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mmWave Automotive Radar and Antenna System Development Using AWR Software 9 www.cadence.com/go/awr Within the AWR VSS software, arrays can be represented as system behavioral blocks using the proprietary phased-array model. This enables designers to specify the array configuration (number of elements, element spacing, antenna radiation pattern, impaired elements, gain tapering, and more) for a high-level understanding of array requirements for desired perfor- mance such as gain and side lobes. This approach is best for large-scale arrays (thousands of elements) and system designers developing basic requirements for the antenna array team. The array can also be modeled with the detailed physical array in the AWR AXIEM or Analyst simulators. Individual port feeds can be specified or, if the feed network is also implemented in the AWR AXIEM/Analyst simulator, a single feed network can be specified (Figure 12). Figure 12: Simulation of published 2 8x8 patch array on RO4003C PCB, approximately 2.3x2.5cm This approach enables the design team to investigate the interaction between the beam angle and the input impedance of each individual element, allowing RF front-end component designers to account for impedance loading effects on transceiver performance. This capability highlights the importance of having RF circuit, system, and EM co-simulation to accurately investigate circuit/antenna behavior before fabricating these complex systems. MIMO and Beam Steering Antenna Technologies For vehicles, a radar will receive unwanted backscatter off the ground and any large stationary objects in the environment, such as the sides of buildings and guardrails. In addition to direct-path reflections, there are also multipath reflections between scatterers, which can be used to mitigate the impact of clutter through the use of multiple-input-multiple output (MIMO) antennas. A MIMO radar system uses a system of multiple antennas with each TX antenna radiating an arbitrary waveform independently of the other transmitting antennas. Each receiving antenna can receive these signals. Due to the different wave forms, the echo signals can be re-assigned to the single transmitter. An antenna field of N transmitters and a field of K receivers mathematically results in a virtual field of K*N elements, resulting in an enlarged virtual aperture that allows the designer to reduce the number of necessary array elements. MIMO radar systems thereby improve spatial resolution and provide a substantially improved immunity to interference. By improving the signal-to-noise ratio, the probability of detection of the targets is also increased. AWR VSS software is able to implement user-specified MIMO algorithms and evaluate the overall performance as it relates to the channel model, which simulates a highly-customizable multipath fading channel that includes channel path loss, the relative velocity between the transmitter and receiver, and the maximum Doppler spread. Supporting independent or continuous block-to-block operation, the channel can contain multiple paths (LOS, Rayleigh, Ricean, frequency shift) that can be individually configured in terms of their fading types, delays, relative gains, and other applicable features.