A Novel Mobile Antenna for Ku‐Band Satellite Communications

A mobile antenna for multimedia communications with Ku‐band geostationary satellite KOREASAT‐3 and JSAT‐2A is presented. The forward link of the satellite communication is 11.7 to 12.75 GHz, and the return link is 14.0 to 14.5 GHz. The mobile antenna is designed to be a stair structure using 24 active phased array elements in order to provide a low profile, and to be at a non‐periodic array distance using the genetic algorithm. Also, the designed antenna uses the double beam forming method for stable satellite tracking. The fabricated mobile antenna is examined using various experiments to confirm its capability for practical application. From the measured results, the fabricated mobile antenna system is confirmed to have a good performance.     

Adaptive frequency‐hopping schemes for CR‐based multi‐link satellite networks

In this paper, we study two dynamic frequency hopping (DFH)–based interference mitigation approaches for satellite communications. These techniques exploit the sensing capabilities of a cognitive radio to predict future interference on the upcoming frequency hops. We consider a topology where multiple low Earth orbit satellites transmit packets to a common geostationary equatorial orbit satellite. The FH sequence of each low Earth orbit–geostationary equatorial orbit link is adjusted according to the outcome of out‐of‐band proactive sensing scheme, performed by a cognitive radio module in the geostationary equatorial orbit satellite. On the basis of sensing results, new frequency assignments are made for the upcoming slots, taking into account the transmit powers, achievable rates, and overhead of modifying the FH sequences. In addition, we ensure that all satellite links are assigned channels such that their minimum signal‐to‐interference‐plus‐noise ratio requirements are met, if such an assignment is possible. We formulate two multi‐objective optimization problems: DFH‐Power and DFH‐Rate. Discrete‐time Markov chain analysis is used to predict future channel conditions, where the number of states are inferred using k‐means clustering, and the state transition probabilities are computed using maximum likelihood estimation. Finally, simulation results are presented to evaluate the effects of different system parameters on the performance of the proposed designs.     

A new design approach for dual‐band patch antenna serving Ku/K band satellite communications

A printed planar antenna with simple and intelligent geometrical structure has been proposed for Ku/K band satellite communication systems. The radiating patch of the antenna is formed by cutting rectangular slots and extending the radiating element to some extent. The final design of the antenna with optimized parameters is fabricated on ceramic–polytetrafluoroethylene substrate materials of dielectric constant ε_r = 10.2. The antenna is excited through a microstrip feed line and has reduced ground plane that covers only the non‐radiating portion of the antenna. The reduced complexity of the antenna is easy to fabricate and has overall dimension of 40 × 35 × 1.905 mm³. The results from experimental analysis show that the proposed antenna can guarantee a wide bandwidth of 12.0 to 16.4 GHz at lower band, and the upper band covers the frequency in the range of 17.53 to 19.5 GHz. The antenna has achieved appreciable gain in the range of 3.14 to 4.68 dBi for lower band and 2.03 to 3.65 dBi for upper band. The proposed antenna has offered almost symmetrical and directional radiation pattern that is essentially suitable for serving Ku/K band satellite applications. Copyright © 2015 John Wiley & Sons, Ltd.     

降雨对于CAPS微小卫星终端通信的影响

中国区域卫星定位系统（CAPS）是卫星导航通信一体化的系统。当利用CAPS微小卫星终端系统进行卫星通信时,所用的天线口径极小,增益低,终端的有效全向辐射功率EIRP。较小,整个通信链路的余量较小。虽然C波段的降雨衰减远没有Ku波段大,但是相对于微小卫星终端的整个卫星通信链路来说,降雨带来的信号衰减、地球站接收天线G／T值的变化以及对卫星通信上、下行链路载噪比的影响也是不可忽视的。文章对这些影响进行了分析,并利用ITU—R给出的降雨衰减预报模式,给出了C波段的降雨衰减的计算方法及结果,并且分析了降雨对CAPS微小卫星通信系统的整个链路余量的影响。     

A simple design of planar microstrip antenna on composite material substrate for Ku/K band satellite applications

A straight forward design of rectangular slotted microstrip planar antenna fed by 50 ohm microstrip line is proposed for Ku/K band satellite applications. The radiating patch of the antenna occupies an area of 17 × 17 mm² and fabricated on 1.0 mm‐thick ceramic filled bioplastic composite material substrate whose dielectric constant (ε_r ) is 10.0. The dual resonant square‐shaped antenna has been formed by inserting four arc shape slots at the corners with the combination of circle and square and wide square shape slot at the center. The results from the measured data show that the antenna has a lower resonant mode impedance bandwidth for S11 < −10 dB is of 18.4% (11.67–14.05 GHz) and upper resonant mode bandwidth is of 8.2% (18.19–19.75 GHz) centered at 12.94 GHz and 19.04 GHz, respectively. The antenna prototype has achieved maximum gains of 3.1 dBi and 4.13 dBi with average radiation efficiencies of 75.3% and 86.4% for the lower band and the upper band, respectively. The numerical data analyses of both the measured and simulated results show relatively good agreement. Moreover, the consistent and symmetrical radiation patters of the proposed antenna make it suitable candidate for the Ku/K band satellite applications. Copyright © 2015 John Wiley & Sons, Ltd.     

The U.S. filings for multimedia satellites: a review

The United States Federal Communications Commission (FCC), in response to industry pressure, has conducted four Notice of Proposed Rule Making (NPRM) sessions in which companies could apply for licenses for satellite systems operating at new frequencies (Ka‐ or Q/V‐band) or in new, non‐geostationary orbits at Ku‐band. The first NPRM resulted in the award, in May 1997, of licenses for 13 systems operating at Ka‐band. Of these, seven propose to offer global or near‐global service. The FCC opened a second window for companies to file for Ka‐band systems, which closed in December 1997 and resulted in nine additional filings, seven of which are for global systems. Thus far, none of these systems have been licensed. In parallel with the second Ka‐band window was one for systems operating at still higher frequencies, in the Q‐ and V‐bands. This resulted in 16 filings, 14 of which are for global systems. Still more recently (January 1999), the FCC concluded an NPRM for non‐geostationary satellite systems operating at Ku‐band. Applications were filed for six systems—all intended for global service. Nearly all of the above systems are intended to serve small offices and consumers by providing broadband services such as multimedia distribution and Internet access. The proposed global systems are reviewed, and the technical approaches taken to provide this type of service at low cost to the user are discussed. Fielding any of the global systems entails significant technical challenges and a large degree of business risk. This seems likely to hamper efforts to raise capital and may defer the completion of any of the systems beyond their announced dates of initial operation (2001–2003). Copyright © 2000 John Wiley & Sons, Ltd.     

Estimation of the Communication Link Status in Satcom on-the-Move

In this paper, a method to estimate the satellite link status for the Satcom on-the-move (SOTM) system at Ku band has been proposed and verified by field tests. The objective of this method is to develop a control strategy under blocked and shadowed conditions for the SOTM system that points the antenna line of sight to the satellite using a closed-loop tracking based on the received signal power. This estimation ensures a fast reacquisition of the target satellite after signal blockage and that the transmitted data be cached in time to avoid the real-time collected data lost during blockage. The basic principles of the method can also be applied to the SOTM system at other bands, such as Ka band.     

Design of Dual‐Band MIMO Antenna with High Isolation for WLAN Mobile Terminal

In this paper, we propose a dual‐band multiple‐input multiple‐output (MIMO) antenna with high isolation for WLAN applications (2.45 GHz and 5.2 GHz). The proposed antenna is composed of a mobile communication terminal board, eight radiators, a coaxial feed line, and slots for isolation. The measured ?10 dB impedance bandwidths are 10.1% (2.35 GHz to 2.6 GHz) and 3.85% (5.1 GHz to 5.3 GHz) at each frequency band. The proposed four‐element MIMO antenna has an isolation of better than 35 dB at 2.45 GHz and 45 dB at 5.2 GHz between each element. The antenna gain is 3.2 dBi at 2.45 GHz and 4.2 dBi at 5.2 GHz.     

Next‐generation global satellite system with mega‐constellations

Mega satellite constellations in low earth orbit (LEO) will provide complete global coverage; rapidly enhance overall capacity, even for unserved areas; and improve the quality of service (QoS) possible with lower signal propagation delays. Complemented by medium earth orbit (MEO) and geostationary earth orbit (GEO) satellites and terrestrial network components under a hybrid communications architecture, these constellations will enable universal 5G service across the world while supporting diverse 5G use cases. With an unobstructed line‐of‐sight visibility of approximately 3 min, a typical LEO satellite requires efficient user terminal (UT), satellite, gateway, and intersatellite link handovers. A comprehensive mobility design for mega‐constellations involves cost‐effective space and ground phased‐array antennas for responsive and seamless tracking. An end‐to‐end multilayer protocol architecture spanning space and terrestrial technologies can be used to analyze and ensure QoS and mobility. A scalable routing and traffic engineering design based on software‐defined networking adequately handles continuous variability in network topology, differentiated user demands, and traffic transport in both temporal and spatial dimensions. The space‐based networks involving mega‐constellations will be better integrated with their terrestrial counterparts by fully leveraging the multilayer 5G framework, which is the foundational feature of our hybrid architecture.     

Novel down link rain fade mitigation technique for Ka‐band multibeam systems

Rain fades at Ka‐Band degrades the link quality and performance significantly. Several rain fade mitigation techniques for Ka‐band satellite systems are being investigated to improve the channel capacity. Methods such as power control and adaptive waveform techniques have been proposed for use in the uplink as they are capable of straightforward implementation. A novel down link power control technique for multi‐beam Ka‐band system has been proposed in this paper. It is based on the use of multi‐port amplifier, which is commonly used for dynamic power sharing of the beams depending upon the traffic. Payload architecture for multi‐beam coverage using multi‐port amplifiers has been designed for the proposed technique. The simulation results to compensate for the rain fade attenuation of one beam by sharing the unused power from other beams have been presented Copyright © 2006 John Wiley & Sons, Ltd.     

Ka‐band HTS channel uplink SNIR probability model

I present a novel analytical study of the signal‐to‐noise‐plus‐interference ratio (SNIR) for Ka‐band high throughput satellite uplink channels. The Ka‐band high throughput satellite systems employ frequency and polarization (color) reuse among the spot beams to achieve throughput increase many times the throughput of the system without reuse. However, color reuse also produces substantial co‐color interference and adding to it, tropospheric precipitation attenuation rises sharply in Ka‐band. The co‐color interference and precipitation induced fading vary randomly; they degrade the system performances. To assess the impact, I develop the uplink channel SNIR probability model in this study. Compared with the known studies of the same topic, this study takes the theoretic approach and is applicable to the urban users in particular. The model is feasible to implement and can provide accurate assessment of the channel SNIR performances statistically in theory for a wide array of system operational scenarios. The SNIR probability model is applied to a model spot beam system of 101 user beams to obtain and compare sample channel performances, which can be used for making system design choices at the early stage of a satellite project. Copyright © 2017 John Wiley & Sons, Ltd.     

Design and fabrication of compact 2 × 2 dual linear polarized wideband and high gain array for Ku-band satellite communication application

In this paper, the design of a planar array antenna for two-way satellite communication is presented. The antenna unit consists of four elements and two waveguide feeding networks used to connect the elements. The radiating elements are small horn apertures. Each element of the array includes two separate ports to radiate vertical and horizontal polarization, respectively. The feeding networks consist of power dividers and bends to connect the vertical and horizontal polarization ports of horns, separately. Radiating elements and feeding networks are designed to cover receive band (10.5–12.75 GHz) and transmit band (13.75–14.5 GHz) within Ku-band. The maximum gain for this type of antenna is 21 dBi.     

Sidelobe Reduction of Low‐Profile Array Antenna Using a Genetic Algorithm

A low‐profile phased array antenna with a low sidelobe was designed and fabricated using a genetic algorithm (GA). The subarray distances were optimized by GA with chromosomes of 78 bits, a population of 100, a crossover probability of 0.9, and a mutation probability of 0.005. The array antenna has 24 subarrays in 14 rows, and is designed as a mobile terminal for Ku‐band satellite communication. The sidelobe level was suppressed by 6.5 dB after optimization, compared to the equal spacing between subarrays. The sidelobe level was verified from the far‐field pattern measurement by using the fabricated array antenna with optimized distance.     

An RFID Tag Using a Planar Inverted‐F Antenna Capable of Being Stuck to Metallic Objects

This letter presents the design for a low‐profile planar inverted‐F antenna (PIFA) that can be stuck to metallic objects to create a passive radio frequency identification (RFID) tag in the UHF band. The designed PIFA, which uses a dielectric substrate for the antenna, consists of a U‐slot patch for size reduction, several shorting pins, and a coplanar waveguide feeding structure to easily integrate with an RFID chip. The impedance bandwidth and maximum gain of the tag antenna are about 0.3% at 914 MHz for a voltage standing wave ratio (VSWR) of less than 2 and 3.6 dBi, respectively. The maximum read range is about 4.5 m as long as the tag antenna is on a metallic object.     

Achievable sum‐rate analysis of correlated two‐antenna MIMO uplink channels

This paper analyzes the achievable sum‐rate of correlated two‐antenna multiple‐input multiple‐output (MIMO) uplink channels. Most of previous works have considered the case when a single user has multiple transmit antennas (i.e. multi‐antenna single‐user scenario). This paper considers the case when two‐antenna MIMO uplink channels comprise two users with a single transmit antenna (i.e. single‐antenna two‐user scenario). The analytic and simulation results show that the achievable sum‐rate of correlated single‐antenna two‐user MIMO uplink channels highly depends on the angle difference between the receive correlation coefficients of two users. It is also shown that the achievable sum‐rate of correlated single‐antenna two‐user MIMO uplink channels is larger than that of correlated two‐antenna single‐user MIMO uplink channels and can even be larger than that of independent and identically distributed Rayleigh two‐antenna MIMO uplink channels. Copyright © 2009 John Wiley & Sons, Ltd.     

A mixed satellite TV channel transmission scheme to enhance frequency bandwidth utilization

In the recent past, television (TV) industry has started to provide users with ultra high definition (ultra‐HD) and/or 3‐dimensional TV programs, which on the one hand, can bring users greatly enhanced viewing experience, while on the other hand, considerably increases the transmission bandwidth requirements and may lead to bandwidth shortage situations in many different types of TV systems. In particular, this bandwidth shortage poses a serious challenge in the current satellite TV broadcasting systems because of the strictly limited bandwidth available in C and Ku frequency bands. Aiming at mitigating the bandwidth shortage problem, this paper proposes an innovative mixed channel transmission scheme for the next generation satellite TV systems. The proposed scheme integrates the merits of using both broadcast and multicast methods, both Ku and Ka frequency bands, as well as both wide‐shaped and spot antenna beam types. According to the conducted comprehensive simulation experiments, this mixed scheme is able to effectively enhance the frequency bandwidth utilization with still providing users affordable quality of experience. Moreover, to cope with the impact brought by ever increasing number of provided TV channels, this paper enhances the proposed scheme by using multicast method to transmit those least popular global channels, which can efficiently reduce the quality of experience degradation up to 90% in Ku‐ and Ka‐band frequency resource restricted scenarios.     

A power-sharing multiple-beam mobile satellite in Ka band

This paper presents a new power-sharing multiple-beam mobile satellite system concept in the Ka band. A wide allocated bandwidth and a large amount of frequency reuse based on hundreds to thousands of small spot beams will allow us to draw a drastically new mobile satellite systems concept in the Ka band. At first, requirements for beam size on the surface of the Earth for various signal transmissions are considered. Based on these requirements, Ka band geostationary systems with 3.5 and 10 m satellite antennas are shown. If the number of beams is hundreds to thousands, it is not appropriate to assume a fixed power transmitter for each beam because the traffic in each beam is not uniform or static. In order to cope with this multiple-beam-varying traffic problem, this paper proposes a new type offset reflector antenna fed through an equal phase-shift active array. The proposed active array consists of hundreds to thousands of equal phase-shift elements. Features and simulated performances of the proposed transmitting antenna are presented. Preliminary experimental results from a 2.1 m reflector fed through 332 hollow elements are also shown. Since each beam commonly utilizes all active array elements, power sharing among beams is possible, allowing traffic variation among beams without loss of power efficiency     

一种Ka/Ku双波段双极化共口径阵列天线

由于运载能力及卫星平台的限制,星载雷达要求雷达天线具有重量轻、功耗低、体积小、效率高等特点,尤其是对天线口径面积限制较为苛刻,双频段天线要想适用于星载条件,就必须考虑全新的结构形式。介绍了一种适应于星载条件的Ka/Ku双波段双极化共口径阵列天线,其中Ku波段天线双极化工作、Ka波段天线单极化工作。Ku波段天线阵采用了具有两阶零点滤波性能的微带耦合馈电辐射缝隙单元,这种天线单元具有易实现双极化、工作频带宽等优点。Ka波段天线阵采用侧馈微带帖片天线单元,其优点是易于实现与Ku波段天线共孔径。     

Data collection from the Antarctic region through a W‐band low Earth orbit satellite

The DAVID (DAta and Video Interactive Distribution) mission is being carried out in the framework of the Science Small Missions Program of the Italian Space Agency. The mission is aimed at the deployment of two scientific telecommunication experiments through a low Earth orbit (LEO) satellite. The paper will focus on one of these experiments, that will test a satellite system architecture for the exchange of a large amount of data and high definition images through a W‐band link and a Ka‐band inter‐satellite link between the LEO and the ARTEMIS satellite. The proposed architecture, that will explore various innovative aspects, will also allow for the first time the distribution of large volumes of scientific data collected from the Antarctic region and other extremely remote areas of the Earth. The availability of a return link in the envisaged system will also allow interactive control of the various laboratories located in the remote sites. Copyright © 2001 John Wiley & Sons, Ltd.     

Design of an Ultra‐Wideband Antenna Using a Ring Resonator with a Notch Function

This paper describes an ultra‐wideband (UWB) antenna that uses a ring resonator concept. The proposed antenna can operate in the entire UWB, and the IEEE 802.11a frequency band can be rejected by inserting a notch stub into the ring resonator. The experiment results indicate that the measured impedance bandwidth of the proposed antenna is 17.5 GHz (2.5 GHz to at least 20 GHz). The proposed UWB antenna has omnidirectional radiation patterns with a gain variation of 3 dBi (1 dBi to 4 dBi).