Tropospheric attenuation on Satellite-aircraft propagation: A concise review

The attenuation time together with the Complementary Cumulative Distribution Function of attenuation values play a vital role in the design of communication systems. Passengers on-board during flight can be connected to the internet either via satellite or earthstation depending on the nature of the flight. For long distance flight, this internet connectivity is provided through satellite when the aircraft is flying at the upper troposphere. However, the satellite-aircraft link is subject to attenuation due to the troposphere. A model to characterize the channel has been proposed. In particular, a methodology for the synthesis of attenuation on aircraft-satellite is given by ITU-R P2041 recommendation. However, it has been shown that the impact of tropospheric parameters such as rainfall, cloud, gases etc. On the satellite-aircraft link at different frequencies are insignificant (i.e decreases with height) on the upper troposphere since the aircraft is flying (about 12 km) above the rain height (5 km). The findings will be useful for researchers, scientists and the aviation industries in planning, design and establishing link budget for aircraft-satellite path

Data distribution satellite

A description is given of a data distribution satellite (DDS) system. The DDS would operate in conjunction with the tracking and data relay satellite system to give ground-based users real time, two-way access to instruments in space and space-gathered data. The scope of work includes the following: (1) user requirements are derived; (2) communication scenarios are synthesized; (3) system design constraints and projected technology availability are identified; (4) DDS communications payload configuration is derived, and the satellite is designed; (5) requirements for earth terminals and network control are given; (6) system costs are estimated, both life cycle costs and user fees; and (7) technology developments are recommended, and a technology development plan is given. The most important results obtained are as follows: (1) a satellite designed for launch in 2007 is feasible and has 10 Gb/s capacity, 5.5 kW power, and 2000 kg mass; (2) DDS features include on-board baseband switching, use of Ku- and Ka-bands, multiple optical intersatellite links; and (3) system user costs are competitive with projected terrestrial communication costs

Proceedings of the Fifteenth NASA Propagation Experimenters Meeting (NAPEX 15) and the Advanced Communications Technology Satellite (ACTS) Propagation Studies Miniworkshop

The NASA Propagation Experimenters Meeting (NAPEX), supported by the NASA Propagation Program, is convened annually to discuss studies made on radio wave propagation by investigators from domestic and international organizations. The meeting was organized into three technical sessions. The first session was dedicated to Olympus and ACTS studies and experiments, the second session was focused on the propagation studies and measurements, and the third session covered computer-based propagation model development. In total, sixteen technical papers and some informal contributions were presented. Following NAPEX 15, the Advanced Communications Technology Satellite (ACTS) miniworkshop was held on 29 Jun. 1991, to review ACTS propagation activities, with emphasis on ACTS hardware development and experiment planning. Five papers were presented

Satellite Communications

This study is motivated by the need to give the reader a broad view of the developments, key concepts, and technologies related to information society evolution, with a focus on the wireless communications and geoinformation technologies and their role in the environment. Giving perspective, it aims at assisting people active in the industry, the public sector, and Earth science fields as well, by providing a base for their continued work and thinking

Frequency diversity wideband digital receiver and signal processor for solid-state dual-polarimetric weather radars

2012 Summer.Includes bibliographical references.The recent spate in the use of solid-state transmitters for weather radar systems has unexceptionably revolutionized the research in meteorology. The solid-state transmitters allow transmission of low peak powers without losing the radar range resolution by allowing the use of pulse compression waveforms. In this research, a novel frequency-diversity wideband waveform is proposed and realized to extenuate the low sensitivity of solid-state radars and mitigate the blind range problem tied with the longer pulse compression waveforms. The latest developments in the computing landscape have permitted the design of wideband digital receivers which can process this novel waveform on Field Programmable Gate Array (FPGA) chips. In terms of signal processing, wideband systems are generally characterized by the fact that the bandwidth of the signal of interest is comparable to the sampled bandwidth; that is, a band of frequencies must be selected and filtered out from a comparable spectral window in which the signal might occur. The development of such a wideband digital receiver opens a window for exciting research opportunities for improved estimation of precipitation measurements for higher frequency systems such as X, Ku and Ka bands, satellite-borne radars and other solid-state ground-based radars. This research describes various unique challenges associated with the design of a multi-channel wideband receiver. The receiver consists of twelve channels which simultaneously downconvert and filter the digitized intermediate-frequency (IF) signal for radar data processing. The product processing for the multi-channel digital receiver mandates a software and network architecture which provides for generating and archiving a single meteorological product profile culled from multi-pulse profiles at an increased data date. The multi-channel digital receiver also continuously samples the transmit pulse for calibration of radar receiver gain and transmit power. The multi-channel digital receiver has been successfully deployed as a key component in the recently developed National Aeronautical and Space Administration (NASA) Global Precipitation Measurement (GPM) Dual-Frequency Dual-Polarization Doppler Radar (D3R). The D3R is the principal ground validation instrument for the precipitation measurements of the Dual Precipitation Radar (DPR) onboard the GPM Core Observatory satellite scheduled for launch in 2014. The D3R system employs two broadly separated frequencies at Ku- and Ka-bands that together make measurements for precipitation types which need higher sensitivity such as light rain, drizzle and snow. This research describes unique design space to configure the digital receiver for D3R at several processing levels. At length, this research presents analysis and results obtained by employing the multi-carrier waveforms for D3R during the 2012 GPM Cold-Season Precipitation Experiment (GCPEx) campaign in Canada

1-D broadside-radiating leaky-wave antenna based on a numerically synthesized impedance surface

A newly-developed deterministic numerical technique for the automated design of metasurface antennas is applied here for the first time to the design of a 1-D printed Leaky-Wave Antenna (LWA) for broadside radiation. The surface impedance synthesis process does not require any a priori knowledge on the impedance pattern, and starts from a mask constraint on the desired far-field and practical bounds on the unit cell impedance values. The designed reactance surface for broadside radiation exhibits a non conventional patterning; this highlights the merit of using an automated design process for a design well known to be challenging for analytical methods. The antenna is physically implemented with an array of metal strips with varying gap widths and simulation results show very good agreement with the predicted performance

Beam scanning by liquid-crystal biasing in a modified SIW structure

A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium

Proceedings of the Third International Mobile Satellite Conference (IMSC 1993)

Satellite-based mobile communications systems provide voice and data communications to users over a vast geographic area. The users may communicate via mobile or hand-held terminals, which may also provide access to terrestrial cellular communications services. While the first and second International Mobile Satellite Conferences (IMSC) mostly concentrated on technical advances, this Third IMSC also focuses on the increasing worldwide commercial activities in Mobile Satellite Services. Because of the large service areas provided by such systems, it is important to consider political and regulatory issues in addition to technical and user requirements issues. Topics covered include: the direct broadcast of audio programming from satellites; spacecraft technology; regulatory and policy considerations; advanced system concepts and analysis; propagation; and user requirements and applications

Fully Integrated 60 GHz Power Amplifiers in 45nm SOI CMOS

With the rapid growth of consumer demand for high data rates and high speed communications, the wireless spectrum has become increasingly precious. This has promoted the evolution of new standards and modulation schemes to improve spectral e fficiency. The allocation of large bandwidths is an alternative to increase the channel capacity and data rate, however the availability of spectrum below 10 GHz is very limited. Recently, the 60 GHz spectrum has emerged as a potential candidate to support multi-Gb/s applications. It off ers 7 GHz of unlicensed spectrum, for development of Wireless Personal Area Networks (WPAN) and cellular backhauls. Meanwhile, the scaling and advancement of low-cost complementary metal-oxide semiconductor (CMOS) technologies has enabled the use of CMOS devices at millimeter wave frequencies and the integration of analogue and digital circuitry has created platform for single chip radio development. However, low power density, low optimum load resistance and poor quality integrated passives (due to lossy silicon substrate) make CMOS technology a poor candidate for power ampli fier (PA) design when, compared to silicon germanium and Group III-V technologies (gallium nitride, gallium arsenide and indium phosphide). In order to overcome the above mentioned challenges in CMOS, this thesis re-explores FET-stacking as a power combining technique at 60 GHz using 45nm silicon-on-insulator (SOI) CMOS for millimeter-wave PAs. The stacking approach enables the use of higher supply voltages to obtain higher output power, and its higher load line resistance Ropt allows for the use of low impedance transformation matching networks. The reliability of CMOS PA under large signal operation is also addressed and improved with the FET-stacking approach applied in this work. This thesis divides the millimeter-wave PA design problem in to two areas, active and passive, both of which are critically designed for optimum performance in terms of effi ciency and output power while taking device and substrate parasitics into consideration. A transistor unit cell combination topology, the 'Manifold', has been analyzed and applied in 45 nm SOI CMOS for large RF power transistor cells. Moreover, various topologies of slow wave coplanar waveguide (CPW) lines are analyzed and implemented on the SOI substrate to synthesize inductors for matching networks at 60 GHz. To demonstrate the active and passive design performance in 45nm SOI CMOS at 60 GHz, a two-stage cascode PA is presented. Measurement under continuous wave (CW) stimulus shows 18.2 dB gain, a 3 dB bandwidth of 20%, 14 dBm saturated output power at 22% peak power-added e fficiency (PAE). Moreover, to validate the FET-stacking analysis, a three-stack PA is designed and fabricated with an output performance of 8.8 dB gain, a 3 dB bandwidth of 20%, 16 dBm saturated output power at 14% peak PAE. Finally, a wideband three stage amplifi er is designed utilizing the two-stage cascode and three-stack PA, achieving 21.5 dB at gain over a fractional bandwidth of 20%, and 16 dBm saturated output power at 13.8% PAE