ESPAR array design for the UHF RFID wireless sensor communication system

In this paper, in order to improve the received signal strength (RSS) and signal quality, three arrays of electronically steerable parasitic array radiator (ESPAR) antennas are suggested for the ultra-high frequency (UHF) radio frequency identification (RFID) communication and sensing system applications. Instead of the single antenna, the array antennas have recently been widely used in many communication systems because of their peak gains, better radiation patterns, and higher radiation efficiency. Also, there are some important issues to use the antenna array like high data rates in wireless communication systems and to better understand the many targets or sensors. In this article, a wireless sensor network (WSN) is being investigated to overcome multipath fading and interference by antenna nulling technology that can be achieved through beam control ESPAR array antennas. The proposed ESPAR array antennas exhibit higher gains like 9.63, 10.2, and 12 dBi and proper radiation patterns from one array to another. Moreover, we investigate the mutual coupling effect on the performance of array antennas with different spacing (0.5λ, 0.75λ, λ) and configurations. It is found that the worst mutual coupling reduced by −28 to −34 dB for 2 × 2 array, −3 to −43 dB for 2 × 3 array, and finally −42 dB to −51 dB due to the antenna spacing from 0.5λ to λ. Thus, these suggested antennas could effectively be applied in the WSN communication systems, internet of things (IoT) networks, and massive wireless and backscatter communication systems.     

基于空间分集的TH-UWB系统性能分析

为了提高UWB系统在低信噪比下的性能,利用IEEE 802.15.3a工作组建议的标准UWB室内信道模型,采用多个接收天线分析了二进制TH-PPM超宽带系统性能的改善。在理想功率控制下,分别采用不同数目的接收天线和不同SRake接收机选择路径数,对2PPM-TH-UWB系统性能进行了分析和仿真。仿真结果表明,随着天线数和选择路径数的增加,系统性能均明显提高,并且空间分集比路径分集对系统性能有更好的改善。     

音频信号的数字处理及其应用设计

提出了2.4G无线影音传输系统中的数字音频传输方案,介绍了AES/EBU数字音频接口标准,并详细阐述了系统的关键技术,包括差错掩盖技术和天线切换技术。采用差错掩盖技术,可以消除“噼啪”声;而运用天线切换技术,提高了音频信号接收质量,有效地抑制干扰,提升了系统的性能。     

Novel slot spiral antenna designs for dual-band/multiband operation

New applications for wireless communications are typically accompanied by a need for antennas that integrate several frequencies and functionalities under a single aperture. Different requirements for pattern, gain, and polarization at each operating frequency further complicate the design of such antennas. Novel slot spiral antenna designs for dual-band/multiband operation are introduced. Typically excited to operate in the first mode, the proposed two-arm slot spiral is redesigned to operate efficiently in the second mode and in a hybrid first/second mode for better functionality. Several key features are introduced to achieve requirements for impedance matching, pattern, and gain suitable for a specific automotive dual-band DAB/SDARS (digital audio broadcasting/satellite digital audio radio services) antenna system. Among these features are new feeding systems, a suitable mix of spiral growth rates, and a low-loss spiral arm termination. The design is accomplished using full-wave finite-element boundary integral simulations and is verified with measurements.     

ASTRA Digital Radio: high‐quality digital audio transmissions via satellite

ASTRA Digital Radio (ADR) is a satellite audio transmission technology which has been designed to be compatible with analogue radio and television transmissions via satellite. It uses QPSK modulated subcarriers above the video spectrum. For source coding, the internationally standardized MPEG 1 Layer II digital audio compression has been selected. Owing to its backward compatibility with the existing analogue audio transmission technology, ADR provides a maximum operational flexibility for both the broadcasters and the satellite operator. For the consumer this technology allows for a very high number of near CD quality radio programmes which may be received with a low‐cost receiver connected to a standard 60 cm satellite reception antenna. ADR was officially launched in August 1995 during the Internationale Funkausstellung in Berlin and currently allows for the reception of over 85 radio programmes in digital quality. Copyright © 2000 John Wiley & Sons, Ltd.     

(3.1–20) GHz MIMO antennas

In this paper, a super-wideband (SWB) printed monopole antenna has been designed and manufactured. The measured frequency band in terms of reflection coefficient is from 3.1 to 20 GHz under a −10 dB criteria, thanks to the inclusion of a taper impedance adapter. This single antenna has been used to implement and analyze several MIMO antenna configurations, where the isolation between the compounding elements has been checked and optimized to improve the Envelope Correlation Coefficient. Two elements MIMO configurations (parallel ports or orthogonal diversity), as well as four element MIMO antennas with parallel ports are presented. Non continuous ground planes of the MIMO antenna elements with the inclusion of L shaped thin strips are proposed as valid structures to significantly improve the side by side mutual coupling from an initial peak value of 15 dB to better than 24 dB within the entire frequency band. In all the presented MIMO antenna structures, the measured values demonstrate good performance up to 20 GHz, both in reflection and isolation. Nevertheless, the influence of the mutual coupling effects has been checked as more significant in the lower part of the frequency band, especially in the 4 element MIMO configuration. The inclusion of the L shaped strips in the ground plane significantly mitigates this effect. Although the antennas have only been measured up to 20 GHz (upper frequency limit of the laboratory Vector Network Analyzer), simulations show satisfactory antennas’ performance up to 50 GHz.     

Switched diversity with feedback for DPSK mobile radio systems

Switched diversity with feedback for differential phase shift keying (DPSK) mobile radio is discussed. The technique uses multiple transmit antennas at the base station but only one receive antenna at the mobile. The base station transmits with one antenna that is switched when the mobile informs the base station that the received signal has fallen below a fixed level. The implementation of switched diversity with feedback in a digital mobile radio system is first described, and then the bit error rate performance of the system is analyzed with fading as a function of several design parameters. Implementation of the system is shown to be relatively simple, yet the system is shown to reduce substantially the required received Eb/N0for a given error rate at the mobile as compared to a system without diversity. For example, with five transmit antennas the required received Eb/N0for a 10^-3bit error rate is 13 dB less. The system capacity and availability assuming 32 kb/s audio and flat fading is then discussed. It is shown that with three-corner base station diversity and four transmit antennas at each base station, 126 two-way circuits per cell can be used in a fully loaded 40-MHz bandwidth system with a ten-percent probability that the error rate exceeds 10^-3.     

System Performance of Transmit Diversity Methods and a Two Fixed-Beam System in WCDMA

Downlink transmit diversity modes for WCDMA together with a two fixed-beam antenna array system are compared relative to the single antenna sectorized system in a radio network simulator. The transmit diversity methods investigated are: space-time transmit diversity and closed-loop mode I transmit diversity. Frequency selective (COST 259) and flat fading channels are considered and their impact to speech-only and data-only services is evaluated. A third service, which highlights the system performance of the various advanced antennas, is also investigated.The results in this investigation point out that the diversity gain in flat fading channels is substantial. In frequency-selective fading, the benefits of fixed beam systems is encouraging, whereas transmit diversity methods (especially Space-Time Transmit Diversity) is unsatisfactory.     

Reduced-Complexity Receiver Structures for Space–Time Bit-Interleaved Coded Modulation Systems

Transmission efficiency in radio channels can be considerably improved by using multiple transmit and receive antennas and employing a family of schemes called space-time (ST) coding. Both extended range and/or improved bandwidth efficiency can be achieved, compared with a radio link with a single transmit and receive antenna. Bit-interleaved coded modulation schemes give diversity gains on fading channels with higher order modulation constellations combined with conventional binary convolutional codes also for the case of a single transmit and receive antenna radio link. In this paper, we study a family of flexible bandwidth-efficient ST coding schemes which combine these two ideas in a narrowband flat-fading channel and single-carrier modems. We address receiver complexity for the case of a large number of transmit antennas and higher order modulation constellations. Especially, we focus on practical configurations, where the number of transmit antennas is greater than that of receive antennas. Simplified receivers using tentative decisions are proposed and evaluated by means of simulations. Tradeoffs between complexity reduction and performance loss are presented. We emphasize systems that are of particular interest in applications where the number of transmit antennas exceeds the number of receive antennas. A system with four transmit antennas with an eight-fold complexity reduction and a performance loss of about 1 dB is demonstrated     

基于LPC2138的AES3数字音频接口设计

随着数字音频技术的不断发展,数字化音频设备已广泛应用于广播电视节目领域。鉴于专业数字音频设备越来越多地需求,以及专用接收发送设备的复杂性,本设计采用Philips公司的ARM7控制芯片LPC2138结合音响设备专用芯片,设计一个简单的AES/EBU(AES3)数字音频收发系统,实现了专业AES3数字音频的接收与发送。实验显示,在输入1 kHz,24 dBu时,本设计的总谐波失真小于0.005%,信噪比大于90 dBu。     

Octagonal DGS based dual polarised ring-shaped antenna for MIMO communications

In this article, a dual polarised Microstrip patch antenna is proposed for 2*2 MIMO communications. The proposed antenna is suitable for GSM/DCS-1800 and LTE-1900 bands as diversity and multiple-input multiple-output (MIMO) antenna. Different from conventional MIMO antennas, the radiating aperture is shared among the radiators, which greatly reduces the overall size of the MIMO antenna system. An isolation enhancement of 30 dB between the input ports is achieved by integrating cross-connected octagonal shaped Defected Ground Structure to the ground plane. Furthermore, the Multi-antenna system performance metrics such as Envelope Correlation Co-efficient, diversity gain and Mean Effective Gain, and Total Active Reflection Co-efficient are also computed. The Proposed antenna shows a gain of 3.63 dBi at 1950 MHz. The simulated and measured results demonstrate that the proposed antenna has good impedance matching, isolation and dual polarisation characteristics. From the performance metrics, the proposed antenna performs well in multipath environment.     

高隔离度宽带双极化微带天线设计

双极化天线由于具有极化分离的优异性能,在无线通信系统中引起了广泛关注,因此本文设计了一个高隔离度宽带双极化微带缝隙天线.为了获得高隔离度特性,该天线采用两个不同结构的微带线馈电,分别激励起垂直极化和水平极化模式.同时在地板上开缝隙来展宽天线带宽和实现天线的小型化.仿真优化结果表明,该天线端口1和端口2的阻抗带宽分别为51%和62%,在1.71GHz~2.69GHz整个工作频带范围内两端口之间的隔离度高于40dB,且结构简单,适用于移动通信的实际应用中.     

Multiband PIFA vehicle telematics antennas

Compact, low-cost antennas for multiband telematics applications on vehicles are described. The multifrequency band antennas are variations on the printed inverted-F antenna (PIFA) principle. One type of PIFA is a compact variation of a conventional antenna while the other is a novel planar version customized for different mounting positions such as bumpers, window, and roof mount. In both derivations the dimensions are small and have been specifically designed for low-cost production. Each antenna was designed for mobile telephone band coverage from 890 to 2100 MHz. Results from free-space simulations are included but more work needs to be carried out as the vehicles have a significant effect on antenna performance. On-vehicle tests are described where the antennas were placed on glass and plastic areas and integrated into an existing multipurpose roof mount antenna.     

多天线系统中的多用户分集方案的性能分析及比较

在多天线多用户无线通信系统中,可以利用用户之间彼此独立的随机衰落信道的特点,结合随机波束成型技术,或者空间分集技术,或者天线选择技术,获得多用户分集增益。然而不同多用户分集方案的系统性能不尽相同。该文分析了在多输入单输出(MISO)信道中目前几种典型的多用户分集方案的性能,给出系统吞吐率的定量表达式,并综合比较了不同用户数和不同天线数对各种多用户分集方案性能的影响,为实际多天线多用户系统设计提供了有益的参考。     

Performance analysis of switch‐and‐examine diversity systems with interference and Rayleigh fading channels

This paper studies the behavior of the low‐complexity switch‐and‐examine diversity combining (SEC) and switch‐and‐examine diversity combining with post‐examine selection (SECps) antenna selection schemes with interference. In this paper, we first derive the cumulative distribution function (CDF) of the end‐to‐end (e2e) signal‐to‐interference plus noise ratio at the selection scheme combiner output. This CDF is then used to derive closed‐form expressions for the e2e outage and symbol error probabilities for the independent nonidentically distributed and independent identically distributed cases of diversity branches. In the analysis, the channels of the desired user and the interferers are assumed to follow Rayleigh distribution. Furthermore, to have more details about the system insights, the performance is evaluated at the high signal‐to‐noise ratio (SNR) values where the diversity order and coding gain are derived and analyzed. The derived analytical and asymptotic results are validated via a comparison with Monte‐Carlo simulations. Main findings show that with interference power does not scale with average SNR; the system can still achieve performance gain when more receive antennas are used. This happens at the values of switching threshold that are close to average SNR. Also, results illustrate that the interference is noticeably affecting the gain achieved in system performance when more antennas are used. Furthermore, findings show that the SECps selection scheme outperforms the conventional SEC scheme when more antennas are added with the switching threshold is much larger than the average SNR. Finally, findings show that the SEC and SECps antenna selection schemes are efficient for systems which operate at the range of low SNR values and this makes them attractive candidates to be implemented in the emerging mobile broadband communication systems. Copyright © 2015 John Wiley & Sons, Ltd.     

Diversity characteristics of four-element ring slot-based MIMO antenna for sub-6-GHz applications

This paper proposes four-ring slot resonator-based MIMO antennas of 75 × 150 mm² without and with CSRR structures in the sub-6-GHz range. These orthogonal-fed antennas have shown diverse characteristics with dual polarization. L-shaped parasitic structures have increased the isolation (i.e., >40 dB) in the single-element antenna over the band of 3.4 GHz–3.8 GHz. A set of three CSRR structures in the MIMO antenna reduced the coupling between antenna ports placed in an inline arrangement and enhanced the isolation from 12 dB to 20 dB and the diversity characteristics. The S-parameters of both MIMO antennas are measured and used to evaluate MIMO parameters like ECC, TARC, MEG, and channel capacity loss. The simulation results show the variations in the gain and directivity on exciting linear and dual polarizations. The diversity performance of the reported MIMO antennas is suitable for 5G applications.     

导航卫星阵列天线的快速现场系统校准算法

阵列天线接收处理全球卫星导航信号时,由于天线和射频前端的非理想性,会在不同方向卫星信号中引入不同的载波相位偏差,从而破坏卫星导航接收机距离观测量准确性。针对此问题,提出了一种易实现的卫星导航阵列天线的快速现场系统校准算法。校准过程分为通道校准和天线校准：通过开机和周期进行的通道校准实现阵列天线接收射频前端的通道响应测量;通过与接收处理不同卫星基带数据的数字接收机配合,实现阵列天线的现场阵列流形矢量校准。仿真验证了所提校准算法的正确性和有效性。     

Investigation of the characteristics of low-cost and lightweight horn array antennas with novel monolithic waveguide feeding networks

3D printed X-Ku band single horn antenna and 2 × 1 and 2 × 2 pyramidal horn array antennas with novel lightweight and monolithic waveguide feeding networks (WFNs) are proposed at 10–15 GHz for satellite communications and radar systems to increase the gain. Proposed novel fabrication method consists of two main steps that are to make the skeleton of horn array antenna from acrylonitrile butadiene styrene (ABS) thermoplastic via 3D printer and to perform copper plating over all surface of antenna by using the electroless plating and electroplating processes. The WFN structures with 3λ element spacing designed and realized by using WR75 waveguide T-junction, E-type bend, and UDR 120 flange. Qualitative agreement between measurement and simulation via CST Microwave Studio is obtained with max 1 dB due to high precision and surface roughness. The gains of array antennas are increased by about 1.5 dB and 3 dB, respectively compared to the single antenna. VSWRs of array antennas are 0.3 dB and 0.6 dB, respectively higher than the single one. In the study, proposed 3D printed components not only with 90% lighter weight than, but also with 80% cheaper than commercial products, and horn arrays with -40 dB cross-polarization values.     

A Compact Diversity Antenna for Handheld Terminals

The handheld terminals antenna should have a small size, sufficient gain and big bandwidth. In this paper, a compact planar inverted-L diversity antenna for handheld terminals is proposed. Three diversity antennas operating at 2.15 GHz are designed and the effect of important parameters of the proposed antenna is measured. The isolation is found to be better than 13 dB, the usable bandwidth is about 13%. Moreover, the measured radiation patterns are also obtained that the backward radiation is decreased.