A microstrip line fed rectangular patch antenna with slots in the patch radiator is designed to realise triple resonant frequencies with satisfactory impedance matching (|S11|≤−10 dB) at 3.36, 5.96, and 9.09 GHz. Current distribution analysis is presented to provide an insight to the mechanism of triple resonance generation. A triple‐band artificial magnetic conductor (AMC) is designed and analysed based on resonance phenomenon of stepped impedance resonators. The resonant frequencies of the AMC coincide with the antenna. A rectangular split‐ring slot is embedded in the metallic ground of the antenna. The designed AMC is placed beneath the antenna maintaining an air gap between the structures. The slot in the ground plane enables the surface waves to interact with the AMC. The proposed arrangement enhances the gain from 1.38 to 3.77 dBi at 3.36 GHz, 3.22 to 6.29 dBi at 5.96 GHz, and 7.58 to 11.16 dBi at 9.09 GHz. The proposed structure exhibits good radiation patterns with low cross‐polarisation and high front to back ratio at all the three resonant frequencies. A prototype of the proposed structure is fabricated and the measured results are in good agreement with the simulated results.

This article presents the design of an ultra‐wideband monopole antenna with a gain enhanced performance using a novel double split ring metasurface reflector. A circular patch configuration is used here as the radiating element for the simplicity and reliability of such structures. The antenna radiates well beyond the ulta wideband (UWB) frequencies but the performance enhancement using double split ring Metasurface reflector is within UWB frequency. The periodic array of dual split ring patches with varying split angles placed in a columnar arrangement is responsible for the metasurface structure to reflect effectively in phase‐agreement over a broadband without affecting the impedance bandwidth of the principal radiator. With such a low profile setup (gap between antenna and reflector is in the order of at the lowest operating frequency of the antenna) the wideband gain‐enhanced characteristic makes the design versatile enough for numerous practical applications. A high increment in the antenna gain performance (nearly 5.5 dB) is recorded over the UWB frequency range. Experimental results are found to be in good agreement with the simulations. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:1296–1300, 2017

In this article, a planar, low profile microstrip line‐fed triple band multiple input multiple output (MIMO) antenna is presented for WiMax (2.5/3.5/5.5 GHz)/WLAN (2.4/3.6/5.8 GHz) applications simultaneously. The single element of the MIMO antenna consists of (i) a rectangular split ring resonator (SRR), (ii) a stepped impedance resonator (SIR) inside the SRR and (iii) a slot on the SIR. Each of the resonators generates its own individual band and each band is independently tunable. The antenna exhibits three operating bands at 2.35‐2.85 GHz, 3.25‐3.90 GHz and 5.45‐5.65 GHz. Four antenna elements are used to design the proposed MIMO antenna. The simulated results are observed and reported in terms of S‐parameters, gain, radiation patterns, envelope correlation coefficient (ECC), diversity gain (DG), channel capacity loss (CCL) and total active reflection coefficient. ECC and CCL are within the acceptable range defined for 4G and 5G application standards. To validate the simulation results a prototype structure is fabricated and the measured results are compared with those obtained from the simulation.

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Abstract-A broadband Perfect Metamaterial Absorber (PMA) on FR-4 Epoxy substrate for X-band and Ku-Band applications is proposed. The unit cell structure is composed of rectangular patches of appropriate shapes and orientation on top of the metal-backed dielectric substrate having a thickness of 2.7 mm (0.16λ L ). The relative absorption bandwidth is 79% (more than 85% absorption) covering the entire X-band and the Ku-Band of the microwave frequencies. The surface current distributions of the top and bottom planes have been analyzed to elaborate the absorption mechanism of the structure. The broadband characteristics of the design support its claim of being useful to a wide range of applications in both commercial and research sectors. Such applications include military and stealth devices, thermal sensors and electronic-cloaking devices.