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Under these conditions, designers resort to shielding to protect sensitive electronics, and can also select radiation- hardened components. Both solutions impact the cost and weight of the vehicle. As discussed in chapter 2, one of the benefits of operating satellites in Low Earth Orbit (LEO) is that their exposure to radiation is relatively low, but it cannot be disregarded completely. The reduced exposure allows the use of commercial-grade components. Many manufacturers offer a commercial space qualification service to provide designers with the confidence to employ commercial parts in spaceflight applications. Component Selection Choosing the right components for space therefore requires careful balancing of capabilities, reliability, and cost. This is especially true of power amplifiers (PAs) used for the high-frequency signals that are central to SATCOM operations. Material choices play an important role in specifying PAs: • PAs use Gallium Nitride (GaN) due to its high power density, thermal robustness, and efficiency at high frequencies. This is especially important for the Ku and Ka bands that are becoming popular in SATCOM systems. • Low-noise amplifiers (LNAs) are constructed of Gallium Arsenide (GaAs) due to its superior noise performance. • Silicon-based technology is best suited for low- transmit power applications. Beamformers use silicon because it enables very compact, highly integrated solutions. It is also a cost-effective solution, particularly in complex mixed-signal environments. Beyond the material selection, a range of key characteristics are important for PA specification, including: • Efficiency is vital in managing thermal loads and power budgets aboard the satellite. • Linearity is critical for maintaining signal integrity with advanced modulation schemes like 256-QAM and beyond, which are highly sensitive to distortion. C h a p t e r 3 | D e s i g n i n g f o r S p a c e Having a clear end goal is essential. Unlike GEO or lunar missions that require heavy shielding and strict radiation tolerance, designing for LEO offers far greater flexibility in component selection." Christopher Rogers Sr. Component Engineer, CesiumAstro 16 Engineering the Future of Satellite Communications