Ultra-wideband Bandwidth Research Articles

Effect of depth and soil moisture on buried ultra‐wideband antenna

Ultra-wideband (UWB) wireless underground sensor networks consist of wirelessly connected underground sensor nodes that communicate through the soil. Performances of buried antennas and of the communication link depend on the soil dielectric characteristics. The effects of soil moisture and depth, in the frequency band of 3.1–10.6 GHz, on an UWB antenna return loss and bandwidth are presented. The measurements are conducted in two different types of soil: sandy soil and railway pebbles. The experimental results show that burying antenna shifts down its bandwidth. This phenomenon is accentuated by the increase of soil moisture and not impacted by the burial depth variations. In a dry sandy soil, the shift of the bandwidth low-end is of 0.75 GHz, while it is 1 and 1.5 GHz at 5 and 20% soil moisture, respectively. This fact has allowed us to further miniaturise the used antenna.

Modified hexagonal Sierpinski gasket-based antenna design with multiband and miniaturized characteristics for UWB wireless communication

A modified hexagonal Sierpinski gasket-based fractal antenna is proposed for ultrawide-band (UWB) wireless applications. The designed antenna has miniaturized (36 $\times $ 48 mm$^{2})$ and multiband characteristics. Two design guidelines, the partial ground plane technique and the circular annular ring patch on the substrate, are applied to improve impedance matching and radiation pattern characteristics. According to the simulation results, the proposed modified antenna has a reflection coefficient $S_{11} $ of less than --15 dB, a linear phase of the reflection coefficient, 80{\%} radiation efficiency, 2--4.5 dBi antenna gain, and omnidirectional radiation pattern properties over the full UWB spectrum (3.1--10.6 GHz). Simulated results obtained for this antenna show the expected good radiation behavior within the full 7.5-GHz UWB bandwidth.

A NEW PRINTED MICROSTRIP UWB POWER DIVIDER WITH NOTCHED BAND

In this paper, a new printed ultra-wideband (UWB) power divider with notched band using square ring multiple-mode resonator (SRMMR) is presented. The characteristics of the proposed SRMMR are investigated by using even- and odd-mode analysis. Then, the initial UWB performance is achieved by introducing SRMMR to the basic Wilkinson power divider. Finally, a pair of parallel coupled lines is embedded into the SRMMR to achieve a desired notched band inside the UWB passband. The central frequency and the bandwidth of the notched band can be easily controlled by the electrical length and coupling coefficient of the coupled lines. To validate the design concept, a novel printed UWB power divider with notched band centered at frequencies of 5.8 GHz is designed and measured. The simulated and measured results indicate that it has a low insertion loss and good return loss performance at all the three ports, and a high isolation between the two output ports across the UWB bandwidth from 3.1 to 10.6 GHz with a small size of 0.46λg × 0.69λg ,w hereλg is the guided wavelength at 6.85 GHz.

Continuously tunable band‐notched ultrawideband antenna

ABSTRACTA compact coplanar wave guide ‐fed elliptically tapered ultrawideband (UWB) antenna with a tunable narrow rejection band of 0.195 GHz with tunable range (5.07–5.83) GHz is presented. The proposed antenna consists of elliptically tapered patch, elliptically tapered and truncated ground plane to achieve the UWB bandwidth. A quarter wavelength stubs loaded with a varactor diode has been used to tune the notched band. The proposed antenna has been fabricated on low cost FR4 substrate with dimensions as (24 × 30 × 1.524) mm3. Both the frequency domain as well the time domain performance characterization have been carried out and discussed. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:924–928, 2015

Ultrawideband reflection-mode optoacoustic mesoscopy

We developed a reflection-mode optoacoustic mesoscopy system, based on raster-scanning of a custom designed spherically focused ultrasound detector, enabling seamless epi-illumination of the volume imaged. We study the performance of acoustic-resolution mesoscopy operating at an ultrawideband bandwidth of 20-180 MHz. i.e., a frequency band spreading over virtually an order of magnitude. Using tomographic reconstruction we showcase previously unreported, to our knowledge, axial resolutions of 4 μm and transverse resolutions of 18 μm reaching depths of up to 5 mm. We further investigate the frequency-dependence of features seen on the images to understand the implications of ultrawideband measurements. We show the overall imaging performance and the frequency ranges that contribute to observable resolution improvements from phantoms and animals.

Substrate-perforated and compact ultra-wideband antenna with WLAN band rejection

This paper presents a designed notched band ultra-wideband (UWB) printed antenna using coplanar waveguide-fed configuration. Simple technique of perforating the substrate and modifying the ground plane and radiator patch was used to achieve UWB for the designed antenna at smaller structure. Narrow arch-shaped slot was introduced to the patch of the proposed antenna to obtain the band rejection function around the 5.4 GHz frequency to avoid the interference with WLAN applications. The proposed antenna was fabricated and the measurement result is found in well agreement with the simulation result. In addition to the acquirable UWB bandwidth, the designed antenna is capable to exhibit high radiation efficiency and omni-directional pattern.

Band‐notched UWB rectangular dielectric resonator antenna

A new ultra-wideband (UWB) rectangular dielectric resonator antenna (DRA) with band-stop performance is proposed. Two symmetrical short-circuited strips together with a slot etched in the feeding patch are introduced to form the notched band. The design principles of the proposed methods are described in detail. The measured result demonstrates that the proposed DRA achieves an UWB bandwidth from 3.6 to 12 GHz for a voltage standing wave ratio <;2 with a notched band from 5.1 to 6.0 GHz.

Printed Newton's egg curved monopole antenna for ultrawideband applications

The edge curve of a planar antenna significantly influences its radiation properties. In this study, a novel egg curve-based design of printed monopole antenna of size 40 × 40 mm2 is proposed for ultrawideband (UWB) applications. The egg shape of the proposed antennas is obtained by Newton's diverging parabolas curve referred in this study as Newton's egg curve. The design equations of the proposed antenna are developed. The variation in impedance bandwidth (BW) with various parametric variations of design curve is studied. The proposed Newton's egg curved monopole antenna (NECMA) is designed, fabricated and measured to validate the theoretical design. Good agreement between the simulated results and the measured ones is observed. An empirical formula is also proposed to approximately determine the frequency corresponding to the lower edge of −10 dB operating BW. The results show that the proposed NECMA can obtain the measured BW of 116.55% (2.9–11.0 GHz) along with stable gain of about 2.2–2.9 dBi. The proposed antenna exhibits almost omnidirectional radiation patterns with low cross polarisation in all directions and consistent group delay over the entire UWB bandwidth (3.1–10.6 GHz).

Research on a Novel Folded Monopole With Ultrawideband Bandwidth

In this letter, a novel folded monopole antenna with an ultrawideband (UWB) bandwidth and omnidirectional radiation performance has been proposed. An inverted “S”-type structure was formed by folding the planar monopole, which not only realizes dimension reduction, but also contributes to a decrease in the size of the ground plane; the proposed monopole antenna, meanwhile, has a more circular radiation pattern with the frequency ratio of 3.4:1, compared to the planar monopole antenna. Simulation has been carried out together with the measurement of the fabricated antenna. Good agreement between the measured and simulated results can be observed, showing that the antenna is capable of working in the frequency range from 3.1 to 10.6 GHz with return loss less than -10 dB.

COMPACT UWB MIMO ANTENNA WITH ACS-FED STRUCTURE

A compact UWB (Ultrawideband) MIMO (Multiple-input multiple-output) antenna with asymmetric coplanar strip (ACS)-fed structure is proposed in this paper. The antenna consists of two modifled ACS feeding staircase-shaped radiation elements which are orthogonally placed, and the wideband isolation is achieved through a fence-like stub between them. The efiectiveness of the fence- like stub is analyzed. Measured results show that the presented antenna can achieve a broad impedance bandwidth (jS11j 6 i10dB) of 3.1{11GHz with good performance in terms of isolation > 15dB. Radiation patterns and correlation coe-cient (ECC) denote the consistent diversity performance across the entire UWB bandwidth. By introducing the ACS-fed structure, the antenna size can be considerably reduced to 43:5mm £ 43:5mm £ 1:6mm compared to the recently published UWB MIMO antennas, which makes the antenna suitable for portable UWB MIMO applications.

Energy Efficient Scalable Sub-band based Ultra-Wideband System

In this paper, a scalable sub-band ultra-wideband (S-SUWB) system is proposed. The technique provides scope for using the ultra-wideband bandwidth efficiently by exploiting the available link margin for short range communications with medium data rates. The bandwidth of 500 MHz or more is divided into a fixed number of sub-bands. The data transmission scheme over multiple sub-bands can be designed to achieve higher data rate or higher reliability while providing multiuser support in both uplink and downlink communications. The proposed system provides enhanced scalability by the efficient utilization of the code-frequency dimensions. Sub-banding in conjunction with orthogonal spreading code facilitates transmission of plurality of data streams within a sub-band and along sub-bands for each user. Very importantly, the proposed system incorporates methods at the receiver facilitating low power receiver designs. Primarily, S-SUWB enables reduced sampling rate receiver designs significantly reducing the power consumption. Also, the spreading code based sub-band selection method obviates the need for individual down-conversion and filtering of the sub-bands thus reducing the complexity. Moreover, an interference rejection filtering (IRF) method incorporated into the despreading process is proposed to improve the performance without significantly increasing the receiver complexity. The simulation results in terms of the bit error rate performance of the scalable multiuser S-SUWB transceiver for the IEEE 802.15.4a channel models are presented demonstrating the usefulness of the proposed scheme. Performance improvements with the use of the IRF and also multi-user results are presented. The results indicate the desirable performance is obtained using the energy efficient techniques for low and medium delay spread channels even without the use of any equalization method.

Planar ultra‐wideband antenna with five notched stop bands

A printed ultra-wideband (UWB) antenna with five notched stop bands is presented. By introducing a pair of arc-shaped slots, two defected ground structures and an open-loop resonator, five sharp notches are achieved at frequencies of 2.4, 3.2, 5.2, 5.8 and 7.5 GHz. The proposed antenna has been fabricated and tested. The measured results indicate that the proposed design not only supports UWB bandwidth requirements but rejects five narrow bands to avoid possible interference with existing communication systems. In addition, the proposed antenna has relatively omnidirectional radiation patterns in passbands.

Design of a new ultra wideband planar antenna for wireless communication systems

AbstractA new planar circular monopole antenna for ultra wideband (UWB) applications is presented. To achieve UWB characteristics, the proposed antenna is constructed by embedding the slot on the partial ground plane. The proposed antenna has been successfully simulated and measured. Experimental results indicate that the proposed antenna yields an impedance bandwidth of 2.3 up to 13 GHz with VSWR &lt; 2, which makes it suitable to operate not only for UWB bandwidth but also it can be used also for WLAN application. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1335–1338, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27584

A compact ultrawideband antenna with two band-notches

A compact ultrawideband (UWB) antenna with two band-notched characteristics is presented and investigated in this article.Two conformal U type slots are etched on the patch to generate two notched bands at 3.5 and 5.2–5.8 GHz, which contribute good rejection of interference with WiMAX (3.5 GHz) and wireless local area network (5.2–5.8 GHz), each of which can be controlled independently. The presented antenna can provide an UWB bandwidth with expected notched band, and it has omnidirectional radiation pattern and stable gain at working frequencies according to simulation and measurement results. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:583–586, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27369

Study of a Class of UWB CPW-Fed Monopole Antenna With Fractal Elements

This letter investigates a multiresonance technique to achieve ultrawideband (UWB) characteristics in a coplanar waveguide (CPW)-fed monopole antenna. It is found that by addition of small fractal elements at the corners of a polygon patch, standard UWB bandwidth can be covered while antenna dimensions are only 25 × 25 mm2. Parametric analysis is performed, and different shapes are added to the antenna as the fractal element in order to realize the multiresonance behavior. Fidelity factor of the antenna is greater than 0.92 in both elevation and azimuth planes. To validate the simulation results, prototypes of the proposed antenna are fabricated and tested.

Modified Hilbert fractal geometry, multi‐service, miniaturized patch antenna for UWB wireless communication

PurposeThe purpose of this paper is to describe a modified Hilbert‐based fractal antenna for ultra wideband (UWB) wireless applications. Simulation results show excellent multi‐band characteristics for UWB wireless applications.Design/methodology/approachA Hilbert curve‐based fractal is optimised for self‐replicating, space‐filling and self‐avoiding properties. In the proposed design, the Hilbert curve is applied to a rectangle as an initial iteration and maintained for the later iterations. Additionally, a Yagi‐like strip is removed from the second iteration of the Hilbert patch and a hexagonal portion is removed from the substrate to achieve good optimization. The antenna feed is created through a micro‐strip line with a feeding section. Finally, a partial ground plane technique is used for improved impedance matching characteristics. A finite element method (FEM) is used to simulate the modified Hilbert model with commercially available Ansoft HFSS software.FindingsThe proposed antenna is miniaturized (39 mm length×30 mm width) and has multi‐band characteristics. The simulation results show that the antenna has a reflection coefficient characteristic of &lt;−10 dB, a linear phase reflection coefficient, better than 65 percent radiation efficiency, 2.2‐4 dBi antenna gain and nearly omni‐directional radiation pattern properties over the UWB bandwidth (3.1‐10.6 GHz).Originality/valueThe antenna shows promising characteristics for the full 7.5 GHz UWB bandwidth. In addition, the performance is achieved by using laceration techniques on the Hilbert patch and substrate, respectively. A partial ground plane ensures impedance matching of 50 over full UWB bandwidth. The simulation analysis of the modified Hilbert fractal antenna design constitutes the main contribution of the paper.

Methods to improve the bandwidth performance for compact dielectric resonator antennas

Two techniques are implemented to improve the impedance matching and the bandwidth of ultrawideband (UWB) rectangular stacked dielectric resonator antennas (DRAs), making them more reliable for FCC UWB application.Cutting a groove on the bottom side of the dielectric resonator can improve the impedance matching within the UWB bandwidth, whereas a square metallic patch connected to a coaxial probe to excite the DRA can extend the entire UWB. Applying the two techniques together to the rectangular stacked DRA can both improve the impedance matching and the bandwidth, without compromising any performance. Theoretical and experimental verification for the two techniques are conducted. A prototype antenna that has a dielectric volume of 12 × 8 × 14.9 mm3 (or 0.124λ × 0.083λ × 0.152λ at 3.1 GHz) achieves a |S11| < −10 dB bandwidth of 111.2%, covering the entire FCC UWB bandwidth (3.1–10.6 GHz, 1:3.4 or 109.5%), and an average measured gain of 6 dBi over the band. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2252–2256, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27058

Planar Ultra-Wideband Antennas in Ku- and K-Band for Pattern or Polarization Diversity Applications

Two planar diversity antennas operating in Ku- (12.4-18 GHz) and K-band (18-26.5 GHz) are proposed for ultra-wideband (UWB) applications. Both of them consist of a monopole radiating element and two orthogonal feeding ports. Their ground planes are modified and optimized to improve the isolation as well as to control the radiation. The first one is a pattern diversity antenna with a disc monopole patch. The second one is a polarization diversity antenna based on a square patch which is able to provide both linear and circular polarizations. Different feeding approaches are adopted to obtain a broadband impedance matching. Two wideband couplers are designed to provide the required feeding circuit. Both the simulated and measured results are presented to verify the proposed idea. Good radiation efficiency and isolation between the two ports are achieved. Consistent diversity performance is observed across the whole UWB bandwidth which is demonstrated by their radiation patterns.

CPW-Fed Fractal Slot Antenna for UWB Application

A novel printed ultrawideband (UWB) CPW-fed Koch fractal slot antenna is proposed. The UWB bandwidth is largely enhanced by the three-iteration Koch fractal slot whose extrusive angle is 900 instead of 600 to obtain better convoluted shape and self-similarity. The −10 dB impedance bandwidth is 3400 MHz (1270–4670 MHz) or about 114% in comparison with 1290 MHz (1620–2910 MHz) or about 57% of the referenced square slot antenna. Details of the proposed antenna design and performance are presented and discussed.

넓은 방사 슬롯을 이용한 초광대역 안테나의 소형화와 Wi-Fi 대역의 노치에 관한 연구

In this paper, it is studied on wide radiating slot antenna`s miniaturization for ultra wide-band(UWB) technologies and notch structure to prevent interference between UWB systems and existing wireless systems for using Wi-Fi service of IEEE standards 802.11 a/n. Proposed antenna that wide slot is decreased from to length of resonant frequency has decreased by 72 % compared with conventional antenna. And optimized T-shaped CPW-fed stub has satisfied UWB bandwidth for 3.0~11.8 GHz. Then, creating 2-order Hilbert curve slot line in the stub`s patch area, 4.9~5.6 GHz that centered frequency is 5 GHz is eliminated. Finally, the designed antenna constructed on FR4-epoxy has dimension. The measured results that are obtained return loss under -10 dB through 3.2~11.8 GHz without Wi-Fi bandwidth, a linear phase characteristic, a stable group delay, and omnidirectional radiation patterns are presented.