Compact Ultrawideband Research Articles

Design and comparative analysis of compact flexible UWB antenna using different substrate materials for WBAN applications

In the present scenario, smart devices are using flexible wearable wireless technologies to enable interaction among people and their surrounding equipments. Due to the commercialization of these flexible electronic devices and systems, these systems require the integration of flexible antennas. The compactness and flexibility of the antenna are the major objectives of the current research. This paper highlights the comparative study of a small-sized swastika-shaped slotted patch ultra-wide-band (UWB) antenna. The designed microstrip patch antenna is simulated using Rogers RT 5880 as a substrate mounted on the partial ground structure. A rectangular substrate with a size of 24.56 × 22.48 mm × 1.575 mm is placed between the partial ground and patch. The dimensions of the radiating patch are 13 mm × 10.5 mm × 0.035 mm. The resonant frequencies of the designed antenna are 4.43 GHz and 8.84 GHz and have a large fractional bandwidth of 110% in the range of 3.1 to 10.7 GHz. The maximum observed gain and directivity of the proposed antenna are 5.9 dB and 6.8 dBi at 4.43 GHz. The simulation of the presented antenna design is performed in CST Microwave Studio 2018. The proposed antenna performance metrics are comparatively analyzed using different substrate materials like Rogers RT 5880, Jeans, and rubber substrates. The developed dual-band antenna can be useful for WBAN communication applications in the UWB band.

A Compact Eight-port CPW-fed UWB MIMO Antenna with Band-notched Characteristic

A compact eight-port coplanar waveguide (CPW)-fed ultra-wideband (UWB) multiple-input-multiple-output (MIMO) antenna with band-notched characteristics in a small size of 54×54×0.8 mm3 is proposed in this paper. The eight-port MIMO antenna consists of four two-port MIMO antennas. For each two-port MIMO antenna, two monopole antenna elements are printed on the FR4 substrate and placed perpendicularly to each other. To increase impedance bandwidth and improve the isolation, a stub is positioned in the middle of two radiating elements. The band-notched characteristic are achieved by etching two L-shaped resonator slots on each radiating elements, respectively. The S11 reflection coefficients, coupling isolation, radiation patterns, peak gain and radiation efficiencies of the MIMO antenna are measured. The MIMO performance of the proposed antenna is analyzed and evaluated by the envelope correlation coefficient (ECC) and total active reflection coefficient (TARC).

Compact Ultrawideband Antenna on Folded Ground Plane

A compact ultrawideband antenna on folded ground plane is proposed, which is a compact and low-profile structure. The proposed antenna mimics the operation of a unit element of the tightly coupled dipole array (TCDA) with modified boundary condition. The antenna does not have the PMC boundary required by the original TCDA, which makes the implementation and the impedance matching of the proposed antenna easy. All the design procedures are explained and confirmed by the EM simulation. The measured results show that the impedance bandwidth (IBW) is 0.72–3.43 GHz (130.6%) for the VSWR $\kappa \alpha $ ) of 0.82 at the lowest operating frequency and an overall dimension of $0.17\lambda _{\mathrm {low}} \times 0.17\lambda _{\mathrm {low}} \times 0.11\lambda _{\mathrm {low}}$ in terms of the wavelength at the lowest operating wavelength.

Isolation Improvement in UWB-MIMO Antenna System Using Slotted Stub

Multiple-input multiple-output (MIMO) scheme refers to the technology where more than one antenna is used for transmitting and receiving the information packets. It enhances the channel capacity without more power. The available space in the modern compact devices is limited and MIMO antenna elements need to be placed closely. The closely spaced antennas undergo an undesirable coupling, which deteriorates the antenna parameters. In this paper, an ultra wide-band (UWB) MIMO antenna system with an improved isolation is presented. The system has a wide bandwidth range from 2–13.7 GHz. The antenna elements are closely placed with an edge to edge distance of 3 mm. In addition to the UWB attribute of the system, the mutual coupling between the antennas is reduced by using slotted stub. The isolation is improved and is below −20 dB within the whole operating range. By introducing the decoupling network, the key performance parameters of the antenna are not affected. The system is designed on an inexpensive and easily available FR-4 substrate. To better understand the working of the proposed system, the equivalent circuit model is also presented. To model the proposed system accurately, different radiating modes and inter-mode coupling is considered and modeled. The EM model, circuit model, and the measured results are in good agreement. Different key performance parameters of the system and the antenna element such as envelope correlation coefficient (ECC), diversity gain, channel capcity loss (CCL) gain, radiation patterns, surface currents, and scattering parameters are presented. State-of-the-art comparison with the recent literature shows that the proposed antenna has minimal dimensions, a large bandwidth, an adequate gain value and a high isolation. It is worth noticeable that the proposed antenna has high isolation even the patches has low edge-to-edge gap (3 mm). Based on its good performance and compact dimensions, the proposed antenna is a suitable choice for high throughput compact UWB transceivers.

Compact Ultra-Wide-Band HI Monopole Antenna Loaded with C-Shaped Parasitic Elements for DVB-T and LTE Applications

In this study, a compact ultra-wide band microstrip antenna loaded with C-shaped parasitic elements, for Digital Video Broadcasting – Terrestrial (DVB-T) and LTE 450 / 700 signal reception, is presented. The proposed antenna is named “HI Monopole”, and its geometry has been designed to be simple and intuitive, lightweight, compact, possessing a low fabrication cost as well as an easy installation process inside electronic gadgets. The HI Monopole operates with ultra-wide bandwidth characteristics for operation within Digital Video Broadcasting – Terrestrial (DVB-T) standard, 470–890 MHz, that has been accomplished by: inserting an indent in its ground plane, adjusting the dimension of the feeding line, and adding two C-shaped parasite elements onto the region posterior to the antenna’s main irradiating element. It was verified through electromagnetic measuring that this device is capable of covering the 429-1022 MHz range, thus having 593 MHz of bandwidth. The superior and inferior cutoff frequencies have been chosen as the values in –10 dB of the device’s return loss. Therefore, the proposed antenna can be utilized in DTV and LTE signal reception through broadcasting in any country, independently of its adopted standard.

Design of Compact UWB Filter Using Parallel-coupled Line and Circular Open-circuited Stubs

This article encompasses the design of compact ultra-wideband (UWB) bandpass filter with low insertion loss and high selectivity using circular open-circuited stubs (COSs). Low insertion loss from two COSs and Multiple Mode Resonator (MMR) from three pairs of parallel-coupled lines are constituted to obtain the UWB band. The proposed filter has multiple resonant frequencies in the passband and two transmission zeros perceived at stop band/passband transition edges. It has a 3-dB fractional bandwidth of 110% and it covers the entire UWB band of 3.1–10.6 GHz. The measured passband insertion loss and group delay are 0.35 dB and 0.42 ns, respectively. Moreover, the presented filter is a single-layered structure since it is more comfortable to be integrated into a printed circuit board (PCB). The simulated and measured performance of the presented filter is in good agreement. The filter finds its application in low power handling single-layered PCBs, unlicensed short and medium distance communications.

A compact multi-band notched characteristics UWB microstrip patch antenna with a single sheet of graphene

A rectangular tuneable Ultra-wideband (UWB) Microstrip Patch (MP) antenna based on a Single Sheet of Graphene (SSG) is designed in this study. The antenna band can be tuned by applying a DC voltage bias perpendicular to the SSG at various values via adjusting the input impedance. The antenna has been analyzed by Computer Simulation Technology (CST) Microwave Studio (MWS) software using an FR4 substrate of thickness 1.6 mm with a dielectric permittivity =4.4 and loss tangent tan =0.02 fed by a 50 Ω microstrip line frequency. The design is compact since the antenna consists mostly of copper and the SSG. Graphene’s low weight, high flexibility, and strength make it more attractive than other semiconductor materials. Then, the study investigates the effects of applying the electrical characteristics of graphene to the antenna’s length, which varies with the ON and OFF states. This UWB MP antenna is also designed with notch characteristics so that it can reject undesired interference signals. Subsequently, this compact UWB MP antenna with tuneable resonance frequency is suitable for most wireless communication applications. The simulation results work in the 3.1 to 10 GHz range, as required for UWB technology.

Impact of Fidelity Factor on Breast Cancer Detection

Two compact ultrawideband antennas with different values of fidelity factors are introduced in this letter to study the impact of the fidelity factor on the tumor detection of microwave imaging systems. The design procedures are based on achieving the largest possible bandwidth. Antenna 1 (Ant. 1) and Antenna 2 (Ant. 2) have an overall size of 20 × 28 mm2 and 16 × 22 mm2, respectively. Two arrays of the proposed antenna are utilized for breast cancer detection. Two 12-element arrays of the antennas are located around a breast tissue model in two scenarios. The results show the promising performance of Ant. 2, which has a higher fidelity factor in detecting a 4 mm tumor. The investigation was also carried out on a clinical tumor model, and Ant. 2 successfully detected it.

A Tripolarized Antenna With Ultrawide Operational Bandwidth

In multiscattering environment, the channel capacity can be enhanced by employing dual-polarized antennas, and more significantly, using tripolarized antennas. Aiming at providing a wide coverage of both existing wireless communication systems and the new 5G sub-6 GHz band, this article presents a compact ultrawideband tripolarized antenna. The proposed design consists of a monopole-equivalent structure for vertically linearly polarized (LP) omnidirectional radiation and two orthogonal stepped dipoles for ±45° LP broadside radiation. Several important design features are proposed and implemented. The dipoles act as parasitic elements for the monopole structure, which broadens the monopole bandwidth and reduces the mutual coupling. Furthermore, the port isolation is improved by inserting two metallic posts between the crossed dipoles and the ground plane. The measured results indicate that the fabricated prototype achieves an overlapped bandwidth of 84.73% (1.68–4.15 GHz) for <−10 dB reflection coefficient and coupling value of <−30 dB among all ports. Tripolarized radiation is verified with pattern measurement, showing peak realized gains of 8.4 and 9.4 dBi in monopole and two broadside modes, respectively.

Design and analysis of a compact UWB MIMO antenna incorporating fractal inspired isolation improvement and band rejection structures

This paper numerically proposes and experimentally investigates a compact coplanar waveguide fed two element ultra-wideband (UWB), multiple-input–multiple-output (MIMO) antenna array accompanying peak isolation and triple band notch mechanism. The proposed antenna consists of two identical printed monopole elements along with the incorporation of multiple 2nd order Hilbert defects in the ground structure and proposes to incorporate three different mechanisms to reduce the electromagnetic interference of the UWB antenna with existing narrowband systems. The measured impedance bandwidth for the intended antenna ranges from 2.7 GHz to 11.22 GHz. The incorporation of notch mechanisms provides interference suppression at the C-band (3.7–4.2 GHz), WLAN (5.15–5.825 GHz), and X-band communication (7.9–8.4 GHz). The overall size of the intended UWB MIMO antenna is 30.75 mm × 37.80 mm. Moreover, the diversity parameters of the proposed UWB MIMO antenna are numerically calculated and empirically investigated, these calculations and investigations depicts high diversity performance. It is noteworthy to observe that the spacing between the elements is staggeringly reduced to 2 mm. The concurrence among the diverse numerical and experimental outcomes supports the candidature of the suggested layout for portable UWB as well as UWB MIMO systems.

Design of a compact UWB Wilkinson Power Divider using ring structured and tapered line matching transformer

There is an increasing interest in the design of ultra-wideband (UWB) microwave components for UWB applications. One of the important components in the ultra-wideband application is power divider. In this paper, an ultra-wideband Wilkinson power divider (WPD) using ring structure and tapered line matching transformer is proposed. The aims of this research are to design an UWB WPD for feeding antenna UWB in use of detecting breast cancer. The method used in this research is simulation using finite integration based on CST STUDIO SUITE 2015 3D EM simulator software. This study shows the improvement of output responses due to the introduction of a tapered line and added isolation resistors. The bandwidth and input reflection coefficient are also improved by the ring structure. The proposed UWB WPD can be used for 1:2-way equal power division application in ultra-wideband range, such as UWB antenna which is operating in frequency 3-13 GHz. The simulation result shows that the return loss is better than -10 dB and the insertion loss is about 3.2 dB until 4.15 dB for the operating frequencies and impedance value of 50 ohms.

A Compact Ultra Wide Band CPW Fed Fractal Antenna with a Tapered Ground Plane

A Compact Ultra Wide Band CPW Fed Fractal Antenna with a Tapered Ground Plane

A compact UWB monopole antenna with penta band notched characteristics

A modified rectangular monopole ultra-wideband (UWB) antenna with penta notched frequency bands is presented. An inverted U shaped and slanted U-shaped on the radiating patch are inserted to achieve WiMAX and ARN bands rejection respectively, two mirrored summation Σ-shaped and four mirrored 5-shaped slots are inserted on the partial ground to achieve WLAN and X-band bands rejection respectively, finally rectangular shaped slot with partially open on the feed is inserted to achieve ITU-8 band rejection. The proposed antenna which was simulated has a compact size 30×35×1.6 m3. It is operated with impedance bandwidth 2.8-10.6 GHz at |S11| < −10 dB, that supported UWB bandwidth with filtering the five narrowbands that avoid the possible interference with them. The simulated resonant frequency for notched filters received 3.55, 4.55, 5.53, 7.45, 8.16 GHZ, for WiMAX, ARN, WLAN, X-Band, ITU-8 respectively. The proposed antenna is suitable for wireless communication such as mobile communication and internet of everything (IoE). Throughout this paper, CST-EM software package was used for the design implementation. Surface current distributions for all notched filters were investigated and shown that it is concentrated around the feeding point and the inserted notched slots proving that there is no radiation to the space due to maximum stored electromagnetic energy around each investigated notch slot, proving that the slots play a role of a quarter wavelength transformer which generates for each notched band, maximum gain, and radiation pattern are also investigated.

An Octagonal Ring-shaped Parasitic Resonator Based Compact Ultrawideband Antenna for Microwave Imaging Applications.

An Ultrawideband (UWB) octagonal ring-shaped parasitic resonator-based patch antenna for microwave imaging applications is presented in this study, which is constructed with a diamond-shaped radiating patch, three octagonal, rectangular slotted ring-shaped parasitic resonator elements, and partial slotting ground plane. The main goals of uses of parasitic ring-shaped elements are improving antenna performance. In the prototype, various kinds of slots on the ground plane were investigated, and especially rectangular slots and irregular zigzag slots are applied to enhance bandwidth, gain, efficiency, and radiation directivity. The optimized size of the antenna is 29 × 24 × 1.5 mm3 by using the FR-4 substrate. The overall results illustrate that the antenna has a bandwidth of 8.7 GHz (2.80–11.50 GHz) for the reflection coefficient S11 < −10 dB with directional radiation pattern. The maximum gain of the proposed prototype is more than 5.7 dBi, and the average efficiency over the radiating bandwidth is 75%. Different design modifications are performed to attain the most favorable outcome of the proposed antenna. However, the prototype of the proposed antenna is designed and simulated in the 3D simulator CST Microwave Studio 2018 and then effectively fabricated and measured. The investigation throughout the study of the numerical as well as experimental data explicit that the proposed antenna is appropriate for the Ultrawideband-based microwave-imaging fields.

Compact UWB flexible elliptical CPW‐fed antenna with triple notch bands for wireless communications

A coplanar waveguide (CPW)-fed flexible elliptical antenna with triple band notched characteristics is presented in this article. The designed antenna consists of an elliptical patch and slots incorporated CPW feed line to cover the bandwidth requirements for ultra-wideband (UWB) applications. The designed UWB antenna has a fractional bandwidth of about 166.19% (1.20-13 GHz) with a center frequency of 7.1 GHz in simulation and about 170.10% (1.05-13 GHz) with a center frequency of 7.025 GHz in measurement. The overall dimension of the proposed flexible antenna is 45 × 35 × 0.6 mm3. The triple notched bands are realized by designing with circular shaped split-ring-resonators (SRRs) and defected ground structure (DGS). According to the measurement, first notched band (2.0−2.70 GHz) is generated for rejecting 2.4 GHz WLAN by introducing a single circular ST-SRR on the radiating patch. The second notch (3.45-3.80 GHz) is obtained by embedding another circular ST-SRR on the patch to mitigate the interference of 3.5 GHz Wi-MAX system. Finally, due to presence of DGS, third notch (5.15-6.20 GHz) is produced which suppresses the interference from 5.5 GHz Wi-MAX and 5.2/5.8 GHz WLAN systems. The proposed antenna offers excellent performance in different flexible conditions that confirm its applicability on curved surfaces for UWB systems.

Compact and low insertion loss UWB on‐chip bandpass filter using coupled meandered line

AbstractFor ultra‐wideband (UWB) communication applications, a low‐loss compact filter is proposed based on coupled lines using the GaAs integrated passive devices (IPD) technology in this letter. The multistage coupling lines are used to realize the ultra‐wide passband with 100% fractional bandwidth. Two modified stubs loaded with shorted capacitors are introduced between coupled lines to produce a new transmission zero near the lower passband edge, resulting in better frequency selectivity performance. Moreover, stepped impedance resonator (SIR) structure is applied to the coupled lines to improve impedance matching performance within ultra‐wide passband. As demonstrated, the proposed filter is fabricated as a chip with a compact size of 1.8 × 1.7 mm2, that is, 0.257 × 0.242 λg2. The measured results show that the insertion loss of the filter is less than 1.5 dB from 6 to 18 GHz with the return loss better than 13.5 dB. All simulated and measured frequency responses of the proposed filter are found to match well with each other, which further demonstrates the claimed superior performances of the proposed filter.

A Compact UWB Bandpass Chip Filter on a GaAs Substrate with Modified Chebyshev Structure

Ultra-Wideband (UWB) systems are widely used in low-power, high-speed, high-security short-range wireless communication systems throughout digital homes and offices. In the RF front-end of a UWB system, bandpass filters (BPFs) are used to put through the passband signals and reject the stopband signals. Most UWB BPFs are designed with dielectric materials on circuit boards or LTCC technology. In this paper, a very compact fully integrated UWB chip filter is proposed and designed on a GaAs substrate with nitride as dielectric layers to meet the small size requirement of portable devices for next-generation UWB applications. The filter is constructed with a modified Chebyshev structure. The final filter circuit contains only four inductors instead of six for the conventional Chebyshev filter, which makes the chip more compact and cost effective. The filter is designed and fabricated on a 0.25 μm GaAs pHEMT technology with a chip size of only 0.73 mm × 0.51 mm including the chip edge and scribe line area, while the filter core area is only 0.61 mm × 0.39 mm, including bonding PADs. The measurement results illustrated that the proposed BPF shows a passband covering the frequency range of 3.1–9.0 GHz, the minimum passband insertion loss is only 1.5 dB, the stopband rejection is better than −30 dB throughout frequencies below 2 GHz and above 12 GHz, S11 is less than −16 dB, and S22 is better than −11 dB during the whole passband range. It demonstrated that the proposed filter can be considered as one of the most compact UWB filters.

Wideband slow phase loaded inductor‐composite right/left‐handed transmission line for compact UWB power divider

AbstractThis article introduces analysis of the new configuration; inductor loaded left‐handed composite right‐/left‐handed transmission line ((L‐CRLH TL). Compared to conventional CRLH and dual CRLH, this configuration has the advantage of very slow phase (almost constant) and nonlinear propagation coefficient which enables it to be very effective in designing compact size and ultra‐wideband (UWB) microwave components. The theoretical and circuit model of the L‐CRLH TL is discussed. As an application, a compact UWB (3.1‐10.6 GHz) L‐CRLH power divider is designed using only one L‐CRLH cell with size of 2.7 × 8.6 mm2 whereas the whole power divider photoprint is 12.14 × 18.83 mm2. The size is 58.5% smaller compared to the conventional narrow band T‐junction power divider designed at the mid frequency. The results reveal good insertion losses (3.2 ± 0.2 dB for both S21 and S31), and good return losses (better than 10 dB within the passband).

Compact Ultra-Wideband Monopole Antenna Loaded with Metamaterial.

A printed compact monopole antenna based on a single negative (SNG) metamaterial is proposed for ultra-wideband (UWB) applications. A low-profile, key-shaped structure forms the radiating monopole and is loaded with metamaterial unit cells with negative permittivity and more than 1.5 GHz bandwidth of near-zero refractive index (NZRI) property. The antenna offers a wide bandwidth from 3.08 to 14.1 GHz and an average gain of 4.54 dBi, with a peak gain of 6.12 dBi; this is in contrast to the poor performance when metamaterial is not used. Moreover, the maximum obtained radiation efficiency is 97%. A reasonable agreement between simulation and experiments is realized, demonstrating that the proposed antenna can operate over a wide bandwidth with symmetric split-ring resonator (SSRR) metamaterial structures and compact size of 14.5 × 22 mm2 (0.148 λ0 × 0.226 λ0) with respect to the lowest operating frequency.

Compact Ultra wide band MIMO Antenna for Isolation

In this article, we have presented various techniques that are used for improving different parameters related to UWB antenna. In this Paper, we planned for high isolation for MIMO antennas in contemporary wireless communication which enhances the bandwidth and gives compact antennas. The antenna band we notched is of planned MIMO which offers an electric resistance bandwidth with an honest electrical phenomenon matching over the operational band-notched at C range. We improve the isolation of port with the extruded isolation of T-shaped antenna assistance. We fabricate the antenna in common size on PCB using FB8 fast fabrication technology, different number of house hold alternative things are studied with connecting the Universal Serial Bus of housing device having very keen and sensible performance of it. For the major applications of antennas pattern this MIMO based UWB frequency movable antenna of planned type are commonly used. The parameters to assess the performance of the MIMO are explained.