Simple and Accurate Analytical Model of Planar Grids and High-Impedance Surfaces Comprising Metal Strips or Patches

Simple analytical formulas are introduced for the grid impedance of electrically dense arrays of square patches and for the surface impedance of high-impedance surfaces based on the dense arrays of metal strips or square patches over ground planes. Emphasis is on the oblique-incidence excitation. The approach is based on the known analytical models for strip grids combined with the approximate Babinet principle for planar grids located at a dielectric interface. Analytical expressions for the surface impedance and reflection coefficient resulting from our analysis are thoroughly verified by full-wave simulations and compared with available data in open literature for particular cases. The results can be used in the design of various antennas and microwave or millimeter wave devices which use artificial impedance surfaces and artificial magnetic conductors (reflect-array antennas, tunable phase shifters, etc.), as well as for the derivation of accurate higher-order impedance boundary conditions for artificial (high-) impedance surfaces. As an example, the propagation properties of surface waves along the high-impedance surfaces are studied.     

Mechanism of Thermally Biological Effects of the Millimeter Waves and Its Properties

We think that the thermally biological effects of millimeter waves are caused by the thermal motions of water molecules in the living systems, according to experimental fact that the millimeter waves can heat water, and the skin effect on the surface of the biological tissues arising from the millimeter waves. For clarifying this idea we studied the states and features of the liquid water and calculated the rotational energy-spectra of water molecules in the living systems by quantum mechanics. In fact, there is a large number of water which are polarized and have certain dipole moments in the living systems. This shows that the millimeter waves can interact with the water molecules. Through calculation of quantum rotational energy-spectra of the water molecules, we can confirm that the water molecules can absorb the millimeter waves with certain wavelength to generate the rotations of water molecules according to the principle of resonant absorption. One mechanism of the thermally biological effect of the millimeter waves is just a result produced by disorderly thermal-motions of the water molecules which are transformed from their rotation energy caused by the millimeter waves. Owing to the fact that water has a lot of biological functions and plays an important role in the living activity. Thus the heating waters by the millimeter waves can cause a lot of biological effects and phenomena in the living systems. Another mechanism of the thermally biological effect of the millimeter waves is caused by the Joule-Lenz heat arising from the skin effect of the millimeter waves in the skin layers of human beings and animals and membranes of cells which can facilitate the blood circulation in them. We finally study this effect. PACSnumbers: 87.50.Hj; 05.70.Ce; 87.15.He; 65.50.tm.     

Theoretical Analysis of the Biological Thermal Effect of Millimeter Waves in Layered-Dielectric-Slabs

The theory is presented for one method of determining the biological thermal effect of millimeter waves in microwave radiometry. It has been studied theoretically that millimeter waves propagation and absorption in a human body. The model is a plane straticulate homogeneous slab of tissues under the irradiance of normal incidence plane wave. It has been discussed by obtaining the electromagnetic field, absorbent power, specific absorption rate, temperature field and their distributions in the human trunk model. Also, the principle of thermal therapeutics of millimeter waves to cancer has been discussed preliminarily.     

具有高模场限制的异质纳米棒结构波导(英文)

现代光学及纳米光学的一个主要发展趋势是从理论和实验两方面探究用于突破传统衍射极限的亚波长级别的电磁波波导结构。表面等离子激源提供了解决此问题的有效突破口。文中根据异质波导结构的耦合以及锲型波导的表面等离子激发理论,提出了异质纳米棒结构波导,该结构具有非常高的模场限制能力,对其传输的模式理论上可实现亚波长级别的限制能力。文中主要对此结构进行了数值仿真,分析了该波导结构的能量以及传输损耗,其结果表明该结构的模场限制能力可达到衍射极限的1/500,而且通过调整结构参数,将模场的传输距离延长到毫米级别。     

Millimeter waves for short-range multimedia communication systems

A framework for the performance characterization of short-range communications systems is developed with the intention of investigating the feasibility of new multimedia wireless services at millimeter waves (MMWs). Both narrow- and wide-band systems are considered for mobile and/or fixed users. This paper aims at defining and evaluating proper metrics to characterize the service quality for the user and jointly takes the propagation characteristics, the transmission techniques, and the multiple access protocols into account. The definition of service-oriented metrics is emphasized. Three different real scenarios operating at MMW are investigated with a unified perspective: intelligent transport systems, wide-band local-area networks, and local multipoint distribution systems for interactive video services. The role played by the MMW band in the development of these services is discussed. In each scenario, accurate propagation analysis is carried out and suitable countermeasure techniques are pointed out in order to join suitable service-quality levels. The methodology considered is based on both analytical and semianalytical tools for performance evaluation     

Frequency Selective Properties of Two-Dimensional Dielectric Gratings: TE- and TM-Polarizations

This work analyzes the propagation characteristics of electromagnetic waves and the frequency selectivity of dielectric gratings with periodicity in two dimensions, having in mind their application as dichroic surfaces in the millimeter wave band. The moment method and the Green's functions, along with the volume equivalence theorem are used. Particular cases were analyzed to compare with results available in the specialized literature and agreement was observed. This work gives evidence that the inclusion of the periodicity along a second dimension allows an additional adjusting parameter of the frequency selective characteristics for the design requirements of dielectric gratings.     

The Effects Induced by Turbulence and Dust Storms on Millimeter Waves

Dust storms and turbulence consist of a random medium system, its effects on milimeter waves propagation are studied. Attenuation of millimeter waves, its phase shift and cross- polar discrimination are presented. Results show that dust storms mainly effects XPD and phase shift of millimeter waves, turbulence chiefly produces attenuation, in mediocre fluctuation.     

On Plane and Quasi-Optical Wave Propagation in Gyromagnetic Media

To promote the development and understanding of microwave magnetic devices, especially in the millimeter and submillimeter range utilizing quasi-optical techniques, a discussion of propagation and polarization of plane waves and narrow rays in gyromagnetic media in an arbitrary direction is considered. It is assumed that the medium can be described by a permeability tensor of the Polder type. The approach is structured after classical crystal optics but yields significantly different results since each of the two permitted rays is elliptically polarized. The ellipticities are derived. The phase surfaces are discussed for the lossless case. There are no optical axes but ranges of forbidden directions exist for one or both rays. D, B, and the wave vector n form an orthogonal set at all times. H is confined to the B, n plane; it gyrates along an ellipse such that the Poynting vector traces in time an elliptical cone which contains the wave vector as one mantle line. Therefore, a narrow ray can be understood to proceed along a helical path.     

Numerical diffraction coefficients for surface waves

The numerical uniform theory of diffraction (UTD) is extended to include surface waves. A method for extracting surface wave diffraction coefficients from moment method data is given and Prony's method is applied to the problem of determining surface wave propagation constants. The method is validated through comparison with the exact solution of the problem of surface wave diffraction by a truncated dielectric slab recessed in a conducting surface. Examples are given for scattering from dielectric slabs and frequency-selective surfaces and for radiation from a conformal microstrip antenna with a truncated substrate. The accuracy obtained is demonstrated by comparison with moment method calculations     

Millimeter-Wave Propagation Channel Characterization for Short-Range Wireless Communications

This paper presents and analyzes the results of millimeter-wave 60-GHz frequency range propagation channel measurements that are performed in various indoor environments for continuous-route and direction-of-arrival (DOA) measurement campaigns. The statistical parameters of the propagation channel, such as the number of paths, the RMS delay spread, the path loss, and the shadowing, are inspected. Moreover, the interdependencies of different characteristics of the multipath channel are also investigated. A linear relationship between the number of paths and the delay spread is found, negative cross correlation between the shadow fading and the delay spread can be established, and an upper bound exponential model of the delay spread and the path loss is developed to estimate the worst case of the RMS delay spread at given path loss. Based on the DOA measurements that are carried out in a room [line of sight (LOS)] and in a corridor with both LOS and nonline-of-sight (NLOS) scenarios, radio-wave propagation mechanisms are studied. It is found that considering the direct wave and the first-order reflected waves from smooth surfaces is sufficient in the LOS cases. Transmission loss is very high; however, diffraction is found to be a significant propagation mechanism in NLOS propagation environments. The results can be used for the design of 60-GHz radio systems in short-range wireless applications.     

Mechanism and Properties of Non-Thermally Biological Effect of the Millimeter Waves

The electromagnetic features of biomacromolecules are foundation of interaction between the millimeter waves and living systems. Therefore we first reveal the electromagnetic features of biomacromolecules, for example, protein, DNA and lipid. Next we calculate the rotational energy-spectra of these biomacromolecules by quantum mechanical theory. The transitions of electrons between the rotational energy-levels can result in radiations or absorptions of millimeter waves. Thus we propose the mechanism and properties of non-thermally biological effect of the millimeter waves, i.e., the millimeter waves are absorbed by these biomacromolecules which can result in rotation and changes of conformations of these molecules, thus the energy of the millimeter waves are to be transformed as the mechanical energy of the conformation changes of the biomacromolecules, but not as thermal energy of motions of these biomacromolecules to increase their temperature. This mechanism is verified by experiments of conformation changes of the protein and amino acid molecules exposed under the millimeter waves. These rotations of conformations of these molecules can results in obvious biological effects. We study the features of the biological effects. PACS numbers: 33.20.-Eat, 33.10.-n, 78.30.-j; 87.50. Hi     

Comparative study of millimeter wave propagation at 30 GHz and 60 GHz in indoor environment

The millimeter wave band appears to be a favourable choice for personal wireless communication systems for indoor environment, as it meets the requirements for sufficient bandwidth, small terminal dimensions and sporadic usage for commercial applications. In this paper measurements of millimeter wave propagation in both 30 GHz and 60 GHz bands, are presented in a comparative way. The topology of measurements covers both a line-of-sight situation and also a case where a direct path between transmitter and receiver does not exist. Although the second case does not seem obvious for outdoor applications in these frequencies, in indoor environment the multipath signals produced by objects like walls, doors, furniture etc., can be utilised in order to overcome the man-made shadowing. Both slow and fast fading characteristics of the received signal are studied and the measurements are modelled by the conventional Rician and Rayleigh distributions. Both frequency bands offer advantages for usage in in-house wireless communication systems. Although in 30 GHz band the coverage area is bigger than in 60 GHz (with the same transmitting power), frequency reuse is easier in 60 GHz band. because even if millimeter waves ‘escape’ through ‘windows’, the specific attenuation due to atmospheric oxygen (15 dB/km) at 60 GHz eliminates the interference between communication channels in neighbouring buildings.     

Millimeter wave beams diffracted from reflecting gratings

According to the angular-spectrum method, a radiation beam of an antenna horn in the Fresnal region is decomposed into the plane waves with the fast Fourier transform algorithm and the waves diffracted from a reflection grating are superposed as a diffracted beam. Compared with the reflected beam from the same size mirror, the radiation half width of the diffracted beam from a grating is narrower and its lateral shape is shift. These performances have been experimentally verified at Ka-band by: (1). The relative diffraction efficiencies in the first order with two triangular gratings which is put along propagating direction of a beam produced by a conical lens-horn. (2). H-plane lateral width with power—3dB lapsed of the focus beam from a grating and a mirror in a grating spectrometer for millimeter waves (25–100 GHz).     

Spatial and Temporal CM Equalization for Broadband Wireless Indoor Networks at Millimeter Waves

Based on a new multipath channel model, a spatial-temporal combined CM equalization approach is derived at millimeter waves. Computer simulations are presented to testify the theoretical analysis. It is shown that this method can compensate the signal degradation caused by indoor multipath propagation. The convergence behavior of the spatial-temporal CMA is also analyzed.     

Propagation of centimeter and millimeter spin-dipolar waves in nonuniform magnetic fields

Propagation of exchangeless spin-dipolar waves (SDW) of centimeter (f ～ 3-20 GHz) and millimeter (f ～ 30–60 GHz) wavelength ranges in ferrite films into nonuniform magnetic fields was researched analytically and numerically. Applied magnetic field is directed along film plane and it is slightly nonuniform in this plane. Proposed SDW propagation in magnetic fields was researched with complex geometric optics. We have shown a possibility of SDW type transformation from superficial SDW into backward volume SDW along propagation trajectory in both centimeter and millimeter wavelength range. An influence of electromagnetic delay on SDW propagation in nonuniform magnetic fields is essential in millimeter wavelength range and it can modify wave trajectories.     

The Ratio of Antenna Heights as a Parameter to Characterize Path Loss: A Millimeter Wave Desktop Propagation Study

This paper contains measured data for desktop propagation path loss at millimeter wave band. Different ratios between transmitting antenna height and receiving antenna height were studied based on a vector network analyzer system. Transmitting and receiving antenna were separated by distances ranging from 5 to 300 cm on a wooden desktop, and the antenna heights were varied from 5 to 25 cm. Average path loss data are coupled with the path loss exponents and the breakpoint locations of piecewise model to provide insight into large scale propagation characteristics of desktop millimeter wave communication systems. These measurement results may aid in the development of future short range wireless propagation in millimeter wave bands.     

基于矢量近似消息传递的智能反射面辅助毫米波信道估计

毫米波属于一种典型的视距传输方式，其受大气吸收影响严重。针对毫米波的非视距传播受限，该文通过智能反射面(IRS)辅助毫米波通信，提出结合Khatri-Rao积的矢量近似消息传递(KR-VAMP)算法来提高毫米波通信系统的信道估计质量。该算法基于Khatri-Rao积将级联信道问题转换为稀疏信号恢复问题，并结合VAMP的矢量和迭代阈值算法的优势，使得整个IRS辅助毫米波系统在减少训练迭代次数的同时，降低了整个系统的信道估计误差。最后通过仿真结果对比，分析了各变量对信道估计的均方误差(MMSE)的影响，以及MMSE随着迭代次数的收敛情况，验证了此算法对比其他近似消息传递(AMP)算法具有更好的性能。     

3D Modeling and Analysis of the Space–Time Correlation for 5G Millimeter Wave MIMO Channels

Wireless Personal Communications - The deployment of millimeter waves (mmW) in 5G mobile networks is considered as a challenging issue due to the lack of knowledge regarding the propagation of mmW...