Closed ring resonator (CRR)-based quad-band metamaterial absorber is presented. The unit cell of proposed absorber consists of four separate CRRs which are diagonally connected to square patches enclosed within an individual CRR. The structure is fabricated on 0.8 mmthick FR4 substrate. Simulated peak absorptivities of 98.5, 97.7, 94.8, and 96% are obtained at 4.34, 6.68, 8.58, and 10.64 GHz, respectively. The measured and simulated absorption characteristics of the proposed absorber are in good agreement. The proposed absorber is wide angle and polarisation insensitive and has identical absorption characteristics for both transverse-electric and transverse-magnetic polarised radiations.

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A novel compact end-fire antipodal Vivaldi antenna is proposed for ultra-wideband (UWB) applications such as in radars, microwave imaging and in high data rate wireless systems. To make the antenna compact, a bending feed line structure and sinusoidal modulated Gaussian tapered slot is used. The proposed antenna has a reflection coefficient of less than −10 dB from 2 GHz to more than 12 GHz (more than 166% fractional bandwidth). The radiation characteristics show an end-fire radiation pattern in the operating frequency band with peak realised gain values in the range of 1.5−5.2 dBi. Time domain analysis shows that the antenna has good pulse handling capability with a high system fidelity factor.

A metamaterial-based novel compact microstrip antenna is presented for ultra-wideband (UWB) applications. The antenna consists of two layers of metamaterials made by etching a π-shaped slot and crossed-shaped slots, on the radiating patch and the ground plane, respectively. The series capacitance and shunt inductance developed due to the patterned radiating patch and ground plane lead to the left-handed behaviour of the metamaterial. The proposed antenna has a compact size of 30.8 × 27.6 × 0.8 mm 3 and is fed by a 50 Ω microstrip line. The impedance bandwidth (−10 dB) is from 3 GHz to more than 14 GHz with maximum radiation in the horizontal plane and tends towards a directional pattern as the frequency increases.

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