TI mmWave radar sensors are used across a wide range of end applications, including automotive and industrial systems. Each application places different demands on the antenna, so the design starts by identifying the use case and translating it into a prioritized list of antenna requirements. For example, long-range automotive radar (for example, front radar) needs high gain, a narrow beam, long detection range, and low sidelobes to separate distant targets. The FOV is relatively small. Corner and short-range radar (for example, blind-spot detection) needs a wide azimuth FOV with moderate gain, since targets are closer. In-cabin sensing needs wide FOV in both azimuth and elevation at short range, with a compact form factor. Industrial sensing (for example, people counting, presence detection, robotics, level sensing) requirements vary widely. Presence detection favors wide coverage, while level or distance sensing favors a narrow, focused beam.

From the use case, the key features are defined and ranked by priority: Gain and range, FOV in azimuth and elevation, operating band and bandwidth (for example, 60–64GHz or 76–81GHz), TX–RX isolation, form factor and sensor placement, and regulatory limits.

These features trade against each other. Higher gain narrows the FOV, wider bandwidth can reduce efficiency, and smaller size limits array aperture. Ranking them early prevents conflicting requirements later in the flow.

Cost also shapes the achievable antenna performance, mainly through the PCB material. Low-cost laminates such as standard FR-4 have a high loss tangent (about 0.02) and a higher, less stable dielectric constant. The high loss tangent causes dielectric loss and reduces radiation efficiency and gain. The higher dielectric constant adds to the problem by making surface waves and field confinement worse, which lowers efficiency and bandwidth. Low-loss mmWave laminates perform much better but cost more.

Designers often balance this with a hybrid stack-up, using a low-loss laminate only for the top RF layer and standard material for the remaining layers. Cost-sensitive applications may also accept reduced performance, for example by using a larger array to offset losses or settling for a shorter range.

The result of end application evaluation is a defined use case, a prioritized antenna feature list, and cost and performance limits. These feed directly into the form factor and stack-up decision (Step 2) and the link budget (Step 3).

Design Example

As a design example for the app note, consider the external automotive near field gesture recognition application like KTO (Figure 2-2). The AWRL1422 radar device is opted for this application because of the low cost and low-power capabilities the device offers since the device is expected to work on the car battery supply. The sensor module design is targeted to be of lowest cost and will majorly impact the form factor and stack-up decision. The AWRL1422 device operates in 76-81GHz frequency band with 2RX and 2TX channels. The targeted FOV for the application is 120° (azimuth) × 90° (elevation) and detection range is two to three meters.