Identify which parts of the board are RF structures

NXP describes automotive radar devices ranging from compact sensors to imaging radar systems. Begin a project by identifying the selected device architecture and its reference documentation. An antenna in package and an antenna implemented on the PCB create different responsibilities for the board designer.

Mark feed lines, transitions, antenna regions and nearby metal in a shared electrical and mechanical model. Establish which geometry is controlled by the RF design and which can be adjusted during fabrication engineering.

Review materials at the relevant frequency

Request the material information needed by the actual RF model, including the conditions under which properties are specified. A generic material family name does not uniquely define every laminate construction. Record copper and surface treatment assumptions along with dielectric geometry.

When comparing a hybrid stack with a uniform material system, include bonding, thickness control and available qualification evidence. The RF benefit of a material choice must be weighed against the feasibility of building the complete multilayer structure consistently.

Protect the antenna while routing the processor

Place digital escapes and power conversion with the RF team's keepouts visible on all relevant layers. A new microvia, fill pattern or shield attachment can change geometry close to the antenna even when the intended signal net is unrelated. Route reviews should include these apparently incidental features.

  • Record the RF reference plane and transition geometry.
  • Freeze antenna and radome related mechanical datums together.
  • Agree on which artwork adjustments need RF approval.
  • Specify inspection evidence for the geometry driving the RF model.

Correlate the fabricated board with measurements

Retain representative construction data with prototype RF results. If measurements differ from prediction, compare actual geometry, material assumptions and assembly configuration before tuning several variables at once. Use the intended enclosure and radome when evaluating the final mechanical arrangement.

For later changes, distinguish a digital only edit from an edit that changes the RF environment. The review boundary should follow fields and physical proximity, not just schematic block names or the number of altered nets.

DESIGN NOTE / SCHEMATIC

Adjacent-layer access, one connection at a time

Signal copper

Dielectric · geometry + material

Reference copper

Core or build-up dielectric

Signal copper

Illustrative only. Copper thickness, dielectric construction and via spans require a reviewed stackup.

Real smartphone circuit board illustrating compact component placement
Illustrative compact electronics example; not a product-specific manufacturing sample. © Raimond Spekking / CC BY-SA 4.0. Credits & license.

Common questions

Does automotive radar always need a specialized RF material?

The device, operating band, antenna architecture and performance budget determine the requirement. Evaluate an actual stackup and channel model rather than choosing by application name alone.

Can the fabricator adjust radar trace widths to meet impedance?

Only within an agreed engineering process. Antenna and RF geometry may have purposes beyond a nominal impedance target, so proposed adjustments need design review.

References & further reading

Method & assumptions · General design guidance. Validate the proposed construction and acceptance criteria for your project.