Channel Sounding System for MM-Wave Bands and Characterization of Indoor Propagation at 28 GHz

The aim of this work is to present a vector network analyzer based channel sounding system capable of performing measurements in the range from 2 to 50 GHz. Further, this paper describes an indoor measurement campaign performed at 26–30 GHz. The sounding system is capable of receiving two channels and transmitting one. Using this feature a channel measurement has been performed using both a directional horn antenna and a virtual uniform circular array (UCA) at the same time. This allows for comparative studies of measured channels with two different antennas in a simultaneous way. The measurement has been conducted with 42 measurement positions distributed along a 10 m long path through an indoor laboratory environment. The transmitter was positioned such that measurements were conducted both in line-of-sight and non-line-of-sight scenarios. The measurements showed good agreement between the measurement data collected with the horn antenna and the data collected with the UCA. The propagation environment was found to be sparse both in delay and angular domain for the given scenario. Based on the performed measurement campaign together with validation measurements of the system stability, it is found that the system works as expected.     

Biconical horn antennas for near uniform coverage in indoor areasat mm-wave frequencies

A method is presented for designing and dimensioning biconical horn antennas in such way that the level of received power does not depend strongly on the separation distance between a centralized base station and a remote radio terminal within an indoor pico-cell. Results of cell-coverage measurements at 58 GHz are presented using these antennas within eight different indoor environments. The measurement results show that, using biconical horn antennas, an overall uniform coverage can be achieved for both line-of-sight and obstructed line-of-sight topologies     

Wideband Millimeter-Wave Channel Characterization in an Open Office at 26 GHz

Based on the newest frequency allocation for the fifth generation (5G) radio systems at 26 GHz millimeter wave band by the World Radio Communications Conference, this paper investigates the wideband channel properties by measurements carried out in the LOS and NLOS environments at 26 GHz with 1 GHz bandwidth in an open office at KeySight Beijing, China, which is a representative of an indoor hotspot scenario. In the time domain measurements, an omni-directional biconical horn is used at the transmitter, while at the receiver a 24.3 dBi horn is applied and rotated with 5° angular step in the whole azimuth plane, and from ?20° to 30° in the elevation plane with 10° angular step. In the work, two kinds of path-loss models are developed, namely directional and omni-directional models by using close-in and float intercept methods. The directional path-loss model is useful for adopting beamforming techniques. The large scale channel parameters such as the shadow fading, root mean square (RMS) delay spread, RMS angular spread in the azimuth and elevation planes, Ricean K-factor, number of clusters and their correlations are investigated for the fifth generation (5G) link and system level simulations. A new method for extracting number of clusters is proposed to find the peak power within a sliding window. The power angular profiles are employed at the measurement locations for propagation mechanisms studies. We believe that the newest results in this work are useful in the simulations and planning for future 5G radio systems at 26 GHz.     

Human body shadowing variability in short-range indoor radio links at 3–11 GHz band

Measurement results for human body shadowing and local environmental effects in short-range indoor radio channels are presented. A narrowband measurement system, comprising a signal generator, two identical triangular monopoles and a spectrum analyser, was used in the measurements. When the radio link was periodically blocked by a human body with various objects in and around the link, fading depths of up to 15 dB and even more were observed at spot frequencies of 3–11 GHz band. Standard deviation and its range for human body blockage are estimated for different radio link scenarios simulating real environments. The distribution of human body shadowing was analysed and compared with known distribution functions.     

Design of multiple-edge blinders for large horn reflector antennas

Attaching blinders to the sides of pyramidal horn reflector antennas and other large aperture antennas is one method of controlling high sidelobes for horizontal polarization. This paper describes analysis and design procedures for arriving at a useful multiple-edge blinder for reducing undesirable sidelobes of a pyramidal horn reflector antenna. Several blinders have been designed and tested for use with a pyramidal horn reflector antenna. They are directed at reducing a high sidelobe near90degin the azimuth plane where levels (referred to the main lobe) of -52 dB at 3.74 GHz and -58 dB at 6.325 GHz are presently typical. A 14-edge blinder designed using these techniques reduced these levels by 20 dB at 3.74 GHz and 12 dB at 6.325 GHz and did not significantly degrade antenna performance for other angles and other polarizations.     

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.     

宽带毫米波全向天线研究

介绍了一种宽带毫米波不对称双锥喇叭全向天线。采用脊波导－同轴线过渡结构馈电网络，既解决了毫米波段双锥喇叭的电问题，又满足了天线输入端口必须为波导形式的实际工程要求。测试结果表明在２６－４０ＧＨｚ频带内，天线的全方向性和输入皮比均满足设计要求。     

New method for measuring properties of nonhomogeneous materials bya two-polarization forward-scattering measurement

A novel method for measuring properties of grainy materials using a two-polarization scattering measurement combined with free-space phase measurement is introduced. The theoretical background of the measurement method is presented. Laboratory measurements of the depolarized scattering cross sections of white rice, green lentils, polystyrene beads, polyethylene beads, and their mixtures at 10 and 35 GHz using a vector network analyzer and two horn antennas are then presented. Results are compared with those based on the first-order multiple scattering theory. A low-cost set-up for industrial measurements is suggested     

Measurements of Earth-Space Attenuation at 230 GHz

Measurements of attenuation at 230 GHz through the total atmosphere due to the presence of oxygen and water vapor molecules, clouds, and rain are presented and discussed. The measurements were carried out using a specially designed superhetrodyne receiver mounted on a sun tracker. Simultaneons measurements were also carried out at 13 GHz. For a measuring site close to sea level at Holmdel, NJ, the "clear-sky" zenith attenuation was found to be given by A (dB) = 0.35 rho, where rho was the measured ground water vapor density in g/m/sup 3/. When the ground temperature was below about 7/spl deg/C, most cloud and overcast gave < 0.5 -dB attenuation whereas with a ground temperature greater than 13/spl deg/C, cloud attenuation was 8-10 times greater. Calculations of zenith attenuation in the 230-GHz atmospheric window were also made using the Gross analytic line shape, Schulze-Tolbert empirical line shape, and an empirically modified Gross line shape. These calculations were based on determinations of water vapor density and temperature made at the measurement site, and on radiosonde measurements made at a distance of 80 km away. Measured and calculated results are graphically compared. It is concluded that either the modified Gross line shape or the Schulze-Tolbert line shape gives conservative estimates of zenith attenuation at 230 GHz for clear days, while the Gross line shape gives fair agreement with measured results.     

Measurements of 1.8--2.7-Ghz Microwave Attenuation in the Human Torso

For the purpose of diagnostic application of microwaves, establishment of techniques to measure the signal transmission through the human torso is attempted. Leakage effects are the most troublesome measuring problem above 1 GHz because of high attenuation within the body. Swept-frequency measurement and close coupling between the flanged aperture antenna and the body assure that the results are free from leakage effects. Experimentally obtained attenuation constants of the abdomen and left thorax are almost the same as those of muscle tissues. In the thorax record, changes of attenuation caused by heartbeats or respirations are observed.     

Hybrid image/ray-shooting UHF radio propagation predictor forpopulated indoor environments

A novel model for indoor wireless communication, based on a dual image and ray-shooting approach, is presented. The model, capable of improved site-specific indoor propagation prediction, considers multiple human bodies moving within the environment. In a modern office at 2.45 GHz, the combined effect of pedestrian traffic and a moving receiver causes rapid temporal fading of up to 30 dB     

60 GHz Single-Chip Front-End MMICs and Systems for Multi-Gb/s Wireless Communication

Single-chip 60 GHz transmitter (TX) and receiver (RX) MMICs have been designed and characterized in a 0.15mum (f_T~ 120 GHz/f _MAX> 200 GHz) GaAs mHEMT MMIC process. This paper describes the second generation of single-chip TX and RX MMICs together with work on packaging (e.g., flip-chip) and system measurements. Compared to the first generation of the designs in a commercial pHEMT technology, the MMICs presented in this paper show the same high level of integration but occupy smaller chip area and have higher gain and output power at only half the DC power consumption. The system operates with a LO signal in the range of 7-8 GHz. This LO signal is multiplied in an integrated multiply-by-eight (X8) LO multiplier chain, resulting in an IF center frequency of 2.5 GHz. Packaging and interconnects are discussed and as an alternative to wire bonding, flip-chip assembly tests are presented and discussed. System measurements are also described where bit error rate (BER) and eye diagrams are measured when the presented TX and RX MMICs transmits and receives a modulated signal. A data rate of 1.5 Gb/s with simple ASK modulation was achieved, restricted by the measurement setup rather than the TX and RX MMICs. These tests indicate that the presented MMICs are especially well suited for transmission and reception of wireless signals at data rates of several Gb/s     

Design and Characterization of Wideband Aperture-Coupled Circularly Polarized Antenna for Gigabits Per Second Wireless Communication System

In this paper, design and characterization of an aperture-coupled circularly polarized (CP) rectangular patch antenna suitable for Gigabit per second wireless communications system is presented. The proposed antenna exhibits a large bandwidth of 2.77 GHz at centre frequency \({\text{f}}_{\text{c}}\) = 19.5 GHz (about 15% of fractional bandwidth (FBW)). It also has a gain of about 7.25 dBi at 18 GHz with good stable gain and radiation characteristics in the frequency band of interest. For indoor wireless channel measurements, two developed prototypes are employed as single input single output transmit receive (TX–RX) antennas with a robust and versatile channel modeling system. We demonstrate a measurement campaign to investigate the dynamic range of the system by calculating path loss. The pulse dispersion effect is quantified by pulse fidelity factor (PFF). The measurements are performed in laboratory environment using Gaussian pulse based sounding signal modulated at 19.3 GHz carrier frequency. The design and characterization of compact size antennas with pertinent bandwidth and excellent radiation characteristics is one of our initiatives towards developing a millimeter wave (MMW) test bed system for channel modeling and measurement, since 5G wireless communication is supposed to operate in MMW band.

     

Walled LTSA Array for Rapid, High Spatial Resolution, and Phase-Sensitive Imaging to Visualize Plastic Landmines

We propose a walled linearly tapered slot antenna (LTSA) array to visualize plastic landmines. Previously, we reported an adaptive nonlinear visualization system based on a complex-valued self-organizing map (CSOM) that deals with complex amplitude texture in reflection images at multiple frequencies. The system distinguishes landmines from clutter by paying attention to textural features obtained by high spatial resolution and wideband reflection measurement. Because the system employed a mechanical scan of a pair of horn antennas, the measurement required a long time. An array antenna can reduce the time. The antenna element to be used there should therefore be compact and wideband. This paper reports the design and fabrication of a walled LTSA array visualization system. The antenna element has a 14 times 28 mm aperture size, and works at the 8-12 GHz frequency band. Because the structure is a simple combination of glass epoxy substrates and metal plates, we can easily fabricate low-cost and lightweight arrays. Electrical switches realize a high-speed scanning of 12 times 12 = 144 elements in total. We also report the results of a visualization experiment, in which plastic landmines are clearly visualized with the array in combination with the adaptive CSOM processing. Detection of landmines at frequencies of 10 GHz is only likely to be possible for targets buried a few centimeter deep or where the soil attenuation is very low. This might be a severe limitation of applicability of the method, as in field conditions soil attenuations of 10 dB or considerably more are commonly encountered, requiring the radar to operate at frequencies below 2-3 GHz. The best solution may be a multisensor system comprising these complementary high- and low-frequency radars.     

26 GHz室内簇的时变特性及建模研究

基于室内大规模单输入单输出（Single-Input Multiple-Output,SIMO）测试,开展了26 GHz毫米波无线信道簇变化量的时变特性建模研究.首先针对构建2020年信息社会的无线通信关键技术（Mobile and Wireless Communications Enablers for the Twenty-twenty Information Society,METIS）标准中分簇算法的不足进行改进,然后通过对功率时延谱求包络,来去除簇内射线及噪声对分簇结果的影响,在此基础上进行分簇会得到更加合理的结果.办公室环境下大规模虚拟天线阵列测试数据的分析结果表明,簇数目的变化量服从正态分布,经过不同时间簇数目变化量的均值和方差与二次函数较吻合.因此,将办公室场景下簇数目的变化量建模成均值和方差为二次函数的正态分布是合适的.     

Electric Probe Measurements on Dielectric Image Lines in the Frequency Range of 26-90 GHz

Electric-field probes, using miniature semirigid coaxial cable in connection with standard metal waveguide detectors, are described and shown to be well-suited for direct standing wave measurements on dielectric image lines. Experiments in the frequency range of 26-90 GHz for the detemination of phase and attenuation constants of image lines as well as experiments for the determination of very small reflections from matched dielectric image-line terminations and the scattering coefficients of dielectric image-line discontinuities are described.     

面向6G的毫米波多频段多天线信道测量系统构建及实测验证

毫米波是5G和6G无线通信系统的关键技术.设计满足6G多频段、多天线、高动态范围需求的信道测量系统是6G无线信道研究面临的首要挑战.针对这一需求,本文构建了一种毫米波多频段多天线信道测量系统,可以覆盖24.25～28.5 GHz、31.8～33.4 GHz、37～42.5 GHz等毫米波频段,支持最高16×16天线配置.首先介绍该信道测量系统的架构与性能指标,提出多通道并行校准方案以及测量数据处理算法;其次,基于该信道测量系统开展26 GHz室内外场景的信道测量实验,分析路径损耗、时延扩展以及奇异值扩展等信道统计特性.通过对实测结果分析,验证了该信道探测器用于毫米波段测量的有效性.     

A simple design substrate-integrated waveguide horn antenna with reduced back lobe

ABSTRACT

A simple technique to design stable gain and low back lobe substrate-integrated waveguide (SIW) horn antenna is proposed. Matching is achieved by placing a metallised via in a specific distance from the aperture of the horn. The proposed design method is based on the analytical equivalent circuit that derived for the impedance of the antenna aperture and the matching metallic via in SIW. The aperture impedance and metallic via in SIW are studied and design curves are extracted for a specified substrate. Also, to reach a directive pattern and reduce the back lobe of the antenna, some chokes are used on the aperture of the horn. The effect of chokes on some parameters such as power flow and radiation pattern, the front to back ratio (FBR), side lobe level (SLL) and increasing directivity of the antenna is reported. The measurement results confirm simulation, appropriately. The proposed structure has high compactness due to the matching technique and design. The proposed SIW horn has compact dimensions as 18.7 * 23.34*7.62 mm (0.93 * 1.16 * 0.37 λ₀) and the measured gain of the horn is about 5.5 dB at 15 GHz and bandwidth of six percent.     

A rectangular horn of four corrugated plates

We describe a rectangular horn with radiation characteristics similar to those commonly obtained with corrugated horns of circular aperture. The horn described here consists of four identical plates, whose grooves can be obtained (straightforwardly and accurately) by numerical machining. Measurements from 8.7 to 12.2 GHz show that the horn aperture illumination is given to a good approximation by the distribution cos (alpha x) cos (gamma y) in agreement with a previous asymptotic theory. An advantage of this horn over a circular horn is that different beamwidths are obtainable in the two principal planes.     

On the scattering mechanism of power lines at millimeter-waves

The radar signature of power lines is of high importance in the design of systems for helicopter collision avoidance. Laboratory measurements have been reported previously, but field measurements at millimeter waves are missing. The present contribution describes measurements done in ground-based configuration with a real aperture scanning-beam radar operating simultaneously at 35 and 94 GHz. By scanning, an aspect angle interval of 60/spl deg/ was covered, including the broadside aspect. The narrow beam width allowed to discriminate between different wires separated horizontally. While these measurements were done under a very shallow incidence angle, assisting measurements were done with the same radar mounted into an aircraft using synthetic aperture radar techniques. The results for shallow and steep incidence are compared and show the significant influence of this parameter on the signature of the power line. Additionally the measurement results are compared with those from model calculations.