Guizhen Lu

The investigation for a circularly polarized radial line slot antenna with low side lobes and high gain

A single-layered circularly polarized radial line slot antenna (CP-RLSA) is designed, which is filled with a high foaming material and its relative permittivity is 1.06. Adjusting the angle and the length of the slots can obtain the high gain and low side lobes. The predicted results are consistent with the measurement results.

Dual-band two-element MIMO antenna for LTE and WLAN

A dual band and compact multi input multi output (MIMO) antenna for WLAN has been present in this letter. The proposed antenna operates over a wide frequency range of 1.93-2.79 GHz and 4.79-6.19 GHz suitable for long-term evolution (LTE) and wireless local area network (WLAN). The two elements antenna with a compact size of 39×40×1.5 mm3 which is designed on a FR4 substrate with a dielectric constant of 4.4. The simulated results show a bandwidth of 860MHz (low-frequency) and 1400 MHz (high-frequency). The maximum gain for each operation element is 2.11dBi. The proposed MIMO antenna can be used in wireless communication system.

A new analysis model of the radial line slot antenna

A radial line slot antenna (RLSA) is a high gain and high efficiency planar antenna. Owing to the fact that thousands of slots are on the surface of the antenna, the simulation data is very large and the time required is longer. Therefore, a sectorial cavity with a periodic boundary condition is used to simulate a sector region of the circular aperture in a CP-RLSA. This analysis provides the basic method for the advanced design of a RLSA.

An improved method of extracting permittivity combined SVM and waveguide theory

A new method of determining permittivity by SVM is studied in this paper. The mapping relationship between the S parameters and the permittivity is set up by calculating a large number of S parameters from the samples with different permittivity using waveguide theory. The simulated data set is used as training data set for SVM. After being trained, the SVM is used to predict the permittivity of material from the scattering coefficients. The validity of the method is also verified using FEM.

Combination of the Improved Diffraction Nonlocal Boundary Condition and Three-Dimensional Wide-Angle Parabolic Equation Decomposition Model for Predicting Radio Wave Propagation

Diffraction nonlocal boundary condition (BC) is one kind of the transparent boundary condition which is used in the finite-difference (FD) parabolic equation (PE). The greatest advantage of the diffraction nonlocal boundary condition is that it can absorb the wave completely by using one layer of grid. However, the speed of computation is low because of the time-consuming spatial convolution integrals. To solve this problem, we introduce the recursive convolution (RC) with vector fitting (VF) method to accelerate the computational speed. Through combining the diffraction nonlocal boundary with RC, we achieve the improved diffraction nonlocal BC. Then we propose a wide-angle three-dimensional parabolic equation (WA-3DPE) decomposition algorithm in which the improved diffraction nonlocal BC is applied and we utilize it to predict the wave propagation problems in the complex environment. Numeric computation and measurement results demonstrate the computational accuracy and speed of the WA-3DPE decomposition model with the improved diffraction nonlocal BC.

A reduced computational method about wave equation for radiowave propagation predications

A reduced computation method is proposed based on paraxial approximation of two-dimensional wave equation. This method is more easily to implement large scale numeric computation about radiowave propagation problems comparison with wave equation. The computational accuracy of this method is higher than parabolic equation (PE). In other words, the discrete size of numeric computation can be larger than PE if the requirement of the computational accuracy is as the same as PE. The correctness and accuracy of this method are proved by using it to compute some propagation examples.

Improved gap waveguide PMC packaging for zeroth-order resonator

This paper presents a new metamaterial-based waveguide technology referred to as packaging gap waveguide, which is used to improve the performance of zeroth-order resonator (ZOR). In this approach, a lid of spiral nails used for perfect magnetic conductor (PMC) together with the ground plane of the substrate created a gap to suppress the power leakage problem of ZOR. Compared with the previous pin surface, spiral nails would reduce the size of packaging. Full-wave simulations of different packaging were carried out.

Radiowave propagation loss measurement of different situated Knife-Edge problems and comparison with PO computing

In this article, an indoor radiowave propagation loss measurement environment which worked at 9.375 Ghz was built and a series of experiments about propagation loss of different situated Knife-Edge were implemented. The Knife-Edge position changes caused by horizontal length change and angle change were experimental studied respectively. The influence of Knife-Edge horizontal length and angle changes on propagation loss was presented. Finally, a comparison between experiment results and PO computing results was given.

Ultra-broadband metamaterial absorber using slotted metal loops with multi-layers and its ECM analysis

An ultra-thin and broadband absorber which consists of periodic rings with gaps is proposed in this paper. The periodic rings are printed on the middle metallic layers in a four-layer substrate of total thickness is only 3.4mm. Simulation results, which are gotten by using FEM, show that the absorption is higher than 90% cover the frequencies range from 8.4GHz to 23.6GHz. The measurement results of the absorption agree with simulated ones very well. We also give the Equivalent Circuit Model (ECM) of the absorber structure.

Design of low-frequency Artificial Magnetic Conductor with interleaved gap and lumped elements

AMC (Artificial Magnetic Conductors) is an important part in the research about artificial electromagnetic materials. Currently, the main two trends in AMC is miniaturization and low-frequency design, especially the latter, which can help applying AMC into wireless communication antennas. This paper discusses some kinds of low-frequency AMC structure, with interleaved gap and lumped elements as key factors, and the lowest working frequency of AMC achieved is 165MHz, which can offer ideas for relating work in future.