Danielle George

A System Engineering Analysis of Highly Adaptive Small Satellites

Spacecraft systems have undergone tremendous system-level transformations following advances in subsubsystems, subsystems, and systems designs and technologies. Furthermore, the ever expanding space applications and entrants necessitate a holistic review of current spacecraft system engineering (SE) margins. This paper seeks to examine contemporary space systems engineering procedures and develop a corresponding SE analysis tool for next-generation small satellites. Mass and power budgets are the considered SE margins. Case studies of highly adaptive small satellites (HASS) for a meteorology mission in low earth orbit are presented. HASS have demonstrated mass-, power-, and cost-savings with advanced capabilities than the conventional ones. The presented SE procedure can be extended to any spacecraft category and mission. As a capability-based SE analysis tool, it will enable the design and development of lightweight, reliable, adaptive, optimal, multifunctional, and economical satellites. This will enhance the provision of space systems that have postmission reapplications capability.

Impact of Noise Figure on a Satellite Link Performance

Small satellite link performance analysis is critical for assessing the adequacy of a transmitter to successfully transfer data at the desired rate. This is especially obvious when considering highly adaptive small satellite systems that exhibit static and active/dynamic power requirements. This paper presents the impact of noise figure on the carrier and data links performances of a highly adaptive small satellite application. The noise figures of a MMIC LNA, designed using GaAs technology operating within the C- and X-bands, were used to study the link performance of a planetary mission. An existing Magellan spacecraft link performance was considered in this study. The analysis reveals that designing a broadband LNA to have a ripple of less than 0.1 dB within its operating bandwidth is essential for a less than 2 dB drop in the carrier and data links margins. This fixes a 6.8 K receiver noise temperature swing margin for reliable, dynamic, broadband and adaptive space operations.

A system-based design methodology and architecture for highly adaptive small satellites

System-level conception, design and analysis are fundamental to ensuring the reliability and operability of complex systems. The ever-expanding and demanding global space activity requires, amongst other performance metrics, multifunctional, reconfigurable and adaptive system architectures. Consequently, there is need for developing a systems engineering tool/platform for assessing multipurpose space applications and decommissioned satellite systems reapplication. This paper presents a system-based design methodology and architecture for highly adaptive small satellites (HASSs). The developed HASS methodology beacons on the basic systems engineering design process and generalised information network analysis (GENA) model. The HASS methodology and architecture address the space mission and conceptual design objectives. The iterative process provides options for mission(s) definition and combinations and space system transformation. It also allows the designer to choose from available device technologies for specific and integrated applications with allowance for trade-offs and evaluation. Depending on the unique attributes of interest, the small satellite subsystem components can be selected for a specific mission. Furthermore, mission-defined quality of service metrics are assigned prior to the system trade space exploration. HASS-based multicriteria studies are then performed for qualifying the optimal system architectures. This adaptive space system-level platform allows the designer to optimize device technologies, systems and subsystems configurations and architectures in an integrated environment. The attendant benefits, are reduced design, launch and operations costs, reliability, adaptive remote monitoring and support for broadband and/or multimedia applications.

4 – 8 GHz LNA design for a highly adaptive small satellite transponder using InGaAs pHEMT technology

The ever increasing global space activity is characterised by emerging space systems, operation and applications challenges. Hence, reliable RF and microwave receivers for in-orbit highly adaptive small satellites are needed to support reconfigurable multimedia/broadband applications in real-time with optimal performance. Though other parameters of the small satellite communication system may be critical, the noise level of the receiver determines the viability, reliability and deliverability of the project. Thus, a good design that delivers low noise performance, high gain and low power consumption for multipurpose space missions is inevitable. This paper describes a 0.15µm InGaAs pseudomorphic high electron mobility transistor amplifier with low noise and high gain in the frequency band 4 – 8 GHz. The monolithic microwave integrated circuit LNA design presented here shows the best performance known using this technology; noise figure of 0.5 dB and gain of 37 ± 1 dB over the characterised bandwidth.

A system engineering consideration for future-generations small satellites design

The conventional point-based satellite system engineering design procedure is insufficient to address the dynamic operations and post-mission reuse of capability-based small satellites. Emerging space systems and missions require an adaptive architecture(s) that can withstand the radiation-prone flight environment and respond to in-situ environmental changes using onboard resources while maintaining its optimal performance. This proactive and reactive response requirement poses an enormous conceptual design task in terms of the trade space - which can be too large to explore, study, analyse and qualify - for a future-generation adaptive small satellite system. This paper involves a careful study of the current and emerging space system technologies, architectures and design concepts for realising adaptive small satellites for future space applications. Adaptive multifunctional structural units (AMSUs) that eliminate subsystem boundaries and enable five levels of inorbit customisations at the system level have been qualified for highly adaptive small satellites (HASSs). The initial system engineering (SE) analyses reveal that the HASS system has mass, cost and power savings over the conventional small satellite implementation. The reported novel research findings promise to enable capability-based, adaptive, cost-effective, reliable, multifunctional, broadband and optimal-performing space systems with recourse to post-mission re-applications. Furthermore, the results show that the developed system engineering design process can be extended to implement higher satellite generation missions with economies of scale.

Comparative Study of HEMTs for LNAs in Square Kilometer Array telescope

The paper focuses on a comparative study of transistors of different dimensions from nine prominent low noise HEMT processes around the world. The transistors include a combination of pHEMTs and mHEMTs based on GaAs and InP substrates with gate lengths ranging from 150nm to 70nm. The Square Kilometre Array telescope will require more than 30 million low noise amplifiers (LNA). Importance of power consumption and variation of ambient temperature of the amplifiers over time and also location are being recognised as two of the primary issues. Here a detailed comparative study of noise and gain indices of HEMTs of nine processes is presented with respect to power consumption. The variation of gain and minimum noise figure with respect to temperature from −50°C to 60°C is also analysed.

A deterministic multifunctional architecture for highly adaptive small satellites

A deterministic multifunctional architecture design approach for a highly adaptive small satellite system is proposed in this paper. It enables five levels of design customisation of all categories of highly adaptive small satellites; adaptive functional modules implement higher-level customised and reconfigurable mission functions. Each adaptive multifunctional structural unit (AMSU) supports the subsystem functions as a ‘structural and functional block’ and comes either as a baseline or hybrid. Associated functional sub subsystem components are contained in each AMSU. This removes the conventional structural and functional subsystem boundaries. A meteorology spacecraft mission using a highly adaptive nanosatellite reveals, besides more advanced mission capabilities, 0.6 kg and 1 W mass- and power-savings respectively over a conventional nanosatellite system implementation. This novelty results in adaptive, reconfigurable and multifunctional architectures with economies of scale, timely launch, system-level reliability, flexible integration and test options, cost-effective mass production, post-mission reapplication and optimal performance at the desired mission objectives.

Estimation of Coupled Noise in Low Noise Phased Array Antennas

There is currently a great deal of interest in the use of phased array receivers for radio astronomy. The Square Kilometer Array (SKA) project plans to utilize phased arrays in at least three different forms: as sparse and dense aperture arrays on the ground, and as phased array feeds on dishes. At frequencies above a few hundred MHz it will be vital to obtain very low noise temperature performance from these arrays in order for them to be practical as radio astronomy receivers. Receiver noise coupled between antenna elements has been thought to be a significant contributor to overall system noise in such phased arrays. This paper uses fundamental principles of noisy networks to estimate the noise waves emanating from the input of each LNA towards the antenna element. The theory has been implemented using MATLAB, and successfully used to predict the noise levels emanating from the input ports of two packaged amplifiers. The theory has been applied to an example two-antenna array model. Results from the noise wave analysis suggest that in reality the coupled noise contribution to system noise temperature should be quite small for practical low noise amplifiers of the type to be used in the SKA.

Broadband MMIC LNAs for ALMA Band 2+3 With Noise Temperature Below 28 K

Recent advancements in transistor technology, such as the 35 nm InP HEMT, allow for the development of monolithic microwave integrated circuit (MMIC) low noise amplifiers (LNAs) with performance properties that challenge the hegemony of SIS mixers as leading radio astronomy detectors at frequencies as high as 116 GHz. In particular, for the Atacama Large Millimeter and Submillimeter Array (ALMA), this technical advancement allows the combination of two previously defined bands, 2 (67–90 GHz) and 3 (84–116 GHz), into a single ultra-broadband 2+3 (67–116 GHz) receiver. With this purpose, we present the design, implementation, and characterization of LNAs suitable for operation in this new ALMA band 2+3, and also a different set of LNAs for ALMA band 2. The best LNAs reported here show a noise temperature less than 250 K from 72 to 104 GHz at room temperature, and less than 28 K from 70 to 110 GHz at cryogenic ambient temperature of 20 K. To the best knowledge of the authors, this is the lowest wideband noise ever published in the 70–110 GHz frequency range, typically designated as

Celestial Signals: Are Low-Noise Amplifiers the Future for Millimeter-Wave Radio Astronomy Receivers?

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