Integrated interpretation of dual frequency induced polarization measurement based on wavelet analysis and metal factor methods

In mineral exploration, the apparent resistivity and apparent frequency （or apparent polarizability） parameters of induced polarization method are commonly utilized to describe the induced polarization anomaly. When the target geology structure is significantly complicated, these parameters would fail to reflect the nature of the anomaly source, and wrong conclusions may be obtained. A wavelet approach and a metal factor method were used to comprehensively interpret the induced polarization anomaly of complex geologic bodies in the Adi Bladia mine. Db5 wavelet basis was used to conduct two-scale decomposition and reconstruction, which effectively suppress the noise interference of greenschist facies regional metamorphism and magma intrusion, making energy concentrated and boundary problem unobservable. On the basis of that, the ore-induced anomaly was effectively extracted by the metal factor method.

Recent Progress in Dual-Polarization Radar Research and Applications in China

Dual-polarization(dual-pol)radar can measure additional parameters that provide more microphysical information of precipitation systems than those provided by conventional Doppler radar.The dual-pol parameters have been successfully utilized to investigate precipitation microphysics and improve radar quantitative precipitation estimation(QPE).The recent progress in dual-pol radar research and applications in China is summarized in four aspects.Firstly,the characteristics of several representative dual-pol radars are reviewed.Various approaches have been developed for radar data quality control,including calibration,attenuation correction,calculation of specific differential phase shift,and identification and removal of non-meteorological echoes.Using dual-pol radar measurements,the microphysical characteristics derived from raindrop size distribution retrieval,hydrometeor classification,and QPE is better understood in China.The limited number of studies in China that have sought to use dual-pol radar data to validate the microphysical parameterization and initialization of numerical models and assimilate dual-pol data into numerical models are summarized.The challenges of applying dual-pol data in numerical models and emerging technologies that may make significant impacts on the field of radar meteorology are discussed.

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.

Identification and Removal of Non-meteorological Echoes in Dual-polarization Radar Data Based on a Fuzzy Logic Algorithm

A major issue in radar quantitative precipitation estimation is the contamination of radar echoes by non-meteorological targets such as ground clutter,chaff,clear air echoes etc.In this study,a fuzzy logic algorithm for the identification of non-meteorological echoes is developed using optimized membership functions and weights for the dual-polarization radar located at Mount Sobaek.For selected precipitation and non-meteorological events,the characteristics of the precipitation and non-meteorological echo are derived by the probability density functions of five fuzzy parameters as functions of reflectivity values.The membership functions and weights are then determined by these density functions.Finally,the nonmeteorological echoes are identified by combining the membership functions and weights.The performance is qualitatively evaluated by long-term rain accumulation.The detection accuracy of the fuzzy logic algorithm is calculated using the probability of detection（POD）,false alarm rate（FAR）,and clutter–signal ratio（CSR）.In addition,the issues in using filtered dual-polarization data are alleviated.

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.

An approach to estimate tree height using PolInSAR data constructed by the Sentinel-1 dual-pol SAR data and RVoG model

We estimate tree heights using polarimetric interferometric synthetic aperture radar(PolInSAR)data constructed by the dual-polarization(dual-pol)SAR data and random volume over the ground(RVoG)model.Considering the Sentinel-1 SAR dual-pol(SVV,vertically transmitted and vertically received and SVH,vertically transmitted and horizontally received)configuration,one notes that S_(HH),the horizontally transmitted and horizontally received scattering element,is unavailable.The S_(HH)data were constructed using the SVH data,and polarimetric SAR(PolSAR)data were obtained.The proposed approach was first verified in simulation with satisfactory results.It was next applied to construct PolInSAR data by a pair of dual-pol Sentinel-1A data at Duke Forest,North Carolina,USA.According to local observations and forest descriptions,the range of estimated tree heights was overall reasonable.Comparing the heights with the ICESat-2 tree heights at 23 sampling locations,relative errors of 5 points were within±30%.Errors of 8 points ranged from 30%to 40%,but errors of the remaining 10 points were>40%.The results should be encouraged as error reduction is possible.For instance,the construction of PolSAR data should not be limited to using SVH,and a combination of SVH and SVV should be explored.Also,an ensemble of tree heights derived from multiple PolInSAR data can be considered since tree heights do not vary much with time frame in months or one season.

A Low Profile Four-Way Directional Antenna with Dual Polarization

This paper presents a low profile dual polarized directional antenna composed of loop and dipole arrays mounted on a ground plane with each loops and dipoles being fed independently. Each loop antenna is paired with a reflector while each dipole antenna is paired with a director and a reflector. The proposed antenna is intended for an indoor base station (BS) with resonance frequency of 2.4 GHz and capable of producing four orthogonal directional pattern with downward elevation angle equals to 30°;and half power bandwidth (HPBW) less than 80°;in both vertical and horizontal polarization. The reflection characteristics of the loop and dipole arrays are less than -10 dB and the mutual coupling between the vertical and horizontal polarization elements is nearly less than -20 dB. In later progress, the dipole antenna was substituted with printed dipole antenna to achieve a better performance. Both the calculated and measured results demonstrated that the desired radiation patterns were achieved, and the measured results agreed well with the calculated ones. Consequently, a low profile antenna with a thickness of 0.16 λ (20 mm) having the expected radiation pattern is successfully designed.

Experimental Research of Dual-Polarization Passive Radar Based on DTTB Signal

The passive radar is a hot research topic. A multi-channel wideband passive radar experimental system is designed and the digital television terrestrial broadcasting (DTTB) signal is chosen to carry out the target detection experiment of civil aviation aircraft. The polarization and spatial filtering methods are used to solve the strong direct path interference suppression problems brought by the receiving system location;combined with the characteristics of DTTB signal, the block length selection interval in the block batch processing method for range-Doppler images calculation is given;the clutter suppression performance is compared through the experimental data receiving from different bistatic polarization channels, the conclusion is different from the monostatic radar and it can guide the passive radar experiment.

Ultra-broadband polarization splitter based on graphene layer-filled dual-core photonic crystal fiber

An ultra-broadband polarization splitter based on graphene layer-filled dual-core photonic crystal fiber （GDC-PCF） that can work in a wavelength range from 1120 nm to 1730 nm is proposed in this paper. Through optimizing fiber configuration, the polarization splitter has an extinction ratio of-56.3 dB at 1.55 μm with a fiber length of 4.8 mm. Compared with the photonic crystal fiber reported splitters, to our knowledge, the GDC-PCF splitter with the extinction ratio below-20 dB has a super wide bandwidth of 610 nm. Due to the excellent splitting characteristics, the GDC-PCF will be used in coherent optical communication systems in a wavelength range from infrared to mid-infraed.

2.5D induced polarization forward modeling using the adaptive finite-element method

The conventional finite-element（FE） method often uses a structured mesh, which is designed according to the user’s experience, and it is not sufficiently accurate and flexible to accommodate complex structures such as dipping interfaces and rough topography. We present an adaptive FE method for 2.5D forward modeling of induced polarization（IP）. In the presented method, an unstructured triangulation mesh that allows for local mesh refinement and flexible description of arbitrary model geometries is used. Furthermore, the mesh refinement process is guided by dual error estimate weighting to bias the refinement towards elements that affect the solution at the receiver locations. After the final mesh is generated, the Jacobian matrix is used to obtain the IP response on 2D structure models. We validate the adaptive FE algorithm using a vertical contact model. The validation shows that the elements near the receivers are highly refined and the average relative error of the potentials converges to 0.4 % and 1.2 % for the IP response. This suggests that the numerical solution of the adaptive FE algorithm converges to an accurate solution with the refined mesh. Finally, the accuracy and flexibility of the adaptive FE procedure are also validated using more complex models.

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.

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.

Measurements of ocean wave and current field using dual polarized X-band radar

A new ocean wave and sea surface current monitoring system with horizontally-(HH) and vertically-(VV) polarized X-band radar was developed.Two experiments into the use of the radar system were carried out at two sites,respectively,for calibration process in Zhangzi Island of the Yellow Sea,and for validation in the Yellow Sea and South China Sea.Ocean wave parameters and sea surface current velocities were retrieved from the dual polarized radar image sequences based on an inverse method.The results obtained from dual-polarized radar data sets acquired in Zhangzi Island are compared with those from an ocean directional buoy.The results show that ocean wave parameters and sea surface current velocities retrieved from radar image sets are in a good agreement with those observed by the buoy.In particular,it has been found that the vertically-polarized radar is better than the horizontally-polarized radar in retrieving ocean wave parameters,especially in detecting the significant wave height below 1.0 m.

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-Polarized Slot-Coupled Microstrip Antenna with Very High Isolation

A wideband dual-polarized slot-coupled stacked microstrip antenna with very high isolation and low cross-polarization is presented. To improve isolation between two poiarization ports, the stacked patches are excited by an open-ended and a T-shaped microstrip lines both via two H-shaped slots placed in a ＂T＂ configuration. The measured isolation is better than 40.5 dB over the bandwidth from 8.8 to 9.8 GHz with cross-polarization level less than - 28.5 dB. The measured VSWR ≤ 2 bandwidths reach 20.7 96 and 19.196 at the verrical and horizontal polarization ports, respectively. This antenna is suitable to be used as array elements in spacebome synthetic aperture radars （SAR） and active phased array radars.

Wideband dual-polarized slot-coupled microstrip array for synthetic aperture radar application

An 8 × 1-element wideband dual-polarized slot-coupled microstrip antenna array with high isolation and low crosspolarization in X-band is presented. The array antenna offers an impedance bandwidth （VSWR≤2） of 23% and 21% for dual polarization ports, respectively. The measured isolation between two polarization ports is better than 35 dB and the measured cross-polarization level below -25 dB in the main beam over the operation frequency band of 9.35 GHz to 9.75 GHz. This array is well suitable for X-band SAR （synthetic aperture radar） antenna apphcation.

Simultaneous polarization separation and switching for 100-Gbps DP-QPSK signals in backbone networks

We propose a novel scheme of simultaneous polarization separation and switching, based on the orthogonallypolarized four-wave mixing(FWM) effect, for ultra-high-speed polarization multiplexing(Pol-MUX) fiber networks such as 100-Gbps and 400-Gbps backbone networks. We use theoretical and experimental analysis of the vector theory of FWM to successfully achieve polarization separation and all-optical switching by utilizing a 100-Gbps dual polarizationquadrature phase shift keying(DP-QPSK) signal and two orthogonally-polarized pumps. Both of the polarization-separated QPSK signals have clear constellation diagrams, with root mean square(RMS) error vector magnitudes(EVMs) of 14.32%and 14.11% respectively. The wavelengths of idlers can be created at 30 different wavelengths, which are consistent with International Telecommunication Union-Telecommunication(ITU-T) wavelengths, by flexibly changing the wavelength of the pump light. Moreover, the idlers that have distinct wavelengths have power distributed in a range from-10 dBm to-15 dBm, which can support error-free transmission. The power penaltyis 5 d B lower than that of back-to-back(BTB)signal for both the X-and Y-polarization components measured at a bit error ratio(BER) of 3.8×10^(-3). Our experimental results indicate that this scheme has promising applications in future backbone networks.

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.

Broadband printed antennas and dual-polarized microstrip and waveguide slot antenna arrays

In order to meet the urgent needs in wireless communications, microwave image synthetic aperture radars （SAR）, and electronic warfare systems, this dissertation studies several types of broadband dual-polarized planar antenna elements and arrays, and proposes a few of novel designs with experimental verification. The main accomplishments reported in the dissertation are as follows.