Entire Ultra-wideband Frequency Range Research Articles

Design of UWB Wearable Conformal Antenna for Body Area Networks

In this paper, a wearable ultra-wideband (UWB) micro-strip antenna is designed to meet the demand for Wireless Body Area Network (WBAN). This is a wearable textile antenna, which was formed on a jeans fabric substrate to reduce surface-wave losses. The single-fed circular strip monopole antenna provides good impedance matching over the entire UWB frequency range of 2.9∼10.6 GHz. The dielectric constant εr 2.2, and the loss tangent tan δ 0.04 of the jean substrates are measured by using the coaxial ring method. The proposed antenna consists of an improved circular radiation patch with the defective ground structure to expand the frequency band of the antenna and improve the radiation characteristics of the antenna with small dimensions of 20 × 30 × 1.4 mm3. In addition, structural deformation of the proposed antenna is performed to analyze the flexibility of the proposed antenna. The simulated SAR values follow the FCC limit, making it most suitable for wearable applications. Key Words: Antenna, S-Parameters, Far Field Directivity, Applications of Antenna, HFSS.

Gain enhancement of ultra-wideband hexagonal slot antenna using tessellated rhombic loops based reflector

Abstract A simple technique for gain enhancement of irregular hexagonal shaped ultra-wide band (UWB) slot antenna by inclusion of closely packed tessellated rhombic loop (TRL) based FSS is presented in this paper. The slot antenna is designed to cover entire UWB (3.1–10.6 GHz) frequency range with stable bi-directional radiation pattern. Also, it exhibits non-uniform boresight gain in zenith (θ = 0°) and nadir (θ = 180°) directions. The slot antenna is further loaded with TRL FSS at both slot and feed side separately to study distinct configurations of antenna integrated with FSS and evaluate the impact of the configurations of FSS on antenna performance. Later, an antenna and antenna loaded with TRL FSS prototype are developed for experimental validations. Through measurements it is found that the slot antenna covers entire UWB frequency band and provides a maximum of 4.31 dB gain in zenith direction while 4 dB gain in nadir direction. A gain enhancement of 2.44 dB in zenith and 3.8 dB in nadir directions are achieved when the slot antenna is integrated with TRL FSS along feed side and slot side separately. The measured results confirm the simulated results well.

Norman window slot antenna with sectoral feed backed by linear phase reflector for ultra wideband applications

An ultra wideband (UWB) slot antenna is proposed, developed, and experimentally validated in this article. The Norman window-shaped UWB slot antenna demonstrates stable radiation characteristics in both directions—zenith (θ = 0°) and nadir (θ = 180°) over the entire UWB frequency range (3.1–10.6 GHz) as observed in both simulations and experiments. A linear phase reflecting UWB frequency selective surface (FSS) is proposed by printing two orthogonal layers of pair of double rectangular loops on the same side of dielectric substrate as a merged frequency selective surface (MFSS). The UWB MFSS is then loaded with the slot antenna and the impact of MFSS on the impedance and radiation characteristics in different configurations of antenna and MFSS together is studied. One configuration with optimum solution is developed for experimental validations followed by the analysis of its radiation characteristics. The proposed antenna demonstrates a directional radiation pattern due to suppression of back lobe radiation when integrated with the UWB MFSS. The proposed antenna demonstrates maximum gain of 7.86 dB with a gain enhancement of 3.6 dB in boresight (θ = 0°) direction when MFSS is applied as a reflector to opposite side of the antenna slot.

Design of UWB Wearable Conformal Antenna Based on Jean Material

In this paper, a wearable ultra-wideband (UWB) microstrip antenna is designed to meet the demand for Wireless Body Area Network (WBAN). This is a wearable textile antenna, which was formed on a jeans fabric substrate to reduce surface-wave losses. The single-fed circular strip monopole antenna provides good impedance matching over the entire UWB frequency range of 2.9∼10.6 GHz. The dielectric constant ε r = 2.2, and the loss tangent tan δ = 0.04 of the jean substrates are measured by using the coaxial ring method. The proposed antenna consists of an improved circular radiation patch with the defective ground structure to expand the frequency band of the antenna and improve the radiation characteristics of the antenna with small dimensions of 20 × 30 × 1.4 mm 3 . In addition, structural deformation of the proposed antenna is performed to analyze the flexibility of the proposed antenna. The simulated SAR values follow the FCC limit, making it most suitable for wearable applications.

Low Noise Amplifier with Improved Gain and Reduced Noise-Figure in 90nm CMOS Technology

A CMOS low noise amplifier (LNA) for ultra-wideband (UWB) wireless applications is presented in this paper. The proposed CMOS low noise amplifier (LNA) is designed using common-gate (CG) topology as the first stage to achieve ultra-wideband input matching. The common-gate (CG) is cascaded with common- source (CS) topology with current-reused configuration to enhance the gain and noise figure (NF) performance of the LNA with low power. The Buffer stage is used as output matching network to improve the reflection coefficient. The proposed low noise amplifier (LNA) is implemented using CADENCE Virtuoso Analog and Digital Design Environment tool in 90nm CMOS technology. The LNA provides a forward voltage gain or power gain (S21) of 32.34dB , a minimum noise figure of 2dB, a reverse-isolation (S12) of less than - 38.74dB and an output reflection coefficient (S22) of less than -7.4dB for the entire ultra-wideband frequency range. The proposed LNA has an input reflection coefficient (S11) of less than -10dB for the ultra-wideband frequency range. It achieves input referred 1-dB compression point of 78.53dBm and input referred 3-dB compression point of 13dBm. It consumes only 24.226mW of power from a Vdd supply of 0.7V.

A Common-Gate Current-Reuse UWB LNA for Wireless Applications in 90 nm CMOS

In this paper, a CMOS low noise amplifier (LNA) for ultra-wideband (UWB) wireless applications is presented. The proposed CMOS LNA is designed using common-gate (CG) topology at the first stage to achieve ultra wideband input matching. The common-gate has been cascaded with common-source (CS) current-reused configuration to enhance the gain and noise figure (NF) performance of the LNA with low power consumption. In order to ensure maximum power flow from CG input stage to gm boosted CS current-reused stage, parallel-series LC matching has been used. The output-matching network is used to improve the output reflection coefficient. The LNA is designed using standard 90 nm CMOS process for 3.1–10.6 GHz UWB. It exhibits a power-gain (S21) of 19.2–20.8 dB, an NF of 2.3–3.7 dB, a reverse-isolation (S12) of less − 53.8 dB and an S22 of less than − 6 dB for the entire UWB frequency range. The proposed LNA has an input reflection coefficient (S11) of less than − 10.6 dB for 3.1–10.6 GHz. It achieves input 1-dB compression point (P1dB) of − 17 dBm at 6 GHz and input third-order intercept point (IIP3) of − 8 dBm, while it consumes only 5.05 mW of power from a Vdd supply of 0.7 V.

Performance and Analysis of UWB Aesthetic Pattern Textile Antenna for WBAN Applications

This article proposes a new aesthetic pattern-three petal flower patch antenna that operates at Ultra Wide Band (UWB) for Wireless Body Area Network (WBAN) applications. The flower structure consists of three petals and a center circle patch with the partial ground plane at the bottom. A double-sided copper-coated conductive fabric, which is 0.08 mm thick, having a surface resistivity of 0.05 Ω/square, serves as the antenna patch and ground material. This conductive patch is placed in a denim jeans material with 1mm thick that forms the substrate. The utilization of a two-layer substrate and partial ground method enhances the impedance bandwidth of the antenna. The size of the antenna is 60 mm × 60 mm × 2.16 mm. The reflection coefficient, gain, efficiency, radiation pattern, and effects of bending were the various parameters analyzed for the flower antenna. The antenna radiates from 3 to 12 GHz, which covers the entire UWB frequency range from 3.1 to 10.6 GHz assigned by Federal Communications Commission (FCC). The measurement results validate the performance of a flower patch antenna.

Compact UWB FSS reflector for antenna gain enhancement

In this study, two compact ultra-wideband (UWB) frequency selective surface (FSS) reflectors, which combine the branch loading method with the design of the traditional FSS, are proposed for antenna gain enhancement application. The working mechanism of the proposed FSS reflectors is analysed by the equivalent circuit model. The first FSS reflector, which is a 10 × 10 array with 8.25 mm × 8.25 mm unit size, not only enhances the gain of the UWB antenna, but also guarantees a constant gain with only 0.5 dB variation across the whole operation band. To further reduce the reflector size, a more compact FSS reflector with 6.25 mm × 6.25 mm unit size is designed by printing similar patterns on both sides of a single-layer dielectric slab. Compared to the first structure, the second reflector can realise a 25% size reduction and the same gain variation in the entire UWB frequency range. The only compromise is a 0.5 dB gain decrease. Finally, a good agreement between the measured and simulated results proves the feasibility of the authors' design.

A Compact UWB Antenna with Independently Controllable Notch Bands.

A minimally-sized, triple-notched band ultra-wideband (UWB) antenna, useful for many applications, is designed, analyzed, and experimentally validated in this paper. A modified maple leaf-shaped main radiating element with partial ground is used in the proposed design. An E-shaped resonator, meandered slot, and U-shaped slot are implemented in the proposed design to block the co-existing bands. The E-shaped resonator stops frequencies ranging from 1.8–2.3 GHz (Advanced Wireless System (AWS1–AWS2) band), while the meandered slot blocks frequencies from 3.2–3.8 GHz (WiMAX band). The co-existing band ranging from 5.6–6.1 GHz (IEEE 802.11/HIPERLANband) is blocked by utilizing the U-shaped section in the feeding network. The notched bands can be independently controlled over a wide range of frequencies using specific parameters. The proposed antenna is suitable for many applications because of its flat gain, good radiation characteristics at both principal planes, uniform group delay, and non-varying transfer function () for the entire UWB frequency range.

Compact wearable MIMO antenna with improved port isolation for ultra‐wideband applications

In this communication, a compact two-element ultra-wideband (UWB) wearable multiple-input multiple-output (MIMO) antenna with high port isolation is presented. The proposed structure is composed of jeans material in which an ‘8’ shaped stub is placed on the middle position of the antenna backside and connected to the partially suppressed ground structure to improve the port isolation characteristics. The antenna covers the frequency range from 2.74 to 12.33 GHz (about 127.27%) with the port isolation of >26 dB over the entire UWB frequency range. The envelope correlation co-efficient is found to be <0.025 with a high diversity gain (DG>9.9) throughout the complete operating band. The channel capacity loss for the proposed MIMO antenna is <0.13 bit/s/Hz. The imprinted optimised UWB MIMO antenna covers the area size of 55 × 35 mm2. The performances of the proposed antenna by the simulation and experimentation equally designated it a blameless candidate for the UWB applications.

Band notched self complementaryultra wideband antenna for wireless applications

This paper presents a band notched WLAN self complementaryultra wide band antenna for wireless applications. The proposed antenna encounters a return loss (RL) less than -10dB for entire ultra wideband frequency range except band notched frequency. This paper proposes a hexagon shape patch, edge feeding, self complementary technique and defective ground structure. The antenna has an overall dimensionof 28.3mm × 40mm × 2mm, builton substrate FR4 with a relative dielectric permittivity 4.4. And framework is simulated finite element method with help of high frequency structured simulator HFSSv17.2.the proposed antenna achieves a impedance bandwidth of 8.6GHz, band rejected WLAN frequency range 5.6-6.5 GHz with vswr is less than 2.

DESIGN OF A PLANAR UWB ANTENNA WITH BAND REJECTION

This paper is oriented on the design of a planar Ultra-Wideband (UWB) antenna covering the entire UWB frequency range with band-rejection of (5.18 – 6.10 GHz) to avoid the interference with other existing wireless communication systems like WLAN and WiMAX. The band-rejection has been performed by adding a slit to the circular radiating patch transversely to the direction of current flow with a length tuned to the effective half-wavelength which is opposite to the center of rejected band (5.5 GHz). The length of the added slit has been chosen according to a suggested formula unlike other previous works done by trial and error method. CST software package has been used to simulate the designed antenna. Simulation results have shown that this antenna obeys the UWB requirements with a reduction in its gain at the rejection band. Practical implementation has also been performed and measurements confirm the design and simulation results.

Structure and EM‐driven design of novel compact UWB slot antenna

In this study, a structure and design optimisation procedure of a novel compact ultra-wideband (UWB) slot antenna has been presented. In order to achieve small size of the structure and maintain acceptable electrical performance, a sufficiently large number of geometry parameters have been introduced. These include a stepped-impedance feed line and a meandered slot with all of dimensions being parameterised and subject to optimisation. All parameters are simultaneously adjusted using automated electromagnetic (EM)-simulation-driven optimisation algorithm. The design process is oriented towards explicit size reduction of the antenna structure. Penalty function approach is utilised to control the reflection response. In order to reduce the computational cost of the optimisation process, variable-fidelity EM models are utilised. The footprint of the optimised antenna is only 8.93 × 17.9 mm (160 mm2) while maintaining reflection below the –10 dB threshold in the entire UWB frequency range. The antenna has been favourably compared with the state-of-the-art compact structures in terms of the size. The obtained numerical results are supported by measurements of the fabricated antenna prototype.

A compact octagonal fractal UWBMIMO antenna with WLAN band‐rejection

ABSTRACTIn this article, a compact octagonal‐shaped fractal ultrawideband (UWB) multiple‐input‐multiple‐output (MIMO) antenna is presented and its characteristics are investigated. The application of Koch fractal geometry at the edges of octagonal monopole provides desired miniaturization and wideband phenomena due to its self‐similar and space filling properties. The two octagonal fractal antennas are placed orthogonal to each other and used to construct UWB MIMO antenna. An L‐shaped stub is used in the ground plane of the geometry to provide an improvement in the isolation. The band rejection in wireless local area network band is achieved by etching a C‐shaped slot from the monopole of the individual antenna. The compact dimension 40 × 25 mm2 of the antenna exhibits nearly omnidirectional radiation pattern, a low envelope correlation coefficient (&lt;0.01), with good S‐parameters over the entire UWB frequency range. The measured results show good agreement with the simulated one. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1919–1925, 2015

A compact octagonal-shaped fractal UWB antenna with Sierpinski fractal geometry

In this letter, a compact ultrawideband (UWB) antenna using Sierpinski fractal geometry is presented and its characteristics are investigated. The miniaturization and wideband phenomena are attained due to introduction of Sierpinski fractal geometry in the UWB antenna design. The proposed antenna has a compact dimension of 25 × 16 mm2. It exhibits nearly omnidirectional radiation pattern, good return loss with good time domain response in terms of fidelity factor (>0.86) over the entire UWB frequency range. The presented prototype is fabricated and it demonstrates good measured characteristics with the simulated one. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:570–574, 2015

Ultra-Wideband $$4\times 4$$ 4 × 4 Butler Matrix Employing Trapezoidal-Shaped Microstrip-Slot Technique

A design of compact and inexpensive two-layer ultra-wideband (UWB) $$4~\times ~4$$4×4 butler matrix beam-forming network employing trapezoidal-shaped microstrip-slot technique is presented in this paper. The proposed design uses multi-layer technology that allows having compact size and broad bandwidth. The proposed $$4\times 4$$4×4 butler matrix configuration consists of four couplers and two phase shifters without using crossovers. Both couplers and phase shifters use trapezoidal-shaped broadside coupled patches and a rectangular slot created in a common ground plane of two Rogers duroid RT5880 dielectric substrates. The simulations and experimental results show a good performance in terms of transmission magnitudes and phases with good return losses and isolation characteristics across the entire UWB frequency range. To demonstrate the functionality of the designed butler matrix, four identical tapered slot antenna (TSA) elements are connected to four output ports of the butler matrix and the radiation pattern characteristics are simulated, presented and discussed.

Hexagonal fractal ultra‐wideband antenna using Koch geometry with bandwidth enhancement

In this study, a design approach to achieve multiresonance phenomena in ultra-wideband (UWB) bandwidth using fractal geometry is investigated. The introduction of Koch fractal geometry in monopole as well as in the ground plane of the antenna generates additional resonances, which helps to achieve entire UWB operational bandwidth. Therefore the bandwidth is increased up to 122%. Moreover, the fractal nature of the antenna also facilitates to obtain the stable radiation pattern. The compact dimension 31 mm × 28 mm of the antenna exhibits nearly omnidirectional radiation pattern, with good reflection coefficient over the entire UWB frequency range. The proposed prototype is fabricated and its measured results are in good agreement with the simulated one. The time-domain analysis of the antenna is performed and it is found that fidelity factor is better than 0.81, which shows good pulse preserving capability of the antenna.

A multinotched octagonal shaped fractal UWB antenna

ABSTRACTIn this article, a simple design approach for small ultrawideband (UWB) antenna is presented. The small size and wideband operability is obtained by introducing Minkowski like fractal geometry in the design. It is observed that addition of fractal elements at the edges of octagonal shape leads to wideband phenomena. Furthermore, the insertion of multiple notches in the ground plane improves return loss characteristic in the desired UWB operational bandwidth of 3.1–10.6 GHz. The compact 16.5 × 13.5 mm2 antenna geometry size exhibits nearly omnidirectional radiation pattern, with VSWR &lt; 2 over the entire UWB frequency range. The optimized antenna is fabricated and measured using vector network analyzer. The measured characteristics are in good agreement with the simulated one. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2469–2473, 2014

Ultra‐wideband antenna using Minkowski‐like fractal geometry

ABSTRACTIn this letter, a Minkowski‐like fractal geometry‐based ultra‐wideband (UWB) monopole antenna is proposed and investigated. The radiator of the antenna is designed using similar segments of the Minkowski‐like structure. The multiple resonance phenomena of fractal geometry are utilized in the proposed structure to obtain the wideband operability by repetition of similar segments in the radiator structure of the antenna. The self‐similar nature of this geometry provides higher effective antenna length and wide operating bandwidth. The multiple slots are introduced in the ground plane to improve the reflection coefficient over the entire UWB frequency range. The proposed antenna has an optimized dimension of 23.5 × 26.5 mm2 and shows the operating bandwidth from 1.4 to 10.4 GHz. The proposed design is fabricated, and its measured result shows good agreement with the simulated one. The proposed antenna exhibits nearly omnidirectional radiation pattern, proper impedance matching over the entire UWB frequency range. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2273–2279, 2014

Compact ultra‐wideband diversity antenna with a floating parasitic digitated decoupling structure

A compact planar ultra-wideband (UWB) multiple-input–multiple-output antenna array with two radiating elements is proposed in this work. Elements separation is kept at 5.5 mm and the isolation is achieved with a floating parasitic decoupling structure not known for UWB diversity antennas previously. The antenna system performs very well over the entire UWB frequency range of 3.1–10.6 GHz. The mutual coupling between the radiating elements is below −20 dB in most of the band. The decoupling structure is investigated in detail and the diversity analysis of the antenna in Rayleigh fading environment for indoor and outdoor propagations is also presented by computing envelope correlation coefficients. The proposed antenna array measures 33 × 45.5 mm2 only and it is suitable for handheld devices, personal digital assistant (PDA)s, next generation home entertainment systems and robots.