This paper presents a novel fractal defected ground structure (FDGS) to reduce mutual coupling between coplanar spaced microstrip antenna elements. The structure of the proposed FDGS is studied. Bandgap characteristic of second and third iterative FDGS is achieved. The second and third iterative FDGSs are used to reduce mutual coupling between microstrip antenna elements. Mutual coupling reduction performance of third iterative FDGS is better than that of second iterative FDGS. And dimension of FDGS can be decreased by using higher level iterative FDGS. The third iterative FDGS is fabricated and measured. Simulated and measured results both show that more than 35-dB mutual coupling reduction is obtained by using the third iterative FDGS. Moreover, the envelope correlation of antenna elements with FDGS is quite smaller than that of antenna elements without FDGS.

Mutual Coupling Reduction by Novel Fractal Defected Ground Structure Bandgap Filter

A novel S-shaped periodic defected ground structure (PDGS) is proposed to reduce mutual coupling between antenna elements. Coplanar placed antenna elements work at the same frequency band with centre frequency 2.57 GHz. Centre-to-centre distance between the antenna elements is 50 mm which is ~0.43λ. The PDGS is three S-shaped defected ground structure units placed between microstrip antenna elements. By using the proposed PDGS, more than 40 dB mutual coupling reduction between microstrip antenna elements is achieved.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/el.2016.0667

S-shaped periodic defected ground structures to reduce microstrip antenna array mutual coupling

This article presents the design and the realization of a tri-band shared-aperture antenna operating at 2.4, 5.2, and 60 GHz. It puts these three bands of antennas within the same radiating aperture and then realizes the Wi-Fi application with MIMO function and the Wi-Gig application with beam-scanning function simultaneously. It consists of two dual-band printed inverted-F antennas (PIFAs) and two SIW leaky wave antennas. By using the structure-reused technology, PIFA for the Wi-Fi application and the SIW antenna for the Wi-Gig application can share the same radiator without adding an extra aperture area. Thus, the ratio of the radiating aperture utilization can be improved greatly. In addition, MIMO technology is also applied to the Wi-Fi antenna design. The envelope correlation coefficients (ECCs) calculated from the simulated and measured data are all lower than 0.04. The measured radiation efficiencies are 74% to 95% and 76% to 95% within these two bands, respectively. Moreover, due to the optimal layout of the whole design, the Wi-Gig antenna can obtain high gain and wide range of beam coverage at the same time. The measured peak gain is 12.29 dBi, and the beam coverage is ±36° from 57 to 64 GHz.

A Tri-Band Shared-Aperture Antenna for (2.4, 5.2) GHz Wi-Fi Application With MIMO Function and 60 GHz Wi-Gig Application With Beam-Scanning Function

Inkjet printing is an established technology that has been revisited in recent years for the low-cost and easy production of electrical sensing and biosensing systems. With this technique, it is possible to produce flexible microsystems on eco-compatible substrates such as polymers and paper. In this sense, we investigated the printing performances of a common office inkjet printer and of a commercial conducting ink, to produce aptamer-based electrochemical biosensors for antibiotics detection. During our analysis we characterized both the morphological and electrical properties of the printed electrodes, considering also their stability over time and tuning all the parameters to obtain reproducible micrometric systems. The produced devices proved to be able to undergo aptamer functionalization and to detect Ampicillin, a common used antibiotic, in few minutes with a LOD of 10 μg/ml in milk. Therefore, in this preliminary work we demonstrated the feasibility of low-cost customized inkjet-printed biosensors, and their possible use to prevent both antibiotic contaminations and antibiotic resistance development.

Silver nanoparticles inkjet-printed flexible biosensor for rapid label-free antibiotic detection in milk

A compact dual-band dual-polarized wearable antenna for on-body communication in the 2.45 and 5.8 GHz ISM bands is presented. The antenna is linearly polarized (LP) at 2.45 GHz and circularly polarized (CP) with the conical pattern at 5.8 GHz, which is suitable for the multisensor link network. By using the characteristic modal analysis initially, the ground plane has been miniaturized and optimized to radiate an omnidirectional beam in the horizontal plane with the excitation of the $\lambda $ /4 resonant mode. The higher order band at 5.8 GHz has been realized by the excitation of the $3\lambda $ /4 resonant mode of the same L-shaped slot. These two odd-order modes radiate horizontally polarized omnidirectional patterns. The combination of the vertical polarization generated from the top-loaded patch antenna along with the $3\lambda $ /4 mode from the L-shaped slot resulted into omnidirectional CP in the 5.8 GHz band. Furthermore, enhancement in axial ratio bandwidth is achieved with the addition of dielectric superstrate over the feed layer. Bending sensitivity study to emphasize for conformal applications, transmission loss along with specific absorption rate analysis has been performed for on-body characterization. The simulated and measured results are found to be in good agreement.

A Compact Dual-Band Dual-Polarized Omnidirectional Antenna for On-Body Applications

Recent wearable health monitoring systems use multiple biosensors embedded within a wireless device. In order to reliably transmit the desired vital signs in such systems, a new set of antenna design requirements arise. In this paper, we present a flexible, ultra-low profile, and compact dual band antenna. The proposed design is suitable for wearable and flexible telemedicine systems and wireless body area networks (WBANs). The antenna is inkjet printed on a 50.8µ mP olyimide Kapton substrate and fed by a Coplanar Waveguide (CPW). The proposed design has the merits of compactness, light weight, wide bandwidth, high efficiency, and mechanical stability. The performance of the antenna is also characterized against bending and rolling effects to assess its behaviour in a realistic setup since it is expected to be rolled on curved surfaces when operated. The antenna is shown to exhibit very low susceptibility to performance degradation when tested against bending effects. Good radiation characteristics, reduced fabrication complexity, cost effectiveness, and excellent physical properties suggest that the proposed design is a feasible candidate for the targeted application.

/pdf/a-compact-dual-band-polyimide-based-antenna-for-wearable-and-ut0uae25js.pdf

A Compact Dual Band Polyimide Based Antenna for Wearable and Flexible Telemedicine Devices

Fractal geometries are attractive for antenna designers seeking antennas with compact size and multiband resonant behavior. This paper presents the design of a new microstrip-fed printed slot antenna for use in dual-band wireless applications. The slot structure of the proposed antenna is in the form of Cantor square fractal geometry of the second iteration. The slot structure has been etched on the ground plane of a substrate with relative permittivity of 4.4 and 1.6 mm in thickness. A parametric study is conducted to explore the effects of some geometrical parameters on the antenna performance. Results show that the antenna possesses a dual-band behavior with a wide range of resonant frequency ratio. In addition to the ease of fabrication and simple design procedure, the antenna offers desirable radiation characteristics. A prototype of the proposed antenna has been simulated, fabricated, and measured. The measured 10 dB return loss bandwidths for the lower and the upper resonant bands are 42% (2.35–3.61 GHz) and 20% (5.15–6.25 GHz), respectively. This makes the proposed antenna suitable to cover a number of operating bands of wireless systems (2.4 GHz-Bluetooth, 2.4 GHz ISM, 2.4/5.8 GHz-WLAN, 3.5 GHz-WiMAX, and 5.8 GHz-ITS).

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S1759078714001469

Cantor fractal-based printed slot antenna for dual-band wireless applications

This paper presents the design of a new Co-Planar Waveguide (CPW) fed dual band printed slot antenna with enhanced bandwidths for use in wireless applications. The fractal based slot structure of the proposed antenna is in the form of Peano fractal curve of the second iteration as being applied to the two sides of a rectangular slot. The proposed antenna is to be etched using a substrate with relative permittivity of 4.4 and thickness of 1.6 mm. The resulting antenna has overall dimensions of 36 mm × 45 mm which is suitable for mobile terminal applications. Modeling and performance evaluation of the proposed antenna have been carried out using the CST Microwave Studio. Simulation results shows that the proposed antenna offers dual -10 dB impedance bandwidths of more than 1.2 GHz and 1.4 GHz for the lower and the upper bands respectively with corresponding average gains of about 2.5 dBi and 4 dBi throughout these bands. The first resonant band, centered at 2.50 GHz, extends from 1.91 to 3.11 GHz. This band covers the 2.4 GHz WLAN band (2.4-2.483 GHz) and the 2.5 GHz mobile WiMAX operating band (2.5-2.7 GHz), while the second resonant band, centered at 5.20 GHz; extends from 4.51 to 5.91 GHz. This band covers the U-NII mid-band (5.47-5.725 GHz) and U-NII high-band (5.725-5.875 GHz). Besides the compact size, the antenna offers reasonable radiation characteristics with omnidirectional radiation patterns in the two bands.

A compact Peano-type fractal based printed slot antenna for dual-band wireless applications

This paper presents the implementation of a fractal based defected ground structure DGS to reduce the interaction between two closely spaced planer monopole patch antennas. The design achieves a −7 dB reduction in mutual coupling level with antennas' edge to edge separation of λ o /25 over a bandwidth of 51.8 % (2 – 3.4) GHz in which the reflection coefficient is less than −10 dB and a realized total gain of 4.8 dB. The proposed structure is a good candidate for IEEE 802.11 WLAN applications operating at 2.4 GHz. The design and simulation results have been obtained using the commercial software High Frequency Structure Simulator (HFSS), Ver. 15.

Mutual coupling reduction between two monopole antennas using fractal based DGS

Recently, the ultra-wideband (UWB) systems have attracted much attention be- cause of its advantages including high speed data, small size, low cost, and low complexity. Consequently, the UWB antenna has received an increased attention due to its impedance band- width, simple structure and omni-directional radiation pattern. In this paper, the efiects of the ground plane of a printed monopole UWB antenna, fed with a 50› microstrip line, have been investigated. A Koch fractal based ground plane structure has been proposed as a means to enhance the UWB antenna performance. Difierent ground plane structures and feeding methods have been applied to a notched band monopole antenna structure that is a nearly square with embedded E-shaped slot. The proposed antenna has been supposed to be etched using a substrate with relative permittivity of 4.6 and thickness of 1.6mm. Modeling and performance evaluation of the presented antenna designs have been carried out using a method of moments based EM simulator, IE3D. Simulation results have shown that the antenna with Koch based ground plane and asymmetrical feed ofiers larger fractional bandwidth of about 124%. By this increment in the antenna bandwidth, it is expected that by suitable dimension scaling of the enhanced bandwidth UWB antenna, many communication services below 3.1GHz could be integrated with the UWB systems.

Ali I. Hammoodi

Papers

A Compact Dual Band Polyimide Based Antenna for Wearable and Flexible Telemedicine Devices

Cantor fractal-based printed slot antenna for dual-band wireless applications

A compact Peano-type fractal based printed slot antenna for dual-band wireless applications

Mutual coupling reduction between two monopole antennas using fractal based DGS

An ultra-wideband printed monopole antenna with a fractal based reduced ground plane