Showing papers in "IEEE Antennas and Wireless Propagation Letters in 2013"
TL;DR: In this article, a dual-band rectenna that can harvest ambient RF power of GSM-1800 and UMTS-2100 bands efficiently is presented, which is based on a broadband 1 × 4 quasi-Yagi antenna array with bandwidth from 1.8 to 2.2 GHz.
Abstract: This letter presents a dual-band rectenna that can harvest ambient RF power of GSM-1800 and UMTS-2100 bands efficiently. The novel rectenna is based on a broadband 1 × 4 quasi-Yagi antenna array with bandwidth from 1.8 to 2.2 GHz and high gains of 10.9 and 13.3 dBi at 1.85 and 2.15 GHz, respectively. Also, a dual-band rectifier that can sufficiently enhance the RF-to-dc power conversion efficiency (PCE) at ambient RF power level is designed for the rectenna. Measurement results show that a PCE of 40% and an output dc voltage of 224 mV have been achieved over a 5-k Ω resistor when the dual-tone input power density is 455 μW/m 2. Additionally, output dc voltage varying between 300-400 mV can be obtained by collecting the relatively low ambient RF power.
354 citations
TL;DR: In this article, a coplanar waveguide-fed compact ultrawideband (UWB) microstrip antenna is proposed for UWB applications, where the ground was vertically extended toward two sides of the single radiator.
Abstract: A novel coplanar waveguide (CPW)-fed compact ultrawideband (UWB) microstrip antenna is proposed for ultrawideband applications. The proposed antenna posseses a method to minimize the monopole antenna by loading of inverted L-strip over the conventional monopole patch antenna to lower the height of the antenna. The ground was vertically extended toward two sides of the single radiator. Therefore, the large space around the radiator that is usually wasted can be effectively saved. The antenna is practically fabricated and simulated. Measured results show a good agreement with simulated results. The prototype with overall size of $25 \times 25 \times 1.6\ {\hbox{mm}}^3$ achieves good impedance matching, constant gain, stable radiation patterns, and constant group delay over an operating bandwidth of 2.6-13.04 GHz (10.44 GHz).
216 citations
TL;DR: In this article, a dual-band rectenna operating at 915 MHz and 2.45 GHz was proposed, which is optimized for low input power densities using harmonic balance (HB) simulation.
Abstract: A compact dual-band rectenna operating at 915 MHz and 2.45 GHz is presented. The rectenna consists of a slot-loaded dual-band folded dipole antenna and a dual-band rectifier. The length of the proposed antenna is only 36.6% of the half-wavelength $(\lambda_{0}/2)$ dipole antenna at 915 MHz while keeping dual-band property at 915 MHz and 2.45 GHz. The rectifier circuit is optimized for low input power densities using harmonic balance (HB) simulation. The efficiencies of the rectifier are evaluated with both single- and dual-frequency input signals. The measured results show an efficiency of 37% and 30% at 915 MHz and at 2.45 GHz when illuminated by a microwave signal of available power of $-$ 9 dBm for a load resistor of 2.2 k $\Omega$ .
207 citations
TL;DR: In this article, the use of graphene for fixed-beam reflectarray antennas at Terahertz (THz) is proposed, which leads to a drastic reduction of the electrical size of the array unit cell and thereby good array performance.
Abstract: The use of graphene for fixed-beam reflectarray antennas at Terahertz (THz) is proposed. Graphene's unique electronic band structure leads to a complex surface conductivity at THz frequencies, which allows the propagation of very slow plasmonic modes. This leads to a drastic reduction of the electrical size of the array unit cell and thereby good array performance. The proposed reflectarray has been designed at 1.3 THz and comprises more than 25000 elements of size about λ0/16. The array reflective unit cell is analyzed using a full vectorial approach, taking into account the variation of the angle of incidence and assuming local periodicity. Good performance is obtained in terms of bandwidth, cross-polar, and grating lobes suppression, proving the feasibility of graphene-based reflectarrays and other similar spatially fed structures at Terahertz frequencies. This result is also a first important step toward reconfigurable THz reflectarrays using graphene electric field effect.
205 citations
TL;DR: In this article, a slotted meander-line resonator (SMLR) is used to block the surface current at the resonant frequency of two patch antennas coupled along H-plane and operating at a frequency of 4.8 GHz.
Abstract: A new approach to enhance the isolation in microstrip patch antenna arrays is described in this letter. The implementation of a slotted meander-line resonator (SMLR) is done by creating defect in the microstrip structure particularly designed for band-notch function. The resonator is designed to block the surface current at the resonant frequency of the two patch antennas coupled along H-plane and operating at a frequency of 4.8 GHz. The interelement isolation before and after the implementation of SMLR has been investigated. The proposed configuration provides an improvement in isolation by 16 dB (measured value) with a reduced edge-to-edge spacing of 7 mm $(\lambda_{o}/9)$ . The configuration has been designed, simulated, and validated experimentally.
160 citations
TL;DR: In this paper, a frequency reconfigurable microstrip patch switchable to slot antenna is proposed, which is capable of frequency switching at nine different frequency bands between 1.98 and 3.59 GHz.
Abstract: A frequency-reconfigurable microstrip patch switchable to slot antenna is proposed. The antenna is capable of frequency switching at nine different frequency bands between 1.98 and 3.59 GHz. The patch is resonating at 3.59 GHz, while the slot produces eight different operating frequencies between 1.98 and 3.41 GHz. Five RF p-i-n diode switches are positioned in the slot to achieve frequency reconfigurability. Simulated and measured results are used to demonstrate the performance of the antenna. The simulated and measured return losses, together with the radiation patterns, are presented.
159 citations
TL;DR: In this paper, two novel preprocessing techniques are applied to reinforce the detection performance and image quality in microwave imaging systems designed for brain stroke detection, which are validated on a realistic head phantom that is fabricated to emulate the electrical properties of real human head.
Abstract: Two novel preprocessing techniques are applied to reinforce the detection performance and the image quality in microwave imaging systems designed for brain stroke detection. The image of energy distribution is obtained by applying a delay-and-sum beamforming to the backscattered signals measured using a hemielliptical array of 16 corrugated tapered slot antenna elements surrounding the head. The beamformer forms a spatially filtered combination of time-delayed response of scattering points in the head exposed to microwave radiation over the band from 1 to 4 GHz. The proposed techniques are validated on a realistic head phantom that is fabricated to emulate the electrical properties of real human head. The results show how the proposed techniques enable the detection and localization of hemorrhagic stroke accurately.
146 citations
TL;DR: In this article, a novel antipodal Vivaldi antenna (AVA) is proposed, which improves the low-end operating frequency by 9% with the dimension unaltered, while the radiation patterns at higher frequencies are improved due to the loaded lens and the choke slot edges (CSE) configuration at the termination of the flares.
Abstract: A novel antipodal Vivaldi antenna (AVA) is proposed in this letter. The addition of regular slot edges (RSE) helps the antenna lower the low-end operating frequency by 9% with the dimension unaltered, while the radiation patterns at higher frequencies are improved due to the loaded lens and the choke slot edges (CSE) configuration at the termination of the flares, which also contribute to the enhancement of antenna gain. The improved antenna is fabricated and verified experimentally. The measured results coincide with the simulated ones perfectly, which proves the feasibility of the novel design.
142 citations
TL;DR: In this article, a wearable textile antenna based on the fundamental mode of a half-mode substrate-integrated semicircular cavity is presented, which operates around 5 GHz and is manufactured with two layers of silver fabric conductors, on the top and bottom of a low-permittivity low-loss foam with minimal water absorption.
Abstract: A wearable textile antenna based on the fundamental mode of a half-mode substrate-integrated semicircular cavity is presented. The antenna operates around 5 GHz and is manufactured with two layers of silver fabric conductors, on the top and bottom of a low-permittivity low-loss foam with minimal water absorption. The vias are realized with five passes of conductive yarn with a diameter of 0.12 mm placed every 1 mm. Their precise arrangement is obtained using computerized embroidery. Compared to other antenna concepts, this design features minimal manufacturing complexity as it does not require accurate patterned cutting of textile conductors. Good isolation from the human body and robustness in terms of deformation are further key characteristics of this structure. This letter provides design guidelines and investigates realistic issues associated with the manufacturing technique. A good agreement between simulated and measured performance with a gain of 7.2 dB validates the concept.
137 citations
TL;DR: In this article, a novel compact printed antenna for triple-band WLAN/WiMAX applications is presented, which consists of three simple circular-arc-shaped strips, whose whole geometry looks like ear-type.
Abstract: In this letter, a novel compact printed antenna for triple-band WLAN/WiMAX applications is presented. The proposed antenna consists of three simple circular-arc-shaped strips, whose whole geometry looks like “ear” type. By adjusting the geometries and the sizes of these three circular-arc-shaped strips, three different resonance modes can be effectively created for three distinct frequency bands, respectively. The overall dimension of the proposed antenna can reach $18\times 37\times 1\ {\hbox{mm}}^{3}$ . Measured results show that the presented antenna can cover three separated impedance bandwidths of 400 MHz (2.38–2.78 GHz), 480 MHz (3.28–3.76 GHz), and 1000 MHz (4.96–5.96 GHz), which are well applied for both 2.4/5.2/5.8-GHz WLAN bands and 2.5/3.5/5.5-GHz WiMAX bands.
130 citations
TL;DR: In this article, a two-pole Butterworth bandpass filter was designed for the modern wireless communication systems, where the second port and resonator were replaced with a fan-shaped patch antenna with defected ground structure (DGS).
Abstract: A compact filtering antenna is designed for the modern wireless communication systems in this letter. First, a two-pole Butterworth bandpass filter is designed. Then, by substituting the second port and resonator with fan-shaped patch antenna (traditional antenna) with defected ground structure (DGS), a filtering antenna is formed. Compared to the traditional antenna, the filtering antenna obtains the flatter gain response within the passband, good selectivity at the passband edge, and the wider bandwidth. Measured results show that the filtering antenna can operate at 2.4 GHz and has a 460-MHz bandwidth and a 2.3-dBi peak gain within the passband. Moreover, a radiation zero occurs at 3 GHz.
TL;DR: In this article, a dual-polarized dipole antenna for base station applications is presented, which is composed of a cross dipole, a square loop, square plate, and a small-size reflector.
Abstract: A novel dual-polarized dipole antenna for base-station applications is presented in this letter. The proposed antenna is composed of a cross dipole, a square loop, a square plate, and a small-size reflector. The square loop and the square plate act as a parasitic radiator and a director, respectively. By introducing the two parts, the impedance bandwidth of the cross dipole can be significantly enhanced, and broadside radiation patterns with narrow beam can be also obtained. Experimental results show that the proposed antenna can operate from 1.71 to 2.69 GHz with low VSWRs at the two ports. High isolation ( > 22 dB) and stable antenna gain (~ 8 dB) are also achieved over the entire operating frequency band. The antenna has symmetrical radiation patterns both in vertical and horizontal planes, and the half-power beamwidth is 70°±5°. Furthermore, the size of the proposed antenna is very compact, which is only 0.513 λ0 ×0.513 λ0 ×0.388 λ0 at the center of the operating frequency band.
TL;DR: In this paper, a planar and coplanar waveguide (CPW)-fed dual-band antenna is designed and proposed using composite metamaterial, which consists of an inner split-ring resonator (SRR) and an outer closed-ring Resonator (CRR).
Abstract: A novel compact, planar, and coplanar waveguide (CPW)-fed dual-band antenna is designed and proposed using composite metamaterial. Such composite metamaterial consists of an inner split-ring resonator (SRR) and an outer closed-ring resonator (CRR). The composite metamaterial can provide dual-band operation at 2.595-2.654 and 3.185-4.245 GHz with reflection coefficient better than -10 dB by the two resonant modes of SRR and CRR, respectively. A CPW-fed line with trapeziform ground plane and tapered impedance transformer line is employed to improve the impedance matching of the antenna. The uniqueness of this design is that the inner SRR with size much smaller than the resonant wavelength is used for obtaining the lower narrow frequency band, which makes the dual-band antenna very compact. Antenna parameters, including reflection coefficient, radiation pattern, radiation efficiency, and gain, are analyzed with numerical simulation and experimental measurement. Good agreement between the simulation and measurement is observed.
TL;DR: In this article, an experimental system for microwave breast cancer detection that uses multistatic radar was presented, which operates by transmitting a short-duration pulse and collecting the signals scattered within the breast.
Abstract: This letter presents an experimental system for microwave breast cancer detection that uses multistatic radar. The system operates by transmitting a short-duration pulse and collecting the signals scattered within the breast. We describe the 16-element array, along with the pulse generation scheme, switches, and all auxiliary equipment. This work provides a sample selection of the collected time-domain data and shows the proof of concept by imaging the breast tumors in realistically shaped breast phantoms.
TL;DR: In this paper, a microstrip-fed monopole mounted on an artificial magnetic conductor is demonstrated to improve the gain by 5 dB over previous works and exhibit much wider impedance bandwidth while maintaining a thin antenna profile and a 20% electrical size reduction.
Abstract: Significant gain and bandwidth improvement of inkjet-printed antennas with integrated artificial magnetic conductor (AMC) is achieved by utilizing wideband ground-backed frequency selective surfaces (FSSs) to overcome the high losses of organic substrates such as paper. A microstrip-fed monopole mounted on an artificial magnetic conductor is demonstrated to improve the gain by 5 dB over previous works and exhibit much wider impedance bandwidth while maintaining a thin antenna profile and a 20% electrical size reduction. The effect of AMC bandwidth on substrate losses and the gain reduction caused by finite AMC array effects are investigated in an effort to produce high-gain, miniaturized, low-cost wearable and structure mount antennas.
TL;DR: It was confirmed that the compact 4 × 4 antenna array could detect a5 × 5 × 5-mm3 tumor phantom in an inhomogeneous structure with a glandular phantom and resolve the two separate tumor phantoms, which were located at the depth of 23 mm with the spacing of 10 mm.
Abstract: A compact 4 × 4 planar ultrawideband (UWB) antenna array with the total size of 44 × 52.4 mm was developed for radar-based breast cancer detection system. The center frequency and the bandwidth of the antenna were 6 and 12.5 GHz, respectively. The breast phantom materials were developed to fit the characteristics of the measured human breast tissues. A quasi-three-dimensional confocal imaging was performed using the breast phantoms. It was confirmed that the compact 4 × 4 antenna array could detect a 5 × 5 × 5-mm3 tumor phantom in an inhomogeneous structure with a glandular phantom and resolve the two separate tumor phantoms, which were located at the depth of 23 mm with the spacing of 10 mm.
TL;DR: In this article, a radio frequency microelectromechanical systems (RF MEMS)-based reconfigurable antenna operating in the United States Public Safety bands is presented, which has two modes of operation with central frequencies of 718 and 4960 MHz.
Abstract: The design methodology, analysis, and characterization of a radio frequency microelectromechanical systems (RF MEMS)-based reconfigurable antenna operating in the United States Public Safety bands are presented. It has two modes of operation with central frequencies of 718 and 4960 MHz, providing a high reconfigurable frequency ratio of $\sim {7}$ . This antenna is electrically small with lateral dimensions being $\sim \lambda/10 \times \lambda/10$ at 718 MHz. The reconfigurability between the modes is achieved by a single RF MEMS switch, which enables changing the length of the current flow path, thereby the resonance frequency is changed. The measurement results for impedance and radiation characteristics of the fabricated antenna prototype agree well with the simulations. The measured bandwidths of the antenna are 2.6% and 7.6% at 718 and 4960 MHz, respectively.
TL;DR: In this paper, an F-shaped microstrip slot antenna for WLAN and WiMAX multiple-input-multiple-output (MIMO) systems is presented, which consists of both open-ended and short-ended slots connected by a metal "via" to a microstrip line.
Abstract: A novel F-shaped microstrip slot antenna for WLAN and WiMAX multiple-input-multiple-output (MIMO) systems is presented. The proposed antenna structure consists of both open-ended and short-ended slots connected by a metal “via” to a microstrip line. The open-ended slot is exploited to obtain resonant mode at 2.4 GHz, and three short-ended slots are aimed to obtain resonant modes at 3.5, 5.2, and 5.8 GHz, whose center frequencies can be adjust by the slot lengths. The parametric studies show that the center frequencies are independent of each other. A four-element array configuration of the proposed antenna for MIMO applications is also studied. The simulation and measurement results of reflection coefficient, mutual coupling, and radiation pattern are presented, which attest to the applicability of antenna.
TL;DR: In this paper, a new framework is proposed to further exploit TCM to enhance the performance of the orthogonal MIMO antennas by correlating the characteristic currents and near fields of modes with high modal significance in a given frequency band.
Abstract: Recent work has shown that, with the help of the Theory of Characteristic Modes (TCM), minor modifications of the terminal chassis can facilitate the design of orthogonal multiple-input-multiple-output (MIMO) antennas with viable bandwidth at frequencies below 1 GHz. Herein, a new framework is proposed to further exploit TCM to enhance the performance of the orthogonal MIMO antennas. By correlating the characteristic currents and near fields of modes with high modal significance in a given frequency band, a single feed may be designed to excite multiple modes, leading to enlarged bandwidth. Similarly, the correlation of characteristic currents and near fields across different bands provides candidate modes that can be excited for multiband operation using a single feed. Moreover, the impedance matching of these modes can be improved by additional structural manipulation. As proof of concept, a dual-band (818-896 MHz, 1841-2067 MHz), dual-antenna prototype was designed on a 130 × 66-mm2 chassis for Long Term Evolution (LTE) operation. Full-wave simulation results were experimentally verified with a fabricated prototype.
TL;DR: In this article, dual-band and wideband designs of dual-polarized cylindrical dielectric resonator antennas (DRAs) are investigated for DCS (1.71-1.88 GHz) and WLAN (2.4-2.48 GHz) bands.
Abstract: This letter investigates dual-band and wideband designs of dual-polarized cylindrical dielectric resonator antennas (DRAs). These designs make use of the fundamental HEM111 mode and higher-order HEM113 mode of the DRA. The strip- and slot-fed excitation methods are used for Ports 1 and 2 of the antennas, respectively. For demonstration, a dual-band dual-polarized DRA for DCS (1.71-1.88 GHz) and WLAN (2.4-2.48 GHz) bands and a wideband version that covers the 2.4-GHz WLAN band were designed. The S-parameters, radiation patterns, antenna gains, antenna efficiencies, and envelope correlations of the two designs are studied. It was found that the dual-band and wideband designs have port isolations of higher than 36 and 37 dB, respectively. Good agreement between the measured and simulated results is observed.
TL;DR: In this paper, a double-slot structure was proposed to improve the directivity of the conventional Vivaldi antenna, which can generate plane-like waves in the E-plane of the antenna.
Abstract: The conventional Vivaldi antenna is known for its ultrawideband characteristic, but low directivity. In order to improve the directivity, a double-slot structure is proposed to design a new Vivaldi antenna. The two slots are excited in uniform amplitude and phase by using a T-junction power divider. The double-slot structure can generate plane-like waves in the E-plane of the antenna. As a result, directivity of the double-slot Vivaldi antenna is significantly improved by comparison to a conventional Vivaldi antenna of the same size. The measured results show that impedance bandwidth of the double-slot Vivaldi antenna is from 2.5 to 15 GHz. Gain and directivity of the proposed antenna is considerably improved at the frequencies above 6 GHz. Furthermore, the main beam splitting at high frequencies of the conventional Vivaldi antenna on thick dielectric substrates is eliminated by the double-slot structure.
TL;DR: In this paper, a wideband printed dual-antenna system for mobile terminals is presented, consisting of two symmetric antenna elements and a neutralization line (NL) is printed on a printed circuit board.
Abstract: A wideband printed dual-antenna system for mobile terminals is presented. The dual-antenna, consisted of two symmetric antenna elements and a neutralization line (NL), is printed on a printed circuit board. The antenna element is an F-like monopole with a grounded branch. The working mechanism of the dual-antenna is analyzed based on the S-parameters and the surface current distributions. A prototype shows the measured -10-dB impedance bandwidth is 1.09 GHz (1.67-2.76 GHz) and the measured mutual coupling is lower than -15 dB at the 1.7-2.76-GHz bands. It covers the GSM1800, GSM1900, UMTS, LTE2300, LTE2500, and 2.4-GHz WLAN bands. The radiation patterns are measured, and the diversity performance is evaluated .
TL;DR: In this article, a compact triband asymmetric coplanar strip (ACS)-fed printed monopole antenna employing open-ended slots for wireless communication is presented, which occupies a very compact size of 27.5 × 13 mm2.
Abstract: A compact triband asymmetric coplanar strip (ACS)-fed printed monopole antenna employing open-ended slots for wireless communication is presented. The proposed antenna is composed of an ACS-fed monopole and two special open-ended slots, which occupies a very compact size of 27.5 × 13 mm2. By carefully selecting the lengths and positions of these slots, good dual stopband rejection characteristic can be achieved. The three obtained bands of 2.35-2.53, 3.34-3.85, and 5.05-6.28 GHz can successfully cover the WLAN and WiMAX operation bands. The principle and key parameters of the slot in producing notched band are analyzed in detail. The measured results demonstrate that the proposed antenna has good omnidirectional radiation patterns with reasonable gains across the operating bands, which is suitable to be integrated within the portable device for wireless communication.
TL;DR: In this paper, a multiband and vertically/horizontally polarized omnidirectional antenna is proposed for 2G/3G/LTE mobile communication systems, which is a combination of a modified asymmetric biconical for vertical polarization and six printed dipoles with concentric placement for horizontal polarization.
Abstract: A novel multiband and vertically/horizontally polarized omnidirectional antenna is proposed for 2G/3G/LTE mobile communication systems. The proposed antenna is a combination of a modified asymmetric biconical for vertical polarization (VP) and six printed dipoles with concentric placement for horizontal polarization (HP). The VP element consists of two modified cones with different diameters, designed to work in the multiband GSM+3G/4G. Printed dipoles of the HP element are fed by a six-way power splitter printed on the substrate. The HP element is nested between two cones of the VP element, forming a compact structure. The bottom cone can be used as the reflector for VP and HP in the overlapping work frequencies band for 3G and LTE communication systems. The VP element achieves a bandwidth of 17.4% and gain of 1.5 dBi in the 806 ~ 960-MHz band. The HP element achieves a bandwidth of 35% (1880 ~ 2700 MHz) directly overlapping with the VP-element higher frequency band. An isolation of 25 dB is achieved in the overlapping band. The cross-polarization levels in the azimuth plane for both VP and HP are lower than -15 dB.
TL;DR: In this article, it is shown that if the slits of these resonators are aligned in a nonorthogonal direction to the line axis, cross-polarization effects arise.
Abstract: The purpose of this letter is to understand and model the electromagnetic properties of transmission lines loaded with split-ring resonators (SRRs) and complementary split-ring resonators (CSRRs) arbitrarily oriented. It is shown that if the slits of these resonators are aligned in a nonorthogonal direction to the line axis, cross-polarization effects arise. Namely, the particles (SRRs or CSRRs) are excited through both magnetic and electric coupling. It is pointed out that the previously reported lumped element equivalent circuit models of SRR- and CSRR-loaded lines (where cross polarization is not considered) are valid as long as the slits are orthogonally oriented to the line axis, and new models that include cross polarization are presented and discussed. The validity and accuracy of the models is demonstrated through parameter extraction and comparison to full-wave electromagnetic simulations and measurements.
TL;DR: In this paper, a reconfigurable five-element Yagi-Uda monopole array that utilizes pressure-driven liquid-metal elements is presented, which allows the array to tune to different operational frequencies, vary the number of director elements, and change parasitic elements from reflectors to directors, and vice versa.
Abstract: A reconfigurable five-element Yagi-Uda monopole array is presented that utilizes pressure-driven liquid-metal elements There is one centrally located driven element and six parasitic elements in the array, all of which utilize liquid metal so that their physical lengths can be varied This allows the array to tune to different operational frequencies, vary the number of director elements, and change parasitic elements from reflectors to directors, and vice versa The measured results show beam steering along a single axis and 133 dB of gain tuning at 24 and 387 GHz
TL;DR: In this paper, a two-element multiple-input-multiple-output (MIMO) metamaterial-based antenna is proposed, which operates at 5.8 GHz for wireless applications.
Abstract: This letter presents a design of a two-element multiple-input-multiple-output (MIMO) metamaterial-based antenna. The two antenna elements operate at 5.8 GHz for wireless applications. The two antenna elements are designed employing only one left-handed unit cell. The reduction of mutual coupling between the two antenna elements is achieved by using a simple defected ground structure between them to limit the surface waves between them. The distance between the two antenna elements is only 1.8 mm (0.034 λ0). The designed antenna elements have better than -45 dB coupling isolation between the two inputs. Moreover, the proposed MIMO antenna has the advantage of compactness (its size is only 2.36 × 2.6 cm2). The design represents size reduction of more than 50% compared to conventional patch antennas operating at the same frequency. The proposed MIMO system has -55 dB correlation coefficient between its two elements.
TL;DR: The presented return loss and radiation pattern results demonstrate that antenna properties have negligible variations when bent at different angles (a possible condition when placed on body) or placed in adverse conditions (under extreme heat and humidity).
Abstract: This letter presents the design of an ultrawideband (UWB) band-notched wearable antenna and its validation using simulation and measurement results. The antenna can be used for ultrawideband applications, while rejecting the higher band assigned to wireless local area network (WLAN 5.25-GHz band). The presented return loss and radiation pattern results demonstrate that antenna properties have negligible variations when bent at different angles (a possible condition when placed on body) or placed in adverse conditions (under extreme heat and humidity). Moreover, reliable performance of antenna for on-body scenario makes the designed antenna a promising candidate for wearable applications.
TL;DR: In this paper, a uniplanar slot antenna for ultrawideband (UWB) polarization-diversity applications is presented, which consists of an annular slot and orthogonal feeding mechanisms to achieve polarization diversity performance across the UWB from 2.8-11 GHz.
Abstract: A uniplanar slot antenna for ultrawideband (UWB) polarization-diversity applications is presented. The antenna consists of an annular slot and orthogonal feeding mechanisms to achieve polarization diversity performance across the UWB from 2.8–11 GHz. By introducing a cross-shaped strip diagonally between the two U-shaped stubs, an interport isolation better than 14 dB is accomplished except at the lower and higher frequency end. The notch band from 5.0–6.3 GHz is realized by embedding arc-shaped slot resonators on the feeding structures. The proposed antenna facilitates nearly omnidirectional radiation pattern, low envelope correction coefficient, moderate gain, and efficiency. Moreover, the time-domain analysis displays minimum dispersion to the radiated pulse. All these features make the proposed antenna a good candidate for future wireless communication systems with polarization-diversity operation, where the challenge such as multipath fading is a major concern.
TL;DR: In this paper, a novel wide-slot ultrawideband (UWB) antenna with dual band-notched characteristics is presented, which consists of an inverted U-shaped slot on the ground plane and a radiation patch similar to the slot that is fed by a 50-Ω microstrip line.
Abstract: A novel compact wide-slot ultrawideband (UWB) antenna with dual band-notched characteristics is presented. The antenna consists of an inverted U-shaped slot on the ground plane and a radiation patch similar to the slot that is fed by a 50-Ω microstrip line. By etching a C-shaped slot on the radiation patch and extruding an L-shaped stub from the ground plane, dual band-notched properties in the WiMAX (3.4-3.69 GHz) and WLAN (5.15-5.825 GHz) are achieved. The proposed antenna has a compact size of 20×27 mm2 and operates from 2.89 to 11.52 GHz. Furthermore, nearly omnidirectional radiation patterns and constant gain are obtained in the working band.