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| 24 without the ability to modify the attached RF system. Alternatively, the design of the entire RF system could be concurrent with the antenna design or selection. In this scenario, engineers can account for antenna performance during system-level design. In the simplest cases, such as selecting a Wi-Fi router antenna or an antenna for a prebuilt Internet of Things (IoT) module, the top concerns are matching antenna bandwidth, gain, directivity, radiation pattern, impedance, interconnect, and power handling. An antenna's cost and physical dimensions often also significantly impact the design and selection. For instance, some IoT module and portable electronics designers may prefer to incorporate extremely compact or integrated antenna designs. There are methods of integrating antenna designs into the electronics housing, fabricating antennas with PCB metallization, using attachable antenna modules to the electronics feed directly on a substrate (i.e., chip antennas), and even using the housing of the electronic structure as an antenna. All these methods are commonly used for portable, mobile, or integrated antennas. Still, external antenna structures are typically used in large platforms, such as vehicles, aircraft, and ships, as the RF equipment is generally protected or housed within the platform, and interconnects are needed to route signals between the RF equipment and antenna. Antenna Arrays and Advanced Design Considerations Antenna arrays can be designed as relatively simple static structures with fixed attenuators or phase shifters that generate a specific antenna pattern and meet other performance specifications. Conversely, some arrays incorporate more advanced attenuation and phase adjustments to enable active beamforming and beamsteering, along with antenna processing circuits that support spatial multiplexing. Such an antenna design is likely not viable without the complex beamforming or beamsteering and spatial multiplexing circuit, in addition to a much more complex RF front-end (RFFE) and antenna feed interconnect. These systems may use multiple transmit and receive (TRX) signal chains, sometimes with a dedicated TRX for each antenna element in the array. The performance and flexibility of such systems can be advantageous for communication and sensing (i.e., radar) applications with extreme performance requirements. However, such system complexity comes with associated high costs and fabrication hurdles that must be overcome. Electromagnetic Simulation for Antenna Design A substantial amount of research has been done on various antenna designs, and guidance has been given on how to approach the designs from a practical standpoint. However, the sensitivity of antenna designs to fabrication tolerances and placement nuances within a structure or environment makes even basic antenna design extremely complex. This is why there are advanced software suites with full-electromagnetic simulation solvers that use a variety of methods to solve the complex interactions of conductors, dielectrics, current, voltage, and fields. These solvers have become incredibly accurate and, with high-performance computing (HPC) and other simulation acceleration technologies, can perform parametric optimizations over wide ranges in relatively short periods of time. However, even with such advanced tools, antenna design is still incredibly nuanced, and getting accurate and repeatable results from these tools requires a steep learning curve. Manufacturers and other companies offer design and validation services that leverage these simulation tools, helping engineers refine their antenna designs before moving to production. Antenna Testing and Verification Using specific software tools can dramatically increase the ease, pace, and accuracy of antenna design. However, even with the highest quality control and precision fabrication, no simulation solver can perfectly predict antenna behavior in a real-world environment. This is why extensive hardware and software tools exist for testing antennas either in isolation or as part of an RF system. For example, basic testing antennas, such as waveguide horns, are often used to perform various tests on other antennas. There are many types of test antennas and