Showing papers on "Slot antenna published in 2017"
TL;DR: Nan et al. as mentioned in this paper developed acoustically actuated antennas that couple the acoustic resonance of the antenna with the electromagnetic wave, reducing the antenna footprint by up to 100. And they demonstrated 1-2 orders of magnitude miniaturization over state-of-the-art compact antennas without performance degradation.
Abstract: State-of-the-art compact antennas rely on electromagnetic wave resonance, which leads to antenna sizes that are comparable to the electromagnetic wavelength. As a result, antennas typically have a size greater than one-tenth of the wavelength, and further miniaturization of antennas has been an open challenge for decades. Here we report on acoustically actuated nanomechanical magnetoelectric (ME) antennas with a suspended ferromagnetic/piezoelectric thin-film heterostructure. These ME antennas receive and transmit electromagnetic waves through the ME effect at their acoustic resonance frequencies. The bulk acoustic waves in ME antennas stimulate magnetization oscillations of the ferromagnetic thin film, which results in the radiation of electromagnetic waves. Vice versa, these antennas sense the magnetic fields of electromagnetic waves, giving a piezoelectric voltage output. The ME antennas (with sizes as small as one-thousandth of a wavelength) demonstrates 1–2 orders of magnitude miniaturization over state-of-the-art compact antennas without performance degradation. These ME antennas have potential implications for portable wireless communication systems. The miniaturization of antennas beyond a wavelength is limited by designs which rely on electromagnetic resonances. Here, Nan et al. have developed acoustically actuated antennas that couple the acoustic resonance of the antenna with the electromagnetic wave, reducing the antenna footprint by up to 100.
241 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: 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 wearable flexible reconfigurable folded slot antenna is presented, where the antenna is composed of a folded slot and a stub where the reconfigurability is achieved by turning a p-i-n diode on and off, which alters the radiation characteristics of the stub.
Abstract: This letter presents a wearable flexible reconfigurable folded slot antenna. The antenna is composed of a folded slot and a stub where the reconfigurability is achieved by turning a p-i-n diode on and off , which alters the radiation characteristics of the stub. The operating frequency and polarization of the slot and stub are different. Hence, a polarization-dependent dual-band artificial magnetic conductor (AMC) surface is integrated with the antenna to improve its radiation performance and to reduce the specific absorption rate (SAR). The antenna is designed and fabricated on a flexible substrate, and its performance is measured for both flat and curved configurations. The measurements show an excellent agreement with the simulations. To examine its performance as a wearable antenna, it is measured on a human body. Simulations show that the SAR level is reduced when the AMC surface is used as an isolator. The proposed wearable antenna structure can be used for wireless body area network (WBAN) and Worldwide Interoperability for Microwave Access (WiMAX) body-worn wireless devices.
130 citations
TL;DR: In this paper, the basic working principles and applications of the NF-focused (NFF) microwave antennas as well as the synthesis procedures suggested for the NF shaping around the focal point and the technologies currently used for their implementation are discussed.
Abstract: Focusing the electromagnetic field radiated by an antenna at a point in the antenna near-field (NF) region is a wellknown technique to increase the electromagnetic power density in a size-limited spot region close to the antenna aperture. This article encompasses the basic working principles and the applications of the NF-focused (NFF) microwave antennas as well as the synthesis procedures suggested for the NF shaping around the focal point and the technologies currently used for their implementation.
128 citations
01 Aug 2017
TL;DR: In this paper, the authors achieved frequency increase in resonant tunneling diode terahertz oscillator by reducing conduction loss in the slot antenna with thick antenna electrode.
Abstract: We achieved frequency increase in resonant tunneling diode terahertz oscillator by reducing conduction loss in the slot antenna with thick antenna electrode. By a graded increase in electrode thickness for 0.1, 1, 2, and 3 μm, increase in oscillation frequency was obtained. A highest oscillation frequency of 1.98 THz was achieved with an optimum electrode thickness of 2 μm.
111 citations
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.
105 citations
TL;DR: In this article, a multilayer corporate-fed slot array antenna with wide impedance bandwidth and high efficiency was proposed, which consists of three unconnected metal layers based on the recently introduced gap waveguide technology.
Abstract: We present a $V$ -band multilayer corporate-fed slot array antenna with wide impedance bandwidth and high efficiency. The proposed antenna consists of three unconnected metal layers based on the recently introduced gap waveguide technology. A $2\times 2$ cavity-backed slot subarray acts as the unit cell of the array. The top metal layer contains the radiating slots, the intermediate layer contains the cavities, formed by pins, and the third layer is the ridge gap waveguide corporate-feed network. The latter is realized by a texture of pins and guiding ridges to uniformly excite the cavities with the same amplitude and phase. The proposed antenna fulfills the radiation pattern requirement of the ETSI 320 standard. A prototype consisting of $16\times 16$ slots was manufactured by a fast modern planar 3-D machining method, i.e., die-sink electric discharge machining. The fabricated prototype has a relative impedance bandwidth of 17.6% with input reflection coefficient better than −10 dB. The E- and H-planes radiation patterns satisfy the ETSI class II copolar sidelobe envelope, and the measured cross-polar level is more than −30 dB below the copolar level over the 56–75 GHz frequency band. The measured antenna efficiency is better than 60% over the same band.
104 citations
TL;DR: In this article, a multiband conformal antenna for implantable as well as ingestible devices is presented, which has the following three bands: medical implanted communication service (MICS: 402-405 MHz), the midfield band (1.45-1.6 GHz), and the industrial, scientific and medical band (ISM: 2.4-2.45 GHz).
Abstract: This paper presents a multiband conformal antenna for implantable as well as ingestible devices. The proposed antenna has the following three bands: medical implanted communication service (MICS: 402–405 MHz), the midfield band (1.45–1.6 GHz), and the industrial, scientific, and medical band (ISM: 2.4–2.45 GHz) for telemetry or wireless monitoring, wireless power transfer (WPT), and power conservation, respectively. A T-shaped ground slot is used to tune the antenna, and this antenna is wrapped inside a printed 3-D capsule prototype to demonstrate its applicability in different biomedical devices. Initially, the performance of the proposed antenna was measured in an American Society for Testing and Materials phantom containing a porcine heart in the MICS band for an implantable case. Furthermore, to stretch the scope of the suggested antenna to ingestible devices, the antenna performance was simulated and measured using a minced pork muscle in the ISM band. A modified version of the midfield power transfer method was incorporated to replicate the idea of WPT within the implantable 3-D printed capsule. Moreover, a near-field plate (NFP) was employed to control the leakage of power from the WPT transmitter. From the simulation and measurements, we found that use of a ground slot in the implantable antenna can improve antenna performance and can also reduce the specific absorption rate. Furthermore, by including the NFP with the midfield WPT transmitter system, unidirectional wireless power can be obtained and WPT efficiency can be increased.
103 citations
TL;DR: A very compact dual-band two-element multiple-input–multiple-output antenna for wireless local area network applications is presented, which uses a simple decoupling network to achieve good isolation between the ports.
Abstract: A very compact dual-band two-element multiple-input–multiple-output antenna for wireless local area network applications is presented in this letter. The antenna occupies an overall area of 24 × 25 mm2. A microstrip-line-fed antenna with two quarter-wavelength slots of different lengths, which radiate at 2.5 and 5.6 GHz, is used as an antenna element. The proposed antenna uses a simple decoupling network, based on a wide slot and a pair of narrow slots, to achieve good isolation (better than 20 dB) between the ports. Moreover, the envelope correlation coefficient of the proposed antenna is within the acceptable limit.
102 citations
TL;DR: In this paper, a traveling-wave circular slot antenna that can generate plane spiral OAM waves is developed and experimentally demonstrated, and the antenna is excited by a 90 $^\circ$ hybrid coupler.
Abstract: Plane spiral orbital angular momentum (OAM) wave is a new form of OAM-carrying electromagnetic wave that propagates along the transverse direction. A traveling-wave circular slot antenna that can generate plane spiral OAM waves is developed and experimentally demonstrated in this letter. The antenna is excited by a 90 $^\circ$ hybrid coupler. In order to ensure that the OAM waves are propagating along the transverse plane, a ring horn is added outside the antenna. A prototype with OAM states l = $\pm$ 3 for 10-GHz operation is fabricated and measured. The near-field phase distributions clearly indicate the azimuth phase shifting, and the radiation patterns show the characteristic of transverse propagation, respectively. The proposed antenna provides a novel approach to implement an OAM wireless communication link that has no phase singularity or divergence problem.
TL;DR: In this paper, a cavity-backed slot antenna with the ability of reconfiguring the frequency, polarization, and radiation pattern is presented, which is realized by electronically controlling the state of switches between two crossed slots etched on the surfaces of a substrate integrated waveguide cavity.
Abstract: A novel cavity-backed slot antenna, with the ability of reconfiguring the frequency, polarization, and radiation pattern, is presented. The reconfigurability is realized by electronically controlling the state of switches between two crossed slots etched on the surfaces of a substrate integrated waveguide cavity. The antenna is capable of simultaneously changing the radiation patterns between forward and backward directions, switching the polarization among two orthogonal linearly polarized (LP) and two orthogonal circularly polarized (CP) states, tuning between three frequency bands for LP states and between two frequency bands for CP states. A fully functional prototype is developed and tested, demonstrating the antenna with measured gains of approximately 4 dBi and stable unidirectional radiation patterns for all 20 states. In addition, the proposed design possesses a low profile of 0.01 free-space wavelength.
TL;DR: In this paper, a miniaturized single-feed multiband patch antennas are proposed for wireless communication. But the antenna size reduction is achieved by loading shorting metalized vias on one edge of the radiating patch, while multiband is obtained by etching inverted multiple U-shapes.
Abstract: This communication introduces an approach for designing miniaturized single-feed multiband patch antennas. The size reduction is obtained by loading shorting metalized vias on one edge of the radiating patch, while multiband is obtained by etching inverted multiple U-shapes. A dual-band antenna with a large measured frequency ratio of 2.74 is first discussed. Then triple-band, and further quad-band antennas are, respectively, designed. The antennas have sufficient electrical small size when considering the radius of the minimum enclosing sphere to the radiating patch. A radius value of 0.09λ
0
is obtained for the quad-band antenna with respect to the lowest operating frequency centered at 3.04 GHz. Simulated and measured results of the antennas' reflection coefficient and radiation patterns are provided. Good agreement between the simulation results and measurement results is achieved. The antennas' measured peak gains and efficiencies vary from 1.43 to 3.06 dBi and 42% to 74%, respectively. Compared with other designs, the proposed antennas exhibit multiband performance by using a simple single-feed structure, realize different combinations of highly isolated frequency bands with wide tunability of frequency ratios, and have directional stable radiation patterns that are compact and of electrically small size. Indeed, they have the potential to meet the practical requirements for wireless applications.
TL;DR: In this paper, a dual-layer partially reflective surface (PRS) was placed above a slot antenna operating at 60 GHz and fed by a printed ridge-gap waveguide for surface-wave suppression.
Abstract: A novel wideband and high-gain millimeter-wave antenna is presented. The wide 3 dB gain bandwidth is achieved by using Fabry–Perot cavity (FPC) and printed ridge-gap waveguide technologies. The FPC is formed by placing a dual-layer partially reflective surface (PRS) above a slot antenna operating at 60 GHz and fed by a printed ridge-gap waveguide for surface-wave suppression. The PRS is based on a 2-D printed unit cell, the unit cell composed of two different frequency-selective surfaces (FSS) provides a positive phase gradient over the desired frequency range. The impedance bandwidth of the proposed antenna is 18.4%, from 55.4 to 66.6 GHz. Moreover, the 3 dB gain bandwidth is 12.5%, from 58.6 to 66.4 GHz. A maximum gain of 16.8 dB is achieved; this is about 12.2 dB over the gain of the slot antenna only. Consistent radiation patterns are achieved over the operating bandwidth. Experimental and numerical results are presented to justify the improved antenna performance. This communication, to the best of our knowledge, is the first one to utilize a dual-layer printed FSS-based superstrate at 60 GHz to enhance the radiation characteristics of a printed ridge-gap waveguide-fed slot antenna.
TL;DR: In this paper, a dual-band cavity-backed substrate integrated waveguide (SIW) array antenna using high-order radiation modes has been proposed, which has the advantages of high gain, high front-to-back ratio, and low cross-polarization level.
Abstract: A novel compact dual-band cavity-backed substrate integrated waveguide (SIW) array antenna using high-order radiation modes has been proposed in this paper. The first high-order hybrid mode (superposition of TM310 and TM130) and the second high-order mode (TM320) of K-band in the SIW cavity are excited by an inductive window for dual-band application. The operation mechanism of high-order modes is analyzed and then verified through simulations by inserting metallic vias in different positions of the resonant SIW cavity. The designed subarray antenna has the advantages of high gain, high front-to-back ratio, and low cross-polarization level. To further validate the design idea, a dual-frequency band $2 \times 2$ array antenna has been fabricated and measured including reflection coefficients, realized gains, and radiation patterns. The measured results show that the 10-dB impedance bandwidths at resonant frequencies of 21 and 26 GHz are 800 MHz (3.7%) and 700 MHz (2.6%), and the realized gains at boresight direction are around 16 and 17.4 dBi, respectively. Moreover, the proposed array antenna also possesses both advantages of metallic cavity-backed antennas and planar patch antennas, such as low cost, easy fabrication with the printed circuit board technology, and integration with other planar circuits.
TL;DR: In this article, a wideband design of power dividers, T-junctions, and transitions based on groove gap waveguide (GGW) technology is presented with the goal to use these components in high-gain millimeter-wave antenna array design at 60 GHz frequency range.
Abstract: Wideband design of power dividers, T-junctions, and transitions based on groove gap waveguide (GGW) technology is presented in this paper with the goal to use these components in high-gain millimeter-wave antenna array design at 60-GHz frequency range. Since this GGW technology does not require electrical contact between the different metal layers of a complex 3-D waveguide structure, the fabrication cost and mechanical complexity are decreased. The designed T-junctions and different power dividers exhibit wide operational bandwidth and low output power and phase imbalance over the 60-GHz frequency band. Also, two transitions from GGW to a standard rectangular waveguide have been designed. To validate the performance of the designed components, a 64-way power divider in combination with 256 radiating slots is designed, prototyped, and measured at 60-GHz band. Measurement results agree well with the simulated performance of the complete array antenna, and the antenna gain is more than 32.5 dBi. The total radiation efficiency is more than 80% over the operating frequency range from 57 to 67 GHz. Also, the measured sidelobe levels are found to be agreeing well with the simulated level.
TL;DR: In this article, a singly-fed wideband circularly polarized dielectric resonator antenna is proposed for C-band communication with multiple orthogonal modes excited in the antenna structure when excitation is applied through a stair-shaped slot.
Abstract: A singly-fed wideband circularly polarized dielectric resonator antenna is proposed in this communication. Antenna structure contains a rectangular and two half split cylindrical dielectric resonators. Multiple orthogonal modes are excited in the antenna structure when excitation is applied through a stair-shaped slot. Measured results show that antenna provides wider 3-dB axial ratio and impedance bandwidths of 41.01% and 49.67%, respectively. Proposed antenna can be utilized in C-band applications.
TL;DR: In this paper, a single-fed, wideband, circularly polarized slot antenna is proposed and fabricated, which is obtained by introducing an antipodal Y-strip to a square slot antenna.
Abstract: A novel single-fed, wideband, circularly polarized slot antenna is proposed and fabricated. Wideband circular polarization is obtained by introducing an antipodal Y-strip to a square slot antenna. The feedline is a U-shaped microstrip line that provides a wide impedance bandwidth. The overall size of the antenna is only 28 × 28 mm
2
(0.3 λ
o
× 0.3 λ
o
). A prototype of the antenna is fabricated and tested. The measured bandwidths for the axial ratio (AR <; 3 dB) and relative impedance (|S
11
| <; -10 dB) are 41.3% (from 4.4 to 6.67 GHz) and 84% (from 3.25 to 8 GHz), respectively, and the antenna has a stable radiation pattern and a gain of greater than 3 dBi over the entire circular polarization frequency band.
TL;DR: In this paper, the authors proposed a symmetrical half-slot antenna with coplanar waveguide-fed structures and a Y-shaped slot that is cut at the bottom center of the common ground plane.
Abstract: In this letter, a multiple-input–multiple-output (MIMO) antenna with very compact size of only $\text{23}\times \text{18}\; \text{mm}^{2}$ is proposed for ultrawideband (UWB) applications. The proposed MIMO antenna consists of two symmetrical half-slot antenna elements with coplanar waveguide-fed structures and a Y-shaped slot that is cut at the bottom center of the common ground plane. The slot efficiently prevents the current from directly flowing between two ports at low UWB frequency. For such a compact-size antenna, the ground plane works as a radiator as well as a reflector that reflects the radiation from radiators at high frequency. The measured impedance bandwidth for $S_{11}, S_{22}$ $S_{12}, S_{21}$ $S_{12}, S_{21}$ < −20 dB is from 4 to 12.4 GHz. The proposed antenna also contains relatively stable radiation patterns and gains. These performances indicate that the proposed antenna is one competitive candidate for UWB applications.
TL;DR: In this article, the authors proposed a dual-polarized antenna subarray with filtering responses, which is a multilayered 3D geometry, including a dualpath $1 \times 4$ feeding network and four cavity-backed slot antennas.
Abstract: A $2 \times 2$ dual-polarized antenna subarray with filtering responses is proposed in this paper. This antenna subarray is a multilayered 3-D geometry, including a dual-path $1 \times 4$ feeding network and four cavity-backed slot antennas. The isolation performance between two input ports is greatly improved by a novel method, which only needs to modify several vias in a square resonator. Cavities in the feeding network are properly arranged and coupled using different coupling structures, so that the operation modes in each cavity for different paths can always remain orthogonal, which enables the subarray to exhibit not only filtering functions (in both reflection coefficients and gain responses), but also a low cross-polarization level. A prototype is fabricated with a center frequency of 37 GHz and a bandwidth of 600 MHz for demonstration. Good agreement is achieved between simulation and measurement, for both $S$ -parameter and far-field results. The proposed filtering dual-polarized antenna array is very suitable to be employed as the subarray in millimeter-wave 5G base stations to reduce the complexity and integration loss of such beamforming systems.
TL;DR: In this article, a compact printed differential multiple-input-multiple-output (MIMO) antenna for ultrawideband system applications with band-notched characteristic is presented.
Abstract: A compact printed differential multiple-input–multiple-output (MIMO) antenna is presented for ultrawideband system applications with band-notched characteristic. The proposed MIMO antenna element consists of a differential U-shaped microstrip feedline and a stepped-shaped slot, printed on the bottom and top of the substrate, respectively. A half-wavelength resonant stub embedded in the stepped-shaped slot is exploited to obtain notched band, whose center frequency can be adjusted by the length of the stub. The staged slots among antenna elements are introduced to enhance the differential isolation. The final antenna has a compact size of $44 \times 44\; \text{mm}^{2}$ . Measured results show that the proposed MIMO antenna achieves −10-dB impedance bandwidth from 2.95 to 10.8 GHz, isolation better than 15.5 dB over the whole operating band, and a notched band from 5.10 to 5.95 GHz.
TL;DR: In this paper, the authors have designed a 16.95% bandwidth covering 54-64 GHz frequency range with the measured gain of the antenna is more than 28 dBi with the efficiency higher than 40% covering 54 -64GHz frequency range.
Abstract: This communication deals with the design of a $16\times 16$ slot array antenna fed by inverted microstrip gap waveguide (IMGW). The whole structure designed in this communication consists of radiating slots, a groove gap cavity layer, a distribution feeding network, and a transition from standard WR-15 waveguide to the IMGW. First, a $2\times 2$ cavity-backed slot subarray is designed with periodic boundary condition to achieve good performances of radiation pattern and directivity. Then, a complete IMGW feeding network with a transition from WR-15 rectangular waveguide to the IMGW has been realized to excite the radiating slots. The complete antenna array is designed at 60-GHz frequency band and fabricated using Electrical Discharging Machining Technology. The measurements show that the antenna has a 16.95% bandwidth covering 54–64-GHz frequency range. The measured gain of the antenna is more than 28 dBi with the efficiency higher than 40% covering 54–64-GHz frequency range.
TL;DR: In this article, a planar antenna with a single-substrate polarizer is presented, which consists of an electronically reconfigurable polarizer integrated with a printed slot for converting linearly polarized (LP) waves radiated by the slot into either right-hand circularly polarized (RHCP) or left-hand CP (LHCP) waves.
Abstract: A novel polarization-reconfigurable planar antenna is presented. The antenna consists of an electronically reconfigurable polarizer integrated with a printed slot. By changing the states of the p-i-n diodes on the polarizer, the linearly polarized (LP) waves radiated by the slot can be converted into either right-hand circularly polarized (RHCP) or left-hand CP (LHCP) waves. The polarizer contains 16 unit cells arranged as a $4\times 4$ array. The antenna radiates RHCP waves if the p-i-n diodes on the top side of the polarizer are switched ON, while LHCP waves are radiated if the p-i-n diodes of the bottom side of the polarizer are switched ON instead. The physical mechanisms of the antenna are discussed and the parametric study is carried out by full-wave simulations. To verify the concept, one prototype at 2.5 GHz is designed, fabricated, and measured. Good agreement between the measured and simulated results is obtained. The antenna achieves a gain ≥8.5 dBic in both RHCP and LHCP with an aperture efficiency of 70%. Advantages of the proposed design include electronically reconfigurable polarizations for RHCP or LHCP, low profile, low cost, high isolation between the dc bias circuit and RF signals, high power handling capability, and easy extension to large-scale arrays without increasing the complexity of the dc bias circuit. To the best of our knowledge, this is the first report of an electronically polarization-reconfigurable CP antenna with a single-substrate polarizer.
TL;DR: In this paper, a spoof surface plasmon polaritons (SSPP) mode coupling was proposed to divide the radiation pattern of omnidirectional antennas into several beams.
Abstract: Wireless link has need of an omnidirectional antenna like dipole, but with higher gains. Of course, there is no way of achieving both of them simultaneously. To solve this contradiction, we propose to design multibeam antennas, which divide the radiation pattern of omnidirectional antennas into several beams. The antenna, based on spoof surface plasmon polaritons (SSPPs) mode coupling, consists of a feed monopole and N double-side corrugated metallic strips circling around the feed. The fields of the feed are coupled into SSPP waves that propagate along the strips and radiate at the end, dividing the omnidirectional radiation pattern into several beams. Three X-band prototypes of multibeam antennas with different radiation characteristics were designed, fabricated, and measured. Both numerical simulations and experimental results verify that the antennas are efficient in generating multiple beams with high gain at the predesigned directions.
TL;DR: In this article, a novel miniaturized five band metamaterial inspired slot antenna is reported, which consists of a ring monopole and metamural Rectangular Complementary Split Ring Resonator (RCSRR) as the radiating part, two L and one T-shaped slot as the ground plane, respectively.
Abstract: A novel miniaturized five band metamaterial inspired slot antenna is reported. The proposed design consists of a ring monopole and metamaterial Rectangular Complementary Split Ring Resonator (RCSRR) as the radiating part, two L and one T–shaped slot as the ground plane, respectively. Miniaturization in the proposed design is accomplished by metamaterial RCSRR, and also, it helps the antenna to operate at 2.9 and 5.2 GHz frequency bands. The aforementioned miniaturization process leads to about 46.8% reduction in volume of the proposed design, as compared to the conventional antenna. The pass band characteristics of the metamaterial RCSRR through waveguide medium are discussed in detail. In order to enhance the operating abilities of the miniaturized antenna, slots are etched out in the ground plane, thereby making the miniaturized antenna further operate at 2.4, 5.6 and 8.8 GHz, respectively. The proposed design has an active patch area of only , with dB bandwidth of about 4.16% (2.35–2.45 GHz), 5.71% (2.63–2.76 GHz), 10.25% (4.44–4.92 GHz), 6.25% (5.42–5.77 GHz) and 2.39% (8.68–8.89 GHz) in simulation, and about 6.86% (2.25–2.41 GHz), 5.01% (2.55–2.7 GHz), 9.16% (4.58–5.02 GHz), 5.38% (5.79–6.11 GHz) and 5.42% (8.44–8.91 GHz) in measurement. The antenna has good impedance matching, acceptable gain and stable radiation characteristics across the operational bandwidths.
TL;DR: The experiment shows that the near-field OAM-based radio communication channels are naturally isolated, employing a pair of four-OAM-mode antennas.
Abstract: Based on metallic traveling-wave ring-slot structure, an easily realized four-orbital angular momentum (OAM)-mode antenna capable of generating four coaxially propagating waves with OAM modes of $l$ = $\mathbf {-3}$ , $\mathbf {-2}$ , $\mathbf {+2,}$ and $\mathbf {+3}$ , respectively, is experimentally demonstrated at 10 GHz. The feeding network is simply implemented using two $\mathbf {90^{\circ }}$ hybrid couplers. A ring-focus double-reflector with a favorable focus-diameter-ratio is specially designed to gain a high directivity. The main characteristics of the antenna—such as $S$ -parameters, directivity, and near-field radiation—are presented both in simulation and experiment. Employing a pair of four-OAM-mode antennas, the experiment shows that the near-field OAM-based radio communication channels are naturally isolated.
TL;DR: In this article, the polarization reconfigurable circular patch antenna with a C-shaped slot is proposed for switching between vertical and horizontal polarizations for a linearly or circularly polarized mode.
Abstract: Polarization reconfigurable circular patch antenna with a C-shaped slot is proposed in this communication. It is demonstrated that by introducing a reconfigurable C-shaped slot in a circular patch antenna, the polarization of the radiation of the antenna, operating either in a linearly or circularly polarized mode, can be switched effectively. It is switched between vertical and horizontal polarizations for a linearly polarized mode and switched between left hand circularly polarization and right hand circularly polarization for a circularly polarized mode. The polarization reconfigurable characteristic is realized by controlling the states of the two switching diodes mounted over a concentric circular slot incorporated on the patch, so as to vary the orientation of the C-slot. Prototypes of both linear polarization and circular polarization designs were developed and the performances were validated against measurements. Both antennas exhibit over 20% impedance bandwidth (standing wave ratio (SWR) < 2) and perform broadside radiation over the operating band. The 3-dB axial ratio bandwidth for the circularly polarized case is 4%.
TL;DR: In this paper, a dual circularly polarized (CP) antenna with an U-shaped slot and two 50-Omega $ microstrip-fed ports was proposed to realize both right-hand circular polarization and left-hand polarization at the same frequency band.
Abstract: In this communication, a novel broadband dual circularly polarized (CP) antenna is presented. This antenna consists of an U-shaped slot to achieve broadband CP radiation and two 50- $\Omega $ microstrip-fed ports to realize both right-hand circular polarization and left-hand circular polarization at the same frequency band. The axial ratio bandwidth (ARBW) is greatly broadened by moving the feeding ports to upper portion of the U-shaped slot. To verify this design, the proposed antenna is fabricated and measured. The measured −10 dB reflection coefficient bandwidth is about 114.4% (1.80–6.61 GHz) and the 3-dB ARBW is approximately 110.5% (1.83–6.35 GHz). The isolation between two ports is better than 14.8 dB within the ARBW.
TL;DR: In this paper, a multibeam antenna array fed by a substrate integrated waveguide 8 × 8 dual-layer Butler matrix within the band from 28 to 31 GHz is presented.
Abstract: This letter presents a multibeam antenna array fed by a substrate integrated waveguide 8 × 8 dual-layer Butler matrix within the band from 28 to 31 GHz. The dual-layer structure is adopted aiming to achieve miniature, so that the size of the structure is reduced by more than 50% compared with similar single-layer design. The utilization of dual-layer structure also decreases the complexity of the whole Butler matrix. A 2 × 8 slot antenna array is used as the radiating portion to obtain high gains and relatively low side lobe levels. The proposed multibeam antenna array is fabricated and tested to verify the performances.
TL;DR: In this article, a triple-resonance and a quad-reonance substrate integrated waveguide (SIW) cavity-backed slot antennas using shorting vias are presented.
Abstract: A triple-resonance and a quad-resonance substrate integrated waveguide (SIW) cavity-backed slot antennas using shorting vias are presented in this paper. The antennas have wide bandwidths and low profiles. The working mechanism of the triple-resonance antenna is explained with its electric field distributions and equivalent circuit models. By loading the SIW cavity with shorting vias, the lowest mode (half-TE110 mode) is shifted upward and coupled with two higher modes (even and odd TE210 modes). As a result, a wide bandwidth with triple resonances is achieved for the antenna. Based on the similar principle, a quad-resonance antenna having an even wider bandwidth is also developed. Prototypes of the two antennas are fabricated and measured. With a low profile of $0.03\lambda _{0}$ (wavelength in free space), the triple-resonance design has a bandwidth of 15.2% and a peak gain of 4.80 dBi, and the quad-resonance design has a bandwidth of 17.5% and a peak gain of 7.27 dBi.