Antenna Unit Research Articles

Investigation of MDRZ and DPSK modulation schemes employed in DWDM systems for smart city 5G access networks

Wavelength division multiplexing (WDM) is one of the emerging technologies for data transmission in 5G access network assembly between the antenna unit (AU) and the distribution unit (DU). Here, in this work, we evaluate and analyze a dense wavelength division multiplexing (DWDM) — passive optical networks (PONs) employing erbium–ytterbium-doped fiber amplifier (EYDFA) [Formula: see text] Raman hybrid optical amplifier (HOA) using two modulation schemes — modified duobinary return to zero (MDRZ) and differential phase shift keying (DPSK) for alternate channels, where the channel count has been varied from 8 to 40. The system has been analyzed over the wavelength span of 1550–1558.8[Formula: see text]nm with a channel spacing, input power and data rate of 25[Formula: see text]GHz, 0[Formula: see text]dB and 40[Formula: see text]Gb/s, respectively. An average gain, gain ripple and optical signal-to-noise ratio (OSNR) of 20.87, 0.95 and 30[Formula: see text]dB, respectively have been observed in the case of HOA along with the achievement of Q-factor of up to 9 at the receiving end of the system. The DPSK-modulated channels result in higher values of gain and OSNR along with lower gain ripple as compared to MDRZ channels making the proposed system a good option for 5G access network applications.

A 262-GHz Wireless IFoF Uplink With Remote Down-Conversion Using Optically Generated Sub-THz LO

We experimentally demonstrate the feasibility of a 262-GHz wireless intermediate frequency (IF)-over-fiber (IFoF) uplink with frequency down-conversion at a remote antenna unit (RAU). To distribute many RAUs for the coverage of terahertz (THz) wireless communications, it is important to simplify the RAU for the THz uplink. The remote down-conversion with a subharmonic mixer and a uni-traveling carrier-photodiode (UTC-PD) is driven by two optical tone signals from the central office (CO). This can reduce the high-frequency and wideband devices of the networks. Instead of coherent detection, the RAU can be simplified with optical transmission and direct detection (DD) by using a conventional optical modulator and a photodiode (PD). We measured the phase noise of the system and compensated for it with blind phase recovery. Then, the error vector magnitudes (EVMs) of the received signals were measured as a function of THz Tx power, optically generated local oscillator (LO) power, and THz wireless link distance. Single-channel 45-and 30-Gb/s data transmission was achieved over a 5-km fiber and 1-m THz wireless link based on soft-(2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 10 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-2}$</tex-math> </inline-formula> ) and hard-decision (3.8 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 10 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-3}$</tex-math> </inline-formula> ) forward error correction (FEC) thresholds, respectively.

Circularly Polarized Leaky-Wave Antennas Based on Periodically Arranged Rotated Right-Angle Triangular Microstrip Patches

In this paper, a scheme to realize the circularly polarized periodic leaky-wave antennas is prosed. A single-row model and a dual-row model are presented based on the series-fed periodically arranged rotated right-angle triangular (RAT) microstrip patches. For either of the two models, the antenna unit of one period occupies four RAT microstrip patches and the units are arranged repetitively on one side or on both side of a transmission line. The open-stopband is eliminated by adjusting the distances between the patches in each unit. The single-row model with 12 units on one side of a transmission line achieves a main beam sweeping angle range of 96° (-56°-40°). The model realizes the left-hand (LH) circular polarization as the main beam is scanning continually from -19° to 22°. The dual-row model includes 20 units of a different form of the rotated RAT microstrip patches arranged on both side of a transmission line. The main beam is able to scan from - 40° to 35° while the antenna is radiating. The model realizes the LH circular polarization while the main beam is scanning from -18° to 13°. The proposed two models can both realize circular polarization and continual beam scanning across the broadside.

Design of a Novel Superwideband Dual Port Antenna with Second-Order Hilbert Branches and a Modified T-Decoupling Structure

A novel super wideband (SWB) dual port antenna with second-order Hilbert branches and a modified T-decoupling structure is proposed. The overall size of the antenna is only 32 mm × 26 mm × 1 mm. The SWB antenna front comprises a “house” shaped radiating patch and a trapezoidal-shaped microstrip line. Two SWB antenna units are placed symmetrically on FR4 dielectric substrate to form the SWB-MIMO (multiple-in multiple-out) antenna. Two second-order Hilbert branches expand the wideband of the SWB-MIMO antenna. The antenna decoupling is mainly achieved by loading a fence-like “T” decoupling structure on the ground plane. The antenna is also miniaturized and isolated by adjusting the distance between the radiating patches of the units. The simulations and measurements show that the SWB-MIMO antenna operates in the frequency band of 1.98-30.8 GHz (175.84% relative bandwidth). The bandwidth dimensional ratio (BDR) (BDR is a measure of the compactness of the antenna, the higher the BDR, the better the compactness of the antenna, and the wider the working bandwidth of the antenna.) is 14653.33. The overall isolation is below −16.4 dB, and the important part (8.5–24.1 GHz) is below −20 dB. The envelope correlation coefficient (ECC) is less than 0.03, and the radiation characteristics are excellent.

An Ultra-Wideband Plane Wave Generator for 5G Base Station Antenna Measurement

Plane-wave generators (PWGs) for over-the-air testing of 5G base stations offer the advantages of efficiency and economy. Many new bands, such as n28, are progressively being introduced, driving the bandwidth improvement of PWGs. The cost of amplitude–phase control networks is also increased by the broadband range required for testing. In view of the above challenges, in this paper, a low-frequency ultra-wideband PWG for testing 5G base stations is reported. Firstly, an electrically small antenna unit based on the Vivaldi antenna is design for the PWG. The antenna unit has a wide operating band and compact size, allowing it to reach a quarter of the minimum frequency wavelength. Then, the operating band from 700 MHz to 4 GHz is divided into three sub-bands, and the amplitude and phase excitations within each sub-band are optimized with multiple frequency points. Finally, the designed ultra-wideband PWG is simulated and experimentally tested. The designed 2.64 m one-dimensional linear-array PWG is able to produce a 1.5 m × 1.32 m quiet zone with less than 1.0 dB and 10°. The results of the radiation pattern measurements for the base station agree reasonably well with the MVG SG128.

Folded Digital Meta-Lenses for on-Chip Spectrometer.

In-plane diffractive optical networks based on meta-surfaces are promising for on-chip application. The design constraints of regular antenna unit place ultimate limits on the functionalities of the meta-systems. This fundamental limitation has been reflected by the large footprints of cascaded meta-surfaces. Here, we propose a digital meta-lens with a large degree of design freedom, enabling significantly improved beam focusing, collimation, and deflection capabilities. A highly dispersive and compact diffractive optical system is constructed for spectrometer via five layers of meta-lenses in a folded configuration. The device only occupies a 100 μm × 100 μm chip area on a silicon photonic platform. Sparse and continuous spectra reconstruction is achieved over a 35 nm bandwidth. Fine spectral lines separated by 0.14 nm are resolved. In addition to such a compact and high-resolution on-chip spectrometer, it is also expected to be promising for imaging, optical computing, and other applications due to the great versatility of the digital lens design.

응답시간이 개선된 액정 기반 능동 반사 배열 안테나 단위 셀 구조

This paper presents a unit cell structure for liquid crystal (LC)-based reconfigurable reflective arrays, aimed at improving the imbalance in response time. Conventional LC-based reflectarray antenna unit cells, which have been widely used as high-gain beam-steerable antennas, have an imbalance in response time because of different alignment of LC molecules during the rise and decay times. By separating the metal layers in contact with the LC layer and applying four bias voltages, we generated both horizontal and vertical electric field. Accordingly, the decay time was improved by unifying the methods in which the LC molecules were aligned during the rise and decay times. Our measurements confirm that the decay time can be reduced to approximately 1/3 compared to the conventional structure, indicating the possibility of resolving the imbalance.

Metasurface Antenna With Cocircularly Polarized Radiation Characteristics for Wideband Monostatic Simultaneous Transmit and Receive Applications

A monostatic simultaneous transmit and receive (STAR) antenna system consisting of a metasurface-based STAR antenna and two elaborately designed microstrip-based feeding networks is proposed to suppress the self-interference (SI) from transmission (TX) to reception (RX), a key challenge in STAR design to realize its potential in doubling system capacity. The metasurface antenna is for the first time used in designing a monostatic STAR antenna system for its compact and wideband characteristics. The proposed STAR antenna system possesses the features of monostatic operation, wide bandwidth, high TX/RX isolation, cocircularly polarized radiation with similar patterns for TX and RX, easy fabrication, and low cost. The metasurface-based STAR antenna is formed by four dual-polarized metasurface antennas, or units, and is used for both TX and RX to achieve monostatic operation. A wide operating bandwidth is obtained for each antenna unit by combining the resonate modes of the unit and a crossed slot, the feeding structure of the unit, using characteristic mode analysis (CMA). To achieve high TX/RX isolation and identical right-handed circular polarization (RHCP), the four TX and RX ports of the STAR antenna, respectively, are excited with equal amplitudes and relative phases of 0°, 90°, 180°, and 270°, by two dedicated-designed wideband feeding networks based on the sensitivity analysis. Accordingly, the proposed STAR antenna system is prototyped. The measurement results show that the STAR antenna system achieves <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&gt;$ </tex-math></inline-formula> 36 dB TX/RX isolation and <3 dB axial ratio from 4.5 to 6 GHz and maintains similar radiation patterns with the same RHCP for TX and RX.

An Electromagnetic Information Theory Based Model for Efficient Characterization of MIMO Systems in Complex Space

It is the pursuit of a multiple-input-multiple-output (MIMO) system to approach and even break the limit of channel capacity. However, it is always a big challenge to efficiently characterize the MIMO systems in complex space and get better propagation performance than the conventional MIMO systems considering only free space, which is important for guiding the power and phase allocation of antenna units. In this manuscript, an Electromagnetic-Information-Theory (EMIT) based model is developed for efficient characterization of MIMO systems in complex space. The group-T-matrix-based multiple scattering fast algorithm, the mode-decomposition-based characterization method, and their joint theoretical framework in complex space are discussed. Firstly, key informatics parameters in free electromagnetic space based on a dyadic Green's function are derived. Next, a novel group-T-matrix-based multiple scattering fast algorithm is developed to describe a representative inhomogeneous electromagnetic space. All the analytical results are validated by simulations. In addition, the complete form of the EMIT-based model is proposed to derive the informatics parameters frequently used in electromagnetic propagation, through integrating the mode analysis method with the dyadic Green's function matrix. Finally, as a proof-or-concept, microwave anechoic chamber measurements of a cylindrical array is performed, demonstrating the effectiveness of the EMIT-based model. Meanwhile, a case of image transmission with limited power is presented to illustrate how to use this EMIT-based model to guide the power and phase allocation of antenna units for real MIMO applications.

Low-Cost Broadband Circularly Polarized Array Antenna with Artificial Magnetic Conductor for Indoor Applications

In this paper, we report a sequential-phase fed broadband circularly polarized array antenna loaded with an artificial magnetic conductor-reflecting surface. Our proposed antenna is a two-part group. The upper structure is a sequential-phase fed circular wide-slot antenna. The lower part is an artificial magnetic conductor structured reflective surface. The overall antenna size is 106 × 106 × 14.9 mm3, both adopting 1.6 mm thick FR4 material. The thickness of the air layer sandwiched between the antenna and the artificial magnetic conductor reflective surface is 14 mm. The antenna consists of four circular wide-slot antenna units with a sequential rotation technique. To broaden the axial ratio bandwidth, three L-shaped branches and four metal plates are attached to the circular wide-slot antenna unit and around the artificial magnetic conductor-reflecting surface, respectively. To verify the accuracy of the simulation, we fabricated the sample and then tested it in an anechoic chamber. The measured results demonstrate that the proposed broadband circularly polarized array antenna realizes an impedance bandwidth of 77.67% (2.74–6.22 GHz) and an axial ratio bandwidth of 65.16% (3.00–5.90 GHz) with a peak gain of 11.1 dBi. The design can be used in space-constrained environments, such as indoor and dense building areas.

An emission enhancement strategy realized by introducing phosphorescent antennas and complexing with Cucurbit[7]uril

An emission enhancement strategy was realized in this study by introducing phosphorescent antennas and complexing with cucurbit[7]uril (CB [7]). The phenylpyridinium antenna units were attached covalently to the luminescence center of Ru (bpy)32+ by a two-step reaction. The resulting compounds showed strong near-infrared emission with quantum efficiencies as high as 6.6% in aerated water. Furthermore, complexing with CB [7] significantly enhanced their emission and improved quantum efficiency to a record value of 11.0% in aerated water by suppressing nonradiative decay of triplet state and improving intramolecular energy transfer. This result provided a general strategy for emission enhancement and will likely promote development of organic photoluminescence.

Decoupling Technique Based on Field Distribution on Ground Plane for WLAN MIMO Antenna Applications

An efficiently-decoupling method for multiple-input multiple-output (MIMO) antenna systems is proposed in this paper. A planar-modified monopole antenna operating at the WLAN band is chosen as the antenna unit. The antenna structure is based on the printed circuit board technique. By observing and analyzing the ground plane’s field distribution generated by high-order modes, it is found that several stable minimum current points can be excited along the edges of the ground plane. In doing so, a high isolation can be obtained if the other antenna is placed at one of these points. The measured results and simulated results have a good agreement with each other, which well validates the proposed design concept. In addition, compared with the traditional decoupling technology, this method can improve the isolation between antennas without adding additional structures, which has excellent practicality in wireless communication system applications.

Archaeological prospection of a prehistoric lithic workshop site using ground penetrating radar with a high‐frequency antenna unit

AbstractWe surveyed in detail the Chalcolithic lithic workshop Fofanovo XIII an East Fennoscandian region by ground‐penetrating radar (GPR). A high‐frequency antenna unit was applied to map small‐scale features, mainly waste flakes. To substantiate the efficiency of the GPR technique, we performed a primary analysis of a set of equivalent models in a sandbox. The laboratory‐scale GPR investigation highlights differences in GPR patterns depending on the spatial arrangement of small features and supports the further interpretation of real‐life data. The GPR survey in the field covered 2200 m2, revealing areas with a high density of artefacts in the cultural layer and locating individual structural elements of the Fofanovo XIII archaeological site. We suggested using microdebitage samples from manual probing to verify the detected anomalous values of GPR attributes. The results point to a significant correlation between microdebitage and the envelope peak amplitude of the echo signal. Ultimately, our study confirmed the cultural layer in the Fofanovo XIII workshop site to be rich in lithic production wastes, indicating it was a place of mass‐scale production of lithic chopping tools.

A Novel Dual-Polarized Magnetoelectric Dipole Antenna and Its Array for LTE and 5G Sub-6 GHz Base Station Applications

This study presents a novel dual-polarized magnetoelectric dipole antenna and its array with director and rectangular parasitic metal patches for LTE and 5G sub-6 GHz base station applications. This antenna is composed of L-shaped magnetic dipoles, planar electric dipoles, rectangular director, rectangular parasitic metal patches, and η-shaped feed probes. The gain and bandwidth were enhanced by using the director and parasitic metal patches. The measured impedance bandwidth of the antenna was 82.8% (1.62-3.91 GHz, VSWR < 1.5), and its gain was 10 ± 0.5 dBi. The profile of the antenna unit, operated at 1.7 GHz, was only 42 mm (0.227λ0, where λ0 represents the free space wavelength corresponding to the lowest resonance frequency point). Subsequently, four antenna units were arranged in a line array with 0.6λ0 spacing. Both the antenna and its array were fabricated and measured. The measurement results show that the array has good radiation characteristics, such as broad bandwidth covering 1.65-3.97 GHz (VSWR < 1.5), high gain (its gain was great than 15.2 dBi), and high radiation efficiency (>90%). Its HPBWs were 63° ± 4° and 15° ± 2° for H- and E-planes, respectively. The design can cover TD-LTE and 5G sub-6 GHz NR n78 frequency bands very well, meaning that this is a good candidate antenna for base station applications.

Broadband Dual-Polarized mm-Wave Antenna Array With Grating Structure for Mobile Devices

In this letter, a broadband dual-polarized millimeter-wave (mm-wave) antenna array for smartphone application is proposed. Different from previous designations, this array utilizes circular-shaped slot to realize a wideband dual-polarized radiation. In addition, a novel grating structure is adopted for circular slot. With the proposed structure, a better radiation performance is realized. Operating frequency of this antenna array is measured from 26 to 38 GHz, which is calculated for more than 30% of bandwidth. In its operating band, return loss of each antenna units exceeds 10 dB and isolation between V-pol and H-pol reaches more than 15 dB. In addition, total efficiency of whole antenna array exceeds −2 dB. Peak realized gain of this antenna array reaches 12.6 and 12.5 dBi for V-pol and H-pol, respectively. Hence, the proposed antenna structure can be a promising candidate for mm-wave application in smartphone.

Realization of wide‐angle scanning with tilted beam units and variable radiation subarrays

AbstractHere, a novel wide‐angle scanning array antenna composed of subarrays with variable radiation patterns is proposed. The subarray consists of two antenna units with tilted beams. With a specially designed feeding network, the phase difference between the antenna units of each subarray keeps the same as that between subarrays. Thus, the radiation pattern of the subarray automatically changes with the array factor. Theoretical analysis shows that the array scanning range can be expanded and the side lobe level (SLL) can be suppressed. A linear array is designed, fabricated, and measured to verify the presented method. The simulated and measured results agree well with each other. The results show that the array can scan from to with gain fluctuation of less than 3 dB and SLL lower than dB.

Design of Miniaturized Wideband Beam Deflection Conformal Array Antenna

Antenna beam deflection, along with miniaturization and wideband of the antenna is in demand for practical applications. In this paper, a cylindrical conformal array antenna with a small-tilt forward beam was designed. The microstrip antenna unit was loaded with the artificial electromagnetic structure, which reduced the size of the antenna unit. As a result, the center spacing of the array elements can be shortened with the same array element spacing. The beam deflection angle can be increased in this way without increasing the coupling effect between the parts. Changing the number of line array elements and the number of line arrays can regulate the beam width of E-field and H-field, respectively. The bandwidth of the antenna can be significantly extended by slotting the ground plane. This work implemented a cylindrical conformal array of the antenna's forward beam with a small dip angle using a cylindrical carrier as an example. The measurement results showed that the angle between the main beam and the carrier axis of the conformal antenna was less than 30°, the bandwidth was more than 30%, and the antenna volume decreased by 40.4%.

A Novel Design of Antenna Array with Two K-Band Circularly Polarized燗ntenna

As an important part of phased array system, the research on phased array antenna is very necessary. The phased array antenna achieves the scanning beam adaptively by regulating the phase difference between each array element. In this paper, a dual K-band circularly polarized antenna with high broadband, broadband beam, wide axial ratio bandwidth and high radiation efficiency is designed. We combine with the advantages of slot antenna and aperture antenna, use multimode waveguide cavity structure to design an aperture antenna, which is fed to waveguide circular polarizer by slot coupling in order to realize circular polarization radiation. Meanwhile, it has the characteristics of broadband, broadband beam, wide axial ratio bandwidth and high radiation efficiency. A slit antenna is designed by using a multimode waveguide cavity structure and a slit coupling feed to a waveguide circular polarizer is used to achieve circularly polarized radiation. The designed antenna consists of two K-band circularly polarized antenna units, and the spacing between the two units is 9.5 mm, which is fed by a K-band T/R module (Transmitter/Receiver module). In order to study the performance of the pattern in the case of the research group, the 2-unit structure is established. The simulation results of frequency–axial ratio bandwidth are given, and the simulation result of the antenna array is shown. The practical results of antenna design and test are also given.

An Energy-Saving Scheme With Edge Computing and Energy Harvesting in mmWaves Backhauling HetNets

The exponential growth of data traffic from mobile devices requires the implementation of heterogeneous networks (HetNets), which densely deploy multiple radio access technologies to match such demands. The deployment of many small base stations (SBSs) leads to backhauling problems where wired backhauling is neither available nor efficient. millimeter waves (mmWaves) can potentially mitigate the backhauling problem by providing high throughput and low capital expenditure (CAPEX). However, due to the high attenuation rate in mmWaves, the increase in the distance between SBS and macro base station (MBS) can severely degrade the system’s overall performance. On the other hand, densely deployed SBSs with wireless backhauling can cause high energy consumption in the system. Therefore, in this work, a novel network model is presented in which a combination of SBS, active antenna units (AAUs), and edge computing units (ECUs) are deployed to minimize the overall energy consumption of the network while maintaining the sufficient quality of service (QoS). A mathematical model based on optimization modeling is introduced to solve user equipments (UEs) association, dynamic sleeping, backhauling and fronthauling, and power transmission. Due to the complexity of the formulated problem, a heuristic algorithm is introduced. Namely, integrated access and backhauling (IAB) with Edge Computing and Dynamic Sleeping Algorithm (IEDS) algorithm is introduced to decompose the formulated problem into two parts and solve them iteratively. Finally, computer simulation results that demonstrate the model’s performance are presented for comparison between optimal solution, IEDS, and HBDS, which shows that IEDS outperformed HBDS in performance with negligible computation difference.

Design of Ka-Band Phased Array Antenna with Calibration Function

In this paper, we have proposed a novel structure of Ka-band based phased array antenna with calibration function. In the design of Ka-band antenna, the active phased array system is adopted and the antenna would work in the dual polarization separation mode. We have given out the schematic diagram for the proposed Ka-band antenna, where the Ka-band antenna is in the form of waveguide slot array antenna, with 96 units in azimuth and 1 unit in distance. Each group of units is driven by a single-channel Transmitter/Receiver (T/R) component, and the whole array contains 192 T/R components in total. The size of the T/R component is 55 mm (length) × 50 mm (width) × 5.8 mm (height), 3 Sub-micro Sub-Miniature Push-on (SSMP) blind sockets and a 21-core low-frequency socket are designed on the two sides of the T/R component. In order to meet the technical specifications of phased array antenna, the Ka-band transceiver component is designed based on Low Temperatrue Co-fired Ceramic (LTCC) technology to achieve miniaturization and lightweight. In our approach, the feed network includes two parts: transceiver network and calibration network. The transceiver network consists of 24 1:8 time-delay power dividers, 12 two-way power dividers and 2 six-way time-delay power dividers. The power supply required by the Ka-band antenna unit is provided to each active component by the power module after Ka band wavelet control distribution. Simulation and measurement results are given in the form of standing wave and scanning capability.