研究内容

  2017年入职起,主持的科研项目包括:国家自然科学基金2项、省部级科研项目2项、国家重点研发计划子课题1项、工信部5G平台建设课题1项(共计250余万元);企业合作项目多项(共计1000余万元);国家人才项目1项、校级人才项目1项(共计400万元)。《B5/6G通信大容量智能天线技术研究》获2022年陕西省高等学校科学技术研究优秀成果一等奖。经费充足,研究生可以根据个人兴趣选择基础理论研究或工程应用研究的课题。与国外多所大学、研究所、公司保持良好的合作关系,可优先推荐优秀博士研究生到国外合作单位留学深造

  课题组研究涉及天线传播与无线通信的交叉领域,具体方向包括(但不限于)5G/6G多天线技术、5G大规模MIMO相关技术及其空口测试、微波混响室、天线设计及测量算法、电磁信息论。主要代表工作如下:

Selective publications:

  • Y. Da, X. Chen, and A. A. Kishk, “In-band mutual coupling suppression in dual-band shared-aperture base station arrays using dielectric block loading,” IEEE Transactions on Antennas and Propagation, accepted, 2022.
  • L. Zhao, Y. He, G. Zhao, X. Chen, G. Huang, and W. Lin, “Scanning angle extension of a millimeter wave antenna array using electromagnetic band gap ground,” IEEE Transactions on Antennas and Propagation, vol. 70, no. 8, pp. 7264-7269, Aug. 2022.
  • S. Zheng, Z. Zhang, X. Chen, and A. Kishk, “Wideband monopole-like cup dielectric resonator antenna with coil feeding structure,” IEEE Transactions on Antennas and Propagation, vol. 70, no. 8, pp. 7118-7123, Aug. 2022.
  • J. Yi, M. Wei, M. Lin, X. Zhao, L. Zhu, X. Chen, and, Z. H. Jiang, “Frequency-tunable and magnitude-tunable microwave metasurface absorbers enabled by shape memory polymers,” IEEE Transactions on Antennas and Propagation, vol. 70, no. 8, pp. 6804-6812, Aug. 2022.
  • S. Huang, F. Li, and X. Chen, “An improved method for total radiated power tests in anechoic chambers,” IEEE Transactions on Instrumentation and Measurement, vol. 71, 1005909, pp. 1-9, 2022.
  • J. Zheng, X. Chen, and Y. Huang, “An effective antenna pattern reconstruction method for planar near-field measurement system,” IEEE Transactions on Instrumentation and Measurement, vol. 71, 8005012, pp. 1-12, 2022.
  • J. Yi, C. Dong, W. Xue, and X. Chen, “A switchable metamaterial absorber for fine tuning of the coherence bandwidth in a reverberation chamber,” IEEE Transactions on Antennas and Propagation, vol. 70, no. 6, pp. 4908-4913, Jun. 2022.
  • L. Lin, C. Liu, J. Yi, Z. Jiang, L. Jiang, X. Chen, H. Xu, and S. N. Burokur, “Chirality-intrigged spin-selective metasurface and applications in generating orbital angular momentum,” IEEE Transactions on Antennas and Propagation, vol. 70, no. 6, pp. 4549-4557, Jun. 2022.
  • M. Lin, J. Yi, J. Wang, L. Zhu, Z. Jiang, P. Qi, and X. Chen, “Single-layer re-organizable all-dielectric meta-lens platform for arbitrary transmissive phase manipulation at millimeter-wave frequencies,” IEEE Transactions on Antennas and Propagation, vol. 70, no. 3, pp. 2050-2069, Mar. 2022.
  • J. Zheng, X. Chen, X. Liu, M. Zhang, B. Liu, and Y. Huang, “An improved method for reconstructing antenna radiation pattern in a loaded reverberation chamber,” IEEE Transactions on Instrumentation and Measurement, vol. 71, 8001812, pp. 1-12, 2022.
  • J. Tang, X. Chen, X. Meng, Z. Wang, Y. Ren, C. Pan, X. Huang, M. Li, and A. A. Kishk, “Compact antenna test range using very small F/D transmitarray based on amplitude modification and phase modulation,” IEEE Transactions on Instrumentation and Measurement, vol. 71, 8001614, pp. 1-14, 2022.
  • F. Li, S. Huang, W. Xue, Y. Ren, and X. Chen, “Signal and coherence bandwidth effects on total radiated power measurements of LTE devices in reverberation chambers,” IEEE Transactions on Instrumentation and Measurement, vol. 71, 5500503, 2022.
  • W. Xue, X. Chen, Y. Yang, and Y. Huang, “Average Rician K-factor based uncertainty model of measured antenna efficiency using reference antenna method in reverberation chambers,” IEEE Transactions on Instrumentation and Measurement, vol. 71, 1000411, 2022.
  • X. Chen, M. Zhao, H. Huang, Y. Wang, S. Zhu, C. Zhang, J. Yi, and A. A. Kishk, “Simultaneous decoupling and decorrelation scheme of MIMO arrays,” IEEE Transactions on Vehicular Technology, vol. 71, no. 2, pp. 2164-2169, Feb. 2022.
  • M. Zhang, S. Zhu, X. Chen, and A. Zhang, “Fast detection of the number of signals based on ritz values: a noise-power-aided approach,” IEEE Transactions on Aerospace and Electronic Systems, vol. 58, no. 1, pp. 651-662, Feb. 2022.
  • Y. Wang, X. Chen, X. Liu, et al., “Improvement of diversity and capacity of MIMO system using scatterer array,” IEEE Transactions on Antennas and Propagation, vol. 70, no. 1, pp. 789-794, Jan. 2022.
  • B. Liu, X. Chen, J. Tang, A. Zhang, and A. Kishk, Co- and cross-polarization decoupling structure with polarization rotation property between linearly polarized dipole antennas with application to decoupling of circularly polarized antennas,” IEEE Transactions on Antennas and Propagation, vol. 70, no. 1, pp. 702-707, Jan. 2022.
  • M. Zhang, J. Li, S. Zhu, and X. Chen, “Fast and simple gradient projection algorithms for phase-only beamforming,” IEEE Transactions on Vehicular Technology, vol. 70, no. 10, pp. 10620-10632, Oct. 2021.
  • M. Li, X. Chen, A. Zhang, A. A. Kishk, and W. Fan, Reducing correlation in compact arrays by adjusting near-field phase distribution for MIMO applications,” IEEE Transactions on Vehicular Technology, vol. 70, no. 8, pp. 7885-7896, Aug. 2021.
  • X. Zhang, J. Zhang, Y. Gao, M. Qian, S. Qu, M. Yu, X. Chen, G. Adriany, and A. W. Roe, “A 16-channel dense array for in vivo animal cortical MRI/fMRI on 7T human scanners,” IEEE Transactions on Biomedical Engineering, vol. 68, no. 5, pp. 1611-1618, May 2021.
  • M. Wang, C. Zhang, X. Chen, and S. Tang, “Performance analysis of millimeter wave wireless power transfer with imperfect beam alignment,” IEEE Transactions on Vehicular Technology, vol. 70, no. 3, pp. 2605-2618, Mar. 2021.
  • W. Xue, F. Li, and X. Chen, “Effects of signal bandwidth on total isotropic sensitivity measurements in reverberation chamber,” IEEE Transactions on Instrumentation and Measurement, vol. 70, 1005408, 2021.
  • W. Xue, F. Li, X. Chen, et al., “A unified approach for uncertainty analyses for total radiated power and total isotropic sensitivity measurements in reverberation chamber,” IEEE Transactions on Instrumentation and Measurement, vol. 70, 1003112, 2021.
  • X. Liu, J. Zhang, X. Chen, Z. Jiang, and A. Zhang, “A generalized accurate model for complementary two-dimensional metasurface based on Babinet principle,” IEEE Transactions on Antennas and Propagation, vol. 68, no. 5, pp. 3780-3790, May 2020.
  • M. Zhang and X. Chen, “The importance of continuity for linear time-invariant systems,” IEEE Signal Processing Magazine, vol. 37, no. 2, pp. 77-100, Mar. 2020.
  • S. Zhu, Y. He, X. Chen, et al., “Resolution threshold analysis of the microwave radar coincidence imaging,” IEEE Transactions on Geoscience and Remote Sensing, vol. 58, no. 3, pp. 2232-2243, Mar. 2020.
  • S. Zhang, X. Chen, and G. F. Pedersen, “Mutual coupling suppression with decoupling ground for massive MIMO antenna arrays,” IEEE Transactions on Vehicular Technology, vol. 68, no. 8, pp. 7273-7282, Aug. 2019.
  • X. Chen, M. Zhang, S. Zhu, and A. Zhang, “Empirical study of angular-temporal spectra in a reverberation chamber,” IEEE Transactions on Antennas and Propagation, vol. 66, no. 11, pp. 6452-6456, Nov. 2018.
  • M. Zhang, J. Wang, X. Chen, and A. Zhang, “The kernel conjugate gradient algorithms,” IEEE Transactions on Signal Processing, vol. 66, no. 16, pp. 4377-4387, Aug. 2018.
  • W. Fan, P. Kyösti, M. Romney, X. Chen, and G. F. Pedersen, “Over-the-air radiated testing of millimeter-wave beam-steerable devices in a cost-effective measurement setup,” IEEE Communication Magazine, vol. 56, no. 7, pp 64-71, Jul. 2018.
  • X. Liu, R. Lu, W. Li, S. Zhu, Z. Xu, X. Chen, and A. Zhang, “Babinet principle for anisotropic metasurface with different substrates under obliquely incident plane wave,” IEEE Transactions on Microwave Theory and Techniques, vol. 66, no. 6, pp.2704-2713, Jun. 2018.
  • X. Liu, W. Li, Z. Zhao, R. Lu, S. Zhu, Z. Xu, X. Chen, and A. Zhang, “Tangential network transmission theory of reflective metasurface with obliquely incident plane waves,” IEEE Transactions on Microwave Theory and Techniques, vol. 66, no.1, pp. 64-72, Jan. 2018.
  • S. Zhang, X. Chen, I. Syrytsin, and G. F. Pedersen, “A planar switchable 3-D-coverage phased array antenna and its user effects for 28-GHz mobile terminal applications,” IEEE Transactions on Antennas and Propagation, vol. 65, no. 12, pp. 6413-6421, Dec. 2017.
  • X. Chen, “Experimental investigation and modeling of the throughput of a 2×2 closed-loop MIMO system in a reverberation chamber,” IEEE Transactions on Antennas and Propagation, vol. 62, no. 9, pp. 4832-4835, Sep. 2014.
  • X. Chen, “Throughput modeling and measurement in an isotropic-scattering reverberation chamber,” IEEE Transactions on Antennas and Propagation, vol. 62, no. 4, pp. 2130-2139, April 2014.
  • X. Chen, “Generalized statistics of antenna efficiency measurement in a reverberation chamber,” IEEE Transactions on Antennas and Propagation, vol. 62, no. 3, pp. 1504-1507, Mar. 2014.
  • X. Chen, “On statistics of the measured antenna efficiency in a reverberation chamber,” IEEE Transactions on Antennas and Propagation, vol. 61, no. 11, pp. 5417-5424, Nov. 2013.
  • X. Chen, “Experimental investigation of the number of independent samples and the measurement uncertainty in a reverberation chamber,” IEEE Transactions on Electromagnetic Compatibility, vol. 55, no. 5, pp. 816-824, Oct. 2013.
  • X. Chen, P.-S. Kildal, and M. Gustafsson, “Characterization of implemented algorithm for MIMO spatial multiplexing in reverberation chamber,” IEEE Transactions on Antennas and Propagation, vol. 61, no. 8, pp. 4400-4404, Aug. 2013. 
  • X. Chen, “Using Akaike information criterion for selecting the field distribution in a reverberation chamber,” IEEE Transactions on Electromagnetic Compatibility, vol. 55, no. 4, pp. 664-670, Aug. 2013.
  • X. Chen, P.-S. Kildal, J. Carlsson, and J. Yang, “MRC diversity and MIMO capacity evaluations of multi-port antennas using reverberation chamber and anechoic chamber,” IEEE Transactions on Antennas and Propagation, vol. 61, no. 2, pp. 917-926, Feb. 2013.
  • P.-S. Kildal, X. Chen, C. Orlenius, M. Franzén, and C. Lötbäck Patané, “Characterization of reverberation chambers for OTA measurements of wireless devices: physical formulations of channel matrix and new uncertainty formula,” IEEE Transactions on Antennas and Propagation, vol. 60, no. 8, pp. 3875 – 3891, Aug. 2012.

1. 4G/5G空口测试技术   Over-the-air (OTA) testing for 4G/5G devices

 

 

 

 

 

 

A very small focal to diameter ratio (F/D) transmitarray for compact antenna test range (CATR) application is proposed in this work. The transmitarray comprises a feed antenna, a metasurface for phase modulation (MPM), and another one for amplitude modification (MAM). The resulting CATR demonstrates a 50% quiet zone of the aperture size with ±0.5 dB amplitude and ±5° phase errors. The F/D (0.287) is at least an order of magnitude smaller than that of the tranditonal technique. More importantly, the cost is just a fraction of the conventional CATR. (专利已授权)

 

Based on ML-powered interpolation, the sampling distance can be as large as 0.7 wavelength (i.e., undersampling), the resulting accuracy is basically the same as that of the oversampled case (with < 0.5-wavelength sampling). The proposed fast plannar near-field testing method can reduce the measurement time by 1/3~2/3, compared to the conventional method.

 

2. 5G毫米波手机天线 5G millimeter-wave (mmWave) array for mobile phones

 

 

 

3. 阵列天线解耦 Decoupling techniques for array antennas

In this work, a concept of decoupling ground is introduced. The mutual coupling is reduced by changing the shape of the ground plane under each element, so that the coupling from the free space and the ground plane can be out of phase and canceled with each other. A single-polarization linear array with 8 elements is simulated and measured to verify the concept. Examples of dual-polarization 2×2 and 4×4 arrays are also verified by simulations. In all of these cases, the isolation is enhanced efficiently without affecting the radiaiton characteristics. Like the array-antenna decoupling surface, the proposed decoupling technique is applicable for 5G massive MIMO array yet with a much lower profile.

In this work, baffle loaded by split-ring resonator (SRR) is proposed to reduce the mutual coupling for ± 45° dual-polarized base station array. Each baffle consists of two rectangular SRR printed on one side of a 1-mm FR4 substrate. The final decoupling structure contains four baffles forming a barrier wall that reduces the coupling over the 5G band of 3.4-3.8 GHz. Dual-polarized cross-dipole array with SRR loading baffles is simulated and measured to demonstrate their effectiveness in the coupling reduction. The results show that the mutual coupling can be effectively reduced below -25 dB over the entire bandwidth while maintaining a compact array.

In this work, we proposes a dielectric superstrate to reduce the couplings between co-polarized and cross-polarized antenna elements in realistic base station (BS) arrays. The mutual couplings are reduced by adjusting the permittivity and profile of the dielectric superstrate to create “reflected” waves to neutralize the original coupling wave. The dielectric superstrate is a simple structure that is easy to design and manufacture. A large dielectric board and four small dielectric blocks help reduce the couplings between horizontal and vertical antenna elements, whereas a dielectric pillar is added to suppress the coupling between diagonal elements. The superior decoupling performance (> 25-dB isolation) is demonstrated for dual-polarized BS arrays over the fifth generation (5G) frequency band of 3.3 - 3.8 GHz, without affecting the matching and radiation performances of the array elements.

Dual-band base station antenna (BSA) arrays with shared aperture have attracted considerable attention for 5G communication. The focus is mainly on decoupling between lower-band (LB) and higher-band (HB) antennas (i.e., cross-band decoupling). The in-band BSA decoupling techniques are usually not applicable to broadband dual-band shared-aperture BSA arrays. HB BSAs’ elements usually are separated by more than half-wavelength to reduce the in-band mutual coupling, which increases the array aperture and causes grating lobes for beam steering. Here, a novel decoupling technique of dielectric blocks is proposed to suppress the in-band couplings in dual-band shared-aperture BSA arrays. The dielectric blocks are placed above the HB elements to neutralize the original coupling by creating partially reflected waves (an addition wave path). A compact interleaved dual-band BSA array with dielectric blocks is designed and manufactured. The LB operates between 1.9 – 2.5 GHz, and the HB covers the 5G band from 3.3 – 3.9 GHz. The HB coupling is effectively reduced below -25 dB while the impedance matching and radiation performance of the HB and LB elements are maintained. Moreover, the dielectric blocks are implemented for stacked and interleaved dual-band BSA arrays with suppressed cross-band interference. The proposed decoupling method has simple structures, easy to design and fabricate, and is compatible with the existing cross-band decoupling techniques for different dual-band BSA array configurations.

In this work, a decoupling structure with polarization rotation property (DSPR) is proposed to reduce the mutual coupling between co- or cross-polarized antennas. The proposed DSPR generates a neutralization wave with two orthogonally polarized components that can be controlled to cancel the original mutual coupling. The DSPR is placed above the arrays with orthogonal and parallel dipole elements. After applying the DSPR, the mutual coupling at the center frequency of 3.5 GHz is reduced to -40 dB for both arrays, and the overall mutual coupling is better than -26 dB within the band of 3.3-3.7 GHz, and the reflection coefficients remain below -12 dB. The antennas maintain stable radiation patterns within the operation bandwidth with a 0.5-dB increase of the realized gain. Since the DSPR can effectively reduce both co- and cross-polarization coupling, the mutual coupling between circularly polarized antennas in a 1×4 array is reduced to below -35 dB thanks to the DSPR. (专利已授权)

 

4. 5G/6G空口波形、非理想硬件影响及其消除算法 5G/6G waveforms, dirty RF and its mitigation

 

MIMO-UFMC tranceiver

 

MIMO-OFDM with various hardware impairments and corresponding mitigation schemes

 

 

Phase noise effect on multi-user OFDM system