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Showing papers in "IEEE Antennas and Wireless Propagation Letters in 2022"


Journal ArticleDOI
TL;DR: In this paper , a novel coding metasurface based on low Q resonators and fast optimization method is proposed to achieve wideband radar cross section (RCS) reduction of the microstrip antenna array (MAA) while maintaining its radiation properties.
Abstract: In this letter, a novel coding metasurface (CM) based on low Q resonators and fast optimization method is proposed to achieve wideband radar cross section (RCS) reduction of the microstrip antenna array (MAA) while maintaining its radiation properties. Theoretical analysis reveals the relationship between the Q value and the phase shift of the resonator, which indicates that the wideband control of the reflected wave can be achieved with the low Q resonator. Moreover, the fast optimization method based on the convolution theorem is proposed, which enhances the optimization efficiency of the coding matrix. Finally, the CM with two kinds of low Q resonators is constructed and applied to the MAA for wideband RCS reduction. The measured results indicate that the proposed low RCS MAA (LRMAA) can realize more than 10 dB RCS reduction in 5.8–21.5 GHz, which also demonstrates superior specular scattering suppression. In parallel, the radiation properties of the LRMAA are consistent with those of MAA. The proposed strategy achieves the high integration of radiation and scattering properties, which has potential applications in antenna systems of stealth platforms.

39 citations


Journal ArticleDOI
TL;DR: In this paper , a low-profile all-textile multiband antenna operating in the 2.45/5.8 GHz ISM bands, mobile WiMAX IEEE 802.16 2005 (3.3/3.4 GHz), and 5G sub-6 NR frequency band n77 (3,85/4.0 GHz) is proposed for wireless body-area network (WBAN) applications.
Abstract: A compact low-profile all-textile multiband antenna operating in the 2.45/5.8 GHz ISM bands, mobile WiMAX IEEE 802.16 2005 (3.3–3.4 GHz), and 5G sub-6 NR frequency band n77 (3.85–4.0 GHz) is proposed for wireless body-area network (WBAN) applications. Good broadside radiations are achieved by properly activating the inherent TM11, TM21, and TM31 modes of a circular patch antenna. An elliptical slot and a C-shaped slot are employed to tune the three modes to the desired operating frequencies. A rectangular slot is used to reduce undesirable depression in the 5.8 GHz radiation pattern. The proposed antenna is fabricated from a conductive fabric layer integrated onto a single layer of denim, making it extremely low-profile and suitable for wearable applications. It has an overall size of 60 × 60 × 1.17 mm (0.64 λg × 0.64 λg × 0.0125 λg at 2.45 GHz). The measured maximum realized gains and bandwidth at the four frequencies are −0.81, −2.81, −1.16, 2.83 dBi, and 90, 190, 230, 570 MHz, respectively. Test results show that when the antenna is placed on and bent around a human arm model, the reflection coefficient has only slight influence. Since the antenna adopts full ground plane structure, the SAR values are far below the EU standard of 2 W/kg limit. With merit characteristics, the proposed design indicates a promising candidate for WBAN applications.

25 citations


Journal ArticleDOI
TL;DR: In this paper , a wideband high-efficiency 1-bit 16 × 16 reconfigurable reflectarray antenna (RRA) is proposed, which consists of double-layer patches printed on two dielectric substrates.
Abstract: In this letter, a wideband high-efficiency 1-bit 16 × 16 reconfigurable reflectarray antenna (RRA) is proposed. First, a wideband and low loss 1-bit RRA element is designed. It consists of double-layer patches printed on two dielectric substrates, respectively, forming a multiresonant behavior to expand the bandwidth.Due to the relatively thin thickness of the double-layer dielectric substrate (0.05 λ0), the element has low reflection loss. Therefore, the high efficiency and wide bandwidth performances can be obtained simultaneously. The phase difference between the two states of the RRA element is stable within 180 ± 20° in the frequency range of 12.9–16.5 GHz. Based on the broadband RRA element, a 16 × 16 RRA was fabricated and measured. Tested results show that the proposed RRA achieves 22.5% of 1 dB gain bandwidth and 25% of maximum aperture efficiency.

24 citations


Journal ArticleDOI
TL;DR: In this article , the authors proposed a compact high-isolated MIMO antenna module based on a chip capacitive decoupler for 5G smartphones, which consists of two feeding ports, radiating metal strips, and a chip CCA within a compact size of 16 × 6 mm2.
Abstract: In this letter, a compact high-isolated multiple-input–multiple-output (MIMO) antenna module based on a chip capacitive decoupler is proposed for the fifth-generation (5G) smartphones. The antenna module consists of two feeding ports, radiating metal strips, and a chip capacitive decoupler within a compact size of 16 × 6 mm2. In this design, two L-shaped metal strips are used as distributed capacitors to compress the size of the module. Meanwhile, a chip capacitive decoupler is added to improve isolation between the two feeding ports, which is realized with an analysis of common and differential modes. In addition, spiral slots are used to adjust the isolation between the modules. A prototype MIMO antenna with four such dual-port antenna modules was tested in the 3.5 GHz band. The measured –6 dB bandwidths of the two ports are 310 MHz (3.42–3.73 GHz) and 360 MHz (3.33–3.69 GHz), respectively, and the isolation is 24 dB at 3.5 GHz. The measured efficiencies are 60.5% and 52.7% at 3.5 GHz. The compact MIMO antenna module with high-isolation property provides a hopeful solution for the 5G mobile terminals.

23 citations


Journal ArticleDOI
TL;DR: In this paper , a 90° twisted quarter sectored circularly polarized and high gain dielectric resonator antenna (DRA) operating within the 5.8 GHz Wi-Fi band was investigated.
Abstract: Radio frequency (RF) energy harvesting is the most adopted technique for replacing conventional batteries. However, the available RF energy in the surrounding atmosphere is low and unstable, so the antenna with high gain and polarization-insensitive characteristics is desired to collect a massive amount of power from the low-density environment. A 90° twisted quarter sectored circularly polarized and high gain dielectric resonator antenna (DRA) operating within the 5.8 GHz Wi-Fi band, is investigated first time of its kind in this letter. A circular-shaped aperture coupled feeding approach is investigated for energizing the proposed antenna. A metallic strip is placed on the right face of the optimized DRA for creating circular polarization characteristics. The optimized antenna (0.67 λ×0.67 λ×0.029 λ) offers a gain value of 7.02 dBc at 5.8 GHz frequency. A shunt-diode rectifier circuit is implemented for rectification purposes. The power conversion efficiency achieved at the operating frequency is 72.5% for an input power level of 5.75 dBm.

20 citations


Journal ArticleDOI
TL;DR: In this article , a double-fold 7×8 Butler matrix (BM) beamforming network (BFN) was proposed for the 5G mobile network applications, which is composed of a 7 × 8 BM feeding network and an 8×8 slot array.
Abstract: A substrate integrated waveguide multibeam antenna fed by a double-fold 7×8 Butler matrix (BM) beam-forming network (BFN) is presented. The proposed antenna is composed of a 7×8 BM feeding network and an 8×8 slot array. By merging the two central input ports of the BM into one port, the BM can provide output signals with equal phase, which can generate a boresight beam. In order to reduce the size of the antenna, the BM is folded twice into a three-layer structure. Measured results show that the proposed antenna has impedance bandwidth of 29.5 ∼ 30.5 GHz, whereas the gain lies in the range of 13.2–17.3 dBi. Seven beams, including a boresight beam, pointing from −58° to 58° are achieved. Compared with counterparts, the proposed antenna features boresight radiation and miniaturized size. It is a good candidate for the fifth-generation (5G) mobile network applications.

18 citations


Journal ArticleDOI
TL;DR: In this paper , a broadband and low loss circularly polarized (CP) electronically reconfigurable reflectarray antenna (RRA) that can operate over the X-band is reported.
Abstract: In this letter, a broadband and low loss circularly polarized (CP) electronically reconfigurable reflectarray antenna (RRA) that can operate over the X-band is reported. The proposed RRA invokes a new reconfigurable magneto-electric (ME) dipole based element for dynamically manipulating the phase of the back-scattered CP wave from each pixel, and hence, the direction of the reflected beam. The engineered wideband ME-dipole element and the design of a low loss reconfigurable perturbation structure contribute jointly to a superior CP bandwidth as well as a high efficiency. A reflectarray prototype with two-dimensional (2-D) beam scanning is designed, fabricated, and measured, demonstrating a wide-angle beam scanning capability. Besides, notable advances in bandwidth and aperture efficiency of the 1-bit CP RRA are identified, over the previous state of the art.

17 citations


Journal ArticleDOI
TL;DR: In this paper , a physics-informed deep neural network was proposed for one-dimensional (1-D) Maxwell's plasma coupling system with inhomogeneous magnetized plasma parameters.
Abstract: Plasma parameter inversion is important for space plasma physics and applications, particularly for inhomogeneous magnetized plasmas. A physics-informed deep neural network for Maxwell’s plasma coupling system is proposed in this letter. The network architecture consists of inhomogeneous plasma parameter inversion and electromagnetic field reconstruction. We verified our physics-informed neural network method for one-dimensional (1-D) Maxwell’s plasma coupling system with inhomogeneous magnetized plasma parameters. The simulation results show that this meshless method can effectively achieve simultaneous inversion of inhomogeneous plasma parameter and global field based on sparse sampling. The physics-informed deep neural network for Maxwell’s plasma coupling system has a certain generalization ability, which may be applied for more complex plasma applications.

16 citations


Journal ArticleDOI
TL;DR: In this paper , an 87 km microwave link over the ocean was constructed using the evaporation duct to realize the wireless communication between the Chinese mainland and the Hainan Island.
Abstract: In this letter, an 87 km microwave link over the ocean was constructed using the evaporation duct to realize the wireless communication between the Chinese mainland and the Hainan Island. During a 24 h uninterrupted experiment, the efficient connection rate reached 97.46%. The median signal-to-noise ratio (SNR) exceeds 40 dB at night, and the partial effect of the channel reception is close to the ceiling of free space. The SNR of 100 Mega-symbols per second (Msym/s) at 10 GHz exceeded 3 dB and reached 10 dB at 10 Msym/s. The experiment results reveal that the communication with evaporation ducts can provide a wide-bandwidth, high-speed, and long-distance propagation method for maritime applications in the South China Sea.

16 citations


Journal ArticleDOI
TL;DR: In this paper , a dual-band antenna with a large frequency ratio of 11.7 (2.4 GHz/28 GHz) was proposed by integrating an mm-wave Fabry-Perot cavity (FPC) antenna into a sub-6 GHz patch antenna.
Abstract: This letter presents a dual-band antenna with a large frequency ratio of 11.7 (2.4 GHz/28 GHz) by integrating an mm-wave Fabry–Perot cavity (FPC) antenna into a sub-6 GHz patch antenna. The patch with periodic slots functions as both the 2.4 GHz radiator and the partially reflective surface (PRS) of the 28 GHz FPC antenna. By properly tuning the length of the periodic slot, the PRS's reflection can be easily adjusted. As the periodic slot's length and width operating at 28 GHz are much smaller than the wavelength at 2.4 GHz, periodic slot operating at 28 GHz have little impact on the radiation of the patch. Furthermore, because of the Fabry–Perot resonance, the antenna can have a peak gain reaching 15 dBi at 28 GHz band with an easy feeding structure. For demonstration, a prototype is fabricated and experimentally verified. Note that the frequency ratio is not limited to the proposed design (11.7 for demonstration). It can be easily adjusted based on the same principle.

14 citations


Journal ArticleDOI
TL;DR: In this article , a wideband circularly polarized folded reflectarray antenna (CPFRA) with a linearly polarized (LP) feed antenna is presented, where the subreflector of the proposed CPFRA is in the form of a polarization-sensitive frequency selective surface (FSS) based on the antenna-filter-antenna (AFA) technology other than the traditional polarizing grid.
Abstract: The design and implementation of a wideband circularly polarized folded reflectarray antenna (CPFRA) with a linearly polarized (LP) feed antenna is presented in this letter. The subreflector of the proposed CPFRA is in the form of a polarization-sensitive frequency selective surface (FSS) based on the antenna-filter-antenna (AFA) technology other than the traditional polarizing grid. The AFA FSS is designed to convert the LP incident wave into circularly polarized (CP) wave within its passband and reflect the orthogonal LP incident wave over a wide frequency band. Futhermore, the sequential rotation technique is applied in the design of main reflectarray and subreflector to greatly enhance the axial ratio (AR) bandwidth of the CPFRA. An antenna prototype has been fabricated and measured at X-band. Good agreement between the measured and simulated results has been achieved by the wideband CPFRA. The measured results show that the maximum antenna gain reaches up to 28.2 dBic at 10.2 GHz with its aperture efficiency of 43.3%. The 3 dB gain frequency band is from 9.1 to 10.6 GHz and the 3 dB AR frequency band from 8.7 to 11.2 GHz, respectively.

Journal ArticleDOI
TL;DR: In this article , a design of a compact wideband end-fire filtering antenna is presented, which starts from an endfire quasi-microstrip antenna, which is unidirectional with a smaller size when compared with a Yagi-Uda antenna.
Abstract: This letter presents a design of a compact wideband endfire filtering antenna. The design starts from an endfire quasi-microstrip antenna, which is unidirectional with a smaller size when compared with a Yagi–Uda antenna. A reflector and a parasitic patch are utilized to introduce two new resonant frequencies to broaden the bandwidth. They also generate two radiation nulls at the lower band and the higher band, respectively. The endfire radiation mechanism can be modeled by a two-element antenna array. The mechanism of these two radiation nulls is explained by the mixed coupling theory. Therefore, the proposed antenna also shows filtering property without any extra circuits. In addition, a capacitive feeding structure is employed to improve the level of the reflection coefficient within the upper stopband. The measured results reveal that the proposed antenna has a bandwidth of 41.9% from 2.00 to 3.06 GHz and a peak gain of 7.3 dBi with an extremely small size of 0.105 λ2 (λ is the wavelength at the center frequency). Two radiation nulls are observed at 1.78 and 3.19 GHz, respectively. The out-of-band roll-off of the antenna gain achieves 15 dB.

Journal ArticleDOI
TL;DR: In this article , a quadruple-ridged waveguide (QRW) antenna with a high gain dual-polarized all-metallic transmit array (TA) with wide gain bandwidth is proposed.
Abstract: By utilizing the quadruple-ridged waveguide (QRW), a high-gain dual-polarized all-metallic transmitarray (TA) antenna with wide gain bandwidth is proposed. The QRW has a fixed height with four identical ridges symmetrically located inside a square waveguide. The phase compensation is obtained by simultaneously controlling the length of the four ridges. The fully symmetrical structure of the QRW enables the proposed TA to achieve dual-polarization and two-dimensional (2-D) beam scanning. The proposed TA antenna with an aperture of 112 × 112 mm is designed and fabricated by utilizing 3-D metallic printed technology. The measured broadside gain at 30 GHz for the two orthogonal polarizations is 28.2 dBi and 28.1 dBi, corresponding to an aperture efficiency of 41.9% and 40.9%, respectively. The measured 1 and 3 dB broadside gain bandwidth is 27.3% and 34.8%, respectively. The 2-D beam scanning range at 30 GHz for the dual polarized radiation covers ±18°, with a maximum scan loss of 2.3 and 3.2 dB, respectively.

Journal ArticleDOI
TL;DR: In this article , the authors investigated the isolation of a multiple-input-multiple-output (MIMO) antenna system, consisting of two circularly polarized antennas with opposite rotating senses.
Abstract: This letter investigates the isolation of a multiple-input–multiple-output (MIMO) antenna system, consisting of two circularly polarized antennas with opposite rotating senses. The challenge in achieving a high isolation for this type of antenna system is analyzed and discussed. Based on this, a low-profile wideband design is proposed and demonstrated, in which the role of the decoupling structure is also explained. As a validation, an antenna prototype is fabricated and measured. The operating bandwidth, in which $|S_{11}|$ and axial ratio are respectively less than –10 and 3 dB, is 8.3% (5.2–5.65 GHz). Within this band, the measured peak realized gain in the broadside direction is 6.2 dBi and the isolation is better than 26 dB. In comparison with other related works, the proposed antenna has one of the smallest spacing while maintaining high isolation characteristics in a relatively wide bandwidth with a low-profile structure.

Journal ArticleDOI
TL;DR: In this article , a 64-element, slot-based and substrate-integrated coaxial line (SICL)-fed dual-polarized antenna array for fully digital massive multiple-input and multiple-output (mMIMO) applications is proposed.
Abstract: This letter reports the concept, design, fabrication, and characterization of a novel 64-element, slot-based and substrate-integrated coaxial line (SICL)-fed dual-polarized antenna array (SICL-SAA) for fully digital massive multiple-input–multiple-output (mMIMO) applications. The proposed array is composed of ±45° polarized elements based on half-wavelength slots. Each slot has its own back cavity, acting as an individual reflector for enabling boresight radiation. The slot is fed using a SICL feeding line for shielding the propagating mode in the feeding network, aiming at low mutual coupling levels. Experimental results in excellent agreement with full-wave numerical simulations demonstrate up to 2 GHz bandwidth from 24.5 GHz to 26.5 GHz for all array elements. Furthermore, the mutual coupling between adjacent elements is kept lower than −23 dB for the entire bandwidth, the radiating elements provide an 85° beamwidth in both planes (ϕ = 0° and ϕ = 90°) and 7.4 dBi gain.

Journal ArticleDOI
TL;DR: In this paper , the authors established a fundamental EM channel model for MIMO wireless communications and clarified the relations between the limit of effective degree of freedom (EDOF) and the optimal number of sources/receivers.
Abstract: Effective degree of freedom (EDOF) of a multiple-input–multiple-output (MIMO) system represents its equivalent number of independent single-input–single-output (SISO) systems, which directly characterizes the communication performance. Traditional EDOF only considers single polarization, where the full polarized components degrade into two independent transverse components under the far-field approximation. However, the traditional model is not applicable to complex scenarios especially for the near-field region. Based on an electromagnetic (EM) channel model built from the dyadic Green’s function, we first calculate the EM EDOF to estimate the performance of an arbitrary MIMO system with full polarizations in free space. Then, we clarify the relations between the limit of EDOF and the optimal number of sources/receivers. Finally, potential benefits of near-field MIMO communications are demonstrated with the EM EDOF, in which the contribution of the longitudinally polarized source is taken into account. This letter establishes a fundamental EM framework for MIMO wireless communications.

Journal ArticleDOI
TL;DR: In this paper , a miniaturized high selectivity frequency selective rasorber (FSR) with a wide interabsorption high transparent bandpass based on multiple 2.5-dimensional (2.5D) resonators is investigated.
Abstract: A miniaturized high selectivityfrequency selective rasorber (FSR) with a wide interabsorption high transparent bandpass based on multiple 2.5-dimensional (2.5-D) resonators is investigated. The main contribution is the achievement of a wide and high transparent passband by combining the large inductance of parallel resonators (PRs) and cascading two 2.5-D PRs, which also provide the function of miniaturization. The 2.5-D PR is implemented by connecting the interdigitated capacitor and the metal meandered strip-line on both surfaces of a lossy layer through metalized vias. The inductor and capacitor values of 2.5-D PR can be individually adjusted to shift the passband's central frequency. The lossy element is realized by inserting two 2.5-D strip-type PRs at the center of each side of a meandered cross-dipole loaded with two resistive sheets on both sides. An equivalent circuit model is proposed to analyze its operating principle. The dimensions of the miniaturized element are 0.12 λL × 0.12 λL × 0.118 λL. While maintaining a good wide passband (−1dB relative bandwidth is 21.2%), the miniaturized FSR satisfies the characteristic of polarization insensitivity (TE and TM), and angular insensitivity (up to 45°). A prototype of miniaturized FSR has been manufactured and measured, showing a reasonable agreement with simulations.

Journal ArticleDOI
TL;DR: In this article , a pattern-reconfigurable dielectric resonator antenna (DRA) with compact structure and high efficiency is proposed by introducing a pair of switchable directors.
Abstract: A novel pattern-reconfigurable dielectric resonator antenna (DRA) with compact structure and high efficiency is proposed in this letter by introducing a pair of switchable directors. The switchable directors are arranged on both sides of an omnidirectional DRA, which operates in the TE01δ mode. Their directing function can be controlled by switching the on/off status of the p-i-n diodes so that one omnidirectional radiation pattern and two unidirectional endfire patterns are provided in the azimuthal plane. To verify this idea, a prototype of the proposed antenna is fabricated and measured. Good agreement between the simulated and measured results can be observed. The peak gain in endfire status reaches 4.5 dBi and the front-to-back ratio is more than 12 dB. Meanwhile, the gain variation of the omnidirectional pattern in the azimuth plane is less than 2 dB, which shows good omnidirectional radiation performance.

Journal ArticleDOI
TL;DR: In this paper , a simple optically transparent absorber based on a double complementary structured layer of the indium-tinoxide (ITO) deposited polyethylene terephthalate film is presented.
Abstract: A simple optically transparent absorber based on a double complementary structured layer of the indium-tin-oxide (ITO) deposited polyethylene terephthalate film is presented. The structure showed more than 90% absorption from 2 to 4.5 GHz of the frequency with a thickness of 0.0847 $\lambda _L$ (wavelength corresponding to the lowest frequency of absorption band). The computed absorptivity of the proposed structure is validated using the transmission line theory and measured experimentally as well. The structure has polarization-insensitive response and is highly stable for the oblique wave incidence over a wide angular range. This absorber can be conformally wrapped on a curved surface and reduces the radar cross section (RCS) by more than 10 dB of a curve cylinder. This 10 dB RCS reduction covers almost the entire S-band of microwave frequencies. Optical transparency and flexibility of the proposed absorber make it suitable for a wide range of applications.

Journal ArticleDOI
TL;DR: In this article , an all-textile cavity-backed substrate integrated waveguide (SIW) antenna is proposed for military applications, which matches standard military badge size, and the measured gain and efficiency of the structure are 5.2 dBi and 79.2% at 8 GHz, respectively.
Abstract: An all-textile cavity-backed substrate integrated waveguide (SIW) antenna is proposed for military applications. The antenna matches standard military badge size. The aircraft-shape badge antenna that operates in X-band is designed for air force. SIW cavity and meandered slots that form the body and wing of the figure provide resonance at 8 GHz with 26% bandwidth. Symmetrical boresight patterns with very low sidelobes are observed. The measured gain and efficiency of the structure are 5.2 dBi and 79.2% at 8 GHz, respectively. This efficiency value is the highest among other SIW cavity textile-antennas. The antenna is investigated on conformal surfaces, as well. Bending of the antenna to follow body movements does not deteriorate performance of the textile antenna sensor. The peak specific absorption rate value over 10 g of tissue was 0.53 and 0.69 W/kg for 30 dBm input power for female and male breasts, which makes it suitable as an on-body antenna. The badge antenna is fabricated with standard textile fabrication techniques and its simulation performance is confirmed successfully by measurements. Usage of standard off-the-shelf parts for the assembly and fabrication with standard textile fabrication techniques enables simple and cost-effective mass production of the proposed badge antenna.

Journal ArticleDOI
TL;DR: In this paper , a 16×16-element dual-polarized antenna array with a reduced sidelobe level is proposed at 28 GHz for 5G communication systems, where a ridge unequal power divider with flexible power ratio and phase difference is devised and applied in the gap waveguide feeding network to reduce the complexity of unequal power structural design.
Abstract: In this letter, a 16×16-element dual-polarized antenna array with a reduced sidelobe level is proposed at 28 GHz for fifth-generation (5G) communication systems. The dual linear polarization operation is carried out through cross-shaped waveguide slots and multilayer feeding networks. Low-loss gap waveguide technology and Taylor distribution are applied in the feeding networks. A ridge unequal power divider with flexible power ratio and phase difference is devised and applied in the gap waveguide feeding network to reduce the complexity of unequal power structural design. A prototype of the proposed dual-polarized antenna array is manufactured by milling technology. Measured results show that the realized gains are higher than 28 dBi over the operating frequency band of 27.4–28.6 GHz. Moreover, the sidelobe level is lower than −18.5 dB for the y-direction polarization and −19.5 dB for the x-direction polarization.

Journal ArticleDOI
TL;DR: In this article , a planar antenna with reconfigurable radiation pattern is investigated for smart Wi-Fi systems, which incorporates one pair of folded dipoles, a microstrip-to-via feeding balun and two reconfigurable parasitic strips which are near-field excited by the dipole pair.
Abstract: In this letter, a planar antenna withreconfigurable radiation pattern is investigated for smart Wi-Fi systems. The design incorporates one pair of folded dipoles, a microstrip-to-via feeding balun and two reconfigurable parasitic strips which are near-field excited by the dipole pair. By controlling the states of two Pin diodes embedded in two reconfigurable printed lines, the proposed antenna can switch between one omnidirectional mode and two unidirectional endfire radiation modes. This optimized antenna exhibits a decent size of 0.5 λ0 × 0.38 λ0 ×0.004 λ0 (where λ0 is free space wavelength at 2.45 GHz). Good agreement is observed between the simulated and measured results. The overlapped impedance bandwidth with |S11| < −10 dB for the three pattern modes is from 2.34 to 2.6 GHz in the measurement. Throughout the overlapping bandwidth, the front-to-back ratios are higher than 15 dB for the two unidirectional radiation modes and out-of-roundness is less than 1.2 dB for omnidirectional radiation mode. The measured peak realized gain of the proposed pattern-reconfigurable antenna is 6 dBi. This proposed Wi-Fi antenna is well poised for intelligent Wi-Fi communication systems.

Journal ArticleDOI
TL;DR: In this article , a dual-band antenna with a very large frequency ratio was proposed for integrated 4G/millimeter (mm)-wave fifth-generation (5G) and beyond 5G applications for Internet of Things devices.
Abstract: This letter first presents a concept of a dual-band antenna with a very large frequency ratio, which can be suitable for integrated 4G/millimeter (mm)-wave fifth-generation (5G) and beyond 5G applications for Internet of Things devices. The antenna is based on a tapered slot, which simultaneously works as a resonant open-ended slot at low frequency and a high-gain Vivaldi antenna at high frequency. The impedance bandwidth is improved by modifying the slot shape, i.e., creating multisections within the slot. Based on this approach, a multibeam antenna (gain of 10 dBi) at an mm-wave frequency which also covers multibands at lower frequency extending from 2.5 to 6 GHz is designed. The design is validated numerically and experimentally in terms of return loss, radiation efficiency, gain, total scan pattern, and coverage efficiency.

Journal ArticleDOI
TL;DR: In this article , a planar half-Luneburg lens antenna based on a glide-symmetric dielectric structure is proposed to steer its beam in a 50 dB range with scan losses lower than 2 dB and side lobe levels below 10 dB.
Abstract: In this letter, we present a planar half-Luneburg lens antenna based on a glide-symmetric dielectric structure. The proposed half-Luneburg lens antenna provides a compact alternative to planar beamformers such as conventional Luneburg and Rotman lenses, as well as pillbox antennas. Importantly, we demonstrate that the peak gain of the half-Luneburg lens antenna is less than 1 dB lower than the peak gain of a conventional Luneburg lens antenna, despite being almost half the size. The proposed antenna can steer its beam in a 50 $^{\circ }$ range with scan losses lower than 2 dB and side lobe levels below $-$ 10 dB. The proposed design is validated experimentally with a robust and cost-effective implementation using additive manufacturing.

Journal ArticleDOI
TL;DR: In this article , a novel frequency-reconfigurable solid-state plasma chip antenna based on plane slot is proposed, where the radiation slot of the antenna is embedded with a surface-PIN (S-PIN) diode and fed by a microstrip line through electromagnetic coupling.
Abstract: A novel frequency-reconfigurable solid-state plasma chip antenna based on plane slot is proposed. The radiation slot of the antenna is embedded with a surface-PIN (S-PIN) diode and fed by a microstrip line through electromagnetic coupling. The state of the S-PIN diode can be switched by applying a forward bias voltage to realize the reconfigurable radiation slot of the antenna. The structure parameters of the S-PIN diode have been optimized. The overall size of the silicon-on-insulator (SOI) substrate is controlled at 20 × 10 × 0.35 mm. A prototype of the proposed antenna is fabricated and measured. The measured results show that the proposed antenna can realize cross-band frequency switching from 6.8 to 15.5 GHz. Meanwhile, the normalized radiation patterns show prominent reconstruction characteristics as the bias voltage changes. The proposed solid-state plasma antenna offers high integration compared with traditional reconfigurable antennas. The experiment results validate the applicability of the S-PIN diodes to manufacture reconfigurable planar slot antennas.

Journal ArticleDOI
TL;DR: In this paper , a low-profile and wideband substrate integrated waveguide (SIW) antenna is proposed and validated for full-duplex systems, which operates at 4.9 and 5.8 GHz wireless local area network bands.
Abstract: In this letter, a low-profile and wideband substrate integrated waveguide (SIW) antenna is proposed and validated for full-duplex systems. The proposed antenna operates at 4.9 and 5.8 GHz wireless local area network bands. Each resonator of the antenna consists of a modified half-mode SIW (HMSIW) cavity, and excited by a 50 $\Omega$ coaxial probe. The wideband response is achieved by coupling the fundamental ${\rm TE}_{10}$ mode with the perturbed ${\rm TE}_{10}$ mode of the HMSIW cavity. The compactness of the proposed design is obtained using two rectangular slots near the closed-ends of the cavities. By properly optimizing the overall geometry, the proposed design exhibits a 10 dB fractional bandwidth of 8.2% (4.78–5.2 GHz) and 7.7% (5.70–6.16 GHz) in the lower (4.9 GHz) and upper (5.8 GHz) frequency bands, respectively. The bandwidths of both frequency bands can be controlled by adjusting the coupling between modes. A high isolation ( $>$ 30 dB) between the two ports is observed due to series of metallic vias between them. This antenna has compact size (0.007 $\lambda _{g}^{3}$ ) with high gains of 5.24 and 5.37 dBi at 4.9 and 5.8 GHz, respectively. The proposed design is suitable for emerging full-duplex systems, thanks to its small size, high isolation, wide bandwidth, and independent resonance and bandwidth control.

DOI
TL;DR: In this paper , a planar half-Luneburg lens antenna based on a glide-symmetric dielectric structure was proposed to provide a compact alternative to planar beamformers such as conventional Luneburg and Rotman lenses.
Abstract: In this letter, we present a planar half-Luneburg lens antenna based on a glide-symmetric dielectric structure. The proposed half-Luneburg lens antenna provides a compact alternative to planar beamformers such as conventional Luneburg and Rotman lenses, as well as pillbox antennas. Importantly, we demonstrate that the peak gain of the half-Luneburg lens antenna is less than 1 dB lower than the peak gain of a conventional Luneburg lens antenna, despite being almost half the size. The proposed antenna can steer its beam in a 50$^{\circ }$ range with scan losses lower than 2 dB and side lobe levels below $-$10 dB. The proposed design is validated experimentally with a robust and cost-effective implementation using additive manufacturing.

Journal ArticleDOI
TL;DR: In this paper , a miniaturized-element dual-polarized frequency selective rasorber (FSR) with independently regulated dual-transmission response has been presented.
Abstract: In this letter, a miniaturized-element dual-polarized frequency selective rasorber (FSR) with independently regulated dual-transmission response has been presented. The proposed FSR is made of two cascaded layers separated by an air spacer, where the top lossy layer provides wideband absorption along with in-band transmission and the bottom lossless layer exhibits a dual bandpass filter. The novelty of the proposed design lies in the use of lumped capacitors in the top layer to realize the independently controlled highly selective transmission frequencies as well as attain a miniaturized unit cell topology (having dimensions of 0.08 λ L × 0.08 λ L , λ L being the lowest operating frequency). In addition, convoluted slot geometries are patterned in the bottom layer to obtain the transmission bands appearing at the same frequencies as that of the top layer. The proposed structure has an operating range of 1.87–7.97 GHz, whereas two distinct transmission responses are located at 3.52 and 5 GHz having insertion losses of 1.2 and 0.82 dB, respectively. Furthermore, the geometry exhibits an angularly stable performance upto 40° for both TE and TM polarizations. A prototype of the proposed FSR was fabricated and measured to validate the simulated responses under normal incidence.

Journal ArticleDOI
TL;DR: In this article , a broadband wide-angle scanning array antenna with suppressed mutual coupling for 5G sub-6G mobile communication applications is presented, where metal columns are positioned below the edge of the dipole, leading to the improved the impedance matching characteristics, the suppressed mutual couplings and a wider scanning angle.
Abstract: A broadband wide-angle scanning array antenn a with suppressed mutual coupling for fifth-generation (5G) sub-6G mobile communication applications is presented in this letter. The metal columns are positioned below the edge of the dipole, leading to the improved the impedance matching characteristics, the suppressed mutual coupling and a wider scanning angle. A 1×8 prototype of the suggested design has been manufactured and tested to ensure its usefulness. The overall dimension is 2.33 λ 0 ×0.28 λ 0 ×0.24 λ 00 is the free-space wavelength at 2.5 GHz). The measured and simulated results are quite consistent. The main lobe achieves a scanning range of ±60° at 2.5–4.5 GHz (57.1%) and yields a scanning range of ±75° at 3–4 GHz (28.6%) with a gain loss of less than 2.5 dB. The sidelobe levels are mostly less than or equal to −7.9 dB and the isolation between the antenna elements can yield a maximal additional 14.7 dB enhancement.

Journal ArticleDOI
TL;DR: In this paper , a dual-mode (on-body and off-body mode), dual-band, designed for the 2.45 and 5 GHz wireless body area network (WBAN) is proposed in this communication.
Abstract: A wideband wearable metasurface antenna with dual-mode (on-body and off-body mode), dual-band, designed for the 2.45 and 5 GHz wireless body area network (WBAN), is proposed in this communication. The TM 11 mode of the circular patch is used for the off-body mode in the 2.45 GHz WBAN band because of its broadside radiation pattern, meanwhile, the TM 02 of the circular patch and metasurface mode are chosen for on-body mode due to their omnidirectional radiation pattern in the second band. A shorting pin is used to tune these modes to the desired operating frequencies and using polydimethylsiloxane (PDMS) makes the antenna easier to be integrated into wearable devices. The prototype is fabricated, and a good performance is realized with a measured S 11 < −10 dB functional bandwidth of 4.9% and 15.7% which can cover the 2.45 and 5 GHz WBAN band, respectively. Moreover, the measured peak gain achieves 5.5 dBi for off-body mode and 5.3 dBi for on-body mode, as well as the specific absorption rate values are lower than the limitation standards of U.S. and Europe throughout the operating band. The acquired performance demonstrates that the proposed antenna has a great potential in the wearable applications.