Showing papers on "Dipole antenna published in 2020"
TL;DR: In this article, a wideband orthogonal-mode dual-antenna pair with a shared radiator for 5G MIMO metal-rimmed smartphones is presented, which shows a wide impedance bandwidth of 3.3-5.0 GHz and a high isolation of more than 21.0 dB across the entire band without using any external decoupling structures.
Abstract: This article presents a wideband orthogonal-mode dual-antenna pair with a shared radiator for fifth-generation (5G) multiple-input multiple-output (MIMO) metal-rimmed smartphones. The wideband decoupling property of the dual-antenna pair is realized by the combination of the orthogonal monopole/dipole modes in the lower band and the orthogonal slot/open-slot modes in the higher band. With the orthogonal-mode design scheme, the dual-antenna pair shows a wide impedance bandwidth of 3.3–5.0 GHz and a high isolation of more than 21.0 dB across the entire band without using any external decoupling structures. By arranging four such dual-antenna pairs at two side edges of the smartphone, an $8 \times 8$ MIMO system is fulfilled. Both the simulation and measurement results show that the proposed $8 \times 8$ MIMO system could offer an isolation of better than 12.0 dB and an envelope correlation coefficient of lower than 0.11 between all ports. The measured average antenna efficiencies are 74.7% and 57.8% for the two antenna elements of the dual-antenna pair. We portend that the proposed design scheme, with merits of shared radiator, wide bandwidth, and metal rim compatibility, has the potential for the application of future 5G smartphones.
152 citations
TL;DR: In this article, a very low frequency (VLF) communication system using one pair of magnetoelectric (ME) antennas has been proposed, where the ME antennas are strain-mediated acoustic resonators operating at their electromechanical resonance in the VLF band.
Abstract: A novel very low frequency (VLF) communication system using one pair of magnetoelectric (ME) antennas has been proposed. The ME antennas are strain-mediated acoustic resonators operating at their electromechanical resonance in the VLF band. The measured near-field radiation pattern reveals ME antennas are equivalent to dipole antennas. The magnetic field radiated by the ME transmitter has been predicted along with distance ranging from 1 mm to 100 km. The measured magnetic field distribution coincided well with the prediction, and the maximum communication distance of 120 m has been achieved. With 80 V driving voltage, the power consumption of the ME transmitter has been measured as 400 mW. Furthermore, the direct antenna modulation (DAM) has also been successfully demonstrated on the ME antennas.
89 citations
TL;DR: In this paper, a flexible high-permittivity dielectric substrate is developed using silicon-based poly-di-methyl-siloxane (PDMS) matrix and microscale of aluminium oxide (Al2O3) and graphite (G) powders.
Abstract: An approach toward designing and building of a compact, low-profile, wideband, unidirectional, and conformal imaging antenna for electromagnetic (EM) head imaging systems is presented. The approach includes the realization of a custom-made flexible high-permittivity dielectric substrate to achieve a compact sensing antenna. The developed composite substrate is built using silicon-based poly-di-methyl-siloxane (PDMS) matrix and microscale of aluminium oxide (Al2O3) and graphite (G) powders. Al2O3 and G powders are used as fillers with different weight-ratio to manipulate and control the dielectric properties of the substrate for attaining better matched with the human head and reducing antenna’s physical size while keeping the PDMS flexibility feature. Using the custom-made substrate, a compact, wideband, and unidirectional on-body matched antenna for wearable EM head imaging system is realized. The antenna is configured as a multi-slot planar structure with four shorting pins, working as electric and magnetic dipoles at different frequency bands. The measured reflection coefficient (S11) shows an operating frequency band of 1–4.3 GHz. The time-average power density and the amplitude of the received signal inside the MRI-based realistic head phantom demonstrate a unidirectional propagation and high-fidelity factor (FF) of more than 90%. An array of 13 antennas are fabricated and tested on a realistic 3-D head phantom to verify the imaging capability of the proposed antenna. The reconstructed images of different targets inside the head phantom demonstrate the possibility of utilizing the conformal antenna arrays to detect and locate abnormality inside the brain using multistatic delay-multiply-and-sum beamforming algorithm.
80 citations
TL;DR: An aperture-sharing technique is developed, so that a four-unit linear 28 GHz array and a 3.5 GHz dipole antenna can be integrated and the same aperture can be shared, and the proposed dual-frequency antenna is suitable for some terminal applications in the next-generation wireless networks.
Abstract: The integration of the sub-6 GHz and millimeter-wave (mmWave) antennas has become an important issue for the next-generation wireless communication. For the mmWave band, adaptive beam steering is required to solve the path loss and coverage range problems. In this communication, an aperture-sharing technique is developed, so that a four-unit linear 28 GHz array and a 3.5 GHz dipole antenna can be integrated and the same aperture can be shared. The SIW is utilized to enable the integration and maintain the radiation of both antennas, without mutual interference. By adopting a separate feeding network, each mmWave array unit is independently excited, so that a beam steerable in the E-plane can be synthesized in the mmWave band. A prototype is fabricated with a compact size owing to the shared aperture. The measured results show good radiation characteristics and broad 10 dB impedance bandwidth exceeding 20% in both bands. Furthermore, the mmWave beam steering is obtained with a stable gain level. The proposed dual-frequency antenna is suitable for some terminal applications in the next-generation wireless networks.
73 citations
TL;DR: In this paper, a dual-polarized end-fire phased array for 5G handset devices at 28 GHz was proposed, which achieved a −10 dB frequency bandwidth of 5.3% and a −6 dB bandwidth of 25% overlapping between the vertical and horizontal polarization.
Abstract: This communication proposes a dual-polarized end-fire phased array for 5G handset devices at 28 GHz. The proposed four-element array has low profile of 1.1 mm, small clearance of 2.7 mm, and symmetric patterns in the vertical plane. The array element is fed by substrate-integrated waveguide (SIW), which works as a waveguide (WG) antenna with vertically polarized radiation pattern. Two transition plates are introduced to improve the impedance matching of the WG antenna. The horizontal polarization is generated by exciting one of the transition plates as an antenna. The other transition plate is modified as a group of triangle strips to minimize its reflection to the horizontal radiation patterns. A −10 dB frequency bandwidth of 5.3% and a −6 dB bandwidth of 25% are achieved, overlapping between the vertical and horizontal polarization. The array scanning angle is from −54° to 44° at 29 GHz for both polarization. Within the scanning range, the end-fire gain varies from 7.48 to 8.14 dBi for the horizontal polarization, whereas from 4.49 to 8.05 dBi for the vertical polarization. Good agreements between simulations and measurements are well achieved and shown in this communication.
71 citations
TL;DR: In this article, a dual-polarized magnetoelectric (ME) dipole antenna with the feeding structure consisting of two orthogonal L-shaped probes with different heights is presented based on the low-temperature co-fired ceramic (LTCC) technology.
Abstract: A Ka -band wideband dual-polarized magnetoelectric (ME) dipole antenna with the feeding structure consisting of two orthogonal L-shaped probes with different heights is presented based on the low-temperature cofired ceramic (LTCC) technology. A simulated overlapped impedance bandwidth of 42.5% is achieved together with an isolation of higher than 24 dB between the two input ports and stable radiation characteristics over the operating band. By combining the radiating elements with a single-layered feed network composed of microstrip lines, a $4\times 4$ dual-polarized ME dipole antenna array is designed, fabricated, and measured. An overlapped impedance bandwidth of 45% that can cover the entire Ka -band, a gain up to 16.1 dBi, and stable symmetrical radiation patterns in the two orthogonal planes with cross polarization of less than −15 dB are experimentally confirmed. With advantages of the compact geometry, wide operating band, and promising radiation performance, the proposed antenna array with dual polarization would be attractive for millimeter-wave wireless applications in Ka -band.
68 citations
TL;DR: In this paper, an ultralow profile, electrically small, pattern-reconfigurable metamaterial-inspired Huygens dipole antenna is presented that operates near 1.5 GHz.
Abstract: An ultralow-profile, electrically small, pattern-reconfigurable metamaterial-inspired Huygens dipole antenna is presented that operates near 1.5 GHz. The design incorporates two pairs of magnetic and electric near-field resonant parasitic (NFRP) elements and a reconfigurable driven element. A pair of p-i-n diodes is integrated into the driven element to enable the antenna pattern reconfigurability. By switching the ON/OFF states of the diodes, the antenna can realize two independent unidirectional endfire radiating states whose peaks point in antipodal directions and a bidirectional endfire radiating state. The measured results, in good agreement with their simulated values, demonstrate that although the antenna is electrically small ( ka = 0.98) and ultralow profile ( $0.0026\lambda _{0}$ ), it can realize uniform peak realized gains (RGs) of ~5.4 dBi, front-to-back ratios (FTBRs) of ~13.3 dB, and radiation efficiencies of (REs) ~85% in its two oppositely directed endfire states, and a RG of ~3.55 dBi and RE of ~87% in its bidirectional endfire state.
64 citations
TL;DR: The proposed configuration paves the way to a new generation of cloaking devices for intelligent antenna systems, extending the concept of antenna as a device capable to sense the external environment and change its electromagnetic behavior accordingly.
Abstract: We present the design of an innovative wire antenna able to automatically hide or reveal its presence depending on the waveform of the received/transmitted signal. This unconventional behavior is achieved through the use of a novel waveform-selective cloaking metasurface exploiting a meander-like unit cell loaded with a lumped-element circuit capable to engineer the scattering of the antenna depending on the waveform of the impinging signal. Due to the time-domain response of the lumped-element circuit, the antenna is able switching its scattering behavior when interacts with either a pulsed wave (PW) or a continuous wave (CW) signal. The proposed configuration paves the way to a new generation of cloaking devices for intelligent antenna systems, extending the concept of antenna as a device capable to sense the external environment and change its electromagnetic behavior accordingly.
64 citations
TL;DR: A fully passive, wireless solution for out-of-sight pipeline monitoring is presented that exhibits robust capability to create frequency signatures to detect and monitor defects underneath the pipeline coating owing to water ingress that could eventuate to corrode the pipeline.
Abstract: In this article, a fully passive, wireless solution for out-of-sight pipeline monitoring is presented. By predicting corrosion before its occurrence, a proactive response may be taken to mitigate the chance of an environmental disaster. The chipless radio-frequency identification system is a combination of a tag ID, consisting of an array of six rectangular spiral resonators, and a tag antenna consisting of two cross-polarized novel patch antennas etched on a skin-thin microwave laminate. The tags are grounded on a carbon steel pipeline coated with $\text{3 mm}$ Teflon (polyethylene-like electrical characteristics). The proposed system exhibits robust capability to create frequency signatures to detect and monitor defects underneath the pipeline coating owing to water ingress that could eventuate to corrode the pipeline. The reader antenna above the pipeline comprises two identically cross-polarized log periodic dipole antennas with the intent to remotely capture resonances of the tag ID in real-time for early detection and prediction of potential pipeline exposure to moisture. The proposed structure provides low-cost real-time solution.
60 citations
TL;DR: The proposed transparent MIMO antenna is evaluated in terms of diversity gain, envelope correlation coefficient (ECC), total active reflection coefficient (TARC), and mean effective gain (MEG) where decent MIMo performance with isolation more than >16 dB between the adjacent and other elements is achieved.
Abstract: A four-element compact wide-band optically transparent MIMO antenna with a full ground plane is proposed. The four elements transparent MIMO system has a compact size of $24\times 20$ mm2 with the undivided ground plane as most of the real-time systems demand a common reference. The complete antenna system achieves around 85% transparency due to a combination of AgHT-8 and Plexiglas which forms the transparent conductive patch/ground and substrate, respectively. The antenna geometry leads dual-band operation ranging from 24.10 - 27.18 GHz (Impedance bandwidth = 12%) and 33 - 44.13 GHz (Impedance bandwidth $=28.86$ %) targeting the mm-wave 5G applications. The 4-element antenna system achieves isolation between inter-elements >16 dB and maximum gain value of greater than 3 dBi with more than 75% efficiency. The proposed transparent MIMO antenna is evaluated in terms of diversity gain (DG), envelope correlation coefficient (ECC), total active reflection coefficient (TARC), and mean effective gain (MEG) where decent MIMO performance with isolation more than >16 dB between the adjacent and other elements is achieved. Transparent MIMO antenna achieves directional patterns for the operating band with the value of DG >9, ECC < 0.1, TARC value less than −15dB, and the ratio of MEG within the agreed limit of ±3 dB confirming acceptable MIMO/diversity performance.
59 citations
TL;DR: A tri-polarized antenna with diverse radiation characteristics is proposed in this paper, which mainly consists of two pairs of loop radiating dipoles and an omnidirectional monopole antenna element used for the fifth generation (5G) and vehicle to everything (V2X) communications, respectively.
Abstract: A tri-polarized antenna with diverse radiation characteristics is proposed in this paper. This design mainly consists of two pairs of loop radiating dipoles and an omnidirectional monopole antenna element, which are used for the fifth generation (5G) and vehicle to everything (V2X) communications, respectively. By adding eight pairs of inverted L-shaped patches with unequal sizes around the proposed dipoles, wide beamwidths in both E- and H-planes can be obtained across the desired lower and upper frequency bands. Furthermore, by employing eight fork-shaped microstrip stubs to combine the circular monopole antenna element and the L-shaped patches, the flare angle of the conical beam can be increased to 180 $^{\circ }$ , which results in gain enhancement in the azimuth plane. Finally, the proposed loop radiating dipoles are excited by a pair of symmetrical differentially-fed feeding lines. Consequently, high port isolation for the proposed loop radiating dipoles as well as low gain variations for the monopole antenna element can be achieved. Measured results show that the impedance bandwidths of 32.84 $\%$ (2.8–3.9 GHz) and 18.18 $\%$ (4.5–5.4 GHz) can be achieved for the 5G communications. Wide half power beamwidths (HPBW) of larger than 103 $^{\circ }$ in E-plane and 91 $^{\circ }$ in H-plane can be achieved across the operating bands. In addition, a bandwidth of 5.5 $\%$ (5.82–6.15 GHz) with gain of 2.47 $\pm$ 0.69 dBi in the azimuth plane can also be obtained for V2X communications.
TL;DR: In this article, a microfluidically frequency and polarization-reconfigurable slot antenna using liquid metal (LM) is proposed, which can achieve three operating frequency bands of LHCP and RHCP states by filling the microchannels with different lengths.
Abstract: In this communication, a microfluidically frequency- and polarization-reconfigurable slot antenna using liquid metal (LM) is proposed. The polydimethylsiloxane (PDMS) structure with narrow-banded microchannels is loaded on the printed circuit board (PCB) of a square slot antenna, providing condition for reconfiguration. The left-hand circular polarization (LHCP), right-hand circular polarization (RHCP), and linear polarization (LP) are achieved by injecting LM into +45° and −45° channels with respect to the $x$ -axis or keeping the channels empty. Three operating frequency bands of LHCP and RHCP states can be realized by filling the microchannels with different lengths. Both states have an overall tuning 3 dB axial ratio bandwidth (ARBW) of 26.42% (2.3–3 GHz). In LP state, the proposed antenna realizes a −10 dB impedance bandwidth of 11.6% (2.03–2.28 GHz). A prototype of the proposed antenna has been fabricated and measured. Good agreement between the simulated and measured results validates the feasibility of this technique.
TL;DR: In this article, a self-decoupled antenna array using the cancellation of two opposite couplings is proposed, where a pair of such antennas can be closely placed with inherent high isolation without using an extra decoupling structure between the antennas.
Abstract: The concept of a self-decoupled antenna array using the cancellation of two opposite couplings is proposed in this article. A pair of such antennas can be closely placed with inherent high isolation without using an extra decoupling structure between the antennas. A pertinent equivalent circuit model is presented to illustrate the physical mechanism of this new concept. It is found that the inductive and capacitive couplings between the antennas can be well canceled out with each other by properly adjusting the antenna dimensions. A demonstrating antenna array with a spacing of $0.024\lambda _{0}$ at the working frequency of 3.5 GHz and its counterpart array are first studied. The measured results show that although the proposed antenna array occupies a slightly larger size than its counterpart array, it presents better performance compared with its counterpart antenna array in port isolation (from 10 to 20 dB), total efficiency (from 68% to 80%), and envelope correlation coefficient (ECC) (from 0.14 to 0.04) throughout the desired frequency band of 3.3–3.8 GHz. A 3-D self-decoupled antenna array is designed to show that the proposed antenna can be in a compact form factor. Another self-decoupled array and its counterpart working at 2.14 GHz (long-term evolution (LTE) band 1) are studied through multi-input multi-output (MIMO) over-the-air (OTA) test when the arrays are integrated with an LTE module, showing significant improvement on the data throughput.
TL;DR: In this article, a linearly polarized ultrawideband design for millimeter-wave phased array antennas over 17-42 GHz is presented, which comprises tightly coupled dipoles, integrated with a specific feeding mechanism.
Abstract: We present a linearly polarized ultrawideband design for millimeter-wave phased array antennas over 17–42 GHz. The design comprises tightly coupled dipoles, integrated with a specific feeding mechanism. The proposed antenna provides a relative bandwidth of 2.7:1 and 2.47:1 with VSWR $8\times 4$ arrays are fabricated using standard PCB technology. The measurement results of the array prototypes show a good agreement with the simulations in terms of VSWR, radiation pattern, and realized gain.
TL;DR: In this paper, a phase compensation method by using a staple-shaped probe for alleviating the largest phase offset is proposed conceptually and verified experimentally, which can be effectively applied to a compact staggered dipole array with a wideband simultaneous decoupling.
Abstract: Staggered array antenna is a common array configuration for large-scale array antennas due to its favorable radiation characteristics and relatively large element spacing. In developing a compact staggered dipole array, the most challenging issue is how to simultaneously reduce the four mutual couplings taking place between adjacent co-polarized antenna elements with diversified phase laggings. A large difference in the phase of different mutual couplings makes simultaneous reduction of all the mutual couplings by applying the recently developed array-antenna decoupling surface (ADS) technique difficult. In this article, a phase compensation method by using a staple-shaped probe for alleviating the largest phase offset is proposed conceptually and verified experimentally. With the proposed phase compensation method, the ADS technique can be effectively applied to a compact staggered dipole array with a wideband simultaneous decoupling. The design guideline for the phase compensation probe is presented by EM simulation and a parametric study. Two practical design examples of dual polarized staggered dipole arrays are given to demonstrate the effectiveness of the proposed phase compensation method in conjunction with ADS, showing a promising potential for wideband simultaneous decoupling of a large-scale dual polarized staggered dipole array-antenna.
TL;DR: In this article, a simple dual-polarized antenna with filtering responses and enhanced bandwidth is proposed for base station applications, which concludes three parts: dipole elements, baluns, and a ground plane.
Abstract: In this article, a simple dual-polarized antenna with filtering responses and enhanced bandwidth is proposed for base station applications. The antenna concludes three parts: dipole elements, baluns, and a ground plane, which is the same as that of a widely used traditional base-station cross-dipole antenna. By employing only two parasitic elements without using very complicated circuits, the proposed dual-polarized antenna achieves not only filtering response but also widened bandwidth. Each parasitic element produces one transmission zero at higher frequency for the polarization it is associated with, while the other parasitic element produces another transmission zero at lower frequency band for the perpendicular polarization. The two introduced radiation nulls near the passband edge are also controllable. The working mechanism for achieving filtering responses is given. To demonstrate the idea, a simple dual-polarized filtering base-station antenna element is fabricated. The proposed antenna obtains 63% (1.68–3.23 GHz) impendence bandwidth with voltage standing wave ratio (VSWR) less than 1.5. The antenna also features good isolation of more than 32 dB and stable beamwidth variation of less than ±5°. The measured gain within working band is around 8.5 dBi, while the radiation suppression level in stopband is 13 dB.
TL;DR: In this paper, a dual-polarized filtering base-station antenna is presented, where the entire size (including the ground plane) of the element is only 0.53λ × 0.14λ (λ is the wavelength of the central working frequency).
Abstract: A compact dual-polarized filtering base-station antenna is presented in this letter. The entire size (include the ground plane) of the element is only 0.53λ × 0.72λ × 0.14λ (λ is the wavelength of the central working frequency). Four vertical slots etched on the coupling cross slot are for improving the high-frequency suppression of the antenna. The C-slots on the Gnd1 reduce the cross-polarization ratio at the axial direction. The antenna shows a wide working bandwidth of 25.6% and a low cross-polarization ratio about 22 dB. In order to validate the design, a 1 × 3 linear array is fabricated and tested. The antenna array works at 3.3–4.0 GHz with the average gain about 11 dBi. Besides, the array remains a good out of band rejection more than −20 dB up to 9 GHz which exhibits a good harmonic suppression performance over a wideband.
TL;DR: In this article, a dual-band, dual-polarized antenna array arrangement for low grating lobe base-station antenna applications is presented, which uses two different lower band elements to achieve a 2.5-time element spacing array scheme.
Abstract: This letter presents a dual-band, dual-polarized antenna array arrangement for low grating lobe base-station antenna applications. The presented array arrangement uses two different lower band elements to achieve a 2.5-time element spacing array scheme, in which lower band elements spacing is 2.5 times of upper band elements spacing. With this arrangement, both the lower and upper band element spacing can be reduced, leading to a better grating lobe performance. To verify the idea, an antenna array operating at two bands, namely, 690–960 and 1690–2690 MHz, is presented. For 690–960 MHz array, two different radiation elements are designed, each of them has two pairs of bent dipoles for dual-polarization operation. The smaller lower band element is embedded with one upper band element. Meanwhile, the larger one is embedded with two upper band elements. An array consisting of five lower band elements and 12 upper band elements is fabricated and tested. Measured results show that the array has a good performance with return loss larger than 15 dB, ports isolation better than 28 dB. Besides, the grating lobe value is better than –12 dB at tilt angle 12° for both upper and lower band, which is a significant improvement over its former counterparts.
TL;DR: In this paper, a dual-polarized antenna is built based on FWDs for base station applications as an example, which can cover both the LTE band from 1.7 to 2.71 GHz and the 5G (sub-6 GHz) band from 3.3 to 3.6 GHz simultaneously.
Abstract: A new method of designing full-wavelength dipoles (FWDs) is presented. A dual-polarized antenna is built based on FWDs for base station applications as an example. The antenna has four FWDs arranged in a square loop array form. The employed FWDs are bent upward to maintain a small aperture size, so that the realized element still fits in traditional base station antenna (BSA) array. The antenna is first matched across the band from 1.63 to 3.71 GHz, which can cover both the LTE band from 1.7 to 2.7 GHz and the 5G (sub-6 GHz) band from 3.3 to 3.6 GHz simultaneously. Then, band-stop filters are inserted in the feed networks of the antenna to suppress the radiation between 2.7 to 3.3 GHz. The antenna is fabricated and tested. Experimental results validate the simulation results. Comparing with the previously available FWD that has a bandwidth of 32%, the FWD proposed in this article exhibits a much wider bandwidth of 78%. Moreover, this bandwidth is also comparable to and wider than those of the state-of-the-art BSAs based on half-wavelength dipoles (HWDs). The bandwidth enhancement and footprint reduction of the FWD in this article demonstrate a high potential of FWDs to be used in other applications.
TL;DR: In this article, a feasibility study on external transparent antennas for ultra-high definition (UHD) TV applications in Korea (470-771 MHz) is presented, where the proposed antennas are patch and dipole types, representing directional and omnidirectional radiation, respectively.
Abstract: The design of an external antenna for digital television (TV) has become more challenging because its relatively large size is not conformal to and esthetically preferred for commercial use. This article presents a feasibility study on external transparent antennas for ultrahigh definition (UHD) TV applications in Korea (470–771 MHz). The proposed antennas are patch and dipole types, representing directional and omnidirectional radiation, respectively. Both antennas use a metal mesh film with an optical transparency above 70% and a low sheet resistance of $0.04~\Omega $ /sq. The transparent patch using a capacitive feed has an average efficiency of 83.8% and a peak gain of 6.2 dBi, and the transparent dipole with widen arms has an average efficiency of 72.1% and a peak gain of 2.4 dBi. To emphasize the potential application to UHD TV, the average Rx peak gain of the patch and dipole antennas, which are 4.8 and 2.0 dBi, respectively, in practical conditions are investigated. The measured results of the proposed antennas offer the feasibility of implementing transparent antennas with performances identical to the nontransparent ones and a soft visual impact as an advantage, thus making them become good candidates as external antennas for UHD TV applications.
TL;DR: In this article, a millimeter-wave aperture-coupled magnetoelectric (ME) dipole antenna with a low profile metallic geometry is proposed based on the 3-D printing technology.
Abstract: A novel millimeter-wave aperture-coupled magnetoelectric (ME) dipole antenna with a low-profile metallic geometry is proposed based on the 3-D printing technology. An impedance bandwidth of 53.7%, a gain up to 10.8 dBi, and stable unidirectional radiation patterns with the cross polarization of less than −38 dB are achieved by the antenna. Its operating mechanism and design process are studied in detail as well. In order to widen the bandwidth of the millimeter-wave full-corporate H-plane air-filled waveguide feed network, a wideband H-plane stepped waveguide T-junction with a compact size is then investigated, which has a bandwidth of about 50% for the reflection coefficient of less than −20 dB. By combining the presented radiating element with the feed network, an $8 \times 8$ ME dipole array is designed, printed, and tested in the Ka -band. An enhanced bandwidth of 31%, symmetric radiation patterns with the cross polarization of less than −35 dB, and a gain varying from 25.5 to 28.5 dBi are experimentally obtained. The proposed design demonstrates the advantage of utilizing the 3-D printing method to improve the operating characteristics of the millimeter-wave antenna array and is attractive for the emerging wideband millimeter-wave wireless applications.
TL;DR: In this paper, an electrically small Huygens circularly polarized (HCP) rectenna whose antenna is directly matched to its rectifying circuit is developed and experimentally validated in the ISM band at 915 MHz.
Abstract: An electrically small Huygens circularly polarized (HCP) rectenna whose antenna is directly matched to its rectifying circuit is developed and experimentally validated in the ISM band at 915 MHz. The HCP antenna is a near-field resonant parasitic (NFRP) design consisting of a driven element and a crossed pair of balanced electric and magnetic NFRP dipole elements. The rectifier circuit is highly capacitive. It is a full-wave design based on two HSMS286C Schottky diodes. Two innovative driven element designs are explored that facilitate the effective conjoin of the antenna to different classes of external circuits. An HCP antenna with a driven spiral line element is demonstrated. Its input impedance is capacitive and, hence, the system is ideal for matching directly to an inductive external circuit. An HCP antenna with a driven loop element is investigated in a similar manner. The system has an inductive input impedance that is subsequently optimized to be conjugately match to the capacitive rectifier directly. The measured HCP rectenna prototype has broad-angle capture capacity, avoids any polarization mismatch issues, and has exceptional ac to dc conversion efficiency, the maximum reaching 90.6%. It is an ideal candidate for wireless power transfer (WPT)-enabled Internet-of-Things (IoT) applications.
TL;DR: In this paper, a filtering magnetoelectronic dipole antenna (MEDA) with quasi-elliptic gain response and wide operating band is investigated, where four driven stubs connected to the shorted walls of MEDA are used to excite the planar dipole arms.
Abstract: A filtering magnetoelectronic dipole antenna (MEDA) with quasi-elliptic gain response and wide operating band is investigated. Different from the conventional MEDA, the antenna studied here is fed by fork-shaped microstrip line aperture-coupled excitation. The intrinsic radiation null of the MEDA at the lower passband edge is utilized, and a mathematical model is first put forward to demonstrate its working mechanism. Four driven stubs connected to the shorted walls of MEDA are used to excite the planar dipole arms. The parasitic inductor and the coupling capacitor introduced by driven stubs form an equivalent low-pass filter network, leading to a radiation null at higher frequency. Furthermore, a third radiation null is generated by introducing two quarter-wavelength U-shaped shorted stubs to improve the out-of-band suppression. Besides, due to the introduction of multiple coupling structure, including the fork-shaped microstrip line coupling slot and driven stubs, a wide operating band can be realized while maintaining a low profile of 0.15 wavelength. The experimental results show that an impedance bandwidth of 53.5% (2.95–5.1 GHz) is achieved and an out-of-band suppression level higher than 17.9 dB is obtained. What is more, an average gain of 8 dBi and good radiation patterns are realized over the whole operating band.
TL;DR: An integrated antenna design, which operates at multi-bands, i.e. sub-6 GHz at 3.6 GHz and mm-wave at 28 GHz, is validated, and the simulated and measured results confirm the validity of the proposed concept.
Abstract: The realization of a common-aperture (or shared-aperture) 5G antenna system is proposed for compact and integrated wireless devices. As a combination of a dipole and tapered slots, an integrated antenna design, which operates at multi-bands, i.e. sub-6 GHz at 3.6 GHz and mm-wave at 28 GHz, is validated. The antenna design procedure starts with a dipole operating at 3.6 GHz, which is fed by a modified balun consisting of a tapered slot and a microstrip line. Here, the tapered slot has a dual feature, i.e., it is used to excite the dipole at 3.6 GHz and works as a tapered slot antenna at 28 GHz. Only a single feeder is optimized and used for both structures making the design unique and provides an extremely large frequency ratio. Moreover, the dipole’s arms are utilized as an antenna footprint for two tapered slot mm-wave arrays, making the dipole dual-functional. The tapered slot antenna and the mm-wave arrays are optimized in a way that the main beams point at different directions. By this configuration, the design is able to cover an angle of $120^{o}$ of space in $\theta -$ direction. As a proof of concept, a prototype is fabricated on Rogers RO-5880 with an overall size of $75\times 25\times 0.254$ mm3. The simulated and measured results confirm the validity of the proposed concept.
TL;DR: This paper details the design, fabrication and testing of flexible textile-concealed Radio Frequency Identification (RFID) tags for wearable applications in a smart city/smart building environment and investigates its suitability for practical deployment.
Abstract: This paper details the design, fabrication and testing of flexible textile-concealed Radio Frequency Identification (RFID) tags for wearable applications in a smart city/smart building environment. The proposed tag designs aim to reduce the overall footprint, enabling textile integration whilst maintaining the read range. The proposed RFID filament is less than 3.5 mm in width and 100 mm in length. The tag is based on an electrically small (0.0033 λ 2 ) high-impedance planar dipole antenna with a tuning loop, maintaining a reflection coefficient less than −21 dB at 915 MHz, when matched to a commercial RFID chip mounted alongside the antenna. The antenna strip and the RFID chip are then encapsulated and integrated in a standard woven textile for wearable applications. The flexible antenna filament demonstrates a 1.8 dBi gain which shows a close agreement with the analytically calculated and numerically simulated gains. The range of the fabricated tags has been measured and a maximum read range of 8.2 m was recorded at 868 MHz Moreover, the tag’s maximum calculated range at 915 MHz is 18 m, which is much longer than the commercially available laundry tags of larger length and width, such as Invengo RFID tags. The reliability of the proposed RFID tags has been investigated using a series of tests replicating textile-based use case scenarios which demonstrates its suitability for practical deployment. Washing tests have shown that the textile-integrated encapsulated tags can be read after over 32 washing cycles, and that multiple tags can be read simultaneously while being washed.
TL;DR: In this paper, a wide-beam antenna at two main planes is proposed, where a pair of parasitic patches with metallic vias is creatively arranged on either side of the original radiation patches.
Abstract: In this letter, a wide-beam (at two main planes) antenna is proposed. To broaden the 3 dB beamwidth of the original antenna, a pair of parasitic patches with metallic vias is creatively arranged on either side of the original radiation patches. Based on the proposed antenna element, two linear phased arrays are fabricated and measured. Measured results reveal that the wide-angle scanning capability of both H -plane and E -plane arrays can be obtained. The scanning beam of the former can cover territories ranging from −90° to 90°, with gain loss within 3 dB (8 GHz–11 GHz). The scanning beam of the latter can cover territories ranging from −70° to 70°, with gain loss of 3–5 dB (8 GHz–10 GHz).
TL;DR: In this article, a compact multibeam end-fire dual-polarized antenna array for low-cost millimeter-wave (mmWave) applications is proposed, which includes a four-element antenna array, an SIW beamforming network, and transitions.
Abstract: A compact multibeam endfire dual-polarized antenna array for low-cost millimeter-wave (mmWave) applications is proposed in this letter. Multimode substrate-integrated waveguide (SIW) section with interactions is applied as the basic beamformer. The dual-mode SIW is used in the beamforming network to support dual-polarization application without occupying an extra area. The printed dipole antenna with integrated balun and the open-ended SIW antenna with metallic strips are integrated to realize an endfire dual-polarized antenna element. Based on this endfire antenna element, a multibeam dual-polarized antenna array is developed. The proposed antenna array includes a four-element antenna array, an SIW beamforming network, and transitions. Additional air gaps between antenna elements are designed for mutual coupling reduction. The fabricated multibeam endfire dual-polarized antenna array achieves an impedance bandwidth of 11.3%, and the overlapped 3 dB beamwidth of the four generated beams in two polarizations are able to cover a wide range between ± 41°. The proposed low-cost multibeam antenna array can be a good candidate for 5G mmWave wireless applications.
TL;DR: In this paper, a dual-band linear-to-circular polarization converter designed on a single-layer substrate is proposed, which consists of split rings and a pair of metallic strips printed on both sides of a single layer substrate for dualband operation.
Abstract: In this article, a compact dual-band linear-to-circular polarization converter designed on a single-layer substrate is proposed The unit cell of the converter has a size of $372\times 390\times 152\,\,\text {mm}^{3}$ ( $00072\lambda ^{3}_{o} $ , $\lambda _{o}$ is calculated with respect to 2067 GHz) The converter consists of split rings and a pair of metallic strips printed on both sides of a single-layer substrate for dual-band operation The proposed converter has a measured 3-dB axial ratio bandwidth of 556% (2010–2125 GHz) in the lower band and 397% (2912–3030 GHz) at the upper band The converter transmits a right-hand circularly polarized (RHCP) wave at the lower band and left-hand circularly polarized (LHCP) wave at the upper band for a linearly polarized (LP) incident wave The characteristics of the polarization converter are validated by integrating an array of $7 \times 7$ elements of its unit cell in the endfire direction of a dual-band LP dipole antenna operating in the same frequency bands such as that of the polarization converter The antenna integrated with the polarization converter exhibits measured circularly polarized (CP) bandwidths of 780% and 657% in the lower frequency band: 2010–2175 GHz and the upper frequency band: 294–314 GHz, respectively The integrated antenna can act as a feed source of a high-gain dual-band transmit array for uplink (300–310 GHz) and downlink (202–212 GHz) of $Ka-$ band military satellite communication
TL;DR: In this article, a beam-steerable dipole array with low radar cross section (RCS) was designed, where a 2D periodical array of dipole antennas was colocated with absorptive frequency-selective reflection (AFSR) structures to reduce the out-of-band RCS and maintain high gain at the in-band frequencies.
Abstract: This communication presents an approach to design a beam-steerable dipole array with low radar cross section (RCS). A 2-D periodical array of dipole antennas is colocated with absorptive frequency-selective reflection (AFSR) structures to effectively reduce the out-of-band RCS and maintain high gain at the in-band frequencies. The AFSR structures consist of 3-D bandstop frequency-selective structure (FSS) and pyramidal-shaped absorbers to provide a reflection band for the dipole array with enhanced front-to-back ratio. Compared with the reference array, the radiation performance of the proposed array is maintained with an aperture efficiency of 70% and a measured peak gain of 21.5 dBi. The beam-steering angle is up to ±45°. Meanwhile, more than 10 dB two-sided out-of-band RCS reduction is achieved with a bandwidth of 96.5% and 30% for copolarization and 142% for cross polarization, and the in-band RCS is unchanged.
TL;DR: In this article, a wearable dual-band dual-mode button antenna for wireless body-area network applications is proposed, which operates from 2.32 to 2.57 GHz as a top-loaded monopole antenna with linear polarization.
Abstract: This letter proposes a wearable dual-band dual-mode button antenna for wireless body-area network applications. It covers the 2.45 and 5.8 GHz Industrial, Scientific, and Medical bands. The two operating modes of the antenna are designed to share a common radiator with different functionalities for distinctive communication requirements. The antenna operates from 2.32 to 2.57 GHz as a top-loaded monopole antenna with linear polarization, which is applicable for on-body communications due to its omnidirectional radiation pattern. In contrast, it works as a crossed-dipole antenna in its higher operation band extending from 5.72 to 7.85 GHz, in which it exhibits broadside radiation with circular polarization suitable for off-body communications. The experimental characterization on the fabricated antenna prototype, both in free space and proximity to the human body, proves that the antenna operates as anticipated with dual-band and dual-polarization characteristics for wearable applications.