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Design of a shielded turntable with reduced radiated emissions for EMC and antenna testing applications
Author(s)
Wait, Ibraheem Gerhard Adriaan
Date Issued
2026
Type
master thesis
Publisher
Cape Peninsula University of Technology
Abstract
Electromagnetic compatibility (EMC) testing is critical for ensuring reliable operation of electronic systems in increasingly complex electromagnetic environments. At the Cape Peninsula University of Technology (CPUT), the need for consistent and repeatable EMC and antenna measurements led to the development of a shielded, automated antenna test turntable (ATT). This research details the design, implementation, and validation of a lowemission, portable turntable platform for use in shielded chambers and open-area test sites. The project followed a structured engineering design methodology, beginning with a comprehensive literature review on EMC principles, EMI sources, coupling mechanisms, and applicable standards such as CISPR 32, IEC 61000, and MIL-STD-461. The ATT was engineered to rotate equipment under test (EUT) through 360° with high positional accuracy (±1°), while minimizing electromagnetic interference using shielded enclosures, filtered connectors, and fibre-optic communication. Subsystems—including a linear power supply, stepper motor with driver, and a microcontroller-based control interface—were housed in dedicated RFI-shielded cavities. Functional testing confirmed reliable rotation under a 25 kg load at speeds up to 3 rpm, precise angular control within ±1°, and robust serial communication over 10 m fibre-optic links. Pre-compliance EMC testing using near-field probing and common-mode current measurements demonstrated emission attenuation of up to 30 dB compared to an unshielded configuration. Common-mode coupling remained below 14 dBμA, supporting the platform’s low-noise design. Compliance-level radiated emissions testing confirmed adherence to CISPR 32 Class B limits, with measured peak emissions at least 15 dB below the limit across 30 MHz–300 MHz and an average margin of 30 dB below the limit from 0.3–6 GHz. No pulsed emissions were detected, validating the system’s suitability for sensitive EMC and antenna testing environments. A cost saving of approximately 80% was achieved compared to commercial EMC turntables. This research delivers a cost-effective, low-noise solution for automated EMC testing and lays the foundation for future enhancements such as closed-loop control, advanced shielding, and integrated sensor feedback.
Additional information
Thesis (MEng (Satellite Systems and Applications))--Cape Peninsula University of Technology, 2026
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Wait, I_214334988 (1).pdf
Size
6.45 MB
Format
Adobe PDF
Checksum
(MD5):e895c99f8d6663e8f92d21489e0343c3