patch with rectangular parasitic elements at the top, whereas a defective ground plane is etched on the flame retardant FR-4 substrate at the bottom with a 50 Ω feed line. The magnitude of S₁₁ < −10 dB of the structure is 2.7–11 GHz which accounts for the fractional bandwidth of 121.1%. The overall volume of the structure has a compact dimension of 20 × 20 × 1.6 mm³. The gain and antenna efficiency of the structure are 3.34 dB and 79.8%, respectively. The structure exhibits stable radiations across the band of operation. Measured and simulated results of co and cross(X)-polarization are in relatively good agreement. All these properties suggest that the proposed structure finds its applications in WiMAX-band 3.5 and 5.5 GHz, WLAN-band 5.2 and 5.8 GHz, data links to satellites along with various other applications in the wireless communication field.

In this article, a dumbbell shaped microstrip broadband microstrip antenna with partial ground plane is presented, The overall dimension of the proposed antenna is 20 × 15 × 1.5 mm³ and is fabricated on FR4 substrate which has electrical permittivity of 4.3 and loss tangent of 0.025. FR4 is a low cost and easily available. The thickness of the substrate is 1.5 mm. The impedance bandwidth of the proposed antenna is 151.11 % (3.48 GHz to 25 GHz). The peak gain and radiation efficiency of the proposed antenna are 4.5 dB and 68 % respectively in the operating frequency band. Due to introduction of rings on the edges of the octagon and cutting of circular slots with the rectangular slits in the ground plane the antenna starts resonating from 3.48 GHz to 25 GHz. Simulated results are in good agreement with the measured results. The proposed antenna covers partial frequency range for ultra-wide band applications, 3.5/5.5 GHz WiMAX band, 5.2/5.8 GHz WLAN band, 8/12 GHz X-band, 12/18 GHz Ku -band. It can be used in space and satellite communications etc. Curves of radiation pattern and S-parameter of both simulated and measured results are shown. The impedance curves, surface current, radiation efficiency, simulated return losses, gain, and radiation patterns of the proposed antenna are described in the paper.