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In this work, a printed coplanar waveguide (CPW) fed single band antenna based on expanded graphite material is introduced. The proposed antenna is based on a CPW-monopole antenna with a U-shape conductor strip connected with the ground. Expanded graphite, a grade of graphene, is used as a conductor to design the uniplanar antenna over a flexible paper substrate. The antenna is designed for 2.4 GHz applications. The antenna design procedures are discussed. The material preparation and analysis are illustrated. Finally, the antenna fabrication and measurements of the reflection coefficient are discussed. The measured antenna reflection coefficient agrees with the simulated one, ensuring the antenna validity for serving the required applications. The radiation antenna parameters are discussed and simulated results from two-simulation software are included for comparison. The antenna has a simulated gain of 4 dBi and simulated efficiency of around 90% at 2.4 GHz. [ABSTRACT FROM AUTHOR]

This paper presents a compact dual-band filtering antenna without extra employing of filter structures. The antenna is designed using a planar dual-composite right/left-handed (D-CRLH) transmission line unit cell, where the filtering function is achieved through current cancellation between the D-CRLH resonators. The antenna is designed to function at 3.0 and 5.1 GHz, which can serve different WLAN applications. The antenna is a co-planar waveguide fed with a very compact size of only 30 × 16 mm2. Compared to the conventional patch antenna, the antenna size is only 17% at 3.0 GHz and 31% at 5.1 GHz. Despite the small size, the antenna preserves a good omni-directional radiation pattern at the two resonant frequencies with a measured realized gain of 2 and 2.7 dB, respectively. At the stopband in-between the two resonant bands, the reflection coefficient is almost 0 dB at 4.25 GHz and complete non-radiation is proved with a −11 dB measured realized gain. The different antenna filtering functions are verified by full-wave simulation and measurements. [ABSTRACT FROM AUTHOR]

Fifth‐generation millimeter‐wave devices with multiple antennas require minimal mutual interference for better overall performance. This article presents a simple but novel technique to improve the isolation between closely packed slot antenna arrays. A printed ridge gap waveguide (PRGW) structure is used to realize a low loss millimeter‐wave array's feeding mechanism. By optimally introducing a defective upper plate within the PRGW structure, the measured port isolation of the antenna elements is improved by 17 dB at 61.3 GHz. The antenna array is impedance matched to the feeding PRGW structure over a wide frequency range of 54–67 GHz. Moreover, the radiation patterns are consistent showing broadside radiation before and after introducing the defect in the PRGW structure. The fabricated prototype of the PRGW fed slot antenna array validated the predicted isolation and return‐loss bandwidths of the proposed radiating system. [ABSTRACT FROM AUTHOR]

Abstract This paper presents the experimental verification of the tunable characteristics of a ferrite composite right/left handed coupled line coupler. The coupler is designed using two coupled CRLH-CRLH transmission lines. The coupler is designed to demonstrate equal through and backward coupling. The novel coupler has been designed and realized in coplanar waveguide configuration on a ferrite substrate. The tunable characteristics are achieved by changing the applied DC magnetic bias to the ferrite substrate. The measurement results reveal that the coupler's fractional bandwidth can be tuned from 29% to 69% by varying the applied DC magnetic bias from 1000 Oe to 1750 Oe. Within the tunable bandwidth, the maximum backward coupling is −5 dB. The coupler has high forward coupling isolation, close to −30 dB at its centre operating frequency. In addition to its tuning capability, the coupler has the advantages of its compact size; it has the length of 11.5 mm and not-so-tight line separations of 2.5 mm. Furthermore the coupler only requires low DC magnetic bias. [ABSTRACT FROM AUTHOR]

ABSTRACT This article presents a new compact asymmetric coplanar strip -fed UWB MIMO antenna. The UWB MIMO antenna consists of two identical elements which have quarter elliptical ring radiating element with asymmetric coplanar strip-fed. By designing the antenna using asymmetric coplanar strip-fed, the antenna size can be reduced (its size is only 6 × 2.6 cm2). The distance between the two antenna elements equals 0.37 λ0-The single antenna element is operated at frequencies from 3.1 GHz to 10.6 GHz with reflection coefficient lower than −10 dB. In addition, the designed antenna elements have less than 15 dB coupling isolation between the two input ports. The diversity performance between two antenna elements such as envelope correlation coefficient and diversity gain are investigated and they are within their allowed limits. This analysis confirms that the designed antenna is suitable for portable UWB MIMO applications. The proposed antenna is designed; simulated and measured. There is a good agreement between the simulated and measured results. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:31-36, 2017 [ABSTRACT FROM AUTHOR]

The theoretical study and experimental results of a compact tunable left-handed (LH) zeroth order metamaterial ferrite resonator is presented. The resonator has been designed and realised using a LH coplanar waveguide transmission line on a ferrite substrate. The theoretical analysis of the operation principles of the resonator has been provided. The detailed measurement setup and experimental results are discussed. The resonator is only 0.19 λg (65% reduced in size comparing with conventional one) at 4 GHz. The resonator has fractional bandwidth of 0.1% and average insertion loss, approximately 4.5 dB. Moreover, the zeroth order metamaterial ferrite resonator has tuning capability and requires lower DC magnetic bias. [ABSTRACT FROM AUTHOR]

In this study, the authors present a novel compact non-reciprocal ferrite forward composite right-/left-handed (CRLH) coupled-line coupler (CLC). The proposed forward coupler is realised in coplanar waveguide configuration using series air gap capacitors and shunt planar segment inductors. A theoretical coupled mode analysis of a general non-ferrite CRLH forward CLC has been proposed. The mode analysis is then extended to ferrite CRLH forward CLC. The ferrite coupler's performance has been further analysed numerically and verified experimentally. Both numerical and experimental results have shown that the coupler demonstrates non-reciprocal operation for both forward coupling and through propagations. The coupler can achieve ~10 dB forward coupling and through levels with nonreciprocity isolation up to 30 dB. Moreover, the coupler has high backward coupling isolation better than 20 dB and very compact size with coupling length = 0.08 λ0 or (0.2 λg) at 8 GHz which is significantly smaller compared with any forward coupler reported to date in the similar operating frequency bands. Although, a conventional ferrite forward CLC can be non-reciprocal, it has long length, resulting in very high losses. This is not the case for the proposed CRLH coupler. Hence, the novelty and advantage of the coupler are its combined properties in compactness and nonreciprocity. Furthermore, the coupler requires very low external DC magnetic bias because of its much lower demagnetisation compared with the microstrip configuration. [ABSTRACT FROM AUTHOR]

This paper presents an ultra compact dual-band coplanar waveguide metamaterial filter based on generalized metamaterial transmission line. The detailed theoretical design steps of the filter are explained. The dual-band filter design performance has been validated using equivalent circuit modeling, electromagnetic full wave simulations, and practical measurement. The results illustrate the filter has dual passbands centered at 0.82 and 1.48 GHz with approximately 1 dB insertion loss and minimum 12 dB return loss. Good agreements between the circuit modeling, electromagnetic full wave simulations, and practical measurements are achieved. Moreover, the filter size is only (18 × 28 mm2) which is only less than (0.2λg × 0.31λg) at the center frequency of the first passband and (0.36λg × 0.56λg) at the center frequency of the second passband. [ABSTRACT FROM PUBLISHER]

This study presents, for the first time, a novel π - T generalised negative refractive index (NRI) transmission line (TL) configuration. It is innovated for increasing the possible passbands in designing microwave components. It is proved that the proposed transmission line can introduce up to seven passbands for completely unbalanced transmission line condition. The detailed mathematical analysis of that configuration based on the periodic network analysis and equivalent circuit model is introduced. As an application for the novel π - T generalised NRI TL configuration, a new compact triple band coplanar waveguide (CPW) metamaterial filter is introduced. The proposed triple bands CPW filter design steps are introduced and its performance is validated using equivalent circuit model simulation, electromagnetic full wave simulation and experimental measurements. Good agreements between the circuit modelling, electromagnetic full wave simulation and practical measurement results are achieved. All the results confirm that the proposed filter has triple passbands from 900 to 960 MHz, 1.4 to 1.48 GHz and 2.4 to 2.45 GHz. Moreover the filter size is compact whose length is only 12.1% λg at first passbands, 18.2 λg% at second passbands and 31.7 λg% at third passbands. [ABSTRACT FROM AUTHOR]