Polarization mode dispersion compensation in a novel dual polarization differential quadrature phase shift keying system

A novel dual polarization differential quadrature phase shift keying （DP-DQPSK） system is proposed, whose receiver is the same as the single polarization DQPSK system, while it does not need polarization de-multiplexing like the conventional polarization division multiplexing QPSK （PDM-QPSK）. Polarization mode dispersion （PMD） is mainly considered and PMD compensation for the DP-DQPSK system is studied. As the feedback signal for PMD compensation, the degree of polarization of the signals is discussed in detail. The results show that PMD tolerance can be improved by 89 ps within 1 dB optical signal noise ratio penalty after PMD compensation for the DP-DQPSK system.

Corner Fed Microstrip Antenna Analysisfor Dual Polarization

This paper investigates a corner fed microstrip patch antenna by means of the cavity model with proposed feed modeling. The input impedance and radiation patterns for a corner feed are calculated. The mutual coupling between two corner feeds is investigated. An improvement in mutual coupling has been found for corner feeds relative to edge feeds, which is helpful for the design of dual polarized antenna arrays in wireless communication and radar applications.

The scattering mechanism of squall lines with C-Band dual polarization radar.Part Ⅰ:echo characteristics and particles phase recognition

Squall line is a kind of common mesoscale disaster weather.At present,there are few studies on the elaborate detection of squall line by dual polarization radar.With the dual polarization upgrade of weather radar network,we need to study the relationship between squall line echoes of base data and polarization data to reveal new echo phenomena and formation mechanisms.The relationship between radar parameters and atmospheric physical processes also need to be examined.Based on the NUIST CDP radar,a squall line in the Yangtze and Huaihe River basin that occurred from July 30 to 31,2014 is analyzed.The results show that polarization parameters have obvious advantages in the characteristics analysis of size,phase state,shape and orientation of the water condensate particles.The phase states of water condensate particles in convection cell can be distinguished through comparative discussion.Several phase states exist in the squall line,including small,medium and large raindrops,melting hails,dry hails and ice crystal particles and the Z_(DR)column can be used to identify the location of the main updraft.In addition,the polarization parameters are more sensitive to the melting layer.The gust front is presented as a narrow linear echo in Z affected by strong turbulence.It is an obvious velocity convergence line in V and approximately 0.70 inρ_(HV).The Z_(DR)can be used as a criterion to distinguish the horizontal and vertical scale of turbulence.The deforming turbulence,which is affected by environmental airflow,will cause an abnormally high Z_(DR)in the gust front and a negative Z_(DR)before and after the gust front.The variation of Z_(DR)depends on the turbulence arrangement,orientation and relative position between turbulence and radar.These dual polarization parameter characteristics offer insights into understanding the structure and evolution of the squall line.

Dual-Polarized RIS-Based STBC Transmission with Polarization Coupling Analysis

The rapid development of the reconfigurable intelligent surface(RIS)technology has given rise to a new paradigm of wireless trans-mitters.At present,most research works on RIS-based transmitters focus on single-polarized RISs.In this paper,we propose a dual-polarized RIS-based transmitter,which realizes 4-transmit space-time block coding(STBC)transmission by properly partitioning RIS’s unit cells and utilizing the degree of freedom of polarization.The proposed scheme is evaluated through a prototype system that utilizes a fabricated dual-polarized phase-adjustable RIS.In particular,the polarization coupling phenomenon in each unit cell of the employed dual-polarized RIS is modeled and analyzed.The experimental results are in good agreement with the theoretical modeling and analysis results,and an initial re-search effort is made on characterizing the polarization coupling property in the dual-polarized RIS.

Space time frequency coding for dual polarization MIMO in hybrid mobile satellite system

The hybrid mobile satellite system operating in a single frequency network （SFN） mode is increasingly becoming attractive. The combination of satellite component （SC） and terrestrial component （TC） promises a better quality of service （QoS）. Multimedia broadcast and multicast services （MBMS） are expected to be prevailed in this kind of system. Several space frequency （SF） or space time （ST） codes have been proposed to enhance the system performance due to the lack of reverse link and omni-directional transmission. However, they mostly consider the system with only one SC and one TC and fail to make full use of available diversities. This paper presents a novel way to realize the dual polarization multiple input multiple output （MIMO） transmission by using the space time frequency （STF） code. The theoretical analysis and simulations indicate that the application of STF code can improve the system performance dramatically. A higher diversity gain can be achieved due to the cooperative transmission of SC and TC, while the coding gain can be enhanced by the reusing of STF code between SCs or TCs. Even if some of the links are lost, it can still work properly and benefit from the STF code. The relative relay can result in a degradation up to 0.5 dB in the coding gain.

The scattering mechanism of squall lines with C-Band dual polarization radar.Part Ⅱ:the mechanism of an abnormal ZDR echo in clear air based on the parameterization of turbulence deformation

In part I,the clear air echo in front of the squall line is caused by turbulence diffraction,which makes the Z_(DR) echo characteristics different from particle scattering.To study the turbulence deformation phenomenon that is affected by environmental wind,the turbulence-related method is used to analyze the characteristics of three-dimensional turbulence energy spectrum density,and the parametric model of turbulence integral length scale and environmental wind speed is established.The results show that the horizontal scale of turbulence is generally larger than the vertical scale.The turbulence is nearly isotropic in the horizontal direction,presenting a flat ellipsoid with the vertical orientation of the rotation axis when there is no horizontal wind or the horizontal velocity is small.When horizontal wind exists,the turbulence scale increases along the dominant wind direction.The turbulence scale is positively correlated with the wind speed.The power function is used to fit the relationships of turbulence integral length scale and horizontal wind speed,which obtains the best fitting effect,and the goodness of fit(GF)is above 0.99 in each direction.The deforming turbulence can cause 8-9 dB Z_(DR) anomalies in the echo of dual polarization radar,which the ratio of scales in the dominant wind and the vertical direction of deforming turbulence(L_(u)/L_(w))is around 4.3.The variation in Z_(DR) depends on the turbulence shape,orientation and the relative position between turbulence and radar.The shape of turbulence derived from radar detection results is consistent with that of the parametric model,which can provide a parametric scheme for turbulence research.The results reveal the mechanism of abnormal Z_(DR) echo caused by deforming turbulence.

Spectrum sensing using multiple dual polarization antennas for cognitive radio systems in microcell environments

Spectrum sensing with multiple antennas for cognitive radio systems in microcell environments is affected by the spatial correlation among multiple antennas.To reduce the adverse effects of the spatial correlation on the spectrum sensing performance,we employ multiple dual polarization antennas at the sensing node of secondary users.The analysis of the spatial correlation is derived using the propagation characteristics of the electromagnetic wave based on the scattering patch model in a multipath microcell environment.The superiority of spectrum sensing with multiple dual polarized antennas over multiple mono-polarized antennas is shown by analyzing the false alarm and detection probabilities with the correlation among the antennas in a microcell environment.

Multiple interferences suppression with space-polarization null-decoupling for polarimetric array

The adaptive digital beamforming technique in the space-polarization domain suppresses the interference with forming the coupling nulls of space and polarization domain.When there is the interference in mainlobe,it will cause serious mainlobe distortion,that the target detection suffers from.To overcome this problem and make radar cope with the complex multiple interferences scenarios,we propose a multiple mainlobe and/or sidelobe interferences suppression method for dual polarization array radar.Specifically,the proposed method consists of a signal preprocessing based on the proposed angle estimation with degree of polarization(DoP),and a filtering criterion based on the proposed linear constraint.The signal preprocessing provides the accurate estimated parameters of the interference,which contributes to the criterion for null-decoupling in the space-polarization domain of mainlobe.The proposed method can reduce the mainlobe distortion in the space-polarization domain while suppressing the multiple mainlobe and/or sidelobe interferences.The effectiveness of the proposed method is verified by simulations.

A New Dual Polarized Aperture-Coupled Printed Array for SAR Applications

This paper presents a new design of dual polarized aperture coupled printed antenna array. The finite difference time domain (FDTD) analysis of an aperture coupled microstrip element is performed, and the effects of antenna parameters on its characteristics are obtained to guide the design of the printed array. Then an 8×2 dual polarized array design in X band is introduced with configuration plots. In order to improve its isolation and cross polarization, an outphase displacement feeding technique is adopted in the feed network. Also, the round bends are used instead of conventional right angle bends so as to achieve better VSWR performance. Experimental results are presented, indicating the validity of the design. This dual polarized array can be applied as a sub array of spaceborne SAR systems.

Dual polarization strategy to enhance CH_(4) uptake in covalent organic frameworks for coal-bed methane purification

The purification of low-grade coal-bed methane is extremely important,but challenging,due to the very similar physical properties of CH_(4)and N2.Herein,we proposed a dual polarization strategy by employing triazine and polyfluoride sites to construct polar pores in COF materials,achieving the efficient separa-tion of CH_(4)from N2.As expected,the dual polarized F-CTF-1 and F-CTF-2 exhibit higher CH_(4)adsorption capacity and CH_(4)/N_(2)selectivity than CTF-1 and CTF-2,respectively.Especially,the CH4 uptake capacity and CH_(4)/N_(2)selectivity of F-CTF-2 is 1.76 and 1.42 times than that of CTF-2.This work not only developed promising COF materials for CH4/N_(2)separation,but also provided important guidance for the separation of other adsorbates with similar properties.

Dual-polarized lens antenna based on multimode metasurfaces

We propose a dual-polarized lens antenna system based on isotropic metasurfaces for 12 GHz applications. The metasurface lens is composed of subwavelength unit cells（0.24λ0） with metallic strips etched on the top and bottom sides of the unit cell, and a cross-slots metallic layer in the middle that serves as the ground. The multimode resonance in the unit cell can realize a large phase shift（covering 0？–360？）, and the total transmission efficiency of the lens is above 80%.The feed antenna at the focal point of the lens is a broadband dual-polarized microstrip antenna. Both the simulated and the measured results demonstrate that the dual-polarized lens antenna system can realize a gain of more than 16.1 dB, and an input port isolation of more than 25.0 dB.

Iterative Detection and Decoding Algorithm in Dual Polarized Land Mobile Satellite MIMO Systems

An iterative detection and decoding algorithm with outer code decision feedback is proposed for the dual polarized( DP) land mobile satellite( LMS) MIMO systems using concatenated codes. A feedback structure is added after the outer decoder in the proposed algorithm. The feedback information is exploited to control the detecting list in the MIMO detector and reduce the number of symbols which have to be processed at each iteration. As a result,the computational complexity is reduced. Meanwhile,the successfully decoded outer code words are used to calculate the more reliable initial information for the inner decoder and the system performance can be improved by this step. The simulation results show that the proposed algorithm can reduce the computational complexity compared to the traditional iterative detection and decoding algorithm and achieve better performance.

Compact Interlaced Dual Circularly Polarized Sequentially Rotated Dielectric-Resonator Antenna Array

In this study,a compact 2×2 interlaced sequentially rotated dual-polarized dielectric-resonator antenna array is proposed for 5.8 GHz applications.The array is composed of a novel unit elements that are made of rectangular dielectric resonator(RDR)coupled to an eye slot for generating the orthogonal modes,TEδx 21 and TE1yδ1 to acquire circular polarization(CP)radiation.For the purpose of miniaturization and achieving dual polarized resonance,the array is fed by two interlaced ports and each port excites two radiating elements.The first port feeds horizontal elements to obtain left hand circular polarization(LHCP).The second port feeds vertical elements to obtain right hand circular polarization(RHCP).A quarter-wave length transformer is employed to reduce the attenuation and consequently increase the array gain performance.The 35×35 mm2(0.676λ0×0.676λ0)gains were 8.4 and 8.2 dBi for port 1 and port 2,respectively,with port isolations of−33.51 dB.The design achieves a voltage standing-wave ratio(VSWR)<−10 dB and an axial ratio(AR)<−3 dB bandwidth of 2.48%(5.766 to 5.911 GHz)for LHCP at port 1 and a VSWR<−10 dB and AR<−3 dB bandwidth of 2.28%(5.788 to 5.922 GHz)for RHCP at port 2.The findings of the proposed design validate its use for ISM band applications.

Polarization Reconfigurable Patch Antenna for Wireless Power Transfer Related Applications

A polarized reconfigurable patch antenna is proposed in this paper.The proposed antenna is a dual cross-polarized patch antenna with a programmable power divider.The programmable power divider consists of two branch line couplers(BLC)and a digital phase shifter.By adjusting the phase of the phase shifter,the power ratio of the power divider can be changed,and thus the feed power to the antenna input port can be changed to reconfigure the antenna polarization.The phase-controlled power divider and the cross dual-polarized antenna are designed,fabricated and tested,and then they are combined to realize the polarized reconfigurable antenna.By moving the phase of the phase shifter,the antenna polarization is reconfigured into vertical polarization(VP),horizontal polarization(HP),and circular polarization(CP).The test is conducted at the frequency of 915 MHz,which is widely used for simultaneous wireless information and power transfer(SWIPT)in radio-frequency identification(RFID)applications.The results demonstrate that when the antenna is configured as CP,the axial ratio of the antenna is less than 3 dB,and when the antenna is configured as HP or VP,the axial ratio of the antenna exceeds 20 dB.Finally,experiments are conducted to verify the influence of antenna polarization changes on wireless power transmitting.As expected,the reconfigured antenna polarization can help improve the power transmitting efficiency.

Statistics-based Optimization of the Polarimetric Radar Hydrometeor Classification Algorithm and Its Application for a Squall Line in South China

A modified hydrometeor classification algorithm （HCA） is developed in this study for Chinese polarimetric radars. This algorithm is based on the U.S. operational HCA. Meanwhile, the methodology of statistics-based optimization is proposed including calibration checking, datasets selection, membership functions modification, computation thresholds modification, and effect verification. Zhuhai radar, the first operational polarimetric radar in South China, applies these procedures. The systematic bias of calibration is corrected, the reliability of radar measurements deteriorates when the signal-to-noise ratio is low, and correlation coefficient within the melting layer is usually lower than that of the U.S. WSR-88D radar. Through modification based on statistical analysis of polarimetric variables, the localized HCA especially for Zhuhai is obtained, and it performs well over a one-month test through comparison with sounding and surface observations. The algorithm is then utilized for analysis of a squall line process on 11 May 2014 and is found to provide reasonable details with respect to horizontal and vertical structures, and the HCA results---especially in the mixed rain-hail region--can reflect the life cycle of the squall line. In addition, the kinematic and microphysical processes of cloud evolution and the differences between radar- detected hail and surface observations are also analyzed. The results of this study provide evidence for the improvement of this HCA developed specifically for China.

Utilization of Specific Attenuation for Rainfall Estimation in Southern China

This study uses rain gauge observations to assess the performance of different radar estimators R(ZH),R(KDP)and R(A)in estimating precipitation based on the observations of an S-band polarimetric radar over southern China during a typical convective storm and an extremely severe typhoon,i.e.,Typhoon Manghkut.These radar estimators were derived from observations of a local autonomous particle size and velocity(Parsivel)unit(APU)disdrometer.A key parameter,alpha(α),which is the ratio of specific attenuation A to specific differential phase KDP with three fixed values(α=0.015 dB deg^(-1),α=0.0185 dB deg^(-1)andα=0.03 dB deg^(-1))was examined to test the sensitivity of the R(A)rain retrievals.The results show that:(1)All radar estimators can capture the spatio-temporal patterns of two precipitation events,R(A)withα=0.0185 dB deg^(-1)is well correlated with gauge measurement via higher Pearson’s correlation coefficient(CC)of 0.87,lower relative bias(RB)of 16%,and lower root mean square error(RMSE)of 17.09 mm in the convective storm while it underestimates the typhoon event with RB of 35%;(2)R(A)withα=0.03 dB deg^(-1)shows the best statistical scores with the highest CC(0.92),lowest RB(7%)and RMSE(25.74 mm)corresponding to Typhoon Manghkut;(3)R(A)estimates are more efficient in mitigating the impact of partial beam blockage.The results indicate thatαis remarkably influenced by the variation of drop size distribution.Thus,more work is needed to establish an automated and optimizedαfor the R(A)relation during different rainfall events over different regions.

Design of a Magneto-Electric Dipole Element for Mobile Communication Base Station Antennas

The magneto-electric dipole antenna is a kind of complementary antenna composed of a planar electric dipole and a shorted patch antenna. It has excellent electrical characteristics including wide impedance bandwidth, low cross-polarization, low back lobe radiation, nearly identical E-plane and H-plane patterns, stable radiation pattern, and steady antenna gain over the operating frequency range. In this paper, the basic characteristics of a linearly polarized magneto-electric dipole antenna are reviewed, and a dual-polarized antenna element based on the magneto-electric dipole is presented. The design of a conical beam wideband antenna with horizontal polarization is also described. These antennas have practical applications in modern 2G, 3G, LTE, WiFi, and WiMax wireless communication systems.

STUDY ON APPLICATIONS OF C-BAND DUAL LINEAR POLARIZATION RADAR IN METEOROLOGY

Theoretical study and development of a dual linear polarization weather radar in China are briefly presented. Also discussed are the potential uses of the new radar system in improving the accuracy of areal rainfall measure- ments and analysing the spacial structure of storms and distribution of hydrometecrs in clouds based on the radar observational data from the field experimcnts during the summers of 1987—1989. The results indicate that a C-band dual polarization weather radar, after considering the microwave attenuation correction, may be employed to quantitatively measure rainfall and to monitor heavy rain and flood events and becomes an impor- rant means to study storm structure.

Self-locked orthogonal polarized dual comb in a microresonator

Dual combs are an emerging tool to obtain unprecedented resolution, high sensitivity, ultrahigh accuracy, broabandwidth, and ultrafast data updating rate in the fields of molecular spectroscopy, optical metrology, as well optical frequency synthesis. The recent progress in chip-based microcombs has promoted the on-chip dual-commeasuring systems to a new phase attributed to the large frequency spacing and broad spectrum. In this paper, wdemonstrate proof-of-concept dual-comb generation with orthogonal polarization in a single microresonatthrough pumping both the transverse-electric(TE) and transverse-magnetic(TM) modes simultaneously. Ttwo orthogonal polarized pumps are self-oscillating in a fiber ring cavity. The generated dual comb exhibits ecellent stability due to the intrinsic feedback mechanism of the self-locked scheme. The repetition rate the two orthogonal combs is slightly different because of the mode spacing difference between the TE anTM modes. Such orthogonal polarized dual-combs could be a new comb source for out-of-lab applicatioin the fields of integrated spectroscopy, ranging measurement, optical frequency synthesis, and microwacomb generation.

Dynamic modulation performance of ferroelectric liquid crystal polarization rotators and Mueller matrix polarimeter optimization

A ferroelectric liquid crystal polarization rotator(FLCPR)has been widely used in polarization measurement due to its fast and stable modulation characteristics.The accurate characterization of the modulation performance of FLCPR directly affects the measurement accuracy of the instrument based on liquid crystal modulation.In this study,FLCPR is accurately characterized using a self-developed high-speed Stokes polarimeter.Strong linear and weak circular birefringence are observed during modulation processes,and all the optical parameters of FLCPR are dependent on driving voltage.A dual FLCPR-based Mueller matrix polarimeter is designed on the basis of the Stokes polarimeter.The designed polarimeter combines the advantages of the high modulation frequency of FLCPR and the ultrahigh temporal resolution of the fast polarization measurement system in the Stokes polarimeter.The optimal configuration of the designed polarizer is predicted in accordance with singular value decomposition.A simulated thickness measurement of a 24 nm standard SiO2 thin film is performed using the optimal configuration.Results show that the relative error in thickness measurement caused by using the unsatisfactory modulation characteristics of FLCPR reaches up to−4.34%.This finding demonstrates the importance of the accurate characterization of FLCPR in developing a Mueller matrix polarizer.