A miniaturized wideband filtering metasurface antenna (MSA) is proposed, comprising 3×3 square metasurface elements and a driven patch. Symmetrically arranged shorting vias and an open stub induce the first two radiation nulls ${f_{\mathrm{{n1}}}}$ and $f_{\mathrm{{n2}}}$ in the lower and upper stop-bands, respectively. To move the newly resonant point caused by $f_{\mathrm{{n2}}}$ forward and expand the impedance bandwidth (IBW) of the filtering MSA, two slots are etched on the driven patch. Meanwhile, introducing the second radiation null $f_{\mathrm{{n3}}}$ in the upper stop-band. After that, two L -shaped branches will help to enhance the roll-off rate by shifting $f_{\mathrm{{n3}}}$ from 5.65GHz to 5.5GHz. Measurement of the prototype reveals a large 10-dB fractional IBW of 35.8% (from 3.55GHz to 5.1GHz) with an average realized gain of 7.1 dBi. What's more, the radiation aperture size is merely 0.41×0.41 ${\lambda _{0}^{2}}$ , while maintaining the radiation suppression level of 16dB and 25.6dB at the lower and upper band edges, respectively, rendering this filtering MSA more promising for 5G (sub 6G) application.

Nowadays, symmetric nonuniform linear arrays (SNLAs) have been considered for mixture near-field (NF) and far-field (FF) source localization since it can provide larger physical array aperture and higher degree-of-freedom (DOF) than uniform linear arrays (ULAs). In this communication, a symmetric extended nested array (SENA) is proposed on the basis of compressed symmetric nested array (CSNA). The closed-form expression for the SENA and its difference coarray (DCA) is presented in detail. For the sake of comparison to the existing SNLAs with sensors, the longer consecutive DCA lags and larger physical array aperture are obtained with optimal design to achieve better estimation results. Numerical results demonstrate that utilizing SS-MUSIC and MUSIC algorithms, the SENA outperforms exiting SNLAs in terms of the DOA and range estimate accuracy for mixture field sources.

This article proposes a novel active localization method based on the mixed polarization multiple signal classification (MP-MUSIC) algorithm for positioning a metal target or an insulator target in the underwater environment by using a uniform circular antenna (UCA). The boundary element method (BEM) is introduced to analyze the boundary of the target by use of a matrix equation. In this method, an electric dipole source as a part of the locating system is set perpendicularly to the plane of the UCA. As a result, the UCA can only receive the induction field of the target. The potential of each electrode of the UCA is used as spatial-temporal localization data, and it does not need to obtain the field component in each direction compared with the conventional fields-based localization method, which can be easily implemented in practical engineering applications. A simulation model and a physical experiment are constructed. The simulation and the experiment results provide accurate positioning performance, with the help of verifying the effectiveness of the proposed localization method in underwater target locating.

This paper establishes an optimal generic function model in order to obtain a continuous phase modulated (CPM) signal with a smoother phase modulation function. This is achieved by finding the solution to the symbol signals at different lengths of the CPM function. In the solution process, the unknown amount that needs to be solved is reduced by using the even function symmetry characteristic of the signal to be solved. For each different form of the signal, the time domain form of the CPM function and the corresponding normalized energy spectral density are compared under the influence of the phase modulation signal length and the generic function parameter n. The data transmission rate is improved by introducing inter-symbol interference, and the modulation process is realized using six-way parallel transmission when the CPM function is 6T. The simulation results show that the CPM function obtained by establishing an optimal generic function model has high-quality time-frequency characteristics. The real-time phase trajectory and the high-order derivative are both continuous, and the modulated signal has constant envelope characteristics. The CPM function has a fast rolling-off in the frequency domain and small out-of-band radiation, which greatly improves the characteristics of the frequency band utilization.

In mixed-field source localization, the physical properties of a sensor array, such as the degrees of freedom (DOFs), aperture, and coupling leakage, directly affect the accuracy of estimating the direction of arrival (DOA). Compared to conventional symmetric uniform linear arrays, symmetric non-uniform linear arrays (SNLAs) have a greater advantage in mixed-field source localization due to their larger aperture and higher DOF. However, current SNLAs require improvements in their physical properties through modifications to the array structure in order to achieve more accurate source localization estimates. Therefore, this study proposes a symmetric double-supplemented nested array (SDSNA), which translates nested subarrays based on symmetric nested arrays to increase the aperture and inserts two symmetric supplemented subarrays to fill the holes created by the translation. This method results in longer consecutive difference coarray lags and larger apertures. The SDSNA is compared to existing advanced SNLAs in terms of their physical properties and DOA estimation. The results show that, with the same number of sensors, the SDSNA has a higher DOF, a larger aperture, and smaller coupling, indicating the advantages of the SDSNA in terms of its physical properties. Under the same experimental conditions, the SDSNA has a lower root-mean-square error of source location, thus indicating better performance in terms of both DOA and distance estimation.

This paper presents a novel method designing an optimized waveform with high spectral efficiency based on minimum out-of-band radiation criterion. Introducing the Pan-function model, Fourier series, and constraints, we achieve the numeric solution of the optimized baseband signals. The optimal waveform provides an excellent bandwidth efficiency, and its bit error rate (BER) performance is improved using the minimum cross-correlation function. To verify the proposed model, we present a simulation of the signal modulation and demodulation schemes using MATLAB software. The results are consistent with expected results, verifying the correctness of this method.