Propagation measurements for satellite radio reception insidebuildings

Swept CW signals (from 700 to 1800 MHz) were received inside six buildings of brick, corrugated sheet-metal, wood-frame, mobile-home, and reinforced concrete-wall construction. A transmitter antenna was mounted outdoors on top of an 18 m tower to simulate a satellite, and a linearly scanned directional receiver antenna was used to probe the spatial, spectral, and temporal variability of the signal indoors. Levels were found to have much structure in the spatial and frequency domain, but were relatively stable in time. Typically, people moving nearby produced variations of less than 0.5 dB, whereas a person blocking the transmission path produced fades of 6 to 10 dB. Severe losses (17.5 dB) were observed in the concrete-wall building, which also exhibited the longest multipath delays (>100 ns). Losses inside a mobile home were even larger (>20 dB) and were independent of antenna orientation. The power-frequency distortion increased with the logarithm of the bandwidth, but could be reduced by moving to a position of higher power. Only the losses showed a clear frequency dependence, but they could be mitigated by moving the antenna     

Modelling direct sequence pseudonoise(dspn) satellite reception with directional antennas in the dense scatterer mobile environment

A geometric propagation model is developed for simulating the reception of direct sequence pseudonoise (DSPN) satellite signals by a directional or omni antenna in the dense scatterer mobile environment. The model is first validated for narrowband signals by a direct comparison of both simulated cumulative signal strength statistics and simulated diffuse Doppler spectra with classical theory. The model is then used to predict fading statistics for DSPN signaling, either with omni or directional antennas. As expected, the mitigation of fading is closely related to the ratio of DSPN chip duration to delay spread of the scatterer medium for both the omni and directional antennas.     

Planar antennas on a dielectric surface

A theory has been developed for planar metal antennas on a dielectric surface and the main predictions have been verified experimentally. Current dipole antennas have radiation diagrams and impedances favourable for microwave to far-infra-red integrated circuits.     

2.6 GHz band satellite ISDB system for mobile reception

At the World Administrative Radio Conference (WARC)-92, the 2.6 GHz frequency band was allocated to a group of East Asian countries including Japan. This band is being studied for use in mobile multimedia broadcasting. This paper describes the outline of a system for 2.6 GHz band mobile multimedia broadcasting services, together with its requirements. In particular, the effects of the broadcasting signals attenuation due to shadowing by buildings and foliage, and the signals deterioration due to multipath propagation and fading, must be taken into account in order to realize the 2.6 GHz band system. This study considers the economic and technical constraints related to the modulation schemes, transmitting power, satellite antenna reflector aperture, the gain of the receiving antennas and the scale of the satellites. The configuration of satellite hardware systems based on the channel plan, channel bandwidth, and other specifications is investigated taking into account of these constraints. For example, a bit-rate of 4.8 Mbps can be provided when a 2-ton class satellite bus is utilized. This indicates that 2.6 GHz band services are technically feasible     

卫星移动通信中的电扫描阵列天线

90年代以来，卫星移动通信发展异常迅速。许多科研组织都对移动地面站中的电扫描阵列天线进行了研究。介绍了目前已经开发并应用于卫星移动通信的几种电扫描阵列天线及其技术细节。     

MIMO transmission and reception techniques using three-element ESPAR antennas

A novel scheme for spatially multiplexing two BPSK signals using a 3-element ESPAR (electronically steerable parasitic array radiator) antenna was reported in. In this paper we first optimize the set of loads controlling the parasitic elements within the transmission mode by maximizing the outage capacity. We also propose different reception techniques for spatially demultiplexing real and complex signals (using the same set of loads). The proposed transmission and reception schemes are evaluated in an indoor peer-to-peer mobile ad-hoc channel via simulations, where each ad-hoc node is equipped with a 3-element ESPAR terminal.     

数字卫星电视接收机的特点和接收方法

介绍了数字卫星电视接收机的特点和技术指标，分析了数字卫星电视接收机的接收方法。     

Planar retrodirective array reflector using dual-slot antennas

An X-band planar reflector with a broad responding beam was developed using the Van Atta retrodirective antenna array. The reflector contained four antenna sub-arrays, each with six dual-slot antennas appropriately fed and paired by microstrip lines on the backside of the substrate. Good agreement has been achieved between theoretical and measured results     

Advances in multibeam communications satellite antennas

The evolution of satellite antennas over the past quarter of a century is presented. Five major areas of advances in communications satellite antenna technology are reviewed: single offset reflectors with feed arrays, shaped reflector systems, active phased arrays, phased-array-fed dual reflector systems, and lightweight feed elements. Examples are given of existing systems and of the ongoing development of new technologies     

Cross-polarization in satellite and earth-station antennas

Cross-plarization in axially symmetric reflector antennas can be reduced, theoretically, to zero by use of special feeds like the Huygens' source. Alternatively, paraboloidal reflectors with large f/D ratio do not deteriorate further the cross polarization level relative to the value due to the feed itself. The Cassegrainian optics is equivalent to a large f/D paraboloid. The reflector of linearly polarized off set fed antennas contribute more cross-polarization than symmetrical reflectors fed by the same feed. With symmetrical reflectors the cross-polarized component generated by the reflector vanishes in the principal planes and is confined to four main lobes that have peak values in planes at 45° to the principal planes. In the case of offset fed reflectors cross-polarization vanishes in the plane of symmetry and has its peak in the plane of asymmetry. The reflector generated cross-polarization with offset fed antennas may be reduced by use of small offset angles and large f/D ratios. Feed offsetting has but little effect on the peak level of cross-polarization. This is usually accompanied with an asymmetry in the cross-polarization radiation pattern. Feed offsetting also results in spatial tilt in the copolarized and cross-polarized lobes with the cross-polar minimum always coinciding with the main beam peak. The effect of surface errors on the antenna cross-polarization is to partly fill the cross-polar along boresight. The peak cross-polarization, however, changes but slightly.     

一种可用于北斗卫星信号接收的微带天线设计

基于微带天线技术提出一种应用于北斗导航系统的新型天线设计。该天线采用FR-4衬底上的弯曲微带和含有通孔的微带贴片实现。天线的小型化设计可使其更好地应用于北斗导航之中。与此同时,与常规的天线相比,该天线拥有更好的反射系数。实验结果表明,这里设计的天线非常适用于北斗导航系统,进而可应用于车辆导航系统之中。     

Unfurlable satellite antennas: A review

A review of unfurlable satellite antennas is presented. Typical application requirements for future space missions are first outlined. Then, US and European mesh and inflatable antenna concepts are described. Precision deployables using rigid panels or petals are not included in the survey.RF modelling and performance analysis of gored or faceted mesh reflector antennas are then reviewed. Finally, both on ground and in orbitRF test techniques for large unfurlable antennas are discussed.     

Planar millimeter-wave antennas using SiNx-membranes onGaAs

Planar aperture coupled microstrip antennas for 77 GHz are demonstrated for the first time. As far as possible standard GaAs monolithic microwave/millimeter-wave integrated circuit (MMIC) technology is used to realize the antennas. The antenna patches are suspended on a thin dielectric SiN_x membrane on GaAs substrate. Therefore a novel plasma-enhanced chemical vapor deposition (PECVD) process step for the fabrication of the membranes is developed and described. The single antenna patches are coupled to a microstrip line through an aperture in the ground metallization. The method of moments in spectral domain is applied to design the patches. The feed network of a 3×1 antenna array for homogeneous excitation is simulated and optimized with a microwave design system (MDS). From reflection measurements the operation frequency of this triple patch antenna is determined to be 77.6 GHz. The farfield antenna characteristics are measured in an anechoic chamber, showing good agreement between simulated and measured results and a co- to cross-polarization isolation better than 30 dB     

Planar FET oscillators using periodic microstrip patch antennas

An integrated oscillator/antenna is presented that uses a single microstrip leaky-wave structure as both the resonant and the radiating element. This resonant antenna is connected to a GaAs metal-semiconductor field-effect transistor which acts as the negative resistance element in the oscillator circuit. This type of oscillator is similar in its operating principle to one reported using Gunn diodes and a periodically notched dielectric image guide. This circuit exhibits the high DC-RF conversion efficiency that is typical of field-effect transistor oscillators. The planar circuit is simple and inexpensive to construct, occupies a small volume, and can conform to different surface profiles. Such circuits are suitable for use in millimeter-wave systems as well as at microwave frequencies. A design procedure is given, and the performance of X-band prototype circuits is reported. Prototype circuits showed a 9 dB isotropic conversion gain and 40 MHz tuning range at 9.5 GHz     

遥感卫星数据接收中的最优任务分配

在多地面站-多卫星的遥感数据接收条件下,通过定义卫星数据接收的任务集合将任务分配表达为任务集合和地面站集合之间的最优分配,并在构造代价函数的基础上实现最优分配算法在遥感数据接收任务管理中的应用。     

Geometric model for DSPN satellite reception in the dense scatterermobile environment

A geometric propagation model is developed for simulating the reception of direct sequence pseudonoise (DSPN) satellite signals by a directional or omni directional antenna in the dense scatterer mobile environment. The model is used to predict fading statistics. As expected, the mitigation of fading is closely related to the ratio of DSPN chip duration to delay spread of the scatterer medium for both the omni and directional antennas. The results suggest a general, frequency domain interpretation for the value of DSPN in mitigating multipath fading     

A metal plate Fresnel lens for 4 GHz satellite TV reception

A metal plate Fresnel lens antenna with aperture dimensions12 ft times 12 ft, and fed by a pyramidal horn has been built for satellite TV reception at 4 GHz. When used with a commercial receiver equipped with a 120K LNA it produced good video pictures from the geostationary satellite Satcom F3. We believe this to be the first application of a Fresnel lens antenna for ground-based satellite TV reception.     

SJ／T11387-2008《直播卫星电视广播接收系统及设备通用规范》概要

本规范依据GD/JN 01-2007<先进卫星广播系统一一帧结构、信道编码与调制>并参考国家广播电影电视总局科技司2008年4月份发布的<中国广播电视直播卫星"村村通"系统技术体制白皮书>(2008)相关要求制定,适用于中国广播电视直播一期工程.     

数字卫星电视节目的快速接收法

随着数字压缩技术的发展 ,我国卫星广播电视已从过去的模拟传输方式进入目前的数字传输方式。中央台的各套节目及各省、市、自治区上行节目绝大多采用数字压缩 (ＭＰＥＧ - 2 )方式传送。对于模拟卫星接收 ,采用天线对空的“扫描法”就能简便地搜寻到所需的卫星节目。但对数字压缩的卫星节目信号 ,不仅要向接收机输入下行频率、极化角、符号率等一系列参数 ,且当数字接收机接收到信号后要对其数据包 (如同步码、分组识别码等 )的标志、状态等 ,进行检索、识别判断、运算处理等复杂工序之后才能输出视、音频信号 ,这个过程大约需要 10ｓ,具有…