Showing papers on "Ka band published in 2014"
TL;DR: In this article, the microwave magnetic and absorption properties were investigated for BaCoxTixFe12−2xO19 (x=0.3, 0.4 and 0.5).
108 citations
TL;DR: This study presents the evaluation of performances of different macro-diversity schemes that may allow mitigating the deep fades experienced at Q/V bands by introducing cooperation and a limited redundancy between the different gateways of the system.
Abstract: To reach the terabit per second of throughput, telecommunication satellites cannot make use of frequency below Ka band only. Therefore, the use of broad portion of the spectrum available at Q/V (40/50 GHz) band is foreseen for the feeder link. This study presents the evaluation of performances of different macro-diversity schemes that may allow mitigating the deep fades experienced at Q/V bands by introducing cooperation and a limited redundancy between the different gateways of the system. Two different solutions are firstly described. The performances resulting from the use of those assumptions are derived in a second stage.
59 citations
TL;DR: In this paper, an attenuation algorithm is provided, based on radar propagation theory, which is a function of atmospheric pressure, temperature, water vapor, and liquid water content, for the short wavelength Ka-band backscatter measurements.
Abstract: SARAL—the Satellite with ARgos and ALtiKa—is the first satellite radar altimetry mission to fly a Ka-band instrument (AltiKa). Ocean backscatter measurements in the Ka band suffer larger signal attenuation due to water vapor and atmospheric liquid water than those from Ku-band altimeters. An attenuation algorithm is provided, based on radar propagation theory, which is a function of atmospheric pressure, temperature, water vapor, and liquid water content. Because of the nature of the air–sea interactions between wind and surface gravity waves, the shorter wavelength Ka-band backscatter exhibits a different relationship with wind speed than at Ku band, particularly at moderate to high wind speeds. This paper presents a new one-dimensional wind speed model, as a function of backscatter only, and a two-dimensional model, as a function of backscatter and significant wave height, tuned to AltiKa’s backscatter measurements. The performance of these new Ka-band altimeter wind speed models is assessed thr...
52 citations
TL;DR: By combining the Cerenkov-type generator with the cascaded resonators, a Ka-band relativistic backward wave oscillator operating under the guide magnetic field 1.0 T with high power handling capability and high conversion efficiency was proposed in this paper.
Abstract: By combining the Cerenkov-type generator with the cascaded resonators, this paper proposes a Ka-band relativistic backward wave oscillator operating under the guide magnetic field 1.0 T with high power handling capability and high conversion efficiency. It is found that TM02 can be selected as the operation mode in order to increase the power handling capability and provide sufficient coupling with the electron beam. In slow wave structure (SWS), ripples composed of semicircle on top of the rectangle enhance the wave-beam interaction and decrease the intensity of the electric field on the metallic surface. Taking advantage of the resonator cascades, the output power and the conversion efficiency are promoted greatly. The front cascaded resonators efficiently prevent the power generated in SWS from leaking into the diode region, and quicken the startup of the oscillation due to the premodulation of the beam. However, the post cascade slightly postpones the startup because of the further energy extraction from the electron beam. The numerical simulation shows that generation with power 514 MW and efficiency 41% is obtained under the diode voltage 520 kV and current 2.4 kA. And the microwave with the pure frequency spectrum of 29.35 GHz radiates in the pure TM01 mode.
47 citations
TL;DR: A sheet-beam coupled-cavity traveling wave tube was used in this paper to achieve 10 kW of peak power at a center frequency of 34 GHz, with a 3-dB bandwidth of almost 5 GHz.
Abstract: A sheet-beam coupled-cavity traveling wave tube has produced over 10 kW of peak power at a center frequency of 34 GHz, with a 3-dB bandwidth of almost 5 GHz. The power of this amplifier is an order of magnitude higher than state-of-the-art conventional amplifiers of comparable frequency, bandwidth, and operating voltage $({ . This unprecedented performance is made possible by a unique, Naval Research Laboratory (NRL)-developed sheet electron beam along with a novel slow-wave interaction structure. High-current, low-voltage operation provides high gain per unit length and allows an interaction structure ${ long to be used to achieve the desired gain of 15 dB at saturation. Measured performance agrees well with 3-D particle-in-cell simulations.
45 citations
TL;DR: In this paper, an E-plane waveguide power divider and a waveguide-to-microstrip transition are used to form a wave-guide magic-T with four arms in the same plane.
Abstract: In this paper, an E-plane waveguide power divider and a waveguide-to-microstrip transition are used to form a waveguide magic-T with four arms in the same E-plane. The input port of the original E-plane waveguide power divider acts as the difference port of the magic-T, and a waveguide-to-microstrip transition is utilized to realize the sum port. The four arms are in the same plane, and traditional matching elements, such as cones, wedges, pins, and irises are not needed. The proposed magic-T features easy connection, fabrication, and assembly. The principle and design procedure are described in detail. A Ka-band E-plane waveguide magic-T is designed, fabricated, and measured. A fractional bandwidth of 21% is achieved. The measured and simulated results show good amplitude, phase, and isolation characteristics validating the proposed magic-T.
42 citations
22 Apr 2014
TL;DR: In this paper, a sheet-beam coupled-cavity traveling wave tube was used to achieve 10 kW of peak power at a center frequency of 34 GHz, with a 3-dB bandwidth of almost 5 GHz.
Abstract: A sheet-beam coupled-cavity traveling wave tube has produced over 10 kW of peak power at a center frequency of 34 GHz, with a 3-dB bandwidth of almost 5 GHz. The power of this amplifier is an order of magnitude higher than state-of-the-art conventional amplifiers of comparable frequency, bandwidth, and operating voltage (<;20 kV). This unprecedented performance is made possible by a unique, NRL-developed sheet electron beam along with a novel slow-wave interaction structure. High-current, low-voltage operation provides high gain per unit length and allows an interaction structure <; 5-cm long to be used to achieve the desired gain of 15 dB at saturation. Measured performance agrees well with 3-D particle-in-cell simulations.
31 citations
TL;DR: In this paper, the channel model of the single-polarization MIMO satellite-earth link is established, which comprehensively takes into account the propagation and scattering effects induced by those environments.
Abstract: The statistic models for evaluating the fading term caused by the incoherent scatter in clear and rainy environments are derived, which are critical for establishing the multiple-input multiple-output (MIMO) channel model at Ka band. The channel model of Ka-band single-polarization MIMO satellite-earth link is established, which comprehensively takes into account the propagation and scattering effects induced by those environments. Based on the channel model, the bit error rate (BER) performances in clear and rainy environments are investigated taking an assumed 2 × 2 satellite-earth link at 30 GHz in circular polarization as an example. During the investigation, the M-ary Phase Shift Keying (M-PSK) modulation modes with different M and the space-time codes of Space-Time Block Code (STBC), Space-Time Trellis Code (STTC) and Vertical Bell Laboratories Layered Space-Time (VBLAST) are considered. It is also discussed that the BER varies with propagation environment parameters, equivalent isotropically radiated power (EIRP), ground receiving antenna gain and elevation angle. The channel model given in this paper is also valid for the single-polarization MIMO satellite-earth link at other frequencies above 10 GHz.
29 citations
TL;DR: An implementation of circularly polarized crossed dipoles in the millimeter-wave band is presented in this paper, where a metallic ridge is added in the cavity to provide a robust feeding structure.
Abstract: An implementation of circularly polarized crossed dipoles in millimeter-wave band is presented in this paper. Novel detached crossed dipoles have been designed to tackle the problems confronted by single-fed crossed dipoles in mm-wave band. An evolution procedure from conventional crossed dipoles to the proposed ones is given. Meanwhile, a metallic ridge is added in the cavity to provide a robust feeding structure. Measurements of an optimized antenna prototype show that it can achieve a bandwidth from 27 to 36.8 GHz for both AR ≤ 3 dB and |S11| ≤ -10 dB and an average broadside gain of 12.4 dBi. The measured results agree reasonably well with simulations. For reference to practical designs, studies on five critical parameters have also been performed in this paper.
27 citations
18 Dec 2014
TL;DR: In this paper, the design of liquid crystal filled waveguide resonators is presented, and a 3-pole bandpass filter operating at a center frequency of 20 GHz and a relative bandwidth of 1% was constructed and measured.
Abstract: In this paper we present the design of Liquid Crystal filled waveguide resonators. Waveguide resonators achieve higher Q-factors then planar technologies, and form the basis for filters of smaller bandwidth. Two possible approaches for positioning the Liquid Crystal inside the cavity are discussed. One of this approaches is designed to fulfill the requirements for mechanical and temperature stability for space applications. Measured Q-factors and tuning ranges for both variants are presented, including the verification of electric biasing. Additionally a 3-pole bandpass filter operating at a center frequency of 20 GHz and a relative bandwidth of 1% was constructed and measured. Tunability with magnetic biasing was verified to be greater than 450 MHz.
23 citations
06 Apr 2014
TL;DR: In this article, the propagation conditions for Earth observation data downlink operating at the Ka band were modeled by using numerical weather forecast models to perform local high-resolution reanalysis of the meteorological conditions on which the propagation effects can be computed.
Abstract: This paper describes a methodology to model the propagation conditions for Earth observation data downlink operating at Ka band. It relies on the use of numerical weather forecast models to perform local high resolution reanalysis of the meteorological conditions on which the propagation effects can be computed. From the meteorological simulations spanning long durations, time series representative of attenuation between an orbiting satellite and a ground station are extracted, knowing orbital and RF characteristics of the system.
06 Apr 2014
TL;DR: In this article, a radiating element to be used in dual band, dual polarized Ka band satcom application is presented, which is based on an annular slot which is grounded with vias to form a coaxial structure.
Abstract: In this paper a radiating element to be used in dual band, dual polarized Ka band satcom application is presented. The radiator is based on an annular slot which is grounded with vias to form a coaxial structure. Two radiating elements operating around 20 GHz and 30 GHz are nested one into the other to form a dual band antenna. The radiator presents good performances and it is suited for array applications. In fact, it shows good isolation between bands and between polarizations and it makes possible to realize well isolated beam forming networks.
TL;DR: In this article, a ka-band multi-channel Doppler reflectometer system was constructed for the Large Helical Device (LHD) using a comb frequency generator as a source.
Abstract: A ka-band multi-channel Doppler reflectometer system was constructed for the Large Helical Device (LHD) using a comb frequency generator as a source. A filter bank system is utilized for precise quadrature phase detection, and preliminary back-scattered waves were obtained in LHD plasma experiments. In addition, a direct digital signal acquisition system was successfully demonstrated for providing a greater number of multi-channel measurements. c © 2014 The Japan Society of Plasma Science and Nuclear Fusion Research
18 Sep 2014
TL;DR: Through a new approach to broadband satellite communications, ViaSat is launching a new era in satellite broadband with the innovative design of its high-capacity Ka-band satellite system, featuring the ViaSat-1 and Viasat-2 satellites.
Abstract: Through a new approach to broadband satellite communications, ViaSat is launching a new era in satellite broadband with the innovative design of its high-capacity Ka-band satellite system, featuring the ViaSat-1 and ViaSat-2 satellites. ViaSat's new satellite architecture is transforming the performance of satellite communications and lifting the satellite industry to a more competitive position in telecommunications.
TL;DR: In this paper, a Ka-Band, High Efficiency, Small Size Spatial Combiner (SPC) is proposed, which uses an innovatively matched quadruple Fin Lines to microstrip (FLuS) transitions.
Abstract: A Ka-Band, High Efficiency, Small Size Spatial Combiner (SPC) is proposed in this paper, which uses an innovatively matched quadruple Fin Lines to microstrip (FLuS) transitions. At the date of this paper and at the Author's best knowledge no such FLuS innovative transitions have been reported in literature before. These transitions are inserted into a WR28 waveguide T-junction, in order to allow the integration of 16 Monolithic Microwave Integrated Circuit (MMIC) Solid State Power Amplifiers (SSPA's). A computational electromagnetic model using the finite elements method has been implemented. A mean insertion loss of 2 dB is achieved with a return loss better the 10 dB in the 31-37 GHz bandwidth.
09 Oct 2014
TL;DR: An efficient clustering methodology is proposed for the M2M sensor devices while the feasibility of the proposed system in terms of connectivity of the satellite gateways using high data rate terrestrial links operating at frequencies above 10 GHz, is investigated.
Abstract: In this paper, we study the performance of satellite-based sensor networks. In particular, we consider dense networks of M2M sensor devices deployed in several geographical locations. The M2M sensor devices are locally grouped into clusters and communicate with a satellite gateway. The proposed network architecture is a potential solution for remote monitoring and surveillance networks usually deployed on border and non-habitable areas. We also consider the employment of Ka band for the broadband satellite connection. Consequently, an efficient clustering methodology is proposed for the M2M sensor devices while the feasibility of the proposed system in terms of connectivity of the satellite gateways using high data rate terrestrial links operating at frequencies above 10 GHz, is investigated. Finally, we present realistic satellite link budget analysis using either GEO or LEO Ka band satellites.
18 Dec 2014
TL;DR: In this article, a hybrid beam steering concept (mechanical/electrical) is proposed and implemented for planar Ka-band antenna demonstrator for nomadic satellite communication (satcom).
Abstract: A planar Ka-Band antenna demonstrator for nomadic satellite communication (satcom) is presented. A hybrid beam steering concept (mechanical/electrical) is proposed and implemented. Here, the electrical beam steering (phased array) with its fast response time can compensate for mechanical pointing errors and hence, reduce the accuracy requirements of the mechanical positioning unit. The aperture of the antenna is realized in conventional waveguide technology with an array of radiating horn elements to achieve an extremely high aperture efficiency and radiation efficiency. Measurements and simulations show an excellent agreement and confirm the high radiation efficiency. Finally, tests of the complete system have been conducted in a life bidirectional satellite link scenario.
01 Jan 2014
TL;DR: In this paper, the applicability of CR in satellite/terrestrial spectrum sharing scenarios by modelling interference relations between these systems is discussed, and the relative impact of several design parameters that can be tuned in order to reach a particular interference target is analyzed.
Abstract: Cognitive radio (CR) is a potentially promising solution to the spectrum crunch problem that faces both future terrestrial and satellite systems. This paper discusses the applicability of CR in satellite/terrestrial spectrum sharing scenarios by modelling interference relations between these systems. It analyses the relative impact of several design parameters that can be tuned in order to reach a particular interference target. A realistic path loss model is considered and gain patterns of directional antennas are taken into account which are found to be efficient in minimising the interference. A generic model that is not restricted to particular systems is developed, and typical parameters are used to analyse the co-existence feasibility in a realistic sharing scenario. The results show that both satellite and terrestrial systems could potentially operate in the same band without degrading each other’s performance if appropriate considerations are taken into account and an appropriate design of the interfering system is carried out.
10 Jun 2014
TL;DR: A novel transmission scheme for the forward link of a broadband satellite system that aims to avoid the need for feeder-link RF spectrum is described, and promising simulation results are presented for a range of channel models, including channel measurements made with ESA's Artemis satellite.
Abstract: A novel transmission scheme for the
forward link of a broadband satellite system that
aims to avoid the need for feeder-link RF spectrum
is described1. The hybrid scheme uses one or more
optical uplinks from a hub station to geostationary
satellite, plus one or more Ka band downlinks. The
approach aims to retain the advantages of strong
channel coding with high spectral efficiency, as used
in recent high-speed digital video broadcast satellites,
yet minimise on-board processing requirements.
Promising simulation results are presented for a range
of channel models, including channel measurements
made with ESA’s Artemis satellite.
TL;DR: In this paper, a liquid crystal based tunable composite right/left-handed transmission line for future leaky wave antennas working at the Ka-band is presented, where the tuning of the liquid crystal is achieved by means of magnetic and electric biasing.
Abstract: In this work, a liquid crystal based tunable composite right/left-handed transmission line for future leaky wave antennas working at the Ka-band is presented. The tuning of the liquid crystal is achieved by means of magnetic and electric biasing. For this purpose, different prototypes are fabricated for each biasing technique and their dispersive characteristics compared. Electric tunability is achieved by implementing highly resistive bias lines in the unit cell layout. Both techniques yield similar tuning capabilities at the operation frequency of 27GHz whereas the electric one has the advantage of being easily integratable in the layout.
TL;DR: In this paper, a fully monolithic Ka-band filter-based voltage-controlled oscillator (VCO) with the 0.15 μm GaAs pseudomorphic high-electron-mobility transistor (pHEMT) active device is presented.
Abstract: This letter presents a fully monolithic Ka-band filter-based voltage-controlled oscillator (VCO) with the 0.15 μm GaAs pseudomorphic high-electron-mobility transistor (pHEMT) as the active device. A three-pole combline bandpass filter is treated as a frequency stabilization element of the feedback oscillator to achieve a low phase-noise performance. The developed VCO has a frequency tuning range of 37.608-38.06 GHz, and in this frequency rage the calibrated output power is from 6.324 dBm to 10.46 dBm. The phase noise measured at 37.608 GHz is -112.31 dBc/Hz at 1 MHz offset frequency, and its corresponding figure-of-merit (FOM) is -182.7 dBc/Hz.
23 Oct 2014
TL;DR: Interference coordination schemes, borrowed from terrestrial cellular systems, are examined in terms of applicability and C/I performance and an algorithm for dynamic interference coordination is proposed to schedule the transmissions of the users in time-frequency domain of the return link, aiming to improve theC/I.
Abstract: Future internet demands are being increased dramatically year by year. Terrestrial systems are unable to satisfy these demands in all geographical areas and thus broadband access by satellite is a key service provision platform. Considering the traffic demands, the raw capacity should approach a Terabit/s by 2020 to meet these demands. The satellite communications network will be a star-based topology, where User Terminals (UT) from multiple beams communicate via central Gateway Earth Stations (GES). The return link from UT to satellite will use DVB-RCS2 Multi-Frequency Time Division Multiple Access (MF-TDMA) transmission scheme in Ka band (30GHz), while the return feeder link from satellite to GES in Q band (40 GHz). Due to generation of large number of narrow user beams, the interference starts becoming a limiting factor in the system's dimensioning. Herein, interference coordination schemes, borrowed from terrestrial cellular systems, are examined in terms of applicability and C/I performance. In addition, an algorithm for dynamic interference coordination is proposed to schedule the transmissions of the users in time-frequency domain of the return link, aiming to improve the C/I. The performance of these schemes and the proposed algorithm is assessed over a 302 user beams satellite system with practical antenna radiation patterns.
06 Apr 2014
TL;DR: In this article, the authors describe a number of innovative flat plate mechanically steered low profile antennas that are being developed in X- and Ka-band to satisfy the conflicting requirements of high efficiency, compliance with regulatory requirements, cost-effective design, mechanical robustness, compact envelope and support for tracking systems.
Abstract: High data rate communications on the move is fast becoming a major application area for satellite systems using X- and higher frequency bands. The ground terminal antenna used in such systems has a profound impact on the system capabilities and is constrained in many often conflicting ways. While simple reflector systems offer the lowest cost solution, there is a widespread need for low profile antennas to minimize the antenna visual signature and to satisfy aesthetic and transportation requirements. In this paper, we will describe a number of innovative flat plate mechanically steered low profile antennas that are being developed in X- and Ka-Band to satisfy the conflicting requirements of high efficiency, compliance with regulatory requirements, cost-effective design, mechanical robustness, compact envelope and support for tracking systems.
01 Dec 2014
TL;DR: In this article, a low noise amplifier (LNA) has been designed to operate across the Ka-band from 26 GHz to 36 GHz, and according to the simulations, it presents an average gain of 33 dB, a noise figure less than 1.8 dB and return loss better than 12 dB at both the input and the output.
Abstract: A low noise amplifier (LNA) has been designed to operate across the Ka-band from 26 GHz to 36 GHz. It has been designed using a commercial 100 nm GaAs process, and according to the simulations, it presents an average gain of 33 dB, a noise figure less than 1.8 dB and return loss better than 12 dB at both the input and the output. To the knowledge of the authors, the performance of this LNA would be superior to any other GaAs based LNA so far reported in the same frequency band at room temperature. Due to the increasing importance of arrays and multi-pixel systems in radio astronomy, the utilization of this low-cost LNA in this new concept of telescopes will be discussed. Two possible applications of this LNA, in the new 13.2 meter radio telescope of Yebes (Spain), and a use in large format arrays, will be highlighted and a possible 10% reduction in observing time will be shown.
06 Apr 2014
Abstract: Single and double layer frequency selective surfaces (FSS) for Circular polarization (CP) operation were designed. The designed FSS provide reflection in the Ku-band (11.7-12.75 GHz) and transmission in the Ka-band (17.3-20.2 GHz). CP is conserved in each of the bands. For the double layer design over the Ku-band the reflection loss was less than 0.05 dB for TE and TM polarizations while the axial ratio was below 0.2 dB. Over the Ka-band transmission loss and axial ratio were each less than 0.25 dB.
TL;DR: In this paper, a tunable single-bandpass microwave photonic filter with a narrow and flat-top shape operating in high frequency range is proposed and experimentally demonstrated, using a specially designed multi-phase-shift fiber Bragg grating (FBG) cascaded with a programmable optical filter (POF).
Abstract: A tunable single-bandpass microwave photonic filter (MPF) with a narrow and flat-top shape operating in high frequency range is proposed and experimentally demonstrated, using a specially designed multi-phase-shift fiber Bragg grating (FBG) cascaded with a programmable optical filter (POF). The key device in the proposed MPF is the multi-phase-shift FBG, providing a flat-top passband with a narrow 3-dB bandwidth of 813 MHz in transmission. Consequently, in the MPF, a single passband with a 3- and 20-dB bandwidths of 840 MHz and 2.43 GHz is achieved, respectively. Moreover, an operating frequency range from 27.1 to 38.1 GHz is realized by tuning the wavelength of the optical carrier and adjusting the transfer function of the POF. To the best of our knowledge, this proposed filter provides the highest tunable frequency coverage in Ka-band ever reported for MPFs with a single narrow and flat-top passband.
TL;DR: In this paper, a cascaded circular-polarisation-selective surface (CPSS) based on bisected split rings is proposed to allow the transmission of one sense of circular polarisation while reflecting the other sense.
Abstract: A cascaded circular-polarisation-selective surface (CPSS) based on bisected split rings is presented. The proposed CPSS allows the transmission of one sense of circular polarisation while reflecting the other sense. To validate the proposed design, a nine-layer prototype that operates in the Ka band has been designed, fabricated and tested. Experimental results show that transmission coefficients higher than −1 dB and axial ratios lower than 3 dB are obtained for one sense of circular polarisation, whereas transmission coefficients lower than −20 dB are obtained for the opposite sense over the frequency band from 26.39 to 35.43 GHz.
06 Apr 2014
TL;DR: In this article, the authors describe a new concept of a mobile Ka band antenna for SATCOM on-the-move applications, which exhibits polarization switching capabilities, low profile and shows a highly efficient performace thanks to the use of rectangular waveguides for the distribution network.
Abstract: This document describes a new concept of a mobile Ka band antenna for SATCOM on-the-move applications. Unlike most antennas in this field, this antenna exhibits polarization switching capabilities, it is low profile and shows a highly efficient performace thanks to the use of rectangular waveguides for the distribution network.
31 Oct 2014
04 Oct 2014
TL;DR: In this paper, the applicability of CR in satellite/terrestrial spectrum sharing scenarios by modelling interference relations between these systems is discussed, and the relative impact of several design parameters that can be tuned in order to reach a particular interference target is analyzed.
Abstract: Cognitive radio (CR) is a potentially promising solution to the spectrum crunch problem that faces both future terrestrial and satellite systems. This paper discusses the applicability of CR in satellite/terrestrial spectrum sharing scenarios by modelling interference relations between these systems. It analyses the relative impact of several design parameters that can be tuned in order to reach a particular interference target. A realistic path loss model is considered and gain patterns of directional antennas are taken into account which are found to be efficient in minimising the interference. A generic model that is not restricted to particular systems is developed, and typical parameters are used to analyse the co-existence feasibility in a realistic sharing scenario. The results show that both satellite and terrestrial systems could potentially operate in the same band without degrading each other’s performance if appropriate considerations are taken into account and an appropriate design of the interfering system is carried out.