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A low-profile wideband tri-polarized MIMO antenna is proposed in this paper. Based on characteristic mode analysis of a circular patch, four slots are etched symmetrically on the patch to transform the high-order monopole-like modes into broadside modes with lower resonant frequencies. Four sets of shorting pins are also applied to simultaneously adjust the resonant frequencies of the monopole-like modes and broadside fundamental modes of the patch. The effects of the slots and the shorting pins on these modes are analyzed in detail. Three dual-resonance ports with high isolation are achieved by exciting three pairs of orthogonal modes of the patch. The proposed antenna is wideband with respect to its profile (bandwidth/height = 216), as facilitated by the dual-resonance property of each port. Experimental results show that the proposed antenna features high port isolation (> 35 dB) and high gain (> 5.58 dB). The proposed low-profile wideband tri-port antenna can be applied in highly integrated MIMO systems.

In this communication, a novel planar structure-shared diverse two-port ultrawideband (UWB) antenna with high isolation and common ground is proposed based on a new slot-loaded method. A tapered slot with an end-fire radiation pattern is etched in the top middle section of a coplanar waveguide (CPW)-fed printed monopole antenna to reduce its effects on the monopole mode. The two-port UWB antenna features diverse patterns which can fully cover the upper space. A nonuniformly symmetric-coupled coplanar waveguide (NSC-CPW) is introduced to enable the two sets of the feeding structures sharing a ground plane with minimum interaction. Due to the modal orthogonality, high isolation between the two ports is obtained without additional decoupling structures. The experimental results of the proposed multiple-input multiple-output (MIMO) antenna indicate that the isolation is higher than 31.4 dB and the diversity gain is approximately 10 dB within a wide frequency range from 2.98 to 10 GHz. Meanwhile, high realized peak gain (>2.5 dB) and good efficiency (>80%) are also obtained for both the ports.

A broadband wide-scanning planar phased array is studied in this letter. An accurate equivalent circuit model is used and studied to provide more insights into the working principle of the proposed antenna element. Surface wave suppression is achieved by introducing an air gap, which also improves the active voltage standing wave ratio (VSWR) in H -plane as a wide-angle matching layer. The infinite array cell in simulation achieves nearly 65.2% bandwidth (6.3–12.4 GHz) with active VSWR E - and H -plane. Scanning patterns are measured and show good agreements with simulated results.

In this letter, we present a systematic approach to design a compact dual-mode monopole-like patch antenna using characteristic mode analysis (CMA). The modal analysis of a slotted circular patch structure incorporating a new shorting pin loading technique is presented. To achieve a compact monopole-like antenna with the wideband operation, it is demonstrated that the first two significant modes with monopole-like patterns are the most suitable ones for dual-mode excitation. Based on the analysis of the modal currents and electric fields, four groups of shorting pins and four slots are introduced to individually tune the two modes, which facilitates the optimization. The effects of these slots and shorting pins on the resonant frequencies of the two modes are analyzed in detail. Finally, a CPW T-junction power divider is applied to simultaneously excite these two modes and suppress the undesired modes. Apart from a more compact form factor and higher gain than existing work, it also features a competitive gain-bandwidth per volume ratio.

A two-port structure-shared planar ultrawideband (UWB) antenna with high isolation is presented in this communication. The proposed antenna consists of a planar monopole and two back-to-back tapered slots etched on the monopole. The monopole and the tapered slots are fed by the microstrip line and the differential feeding network, respectively. The differential feeding network of the tapered slots excites the modes, which are orthogonal to those of the monopole. Therefore, high isolation between the two ports can be achieved without additional decoupling structures. The measured results show that the proposed antenna can operate from 3 to 10 GHz with the reflection coefficient of the two ports lower than −10 dB and the isolation higher than 38 dB. The measured realized peak gains are above 2.6 dB, and the measured envelope correlation coefficients are less than $9 \times 10^{-5}$ . The proposed UWB multiple-input-multiple-output (MIMO) antenna can be applied in the MIMO communication systems, especially those requiring high isolation.

A planar multifunctional four-port antenna system integrated on one substrate applied in the suburban mobile tablet is presented in this paper. The types of these antennas are selected based on different functions and the interactions between them are analyzed and reduced. Two identical T-shaped printed monopole antennas are designed for the MIMO mobile ad-hoc networks (MANET) application. The mutual coupling between the ports of these two MANET antennas is decreased by introducing a decoupling metal strip loaded with an inductor. Two horizontal printed dipoles with parasitic strips are developed to operate in the satellite navigation and communication frequency bands. Through the analysis of the interaction between the MANET antenna and satellite antennas, the satellite antennas with improved broadside radiation patterns are obtained. The performance stability of the proposed antenna system is verified by the investigation of the performances in different gestures. A prototype of the antenna system is fabricated and the measured results show that the proposed antenna system can cover the frequency bands of MANET communication, satellite navigation, and satellite communication with good performances. This proposed multifunctional antenna system is a good choice for the sub-urban mobile terminal systems.

This paper presents a low-profile coplanar dual-polarized dual-band base station antenna array. A slotted patch antenna operating from 0.82 to 0.99 GHz with four shorting strips is proposed and analyzed. The four shorting strips are employed not only to improve the impedance matching in the lower band but also to remove the center part of the patch, thus making room for higher band dipoles operating from 1.68 to 2.86 GHz. The height of the proposed array is nearly half of the conventional base station array while other performances are guaranteed. The measured results show that the proposed antenna array has wide impedance bandwidths of 18.7% (0.82–0.99 GHz) and 57.9% (1.68–2.86 GHz) (VSWR $0.109\lambda _{0}$ at 820 MHz). The measured gains are 13.8±0.5 dB and 16.7 ± 1 dB in lower and upper bands. Large front-to-back ratio (>24.6 dB) and high isolations (>30 and >25 dB in lower and upper bands, respectively) are achieved. The proposed antenna can be easily built with printed circuit board fabrication technique and applied in low profile multiband base stations for 2G/3G/4G and the next-generation systems.

A coplanar linear polarized dual-band antenna with very low profile is proposed in this paper. The evolution of the dipole antenna based on the slotted patch is introduced. The effects of the patch on the central dipole are analyzed in detail. A low profile single polarized dual-band coplanar antenna with wide impedance bandwidths of 21.12% and 61.43% is realized and fabricated. The proposed antenna has peak gains higher than 9.1 dB in the lower band and 7.9 dB in the higher band. The measured isolation between the two ports is greater than 23 dB. It can be applied in low-profile multiband small base stations in the next generation system.

In recent years, the screen-to-body ratio of mobile handsets has been increasing. Today, the screen nearly fills up the entire front side. Conventionally, the screen is mainly seen as a metallic object that adversely affects antenna performance. In this paper, the large screen is used for the first time to facilitate an additional uncorrelated MIMO port in a tri-port design, for several LTE bands below 1 GHz. To this end, the design procedure explicitly considers the screen together with the terminal chassis, which can be simply modelled as two metal plates. In particular, characteristic mode analysis of the double-plate model enables a sufficient number of resonant modes to be created, tuned and selectively excited to yield three uncorrelated MIMO ports in the low band. Simulation and measurement results are found to be in good agreement. The measured bandwidths of the three ports are 23%, 17% and 21%, respectively. Within the operating band, the measured isolation is above 13 dB, envelope correlation coefficient below 0.16 and average total efficiency above 72%.

The authors propose the design of a compact mechanically frequency and pattern reconfigurable patch antenna. The frequency tuning is achieved by changing the positions of two adjustable shorting screws which are used to modify the length of the antenna radiating patch. Simulated and measured results are carried out to validate the proposed approach. When the screws are symmetrically positioned, the measured operating frequency can be tuned from 2.95 to 5.16 GHz without degrading the radiation characteristics over the entire comparatively wide measured tuning range of 54.5%. The antenna main radiating beam can be tilted from θ = 0° to θ = 30 ° when the screws are asymmetrically positioned. The measured gains and efficiencies range from 3.01 to 5.53 dBi and 68 to 74%, respectively. The overall antenna size is only 0.39 λ 0 × 0.39 λ 0 × 0.02 λ 0 .

We propose a miniaturized design of a four-element dual-band multiple-input–multiple-output (MIMO) antenna system. The dual-band function is obtained by etching an “L” slot in the radiating patch. The edge-to-edge elements spacing is only 0.023 λ0 . A decoupling structure consisting of cross-shaped metal strips shorted to the ground plane using vias is first introduced. Then, metalized walls are used to enhance the isolation level by realizing the pattern diversity. The measured resonant frequencies are centered at 3.5 and 5.7 GHz with bandwidths of 58 and 43 MHz, peak gains of 2.7 and 2.85 dBi, and peak efficiencies of 63% and 65%, respectively. A considerable measured mutual coupling reduction of 10.8 dB in the lower band and 15.6 dB in the upper band is realized. The overall size of the design is 0.41λ0 × 0.41λ0 × 0.04λ0 with minimum isolation levels of 18.4 and 22.7 dB in the lower and upper bands, respectively. The envelope correlation coefficient is lower than 0.08 across both operating bandwidths. The measured results validate the good diversity performance of the MIMO system.

This paper presents a broadside antenna with three ports operating at the same frequency. The TM030 and TM003 modes of a patch are excited by two coaxial cables to generate two orthogonal linear polarizations. The patch can be transformed into a slotted SIW cavity whose TE201 and TE102 modes are jointly excited by the third cable. A matching cavity and a matching patch are introduced to broaden the impedance bandwidth of the third port. The simulated results show that the isolations between these three ports are higher than 18 dB, even though the radiation patterns of the three ports are all broadside. The proposed three-port antenna can provide a solution to increase the number of the ports per unit area in outdoor massive MIMO antennas.

A composite antenna consisting of patch and slotted cavity antennas based on substrate integrated waveguide (SIW) is proposed in this paper. TM 020 mode is simply excited by a coaxial probe located at the center of the cavity. Energy is coupled out of the cavity by six symmetric curved slots etched in the top metal layer. Thus, a conical-beam radiation pattern with horizontal linear polarization is obtained from 25.37 to 33.1 GHz $(\vert \mathrm{S}_{11}\vert dB). In addition, a patch antenna operating from 5.06 to 5.30 GHz (VSWR < 2) is achieved when the slotted cavity is excited from the bottom metal layer. The reflector of the slotted cavity antenna is reused as the ground of the patch antenna. This composite antenna can be applied for future 5 G wireless communication.

Patch antennas with a meandering slot and different distributions of grounded metallic vias are presented in this paper. The meandering slot is adopted to stimulate dual-band operation, while the number and position of the grounded metallic vias are suggested to achieve different radiation performances. The characteristics are analyzed in detail where we find that the existence of the vias also improves the impedance matching. Four samples are designed, where dual-band with both linear polarization, dual-band with circular- and linear-polarization, and single band with linear polarization are obtained, respectively. The samples are finally fabricated and the measurement results agree well with the simulation results.

A wideband dual-polarization patch antenna array is proposed in this letter. The array is fed by a parallel strip line balun, which is adopted to generate 180° phase shift in a wide frequency range. In addition, this balun has simple structure, very small phase shift error, and good ports isolation. The working band of the antenna array is from 1.88 to 2.9 GHz with a relative bandwidth of 41.7%. The height of the antenna array is only $0.144\lambda $ , and the cross polarization is below $- \hbox{20 dB}$ . Two feeding ports are presented, which correspond to two orthogonal linear polarization. The isolation between the ports is higher than 30 dB. The simulation and measurement turns out to be similar. This antenna array can be used in TD-LTE base stations, and the design methods are also useful to other wideband microstrip antennas.

To accommodate the need of full metal tablet PC, an antenna designed to be applicable to GPS, WLAN and communication is proposed. Some techniques of frequency adjustment and impedance matching are employed, such as the use of shorted metal post, and slotting. The proposed antenna is planar and can be fabricated by printed circuit board technology. High efficiency and gain compared to traditional antenna of tablet PC are obtained.

Pasco-Kennewick (PK) section girder is widely used in the concrete cable stayed bridges with double cable planes, because of its excellent mechanical properties. By created the double girder finite element model, this paper analyzed the dynamic response of one concrete cable stayed bridges with PK section and the dynamic response of the diaphragms. According to the results of the analysis, the diaphragms which near the auxiliaries’ pier s and pylons generated large seismic internal force under the seismic load, and it is account for large proportion when compared with the static load. So, single-girder model can not satisfy the requests for the dynamic analysis of the girder. Due to the cross beams generated large positive, negative bending moment when seismic load impact, we must take notice of strengthening reinforcement in diaphragms. Especially the reinforcement for the negative bending moment, so as to meet the requests for the anti-seismic.

An ultra-wide tuning range filtering antenna is proposed in this paper. The frequency tuning range is from 200 MHz to 1.8 GHz which covers from P to L bands by a varactor and two single-pole-doube-throw switches. The switches controls two groups of inductors which corresponding to two frequency tuning range. The filtering antenna has high selectivity and low insertion loss and very wide frequency tuning range.

Six equivalent linearization methods are summarized and calculation process of applying equivalent linearization method for displacement-based design of bridge engineering is studied. With the evaluation of volume stirrup ratio and safety performance of design structure, six different equivalent linearization methods are used in displacement-based design of bridge columns. The influence of equivalent linearization model and the damping adjust coefficient to seismic design results is studied. Study shows that there are big differences among the seismic design results based on different equivalent linearization methods. Equivalent damping ratio model and the damping adjust coefficient have great influence on seismic design results. Calculation errors of Kowalsky method and Iwan method and Ou method are very small. Calculation error of Kowalsky method is decreasing when displacement ductility factor increases. The calculated result based on the damping adjust coefficient provided by Eurocode8 specification is more close to the real one. Kowalsky method and the damping adjust coefficient of Eurocode8 specification is recommended to be used in displacement-based design of bridge engineering.

In this paper, a low-profile dual-polarized antenna integrated with bandpass filter based on dual-mode open-loop resonant is proposed. The antenna design employs the concept of multistacked square patches fed by two probes located in two orthogonal directions. The two bandpass filters used to feed the antenna are on the bottom layer which share the same ground with the antenna. Both the separate and composite performance are simulated and measured in this design.

A comprehensive study of displacement-based design for reinforced concrete bridge columns is conducted. Section analysis software UC-Fyber is used to analyze the bending moment and curvature performance of columns’ sections, based on this, a new calculation method of target displacement of RC bridge columns is educed. Elastic displacement response spectrum, inelastic displacement response spectrum and inelastic demand spectrum are educed from acceleration spectra of Chinese Code JTG/T B02-01-2008; three simplified methods for displacement demand determination are developed. Example of the displacement-based design of bridge column was studied and checked by dynamic inelastic time-history analysis to clarify the reasonableness of the developed methods. Research shows that target displacement of RC bridge columns is relevant with concrete strength grade, longitudinal reinforcement ratio, height and the section form, etc; equivalent linearization method and inelastic displacement response spectrum method are based on the design response spectrum, could reach the target displacement and consider structure safety requirement; demand spectrum method is a simple and direct way to show design with graphics mode, with deficiency of structure capacity spectrum curve from pushover analysis differing from the reality.