Antenna For Mobile Satellite Communications Research Articles

Additively Manufactured Half-Gutman Lens Antenna for Mobile Satellite Communications

In this letter, we present an additively manufactured half-Gutman lens antenna operating at 30 GHz. The hemispherical lens allows for a compact beamformer while maintaining the wide scanning capabilities of Gutman lenses. This solution further enables to better integrate the feed system when compared to a more conventional half-Luneburg lens antenna design as the focal arc is moved inside the lens. The graded-index of the lens is implemented with a periodic structure arranged in a body-centred cubic (BCC) lattice. We demonstrate that the BCC structure provides attractive properties for the design of inhomogeneous dielectric lenses. Importantly, the BCC structure can be used to alleviate the manufacturing constrains compared to conventional periodic structures. The lens is fed by a dielectric-loaded square waveguide. The proposed antenna produces a directive beam with a simulated and measured peak gain of 26.2 and 25.3 dBi. The antenna can steer its beam in a 50 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ$</tex-math></inline-formula> range in elevation with measured scan loss and sidelobe levels below 1 dB and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$-$</tex-math></inline-formula> 10 dB, which agree with the simulated values. The measured cross polarization discrimination is better than 20 dB. The proposed antenna is intended for the ground segment of the emerging low-Earth-orbit satellite communication applications.

Simultaneously RHCP and LHCP Radiating Polarization Diversity C-Slot Antenna for Mobile Satellite Communications

A new antenna for satellite-based mobile radio systems for communication with geostationary satellites is presented. The antenna allows the both right-handed (RH) and left-handed (LH) circular polarized (CP) waves to be transmitted/received independently over an elevation range from −20° to −75° and 20°–75° in the direction of zenith concurrently. The concurrent transmission of dual-sense CP in the non-identical spatial directions allows the antenna to behave as polarization diversity transceiver. Simultaneous dual-sense CP is achieved primarily by exciting the C-shaped slot of approximately one full wavelength symmetrically with a microstrip line. The simulated impedance bandwidth is 12.5% with respect to the center frequency of 4.8 GHz and axial ratio bandwidth of 11.7% is attained. In the aforementioned elevation ranges, the measured gain isolation between the RHCP and the LHCP components is maintained above 10 dB. The back radiation of antenna is shown to be minimized by using a square-shaped mushroom-based artificial magnetic conductor.

Modelling and stabilization of a three-axis ship-mounted mobile antenna system

A mobile satellite communication antenna is a device installed on a moving carrier for mobile satellite communication. Gimballed motorized pedestals are used to eliminate the effect of disturbance and maintain uninterrupted communication when the carrier is moving. Mobile satellite communication antennas are becoming increasingly more popular due many advantages of mobile satellite communication. In this paper, a three-axis ship-mounted antenna on a pedestal gimbal system is studied. We study the problem with a different perspective and method from the previous work for two-axis antenna pedestals. The former studies treat the subsystems to be isolated and design controllers separately, which neglect the coupling effects in the dynamics of two or three-axis antenna pedestal gimbals. We treat three sub-systems as a whole and derive the dynamic model of the system using the Newton–Euler method. Based on the dynamic model, linear PI controllers are designed to stabilize the antenna to keep its orientation towards the satellite. The design objective of the control system is to direct the on-board antenna toward a satellite and to keep its orientation unaltered despite the effect of sea waves disturbing the antenna. Simulation results are presented to show the stabilization performance of the system with the synthesized controllers.

High-Gain Planar Antenna Arrays for Mobile Satellite Communications [Antenna Applications Corner

Two large and low-profile panel antenna arrays, used as receiving and transmitting antennas for mobile satellite communications, are described. The receiving and transmitting arrays have overall dimensions of 120 cm × 20.7 cm × 1.3cm and 107.5 cm × 20.4 cm × 1.7 cm, respectively. They exhibit high gains and adequate efficiencies, due to integrated array designs. For the receiving panel array, a method using a number of high-efficiency subarrays, combined with a novel active integrated global feed network, is proposed. For the transmitting panel array, a number of high-efficiency subarrays, together with a novel compact waveguide feed network, is employed. Based on the above techniques, two large panel antenna arrays were successfully developed. We present the detailed designs of the subarrays, the passive and active feed networks, and the vertical transitions. Simulated and experimental results showed that the designed receiving and transmitting panel arrays achieved measured gains and efficiencies of 34.1 dBi and 48.2%, and 33.5 dBi and 36.3%, respectively, in each band. This indicated that the proposed antenna panels are good candidates for future satellite communications applications.

Phased array antenna with crossed dipole antenna for mobile satellite communications

AbstractIn this article, we propose a phased array antenna which uses a crossed dipole antenna with a reflector as an element antenna.The element antenna has conical radiation pattern which is useful for a satellite communication mobile station antenna. The element antenna radiates linearly polarized wave. Both simulation with electromagnetic simulator and experiment are performed in 19‐element array antenna for the beam scanning characteristics. From measured results, the obtained antenna gain is more than 10 dBi from 30° to 60°. It is shown that the characteristics of the array antenna are effective to use for a satellite communications. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 2805–2809, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26424

Circularly polarised equilateral triangular patch array antenna for mobile satellite communications

A satellite-tracking left-handed circularly polarised triangular-patch array antenna has been developed to support the next generation of mobile satellite communications using Japanese Engineering Test Satellite VIII. The targeted minimum gain of the antenna was set to 5 dBic at an elevation of 48° in the Tokyo area, for applications of about a hundred kbit/s data transfer. The antenna is composed of three equilateral triangular patches and fed by a dual-proximity feed. The influence of the array configuration on the characteristic of this antenna is investigated using a method of moments (MoM) approach and a simple point source model. The measurement of the fabricated antenna was then performed to confirm the simulation results. The result showed that the 10 mm distance between the patch apex to the centre of the array antenna satisfies the target. The frequency characteristic of the fabricated antenna is 0.7% shifted to the higher frequency, and the maximum gain is 0.9 dB lower than the simulation results. The result also shows that the characteristic of the patch array antenna satisfies the specification at elevation angle El=48°, especially the 5 dBic gain coverage of the results covers the whole azimuth angle in a conical-cut plane at El=48°.

Circularly polarised equilateral triangular patch antenna for mobile satellite communications

A left-handed circularly polarised (LHCP) triangular patch antenna is developed to support the next generation of mobile satellite communications using Engineering Test Satellite VIII (ETS-VIII). The targeted minimum gain of the antenna is set to 5 dBic for applications of a hundred kbps data transfer with an axial ratio less than 3 dB for circular polarisation. A dual-proximity-coupled equilateral triangular patch antenna is proposed and simulated by the method of moments (MoM) for finite and infinite ground plane models to investigate the ground plane effect. Then measurements of the fabricated antenna are performed to confirm the simulation results. The measurement results show that the frequency characteristics of the fabricated antenna is 0.2% shifted to the higher frequency, and the maximum gain is 0.45 dB lower than the result of the finite ground plane model. Additionally, the simulation results show the ground plane size influences the antenna characteristics, especially the gain and axial ratio of the developed antenna.

Numerical analysis of ground plane size effects on patch array antenna characteristics for mobile satellite communications

In this research, a patch array antenna for mobile satellite communications aiming at ETS-VIII applications has been developed. The ground plane size effects on the antenna characteristics were investigated. Finite and infinite ground planes were analysed by the finite integration technique (FIT) for time domain analysis, the finite element method (FEM) and the method of moments (MoM) for spectral domain analysis. Then measurements of the fabricated antenna were performed to confirm the analysis results. It is clear that the frequency characteristics of the axial ratio are influenced by the variation in the ground plane size. When the ground plane size is increased, the edge-diffracted field causes tilting of the beam in the direction of low elevation angles and causes a decrease in the maximum gain and in the 3 dB-beamwidth of axial ratio in the elevation plane. In the conical-cut direction, an increase in ground plane size induces a decrease in the 3 dB-beamwidth of axial ratio for FEM, but shows the opposite result for FIT and measurement. In addition, an increase in ground plane size also induces increases in maximum gain and its 6 dBic-beamwidth along with a shift in the maximum gain in the direction of low azimuth angle. Copyright © 2004 John Wiley & Sons, Ltd.

Simple satellite-tracking stacked patch array antenna for mobile communications experiments aiming at ETS-VIII applications

The Japan Aerospace Exploration Agency (JAXA) plans to launch a geostationary satellite called Engineering Test Satellite-VIII (ETS-VIII) in 2004. In the paper, the feasibility of reaching a relatively high value of gain at low elevation angle by use of a simple left-handed circularly polarised four-element stacked patch array antenna for mobile satellite communications in the S-band frequency aiming at ETS-VIII applications is discussed. The characteristics of this antenna are confirmed by two numerical methods (the method of moments and the finite element method) and by measurements. Furthermore, the influence of the finite size of the ground plane was analysed using of the finite element method. Both numerical analyses and measurements are presented. In addition, the operation of beam-switching is experimentally confirmed. It is revealed that, by properly feeding the patches constituting the antenna, for an elevation El=48° (θ=42°) in Tokyo, four beams are created in the conical-cut direction at azimuth Az=6°, 96°, 190°, and 276°. The gain reached more than 6.5 dBic on the whole azimuthal range, with an axial ratio less than 3 dB.

A two-ring circular phased-array antenna for mobile satellite communications

This paper presents the design and development of an L-band planar, multi-layer circular array for possible use with the Australian geostationary mobile-satellite-communications system, Mobilesat/sup TM/. Twelve single-feed, stacked aperture-coupled microstrip patches, interleaved with low-cost dielectric foam and arranged in two rings, form the array. The beam-forming network is comprised of three-bit phase shifters, which are located under the antenna elements. Low-cost UHF-band switching diodes were used to minimize the developmental cost of these phase shifters. In order to make the diodes operational at L-band, an LC compensation technique was applied to the diodes to tune out parasitic reactance. Experimental results for individual antenna elements and phase shifters, followed by the results for the entire array, are presented. The indoor testing results for the manufactured antenna showed that the array satisfies the specifications of Mobilesat/sup TM/. This was also confirmed by outdoor field trials with a NEC S1 transceiver terminal.

A compact switched‐beam array antenna for mobile satellite communications

This paper presents the design and development of a compact switched-beam array antenna for operation with the Australian mobile satellite communications system. MobilesatTM. The antenna is formed by eight aperture-coupled microstrip patch elements that are positioned on the side of a truncated cone. Two elements, facing the satellite, are activated using an eight-way two-ports-on radial switch. The output ports of the radial switch incorporate 1-bit phase shifters. A total of 24 beams are produced using this beam-forming system. In order to reduce the manufacturing cost, inexpensive substrates and low-cost UHF p-i-n diodes are employed. Further reduction in cost is achieved by eliminating coaxial connectors between the beam-forming network and the antenna elements. Experimental results are presented for the individual antenna elements, the beam-forming network, and the entire switched-beam array. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 21: 186–191, 1999.

A compact switched-beam array antenna for mobile satellite communications

This paper presents the design and development of a compact switched-beam array antenna for operation with the Australian mobile satellite communications system. Mobilesat(TM). The antenna is formed by eight aperture-coupled microstrip patch elements that are positioned on the side of a truncated comb Two elements, facing the satellite, are activated using an eight-way two-ports-on radial switch. The output ports of the radial switch incorporate 1-bit phase shifters A total of 24 beams are produced using this beam-forming system. lit order to reduce the manufacturing cost, inexpensive substrates and low-cost UHF p-i-n diodes are employed Further reduction in cast is achieved by eliminating coaxial connectors between the beam-forming network and the antenna elements. Experimental results are presented for the individual antenna elements, the beam-forming network, and the entire switched-beam array. (C) 1999 John Wiley & Sons, Inc.

Slot-coupled self-diplexing array antenna for mobile satellite communications

An experimental investigation of a novel two-layered slot-coupled self-diplexing antenna for mobile satellite communications is presented. A transmitting circular patch antenna is stacked on a receiving ring patch antenna. A modified symmetrical cross-slot is used to feed the circular patch antenna. Orthogonal two-point and four-point feeding methods for the ring patch antenna are compared. Characteristics of an isolated antenna element and a 16-element phased array antenna are presented. For the 16-element array, isolation between the transmitting and receiving ports was greater than 20 dB for a scanning angle of /spl plusmn/60.

Channel-individual adaptive beamforming for mobile satellite communications

A digital frequency-division multiplex demultiplexer for single channel per carrier (SCPC) signals was developed for use in a digital channel-individual beamforming network for an adaptive satellite array antenna for mobile satellite communications. The available ASIC (35000 gate functions in CMOS technology, clock rate up to 30 MHz with low power consumption) permits the separation of FDM signals comprising up to 16 channels. Starting from a suitable model for the demultiplexer beamforming system, this paper describes the analysis, design, simulation and implementation of the hierarchically structured demultiplexer. Aspects of digital beamforming are only discussed as far as necessary for understanding. >

One-point feed printed crossed dipole with a reflector antenna combined with a reactively loaded parasitic loop for land mobile satellite communication antennas

A one-point feed printed crossed dipole with a reflector antenna combined with a reactively loaded parasitic loop is proposed. The parasitic loop contributes mainly to the improvement of the antenna gain, and the reactive loads contribute mainly to the improvement of the frequency response of axial ratio. Using the proposed antenna, a 4-element printed array antenna is constructed for land mobile satellite communications to obtain highly efficient, compact, light weight array antenna.

Feed circuits of double-layered self-diplexing antenna for mobile satellite communications

An analysis of feed circuits for a double-layered self-diplexing antenna for mobile satellite communications is presented. It is possible to reduce the weight of the diplexer for a self-diplexing antenna by getting large internal isolation between transmitting and receiving. The internal isolation is shown to be heavily dependent on the configuration and errors of the feed circuits of the antenna. The feed circuits of two- and four-point feeds for the antenna are discussed, using the cavity model of microstrip elements, and an error analysis of the feed circuit is carried out. >

Spherical array antenna using digital beamforming techniques for mobile satellite communications

AbstractProblems arise in providing excitation phases and amplitudes to individual antenna elements for wide‐angle scanning by applying spherical array antennas for mobile satellite communications for ships, automobiles, and aircraft. These antennas do not have many antenna elements. Thus, emphasis is on obtaining the maximum gain rather than realizing the characteristics of low sidelobe levels.This paper considers the application of spherical arrays for antennas of mobile satellite communications. An adoption of a control method is assumed which regulates the phases and amplitudes freely and accurately for individual antenna elements for the beamforming circuits of digital beamforming antennas. A beamforming method is examined for spherical arrays.First, a selection of necessary antenna elements is proposed utilizing the received signals and an adjustment of their phases and amplitudes. This method is applied to a 16‐element spherical array which had circular micro‐strip antennas. Their radiation characteristics are calculated. As a result, it was clarified that the maximum directive gain could be obtained almost without being influenced by the properties of individual antenna elements.Next, circuits are designed for the reception of binary PSK signals of constant envelope modulated waves. Carrier recovery circuits are established for individual antenna elements for spherical arrays, and a method is used to detect their phases and amplitudes. The method shows the effectiveness in obtaining the amount of gain reduction due to the detected phase and amplitude errors.

Conformal array antenna for mobile satellite communications

In the case of mobile satellite communication antennas for automobiles and aircraft, a necessary electrical characteristic is to scan the beam over a wide angle. Also, from the viewpoint of aerodynamics and design, conformal arrays are desirable which are fit to the shape of the moving body. This paper discusses the radiation characteristics of a conformal array suitable for mobile satellite communications. In addition, a one-piece fabrication of a conformal array is carried out and its electrical characteristics are evaluated. First, it is shown by means of computation of a 16-element partial spherical array with icosahedron arrangement that the radiation characteristics can be varied by adjusting the curvature in the conformal array and there exists an optimum value. Next, a trial fabrication is carried out to establish a one-piece fabrication technique. The test results are described for a 16-element hemispherical array made by a vacuum-forming method and a 16-element partial spherical array made by a roundfaced compression method which is employed to improve the fabrication accuracy of a thin partial spherical array. Excellent single-element characteristics and array radiation characteristics are obtained with the 16-element partial spherical array using the round-faced compression method. Hence, the validity of the fabrication method is verified.