Showing papers on "Dipole antenna published in 2017"
TL;DR: In this article, the issues involved in the design of antenna array architecture for future 5G mmw systems, in which the antenna elements can be deployed in the shapes of a cross, circle, or hexagon, are discussed, in addition to the conventional rectangle.
Abstract: As there has been an explosive increase in wireless data traffic, mmw communication has become one of the most attractive techniques in the 5G mobile communications systems. Although mmw communication systems have been successfully applied to indoor scenarios, various external factors in an outdoor environment limit the applications of mobile communication systems working at the mmw bands. In this article, we discuss the issues involved in the design of antenna array architecture for future 5G mmw systems, in which the antenna elements can be deployed in the shapes of a cross, circle, or hexagon, in addition to the conventional rectangle. The simulation results indicate that while there always exists a non-trivial gain fluctuation in other regular antenna arrays, the circular antenna array has a flat gain in the main lobe of the radiation pattern with varying angles. This makes the circular antenna array more robust to angle variations that frequently occur due to antenna vibration in an outdoor environment. In addition, in order to guarantee effective coverage of mmw communication systems, possible solutions such as distributed antenna systems and cooperative multi-hop relaying are discussed, together with the design of mmw antenna arrays. Furthermore, other challenges for the implementation of mmw cellular networks, for example, blockage, communication security, hardware development, and so on, are discussed, as are potential solutions.
271 citations
TL;DR: In this paper, a new concept that is called array-antenna decoupling surface (ADS) for reducing the mutual coupling between antenna elements in a large-scale array antenna is proposed for the first time.
Abstract: Massive multiple-input multiple-output (M-MIMO) technology is considered to be a key enabling technology for future wireless communication systems. One of the challenges in effectively implementing an advanced precoding scheme to a large-scale array antenna is how to reduce the mutual coupling among antenna elements. In this paper, a new concept that is called array-antenna decoupling surface (ADS) for reducing the mutual coupling between antenna elements in a large-scale array antenna is proposed for the first time. An ADS is a thin surface that is composed of a plurality of electrical small metal patches and is placed in front of the array antenna. The partially diffracted waves from the ADS can be controlled to cancel the unwanted coupled waves. Two practical design examples are given to illustrate the design process and considerations, and to demonstrate the usefulness of ADS for the applications of phased array antennas and M-MIMO systems when commonly used precoding schemes are applied. The attractive features of ADS include its applicability to a large-scale array antenna; suitability for a wide range of antenna forms; wide decoupling bandwidth; and simplicity in implementation.
238 citations
TL;DR: In this article, a dual-band inverted-F multiple-input-multiple-output (MIMO) antenna with improved isolation was proposed for the 2.4/5 GHz WLAN band.
Abstract: This letter presents a dual-band inverted-F multiple-input-multiple-output (MIMO) antenna with improved isolation, covering the 2.4/5-GHz wireless local networks (WLAN) band. The proposed MIMO antenna is composed of two symmetrical winding inverted-F antenna elements. The two antenna elements are closely spaced with about 0.115 λ
0
of the lower band. The high isolation is achieved by building two decoupling devices, a meandering resonant branch and an inverted T-shaped slot etched on the ground for the higher band and the lower band, respectively. Furthermore, two U-shaped slits achieving better impedance matching are etched on the 50-Ω feeding lines to broaden the bandwidth of the high band. The impedance bandwidth (S
11
<; -10 dB) of the proposed antenna covers 2.4-2.48 GHz in the lower band and 5.15-5.825 GHz in the upper band, and the proposed configuration obtains 15-dB isolation within the 2.4- and 5-GHz WLAN bands, which shows a significant improvement compared to the initial design of the MIMO antenna. The simulation and measurement results indicate that the proposed inverted-F MIMO antenna system is quite suitable for WLAN applications.
213 citations
TL;DR: In this paper, a broadband printed-dipole antenna and its arrays for 5G wireless cellular networks are proposed, which is fed by an integrated balun, which consists of a folded microstrip line and a rectangular slot.
Abstract: In this letter, we propose a broadband printed-dipole antenna and its arrays for fifth-generation (5G) wireless cellular networks. To realize a wide frequency range of operation, the proposed antenna is fed by an integrated balun, which consists of a folded microstrip line and a rectangular slot. For compactness, the printed dipole is angled at 45°. The single-element antenna yields an |S
11
| <;-10-dB bandwidth of 36.2% (26.5-38.2 GHz) and a gain of 4.5-5.8 dBi. We insert a stub between two printed-dipole antennas and obtain a low mutual coupling of <;-20 dB for a 4.8-mm center-to-center spacing (0.42-0.61 λ at 26-38 GHz). We demonstrate the usefulness of this antenna as a beamforming radiator by configuring 8-element linear arrays. Due to the presence of the stubs, the arrays resulted in a wider scanning angle, a higher gain, and a lower sidelobe level in the low-frequency region.
209 citations
TL;DR: The proposed rectenna is general and simple in structure without the need for a matching network, suitable for high-efficiency wireless power transfer or energy harvesting applications and of great significance for many applications.
Abstract: Impedance matching networks for nonlinear devices such as amplifiers and rectifiers are normally very challenging to design, particularly for broadband and multiband devices. A novel design concept for a broadband high-efficiency rectenna without using matching networks is presented in this paper for the first time. An off-center-fed dipole antenna with relatively high input impedance over a wide frequency band is proposed. The antenna impedance can be tuned to the desired value and directly provides a complex conjugate match to the impedance of a rectifier. The received RF power by the antenna can be delivered to the rectifier efficiently without using impedance matching networks; thus, the proposed rectenna is of a simple structure, low cost, and compact size. In addition, the rectenna can work well under different operating conditions and using different types of rectifying diodes. A rectenna has been designed and made based on this concept. The measured results show that the rectenna is of high power conversion efficiency (more than 60%) in two wide bands, which are 0.9–1.1 and 1.8–2.5 GHz, for mobile, Wi-Fi, and ISM bands. Moreover, by using different diodes, the rectenna can maintain its wide bandwidth and high efficiency over a wide range of input power levels (from 0 to 23 dBm) and load values (from 200 to 2000 Ω). It is, therefore, suitable for high-efficiency wireless power transfer or energy harvesting applications. The proposed rectenna is general and simple in structure without the need for a matching network hence is of great significance for many applications.
190 citations
TL;DR: In this article, a dual-band dual-polarized array antenna with low frequency ratio and integrated filtering characteristics is proposed, which employs a dualmode stub-loaded resonator to feed and tune with two patches, resulting in the reduction of the feed networks and the input ports.
Abstract: In this paper, a novel dual-band dual-polarized array antenna with low frequency ratio and integrated filtering characteristics is proposed. By employing a dual-mode stub-loaded resonator (SLR) to feed and tune with two patches, the two feed networks for each polarization can be combined, resulting in the reduction of the feed networks and the input ports. In addition, owing to the native dual resonant features of the SLR, the proposed antenna exhibits second-order filtering characteristics with improved bandwidth and out-of-band rejections. The antenna is synthesized and the design methodology is explained. The coupling coefficients between the SLR and the patches are investigated. To verify the design concept, a C-/X-band element and a $2 \times 2$ array are optimized and prototyped. Measured results agree well with the simulations, showing good performance in terms of bandwidth, filtering, harmonic suppression, and radiation at both bands. Such an integrated array design can be used to simplify the feed of a reflector antenna. To prove the concept, a paraboloid reflector fed by the proposed array is conceived and measured directivities of 24.6 dBi (24.7 dBi) and 28.6 dBi (29.2 dBi) for the X-polarization (Y-polarization) are obtained for the low- and high-band operations, respectively.
176 citations
TL;DR: In this paper, the beam of a resonant cavity antenna is steered by transforming phase of the antenna near field using a pair of totally passive metasurfaces, which are located just above and parallel to the antenna.
Abstract: A method to steer the beam of aperture-type antennas is presented in this paper. Beam steering is achieved by transforming phase of the antenna near field using a pair of totally passive metasurfaces, which are located just above and parallel to the antenna. They are rotated independently or synchronously around the antenna axis. A prototype, with a peak gain of 19.4 dBi, demonstrated experimentally that the beam of a resonant cavity antenna can be steered to any direction within a large conical region (with an apex angle of 102°), with less than 3-dB gain variation, by simply turning the two metasurfaces without moving the antenna at all. Measured gain variation within a 92° cone is only 1.9 dBi. Contrary to conventional mechanical steering methods, such as moving reflector antennas with multiaxis rotary joints, the 3-D volume occupied by this antenna system does not change during beam steering. This advantage, together with its low profile, makes it a strong contender for space-limited applications where beam steering with active devices is not desirable due to cost, nonlinear distortion, limited power handling, sensitivity to temperature variations, radio frequency losses, or associated heating. This beam steering method using near-field phase transformation can also be applied to other aperture-type antennas and arrays with medium-to-high gains.
174 citations
TL;DR: In this article, a low-complexity metallic tapered slot antenna (TSA) array for millimeter-wave multibeam massive multiple-input multiple-output (MIMO) communication is proposed.
Abstract: A low-complexity metallic tapered slot antenna (TSA) array for millimeter-wave multibeam massive multiple-input multiple-output communication is proposed in this paper. Good beamforming performance can be achieved by the developed antenna array because the element spacing can easily meet the requirement of half-wavelength in the H-plane. The antenna element is fed by a substrate-integrated waveguide, which can be directly integrated with the millimeter-wave circuits. The proposed TSA is fabricated and measured. Measured results show that the reflection coefficient is lower than −15 dB Voltage Standing Wave Ratio ((VSWR) ≤ 1.45) within the frequency range from 22.5 to 32 GHz, which covers the 24.25–27.5-GHz band proposed by International Telecommunications Union (ITU) and the 27.5–28.35-GHz band proposed by Federal Communications Commission (FCC) for 5G. The gain of the antenna element varies from 8.2 to 9.6 dBi over the frequency range of 24–32 GHz. The simulated and measured results also illustrate good radiation patterns across the wide frequency band (24–32 GHz). A $1\times 4$ H-plane array integrated with the multichannel millimeter-wave transceivers on one PCB is demonstrated and excellent performance is achieved.
160 citations
TL;DR: In this article, a novel integrated antenna solution for wireless handheld devices is proposed for the existing 4G standards and upcoming 5G systems for broadband, high data rate communications, which is a unique combination of a multiple-input-multiple-output (MIMO) antenna system at microwave frequencies and a millimetre (mm)-wave antenna array.
Abstract: A novel integrated antenna solution for wireless handheld devices is proposed for the existing 4G standards and upcoming 5G systems for broadband, high data rate communications. The complete antenna system is a unique combination of a multiple-input-multiple-output (MIMO) antenna system at microwave frequencies and a millimetre (mm)-wave antenna array. The MIMO antenna system consists of two reactive loaded monopoles while the mm-wave array consists of a planar 2 by four slot antennas. The integrated antenna system covers the frequency bands from 1870 to 2530 MHz for 4G standards along with the upcoming 5G mm-wave band at 28 GHz. In addition, the integrated antenna system is planar and is designed for typical smart phone devices with a standard 60 mm by 100 mm by 0.965 mm back plane. Excellent field correlation values were obtained across the 4G band while realised peak gain values of 4 and 8 dBi were, respectively, measured for the MIMO and mm-wave antenna arrays. The proposed antenna design may also be useful for other compact implementations that support 4G and 5G communications.
152 citations
TL;DR: In this paper, a dual-band antenna for off-and on-body communications in the 2.45- and 5.8-GHz Industrial, Scientific, and Medical bands is presented.
Abstract: A dual-band antenna for off- and on-body communications in the 2.45- and 5.8-GHz Industrial, Scientific, and Medical bands is presented. The two radiation characteristics, i.e., patch-like radiation for the off-body link and monopole-like radiation for the on-body link, are achieved by utilizing inherently generated TM $_{11}$ and TM $_{02}$ modes of a circular patch antenna. A shorting pin and two arc-shaped slots are employed to tune both modes to the desired operating frequencies. This approach allows a realization of a dual-band dual-mode antenna with a very simple structure, i.e., a single radiator with a simple feed. A further advantage of the proposed antenna is its realization using a silver fabric integrated onto a flexible polydimethylsiloxane substrate that makes it more practical for wearable applications. An experimental investigation of the antenna performance has been carried out in free space and on a semisolid human muscle equivalent phantom, which shows a robust performance against the human body loading effect. When placed on the phantom, the measured bandwidths of 84 and 247 MHz in the 2.45- and 5.8-GHz bands, respectively, are achieved with the corresponding peak gains of 4.16 and 4.34 dBi, indicating a promising candidate for body-centric communications.
146 citations
IBM1
TL;DR: A practical Ka-band AiP structure based on multilayer organic buildup substrates that is suitable for phased-array module integration needs and supports both horizontal and vertical polarizations is introduced.
Abstract: Phased-array modules at frequencies >20 GHz are expected to play an important role for 5G applications. Antenna-in-package (AiP) is a reliable and cost-effective method to realize these phased arrays. This paper introduces a practical Ka-band AiP structure and discusses the antenna element design and implementation tradeoffs. The AiP design is based on multilayer organic buildup substrates that are suitable for phased-array module integration needs and supports both horizontal and vertical polarizations. Measurement results from the fabricated antenna prototypes show 0.8 GHz return loss bandwidth and 3.8-dBi peak gain at 30.5 GHz. Simulation results agree with the measured ones.
TL;DR: In this paper, a broadband dual-polarized base station antenna with sturdy construction is presented, which mainly contains four parts: main radiator, feeding baluns, bedframe, and reflector.
Abstract: A broadband dual-polarized base station antenna with sturdy construction is presented in this letter. The antenna mainly contains four parts: main radiator, feeding baluns, bedframe, and reflector. First, two orthogonal dipoles are etched on a substrate as main radiator forming dual polarization. Two baluns are then introduced to excite the printed dipoles. Each balun has four bumps on the edges for electrical connection and fixation. The bedframe is designed to facilitate the installation, and the reflector is finally used to gain unidirectional radiation. Measured results show that the antenna has a 48% impedance bandwidth with reflection coefficient less than –15 dB and port isolation more than 22 dB. A four-element antenna array with 6° ± 2° electrical down tilt is also investigated for wideband base station application. The antenna and its array have the advantages of sturdy construction, high machining accuracy, ease of integration, and low cost. They can be used for broadband base station in the next-generation wireless communication system.
TL;DR: To develop a 16‐channel transceive body imaging array at 7.0 T with improved transmit, receive, and specific absorption rate (SAR) performance by combining both loop and dipole elements and using their respective and complementary near and far field characteristics.
Abstract: Purpose
To develop a 16-channel transceive body imaging array at 7.0 T with improved transmit, receive, and specific absorption rate (SAR) performance by combining both loop and dipole elements and using their respective and complementary near and far field characteristics.
Methods
A 16-channel radiofrequency (RF) coil array consisting of eight loop-dipole blocks (16LD) was designed and constructed. Transmit and receive performance was quantitatively investigated in phantom and human model simulations, and experiments on five healthy volunteers inside the prostate. Comparisons were made with 16-channel microstrip line (16ML) and 10-channel fractionated dipole antenna (10DA) arrays. The 16LD was used to acquire anatomic and functional images of the prostate, kidneys, and heart.
Results
The 16LD provided > 14% improvements in the signal-to-noise ratio (SNR), peak B1+, B1+ transmit, and SAR efficiencies over the 16ML and 10DA in simulations inside the prostate. Experimentally, the 16LD had > 20% higher SNR and B1+ transmit efficiency compared with other arrays, and achieved up to 51.8% higher peak B1+ compared with 10DA.
Conclusion
Combining loop and dipole elements provided a body imaging array with high channel count and density while limiting inter-element coupling. The 16LD improved both near and far-field performance compared with existing 7.0T body arrays and provided high-quality MRI of the prostate kidneys and heart. Magn Reson Med 77:884–894, 2017. © 2016 International Society for Magnetic Resonance in Medicine
TL;DR: In this paper, a wide-angle beam-scanning antenna with circular polarization (CP) characteristic is proposed, where the antenna consists of two layers and a series of circular patches are placed on the top layer as radiating elements.
Abstract: In this letter, a wide-angle beam-scanning antenna with circular polarization (CP) characteristic is proposed. The antenna consists of two layers. Microstrip spoof surface plasmon polariton (SPP) is introduced on the bottom layer as a slow-wave feeding line. A series of circular patches are placed on the top layer as radiating elements. Simulated and measured results indicate that beam-scanning angle of the proposed antenna is improved and CP beam-scanning ability is obtained by introducing perturbation on the radiating elements. In the operating band of 11–15 GHz, measured scanning angle of the fabricated antenna is from –32° to +34°. The antenna axial ratio (AR) is below 3 dB at the corresponding beam direction, and gain is above 12.8 dBi over the whole band. It has potential applications in radar and wireless communication systems for simple structure, low-cost fabrication, wide beam-steering, and CP properties.
TL;DR: In this paper, a new type of wearable button antenna for wireless local area network (WLAN) applications is proposed, which is composed of a button with a diameter of circa 16 mm incorporating a patch on top of a dielectric disc.
Abstract: A new type of wearable button antenna for wireless local area network (WLAN) applications is proposed. The antenna is composed of a button with a diameter of circa 16 mm incorporating a patch on top of a dielectric disc. The button is located on top of a textile substrate and a conductive textile ground that are to be incorporated in clothing. The main characteristic feature of this antenna is that it shows two different types of radiation patterns, a monopole type pattern in the 2.4 GHz band for on-body communications and a broadside type pattern in the 5 GHz band for off-body communications. A very high efficiency of about 90% is obtained, which is much higher than similar full textile solutions in the literature. A prototype has been fabricated and measured. The effect of several real-life situations such as a tilted button and bending of the textile ground have been studied. Measurements agree very well with simulations.
TL;DR: In this article, a 4 × 4 cm 2 MIMO antenna for UWB applications is proposed, which consists of four symmetric circular elements printed on low cost FR4 substrate with partial slotted ground plane.
Abstract: This paper presents compact size 4 × 4 cm 2 MIMO antenna for UWB applications. The proposed antenna consists of four symmetric circular elements printed on low cost FR4 substrate with partial slotted ground plane. The two sides of the substrate are symmetric and each side is consisting of two radiators with the partial ground planes associated to the two other elements mounted on the other side. The two elements of the front side are orthogonal to the two other elements of the back side in order to increase the isolation between elements. For further reduction in the mutual coupling between elements, decoupling structures are presented in the top and bottom layers of the substrate. The simulated and measured results are investigated to study the effectiveness of the MIMO-UWB antenna. The results demonstrate the satisfactory performance of MIMO-UWB antenna, which has a return loss less than −10 dB from approximately 3.1 GHz to more than 11 GHz with an insertion loss lower than −20 dB through the achieved frequency band, and a correlation less than 0.002. Moreover, the proposed MIMO model exhibits a nearly omni-directional radiation pattern with almost constant gain of average value 3.28 dBi.
TL;DR: A single-layered leaky wave antenna (SL-LWA) exploiting the groundless spoof plasmons (SPs) structure is presented and validated to achieve consistent scanning beam and broadside gain across a wide bandwidth.
Abstract: A single-layered leaky wave antenna (SL-LWA) exploiting the groundless spoof plasmons (SPs) structure is presented and validated to achieve consistent scanning beam and broadside gain across a wide bandwidth. The antenna is composed of single-layered meander SP cells and coplanar waveguide to SP structure converters. The periodically arranged SP cells of the SL-LWA generate a radiating space harmonic with forward, backward, and broadside radiation against frequency change. The study and experimental validation show that the proposed SL-LWA provides the consistent gain variation less than 2.5 dB of scanning beams within the 10-dB reflection bandwidth of 10.4-24.5 GHz (or 80%). In addition, the proposed antenna offers the wideband broadside radiation with 1-dB gain variation within the frequency range of 16.5-17.2 GHz (or 4.2%). The method to design the antenna operating at desired frequencies is provided. Benefiting from the low-profile compactness and unprecedented performance, the proposed SL-LWA has promising potentials for applications in wireless systems.
TL;DR: In this paper, a pair of parallel coupled-line resonators (PCRs) are used for isolation enhancement in planar microstrip patch array antennas. But the proposed antenna is deployed in a two-element antenna array, and the mutual coupling characteristics are studied.
Abstract: This letter presents the implementation of a pair of parallel coupled-line resonators (PCRs) for isolation enhancement in planar microstrip patch array antennas. Each PCR consists of three coupled lines separated by a small coupling distance. The attempted configuration provides band-reject characteristics at the design frequency of 3.5 GHz. Two such PCRs are replicated to provide higher order rejection that enhances the bandstop characteristics. The designed PCR is deployed in a two-element microstrip patch antenna array, and the mutual coupling characteristics are studied. The proposed PCR-based decoupling unit cell provides additional 12–26.2-dB coupling reduction with an enhancement of antenna gain up to 1.25 dB. The prototype antenna is fabricated, and the simulation results are validated using experimental measurements.
TL;DR: In this paper, an effective technique for reducing the mutual coupling between two dielectric resonator antennas (DRAs) operating at 60 GHz bands is presented by incorporating a metasurface between the two DRAs, which are arranged in the H-plane.
Abstract: An effective technique for reducing the mutual coupling between two dielectric resonator antennas (DRAs) operating at 60-GHz bands is presented. This is achieved by incorporating a metasurface between the two DRAs, which are arranged in the H-plane. The metasurface comprises an array of unique split-ring resonator (SRR) cells that are integrated along the E-plane. The SRR configuration is designed to provide bandstop functionality within the antenna bandwidth. By loading the DRA with 1 × 7 array of SRR unit cells, a 28-dB reduction in the mutual coupling level is achieved without compromising the antenna performance. The measured isolation of the prototype antenna varies from -30 to -46.5 dB over 59.3-64.8 GHz. The corresponding reflection coefficient of the DRA is better than -10 dB over 56.6-64.8 GHz.
TL;DR: The proposed multi-dipole antenna with switchable 0°, +45°, 90° and −45° linear polarizations is able to overcome the polarization mismatching and multi-path distortion in complex wireless channels as in BWCS.
Abstract: This paper presents a multi-polarization reconfigurable antenna with four dipole radiators for biomedical applications in body-centric wireless communication system (BWCS). The proposed multi-dipole antenna with switchable 0°, +45°, 90° and −45° linear polarizations is able to overcome the polarization mismatching and multi-path distortion in complex wireless channels as in BWCS. To realize this reconfigurable feature for the first time among all the reported antenna designs, we assembled four dipoles together with 45° rotated sequential arrangements. These dipoles are excited by the same feeding source provided by a ground tapered Balun. A metallic reflector is placed below the dipoles to generate a broadside radiation. By introducing eight PIN diodes as RF switches between the excitation source and the four dipoles, we can control a specific dipole to operate. As the results, 0°, +45°, 90° and −45° linear polarizations can be switched correspondingly to different operating dipoles. Experimental results agree with the simulation and show that the proposed antenna well works in all polarization modes with desirable electrical characteristics. The antenna has a wide impedance bandwidth of 34% from 2.2 to 3.1 GHz (for the reflection coefficient ${\leq}$ −10 dB) and exhibits a stable cardioid-shaped radiation pattern across the operating bandwidth with a peak gain of 5.2 dBi. To validate the effectiveness of the multi-dipole antenna for biomedical applications, we also designed a meandered PIFA as the implantable antenna. Finally, the communication link measurement shows that our proposed antenna is able to minimize the polarization mismatching and maintains the optimal communication link thanks to its polarization reconfigurability.
TL;DR: It is demonstrated that the proposed antenna element and arrays can be used for future 5G applications to cover the 22% bandwidth of the unlicensed band with high gain and low loss.
Abstract: A wideband linearly polarized antenna element with complementary sources is proposed and exploited for array antennas. The element covers a bandwidth of 38.7% from 50 to 74 GHz with an average gain of 8.7 dBi. The four-way broad wall coupler is applied for the 2 $\times $ 2 subarray, which suppresses the cross-polarization of a single element. Based on the designed 2 $ \times $ 2 subarray, two larger arrays have been designed and measured. The $4 \times 4$ array exhibits 26.7% bandwidth, fully covering the 57–71 GHz unlicensed band. The $8 \times 8$ array antenna covers a bandwidth of 14.5 GHz (22.9%) from 56.1 to 70.6 GHz with a peak gain of 26.7 dBi, and the radiation efficiency is around 80% within the matching band. It is demonstrated that the proposed antenna element and arrays can be used for future 5G applications to cover the 22% bandwidth of the unlicensed band with high gain and low loss.
TL;DR: In this article, a planar switchable 3D-coverage phased array for 28 GHz mobile terminal applications is proposed, where three identical slot subarrays switch their beams to three distinct regions.
Abstract: This paper introduces a planar switchable 3-D-coverage phased array for 28-GHz mobile terminal applications. In order to realize 3-D-coverage beam scan with a simple planar array, chassis surface waves are efficiently excited and controlled by three identical slot subarrays. Three subarrays switch their beams to three distinct regions. Each subarray works as a phased array to steer the beam within each region. Large coverage efficiency is achieved. (e.g., 80% of the space sphere has the realized gain of over 8 dBi.) The proposed antenna covers a bandwidth of over 2 GHz in the band of 28 GHz. User effects on the switchable array are also studied in both data mode and talk mode (voice) at 28 GHz. In talk mode, good directivity and beam switching can be realized by placing the switchable array at the top of the chassis (close to the index finger). And the user shadowing can be significantly reduced by placing it at the bottom of the chassis (close to the palm). In data mode, the switchable array, mounted at the top, achieves less body loss and larger coverage than at the bottom. The proposed antenna is fabricated and measured. The array at the top in talk mode is measured with a real human. The measurements align well with simulations.
TL;DR: In this article, a 94 GHz substrate integrated waveguide (SIW) parallel-plate long-slot array antenna is presented, which is able to generate dual-circular-polarization (CP) low sidelobe level (SLL) beams from a single radiating aperture.
Abstract: In this paper, a 94 GHz substrate integrated waveguide (SIW) parallel-plate long-slot array antenna is presented, which is able to generate dual-circular-polarization (CP) low sidelobe level (SLL) beams from a single radiating aperture. This antenna consists of two layers of substrates. One is used to construct the unequal feeding network and the other is used to construct a $15 \times 15$ shared-aperture parallel-plate long-slot array antenna. This multilayer topology has a smaller size compared with the single-layer design. A simple and feasible method is applied to control the radiation pattern, which is able to realize dual-CP low SLL beams without a complicated feeding network. Two 1-D sixteen-way unequal dividers are employed to suppress the SLL in two planes of a CP array. Then, a 90° coupler is employed in the feeding network to switch the polarization modes between left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP). Finally, a prototype of SIW parallel-plate long-slot array antenna is fabricated. Simulation and measured results show that SLLs of the fabricated antenna are under −18.5 dB in two planes.
TL;DR: A novel 3-D-printed polarizer is introduced, which consists of several air and dielectric slabs to transform the polarization of the antenna radiation from linear to circular, to develop a wideband, high-gain, and low-cost antenna for the mmw frequency band.
Abstract: This paper presents a wideband circularly polarized millimeter-wave (mmw) antenna design. We introduce a novel 3-D-printed polarizer, which consists of several air and dielectric slabs to transform the polarization of the antenna radiation from linear to circular. The proposed polarizer is placed above a radiating aperture operating at the center frequency of 60 GHz. An electric field, ${E}$ , radiated from the aperture generates two components of electric fields, ${E} _{\mathrm {x}}$ and ${E} _{\mathrm {y}}$ . After passing through the polarizer, both ${E} _{\mathrm {x}}$ and ${E} _{\mathrm {y}}$ fields can be degenerated with an orthogonal phase difference which results in having a wide axial ratio bandwidth. The phase difference between ${E} _{\mathrm {x}}$ and ${E} _{\mathrm {y}}$ is determined by the incident angle $\phi $ , of the polarization of the electric field to the polarizer as well as the thickness, ${h}$ , of the dielectric slabs. With the help of the thickness of the polarizer, the directivity of the radiation pattern is increased so as to devote high-gain and wideband characteristics to the antenna. To verify our concept, an intensive parametric study and an experiment were carried out. Three antenna sources, including dipole, patch, and aperture antennas, were investigated with the proposed 3-D-printed polarizer. All measured results agree with the theoretical analysis. The proposed antenna with the polarizer achieves a wide impedance bandwidth of 50% from 45 to 75 GHz for the reflection coefficient less than or equal −10 dB, and yields an overlapped axial ratio bandwidth of 30% from 49 to 67 GHz for the axial ratio ≤ 3 dB. The maximum gain of the antenna reaches to 15 dBic. The proposed methodology of this design can apply to applications related to mmw wireless communication systems. The ultimate goal of this paper is to develop a wideband, high-gain, and low-cost antenna for the mmw frequency band.
TL;DR: In this paper, a dual-band and dual-sense circularly polarized coplanar-waveguide-fed monopole antenna with two rectangular parasitic elements and an I-shape grounded stub is presented.
Abstract: A novel design of a dual-band and dual-sense circularly polarized coplanar-waveguide-fed monopole antenna with two rectangular parasitic elements and an I-shape grounded stub is presented here. The monopole consists of a vertical and a horizontal section. Lower band is obtained due to 90° phase difference between currents in the two orthogonal branches of the monopole. Upper band is obtained due to the I-shape stub. Parasitic elements help in input impedance matching. The dual-band and dual-sense antenna provides wide 10-dB impedance bandwidth of 71.63% at 2.82 GHz. The 3-dB axial-ratio bandwidths are 27.45% at 2.55 GHz (right-hand circular polarization) and 7.1% at 3.53 GHz (left-hand circular polarization).
TL;DR: A new dielectric resonator antenna for a millimeter-wave (mm-wave) multiple-input–multiple-output system is presented, indicating that the proposed antenna can provide spatial or pattern diversity to increase the data capacity of wireless communication systems at mm-wave bands.
Abstract: A new dielectric resonator antenna (DRA) for a millimeter-wave (mm-wave) multiple-input–multiple-output system is presented. Two approaches are exploited to reduce the mutual coupling between two antenna elements. First, a frequency selective surface (FSS) wall is inserted between the DRAs to reduce the free-space radiation. Then, two slots with different size acting like an $LC$ resonator are etched from the common ground plane of the structure to reduce the surface current. The designed FSS has a wideband characteristic from 40 to 70 GHz. The FSS is optimized for the desired frequency of 57–63 GHz. A high isolation of −30 dB is achieved when both FSS wall and slots are used. A prototype of the structure is fabricated and measured. The results give a low correlation coefficient ( $e$ –6) and a good agreement with simulation ones, indicating that the proposed antenna can provide spatial or pattern diversity to increase the data capacity of wireless communication systems at mm-wave bands.
TL;DR: A novel 2-element ultrawideband Yagi-based multiple-input–multiple-output (MIMO) antenna system is presented based on loop excitation, where half of the driven loop element is implemented on each side of the substrate, which reduces the overall size of the antenna by half and increases its bandwidth significantly.
Abstract: A novel 2-element ultrawideband Yagi-based multiple-input-multiple-output (MIMO) antenna system is presented based on loop excitation. Half of the driven loop element is implemented on each side of the substrate, which not only reduces the overall size of the antenna by 45%, but also increases its bandwidth significantly. The center frequency of operation is 5.8 GHz targeting WLAN applications. The proposed design has a wide measured bandwidth of 2.401 GHz covering 4.183-6.584 GHz. The proposed compact MIMO antenna system has an overall size of 50 × 80 × 0.76 mm
3
with a single element size of 50 × 40 × 0.76 mm
3
. The proposed Yagi antenna has high directional radiation characteristics with a minimum measured front-to-back ratio of 18 dB, minimum measured gain of 6 dBi, and directivity of 6.6 dB using a single director element only, at 5.8 GHz. It has a minimum measured isolation of 17 dB, measured maximum envelope correlation coefficient value of 0.0568, and measured total efficiency above 80% across the band of operation.
TL;DR: In this paper, the authors proposed a compact wideband circularly polarized antenna array, which is a set of 2 × 2 metasurface-based CP patch antennas fed by a sequential-phase (SP) network.
Abstract: This letter proposes a compact wideband circularly polarized (CP) antenna array, which is a set of 2 × 2 metasurface-based CP patch antennas fed by a sequential-phase (SP) network. The single element is composed of a truncated corner square patch sandwiched between the ground plane and the metasurface of a lattice of 4 × 4 periodic metal plates. These metasurface-based antennas are incorporated with the SP network of a sequentially rotated series-parallel feed to achieve wideband operation. The radiation pattern and operational bandwidth in the high-frequency region were improved by reducing the spacing between the driven patches while maintaining the structure and overall size of the metasurface. The final design, with an overall size of 64 × 64 × 2.34 mm3 (approximately 1.26λo × 1.26λo × 0.046λo at 5.9 GHz), was fabricated and measured. The antenna array has a measured | $S_{11}$ | < −10-dB bandwidth of 4.40–8.00 GHz (58.06%), a 3-dB axial ratio bandwidth of 4.75–7.25 GHz (41.67%), a 3-dB gain bandwidth of 4.8–7.0 GHz (37.3%), and a peak gain of 12.08 dBic at 6.0 GHz. In addition, the antenna array yielded a broadside, left-hand CP radiation with a symmetrical profile, low sidelobe level, and high radiation efficiency.
TL;DR: In this paper, a radial uniform circular array (UCA) is proposed for orbital angular momentum (OAM) generation and dual-mode communication based on a multilayer design, which achieves good −15-dB bandwidths at the ±1 modes, and a very weak cross coupling (less than −24 dB) exists in this frequency band.
Abstract: A radial uniform circular array (UCA) is proposed for orbital angular momentum (OAM) generation and dual-mode communication based on a multilayer design. Theoretical derivation is presented for the demonstration of the OAM generation from radial UCAs. The UCA of single mode is realized by cascading an eight-dividing feeding network with equal magnitude and specific phases for each of two neighbor ports and eight microstrip antenna elements. Both the full-wave simulations and measurements of a final fabricated antenna array are carried out. From 5.72 to 5.95 GHz, the proposed antenna possesses good −15-dB bandwidths at the ±1 modes, and a very weak cross coupling (less than −24 dB) exists in this frequency band. The helical phase wavefronts are obtained, and the radiation patterns are presented. Moreover, the dual-mode multiplexing is achieved with isolations of different channels more than 19 dB in measurements.
TL;DR: In this paper, a highly isolated compact four-element planar ultrawideband (UWB) multiple-input-multiple-output (MIMO) antenna array configuration is presented.
Abstract: This letter presents a highly isolated compact four-element planar ultrawideband (UWB) multiple-input-multiple-output (MIMO) antenna array configuration. The main advantages of the proposed array configuration are that it requires no isolation/decoupling circuit and the configuration is easily extendable to larger size array. The array consists of novel miniaturized slotted annular ring monopole antenna and each element in the array is placed orthogonal to its adjacent elements. The fabricated structure provides good impedance bandwidth matching and high isolation between elements over the range from 3 to 15 GHz. The absence of decoupling circuit results in overall compact size of the proposed design. The prototypes are fabricated and tested. The simulated and measured results are in good agreement. Moreover, the envelope correlation coefficient and channel capacity loss of the array are calculated, which shows good MIMO performance. The proposed monopole antenna structure supports multielement UWB MIMO antenna array design with easy extension of elements and without any decoupling circuit. An example of eight-element array is also investigated.