Multi-beam Phased Array Antennas Research Articles

Adaptive multibeam hopping in geo satellite networks with non-uniformly distributed ground users

This paper designs a novel low-complexity user-cluster grouping algorithm for adaptive beam hopping in geostationary satellite networks equipped with multibeam phased-array antennas. Each beam serves a cluster of users, and the challenge is to design a beam-hopping pattern where no beams are simultaneously serving nearby user clusters. We develop a line search procedure to identify near-optimum groupings for heterogeneous traffic demands. We provide a necessary condition to determine the boundaries of the line search space. Our approach employs exclusion regions around critical user clusters in congested areas, iterates a sequential congestion-based grouping algorithm, and applies a group-member-swapping procedure. It provides max-min fairness for ground users. Extensive numerical studies have shown that our user grouping algorithm produces near-optimum beam-hopping schedules with low outage probability. It achieves an improvement of up to 13dB in the worst-case signal-to-interference and noise ratio, and doubles the zero-outage data rate, compared to benchmark approaches.

Spaceborne Multibeam Phased Array Antennas for Satellite Communications

Multibeam phased array antenna is one of the core payloads of the satellite communication system, which has the potential to realize the transformation of the satellite communication system from application-adapted satellite to satellite-adapted application. This article provides a brief overview of the beamforming technologies used in spaceborne multibeam phased array antennas from three perspectives: analog beamforming, digital beamforming, and optical beamforming. The application status of multibeam phased array antennas in satellite communication is then classified and explained. Finally, the development trend of spaceborne multibeam phased array antenna is analyzed.

A Review of Multibeam Phased Array Antennas as LEO Satellite Constellation Ground Station

Small satellites in low Earth orbit (LEO) are typically organized as a satellite constellation. The satellite number of a LEO satellite constellation would be several hundred or even tens of thousands to realize a fully global coverage. This imposes a big challenge on ground station for satellite ordinary management and control operation. Phased array antennas are considered as attractive candidates for future satellite ground station. The primary reason is that phased array antennas can produce numbers of beams by the beamforming network thus support multiple satellites simultaneously. This paper aims to provide a tutorial-like review on phased array antennas as satellite ground station. The advantages of phased array antennas for this application are summarized by comparing them with traditional reflector antennas. Several array geometries for realizing the hemispherical coverage required for satellite tracking are presented. System architecture are given, and some considerations for engineering practice about phased array antenna based satellite ground station are also discussed.

Butler Matrix Based Beamforming Networks for Phased Array Antenna Systems: A Comprehensive Review and Future Directions for 5G Applications

Due to the rapid development of wireless communication technologies, the number of wireless users are radically increasing. Currently, ~23 billion wireless devices are connected to the internet, and these numbers are expected to increase manifolds in the years to come. The technology growth of the fifth-generation (5G) wireless systems will be needed to meet this high demand of the network. 5G wireless systems offer data-rates of up to 10Gbps, 1-ms latency, and reduced power consumption. It is a known fact that 5G wireless systems will be exploiting beyond the presently used 3 GHz microwave and millimetre-wave (mm-wave) frequency bands. This is the primary driver in the development of the 5G wireless system. Multi-beam Phased array antenna (PAA) systems are typically used in the deployment of 5G systems for high-gain and directionality. In current 5G and future Beyond 5G (B5G) antenna array systems, beamforming networks (BFNs) such as the Butler Matrix (BM) will play a key role in achieving multi-beam characteristics. So, this paper presents an extensive review of the BM based BFNs, and discusses which type of BM will be suitable for the phased array antenna (PAA) systems in the upcoming 5G and next-generation of B5G wireless systems. Moreover, this paper also summarizes the different types of BM designs based on the number of layers. The BMs are classified into the bi-layer, tri-layer, and four-layer structures. It includes different techniques that have been used to solve the problem of crossing, narrow bandwidth, and size reduction of the BM. From the previous studies, it is found that most of the past research work was performed using the bi-layer BM system, whereas the difficult geometries like tri- and four-layer BM are avoided due to their complex fabrication process. It is also found in this paper that the metamaterial (MTM) based bi-layer BM achieves low insertion-loss and phase-error, excellent bandwidth and compact size, and good S-parameter performance, which makes them an ideal BFN candidate for the upcoming 5G and next-generation B5G systems.

A Necessary Model to Quantify the Scanning Loss Effect in Spaceborne iGNSS-R Ocean Altimetry

When the interferometric global navigation satellite system reflectometry (iGNSS-R) altimeter receives the direct and reflected signals through the digital multibeam phased array antenna, the roll-off of element radiation pattern will cause the scanning loss of directivity. If the scanning loss is neglected, the ocean altimetric precision will be biased with possible consequences for the instrument design. This article carries out the following research on this. First, based on the geometry of iGNSS-R altimetry and the principle of phased array antenna beamformer, the scanning loss model with the elevation angle at the specular point as a parameter is established. Second, this article uses the measured data of the phased array antenna to verify the model, and the result shows that the simulated value is in good agreement with the measured value, with an average deviation of 0.07 dB. Third, taking the GPS L1 signal (full composite) as an example, the model is used to analyze the influence of the scanning loss on the iGNSS-R altimetric precision estimation. The research results show that when the phased array antenna synthesizes four beams for iGNSS-R altimetry, the comprehensive effect of scanning loss on altimetric precision estimation is 0.16 m. The influence of scanning loss should be considered in the future high-precision iGNSS-R altimetry instrument design.

Multibeam Antenna Technologies for 5G Wireless Communications

With the demanding system requirements for the fifth-generation (5G) wireless communications and the severe spectrum shortage at conventional cellular frequencies, multibeam antenna systems operating in the millimeter-wave frequency bands have attracted a lot of research interest and have been actively investigated. They represent the key antenna technology for supporting a high data transmission rate, an improved signal-to-interference-plus-noise ratio, an increased spectral and energy efficiency, and versatile beam shaping, thereby holding a great promise in serving as the critical infrastructure for enabling beamforming and massive multiple-input multiple-output (MIMO) that boost the 5G. This paper provides an overview of the existing multibeam antenna technologies which include the passive multibeam antennas (MBAs) based on quasi-optical components and beamforming circuits, multibeam phased-array antennas enabled by various phase-shifting methods, and digital MBAs with different system architectures. Specifically, their principles of operation, design, and implementation, as well as a number of illustrative application examples are reviewed. Finally, the suitability of these MBAs for the future 5G massive MIMO wireless systems as well as the associated challenges is discussed.

Modeling of the zones of the Earth surface illuminated by the directional patterns of active multibeam antenna arrays

A kinematic model of the motion of a spacecraft (SC) constellation along circular orbits and an expression for calculation of the number of SCs required to completely illuminate the entire Earth surface with the visibility cones of the directional patterns (DPs) of onboard antennas are presented. A simplified procedure for construction of multiple footprints of partial DPs formed by multibeam phased-array antennas on the Earth surface has been developed. Expressions for calculation of the slant distance, the grazing angle, and zones of visibility of the Earth surface from the SCs at the normal and oblique incidence of the antenna beam have been obtained. Numerical examples and the respective graphic illustrations are given.

An Effective Design Procedure of Multibeam Phased Array Antennas for the Applications of Multisatellite/Coverage Communications

This paper presents the design methodology of phased array antennas to radiate multiple beams, where each beam is equipped with an I/O port to allow independent uses. The potential applications include multicoverages in the mobile communications and multisatellite signal receptions using a single set of antennas. In particular, the beam-forming circuits employ Butler matrix (BM) as the core. Both the beam-forming mechanisms and the implementation of BM are presented. The uniqueness of this paper is that the coverage domain can be relatively arbitrarily defined, within which the beams will uniformly distributed. The beamwidth can be further flexibly controlled to provide an appropriate beam overlapping, which is important for the isolation of coverages. Numerical examples are presented to investigate the characteristics of this method and also demonstrate the feasibility.

Optical true time delay unit for multi-beamforming.

An optical true time delay (TTD) unit capable of adding independent time delays to multiple RF signals is proposed, which can be used for multi-beamforming in both transmit and receive modes. In the proposed unit, N RF signals with different center frequencies are modulated on an optical frequency comb (OFC). After transmission through a dispersive element, the RF-modulated OFC is split into N paths. In each path, a comb line is selected by a tunable optical filter. Thanks to the chromatic dispersion of the dispersive element, independently-controllable TTDs can be obtained in all paths. Then, a microwave photonic filter (MPF) is incorporated in each path, allowing a designated RF signal to undergo the TTD in that path. A proof-of-concept experiment is carried out. A two-path unit with a low-pass MPF in one path and a high-pass MPF in the other path is built. Controllable TTDs up to ~1.4 ns with a step of ~69 ps are demonstrated based on a 25-GHz-spacing OFC. In addition, a wideband multi-beam phased-array antenna system that can work in both transmit and receive modes is designed using the proposed TTD unit.

Geometric interpretation of synthesis of a quasi-optical distribution system for multibeam phased array antennas

A geometric interpretation is proposed for synthesis of a quasi-optical system employed in multi-beam active phased array antennas (APAAs). Relationships are obtained for the angles of deflections of APAA beams and for optimum positions of the probes of the distribution system. The optimization is performed according to two criteria: the minimum mean deflection and the minimum local deflection. The example of construction of a quasi-optical distribution system for a five-beam APAA is presented. Dependences of phase errors on the positions of radiators and patterns of an APAA with a sidelobe level not exceeding 40 dB are obtained.

Low-cost multibeam phased array antenna for communications with GEO satellites

In this article, we have shown the development of a unique design concept in which a single planar array antenna consisting of N × M elements on a mobile earth station, such as a navy ship, will require only M phase shifters (for each beam) and one or two hard-wired squints to communicate with several GEO satellites simultaneously by generating multiple independent beams. Our simplified design enables a reduction in both the cost and the complexity of a PAA. This unique concept reduces complexity by requiring full scan capability only in the azimuth plane, thereby reducing the number of phase shifters from NM to M for each beam. At the same time, only one or two hard-wired squints are used in the elevation plane, further reducing the complexity and thus the cost of development of such a PAA.

Application of an imaging HF riometer for the observation of scintillations of discrete cosmic sources

Scintillations of discrete cosmic radio sources have been investigated theoretically and experimentally for radiation scattered from natural and artificial inhomogeneities in the auroral zone ionosphere. The observations were performed at a frequency of 38.2 MHz with the multibeam phased array antenna of the imaging riometer located at Poker Flat, Alaska. For quiet ionospheric conditions and weak scintillations, the spatial spectrum and transverse motion velocities of the Fresnel inhomogeneities have been recovered. A theoretically based approach has been developed to estimate the time coherence interval of the radiation for the case of saturated scintillations and strong ionospheric turbulence. Examples of scintillation records are analyzed for the case of scattering from artificial ionospheric irregularities induced by high‐power HF radiation from the high‐power auroral simulation (HIPAS) ionospheric modification facility. The effect of aspect‐sensitive scattering of the cosmic source radiation by artificial field‐aligned small‐scale irregularities has been predicted and detected. Prospects for routine observations of the effects of scintillations and aspect‐sensitive scattering are discussed for special operation modes of the ionospheric modification facility.

Location and Propagation Status Sensing of Interference Signals in Cognitive Radio

In a Cognitive Radio system, it is essential to recognize and avoid sources of interference signals. This paper describes a study on a location sensing scheme for interference signals, which utilizes multibeam phased array antenna for cognitive wireless networks. This paper also elucidates its estimation accuracy of the interference location for the radio communication link using an OFDM signal such as WiMAX. Furthermore, we use the frequency spectrum of the received OFDM interference signal, to create a method that can estimate the propagation status. This spectrum can be monitored by using a software defined radio receiver.

Satellite interference location system using on‐board multibeam antenna

In satellite communication using a high-gain on-board antenna, there may be a problem with up-link interference, which depends on the directivity of the on-board antenna or the position of the satellite on the orbit. In order to cope with radio frequency interference, it is important to locate (specify) the position of the interference wave radiation source, as seen from the position of the satellite. Technical difficulties are that the characteristics of the interference wave are unknown and there is a limit in the installed weight, making it difficult to add dedicated on-board equipment for location. In a conventional location system, the wave is received simultaneously by two or more satellites. Correlation processing is applied on the ground to the interference waves in order to estimate the location of the radiating source based on the frequency and time differences. In this paper, the following location system is discussed. Angle measurement, based on the received amplitude comparison of multiple beams, is applied to the interference, overlapping with the communication signals received by the multibeam satellite antenna where the interference power ratio between the beams is measured on the ground. A feature of the system is that the source can be located using only a single satellite and no additional on-board equipment. An experimental system was constructed using the S-band multibeam phased array antenna on the experimental Engineering Test Satellite VI. The results of the experiment, for an interference source with known position and for a radiation source with the properties of a radar wave with an unknown position, are presented, together with a discussion of the estimation error and of its improvement. © 1997 Scripta Technica, Inc. Electron Comm Jpn Pt 1, 80(11): 22–33, 1997

Development of multibeam phased array antenna on ets‐vi for s‐band intersatellite communications

AbstractThis paper describes the S‐band intersatellite communication (SIC) antenna to be carried on the Engineering Test Satellite VI scheduled for launch in 1994, to undertake the first intersatellite data relay experiments in Japan. The SIC antenna is an on‐board formed multibeam phased array antenna, the first of this kind in the world to be carried on a satellite. The SIC antenna is capable of simultaneous data relays to several orbiting satellites (user satellites) by means of an electrically scanned beam. With an on‐board microprocessor, the location of a user satellite can be computed, and the beam is pointed toward that direction automatically.In comparison with the system used in the data relay satellite of the United States, the on‐board beam‐forming system has several advantages, such as the effective use of power and frequency in the case in which the number of user satellites is small, as in Japan. In this paper, the function and the configuration of an SIC antenna are described first. Next, analysis of the antenna is presented, including the effect of the phase and amplitude errors caused by temperature fluctuations. Further, as the main components, the newly developed broadband microstrip antenna, a small beam‐forming network with small phase errors, and the phase shifter controller making the computation of the orbit of the user satellite are presented. Finally, the total test results of the on‐board model of the SIC antenna are described.

ＥＴＳ−ＶＩ搭載Ｓバンド衛星間通信用オンボード軌道計算追尾システム

On-board orbit calculation and tracking system of the S band inter-satellite communication equipment (SIC) for Japan's Engineering Test Satellite-VI (ETT-VI) to be launched in 1992, is presented. The SIC provides a multibeam phased array antenna with 54 phase shifters for beam pointing. The beams are directed to any desired user satellites automatically by controlling 54 phase shifters according to results of on-board orbit calculations by an on-board microprocessor. As accurate on-board beam pointing is required in inter-satellite communications, this paper describes a method of on-board orbit calculation and estimations of beam pointing errors caused by using the system considering perturbations.