Automated Angular Received-Power Characterization of Embedded mmWave Transmitters Using Geometry-Calibrated Spatial Sampling

TL;DR

This work tackles the challenge of characterizing the angular received-power of embedded mmWave transmitters under realistic installation constraints. It introduces RAPTAR, an autonomous measurement system that uses geometry-calibrated hemispherical sampling with a collaborative robot to acquire amplitude-only received-power measurements while ensuring deterministic pose-indexing and quasi-static stabilization. The approach is validated against full-wave simulation references and a manual baseline across multiple radii, achieving mean absolute errors below 2 dB, high angular-trend correlation ($\rho>0.98$), and up to 36.5% reduction in error compared to manual methods, all within a semi-anechoic, absorber-enhanced environment. The method provides a practical, portable alternative for engineering validation and comparative characterization of embedded mmWave modules in real-world platforms, and it lays the groundwork for extensions to coherent measurements and multi-robot configurations.

Abstract

This paper presents an automated measurement methodology for angular received-power characterization of embedded millimeter-wave transmitters using geometry-calibrated spatial sampling. Characterization of integrated mmWave transmitters remains challenging due to limited angular coverage and alignment variability in conventional probe-station techniques, as well as the impracticality of anechoic-chamber testing for platform-mounted active modules. To address these challenges, we introduce RAPTAR, an autonomous measurement system for angular received-power acquisition under realistic installation constraints. A collaborative robot executes geometry-calibrated, collision-aware hemispherical trajectories while carrying a calibrated receive probe, enabling controlled and repeatable spatial positioning around a fixed device under test. A spectrum-analyzer-based receiver chain acquires amplitude-only received power as a function of angle and distance following quasi-static pose stabilization. The proposed framework enables repeatable angular received-power mapping and power-domain comparison against idealized free-space references derived from full-wave simulation. Experimental results for a 60-GHz radar module demonstrate a mean absolute received-power error below 2 dB relative to simulation-derived references and a 36.5 % reduction in error compared to manual probe-station measurements, attributed primarily to reduced alignment variability and consistent spatial sampling. The proposed method eliminates the need for coherent field measurements and near-field transformations, enabling practical power-domain characterization of embedded mmWave modules. It is well suited for angular validation in real-world platforms where conventional anechoic measurements are impractical.

Figures (8)

• Figure 1: Applied setup overview of the RAPTAR system with attachments.
• Figure 2: Overview of the RAPTAR measurement pipeline illustrating geometry-calibrated hemispherical spatial sampling, robotic pose execution, and time-aligned acquisition of angularly indexed received-power measurements.
• Figure 3: Three-dimensional sampling grid illustrating the hemispherical measurement geometry in azimuth ($\phi$), elevation ($\theta$), and radius ($r$). The DUT operates as the transmitter, while a receiving antenna is spatially positioned by the collaborative robot to acquire angularly indexed received-power measurements.
• Figure 4: Full-wave simulation setup illustrating the embedded mmWave radar module layout, including the transmit (Tx) antenna and multiple receive (Rx) channels, together with the receive-probe orientation in the H-plane and E-plane configurations.
• Figure 5: Experimental measurement setup showing the embedded radar DUT, collaborative robotic manipulator with horn receive probe, spectrum analyzer, radar control and time-aligned data acquisition systems, and overhead RF absorber sheets used to mitigate environmental multipath during received-power measurements.