arXiv subjects

Simon Tewes

Publications and source records attributed to Simon Tewes.

8 recordsLinked to original sources

arXiv2026

From Prompt to Prototype: Towards a Frontier LLM Driven RF Engineering Workflow

Agentic coding environments give a frontier large language model (LLM) direct access to a workstation's terminal, file system, and software. This work demonstrates they extend to professional RF hardware design: an active GNSS L1-band antenna - a circularly polarized patch, surface acoustic wave (SAW) prefilter, and two-stage low-noise amplifier (LNA) on one printed circuit board (PCB) - was designed, optimized, and made manufacturing-ready. The LLM agent autonomously operated CST Studio Suite, Keysight ADS, and KiCad via scripting interfaces. Engineer input was limited to the specification, trade-off decisions, and design reviews. Workflow, results, and the RF engineer's evolving role are discussed.

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arXiv2026

Measurement-Based Validation of Geometry-Driven RIS Beam Steering in Industrial Environments

Reconfigurable intelligent surfaces (RISs) offer programmable control of radio propagation for future wireless systems. For configuration, geometry-driven analytical approaches are appealing for their simplicity and real-time operation, but their performance in challenging environments such as industrial halls with dense multipath and metallic scattering is not well established. To this end, we present a measurement-based evaluation of geometry-driven RIS beam steering in a large industrial hall using a 5 GHz RIS prototype. A novel RIS configuration is proposed in which four patch antennas are mounted in close proximity in front of the RIS to steer the incident field and enable controlled reflection. For this setup, analytically computed, quantized configurations are implemented. Two-dimensional received power maps from two measurement areas reveal consistent, spatially selective focusing. Configurations optimized near the receiver produce clear power maxima, while steering to offset locations triggers a rapid 20-30 dB reduction. With increasing RIS-receiver distance, elevation selectivity broadens due to finite-aperture and geometric constraints, while azimuth steering remains robust. These results confirm the practical viability of geometry-driven RIS beam steering in industrial environments and support its use for spatial field control and localization under non-ideal propagation.

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arXiv2024

Realization of Reconfigurable Intelligent Surfaces with Space-Time Coded Metasurfaces

This paper presents experimental realization of a reconfigurable intelligent surface (RIS) using space-time coding metasurfaces to enable concurrent beam steering and data modulation. The proposed approach harnesses the capabilities of metasurfaces, allowing precise temporal control over individual unit cells of the RIS. We show that by employing proper binary codes manipulating the state of unit cells, the RIS can act as a digital data modulator with beam steering capability. We describe the experimental setup and computational tools, followed by validation through harmonic generation and investigation of beam steering and data modulation. Additionally, four digital modulation schemes are evaluated. By implementing customized binary codes, constellations under varying conditions are compared, showcasing the potential for real-world applications. This study offers new insights into the practical implementation of RIS for advanced wireless communication systems.

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arXiv2024

Wireless Localization with Space-Time Coded Reconfigurable Intelligent Surfaces

In this paper, a novel approach for wireless localization is proposed and experimentally validated that leverages space-time coded reconfigurable intelligent surfaces (RIS). It is demonstrated that applying proper single-bit codes to each RIS element, enables accurate determination of the direction of arrival (AOA) at the receiver. Moreover, we introduce different scenarios that such technique can be used for localization. By incorporating RIS, a passive component, the method significantly reduces the complexity found in previous localization techniques. Additionally, the use of 1-bit codes minimizes hardware requirements, offering a reliable, low-cost solution for localization in advanced telecommunications networks.

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arXiv2024

Show Me the Way: Real-Time Tracking of Wireless Mobile Users with UWB-Enabled RIS

The integration of Reconfigurable Intelligent Surfaces (RIS) in 6G wireless networks offers unprecedented control over communication environments. However, identifying optimal configurations within practical constraints remains a significant challenge. This becomes especially pronounced, when the user is mobile and the configurations need to be deployed in real time. Leveraging Ultra-Wideband (UWB) as localization technique, we capture and analyze real-time movements of a user within the RIS-enabled indoor environment. Given this information about the system's geometry, a model-based optimization is utilized, which enables real-time beam steering of the RIS towards the user. However, practical limitations of UWB modules lead to fluctuating UWB estimates, causing the RIS beam to occasionally miss the tracked user. The methodologies proposed in this work aim to increase the compatibility between these two systems. To this end, we provide two key solutions: beam splitting for obtaining more robust RIS configurations and UWB estimation correction for reducing the variations in the UWB data. Through comprehensive theoretical and experimental evaluations in both stationary and mobile scenarios, the effectiveness of the proposed techniques is demonstrated. When combined, the proposed methods improve worst-case tracking performance by a significant 17.5dB compared to the conventional approach.

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arXiv2023

Validating Properties of RIS Channel Models with Prototypical Measurements

The integration of Reconfigurable Intelligent Surfaces (RIS) holds substantial promise for revolutionizing 6G wireless networks, offering unprecedented capabilities for real-time control over communication environments. However, determining optimal RIS configurations remains a pivotal challenge, necessitating the development of accurate analytical models. While theoretically derived models provide valuable insights, their potentially idealistic assumptions do not always translate well to practical measurements. This becomes especially problematic in mobile environments, where signals arrive from various directions. This study deploys an RIS prototype on a turntable, capturing the RIS channels' dependency on the angle of incoming signals. The difference between theory and practice is bridged by refining a model with angle-dependent reflection coefficients. The improved model exhibits a significantly closer alignment with real-world measurements. Analysis of the reflect coefficients reveals that non-perpendicular receiver angles can induce an additional attenuation of up to -14.5dB. Additionally, we note significant phase shift deviations, varying for each reflect element.

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arXiv2022

IRS-enabled Breath Tracking with Colocated Commodity WiFi Transceivers

Intelligent reflecting surfaces (IRS) are a key enabler of various new applications in 6G smart radio environments. By utilizing an IRS prototype system, this paper aims to enhance self-interference (SI) cancellation for breath tracking with commodity WiFi devices. SI suppression is a crucial requirement for breath tracking with a single antenna site as the SI severely limits the radio sensing range by shadowing the received signal with its own transmit signal. To this end, we propose to assist SI cancellation by exploiting an IRS to form a suitable cancellation signal in the analog domain. Building upon a 256-element IRS prototype, we present results of breath tracking with IRS-assisted SI cancellation from a practical testbed. We use inexpensive WiFi hardware to extract the Channel State Information (CSI) in the 5~GHz band and analyze the phase change between a colocated transmitter and receiver with added local oscillator (LO) synchronization. We are able to track the breath of a test person regardless of the position in an indoor environment in a room-level range. The presented case study shows promising performance in both capturing the breath frequency as well as the breathing patterns.

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arXiv2022

Full-Duplex meets Reconfigurable Surfaces: RIS-assisted SIC for Full-Duplex Radios

Reconfigurable intelligent surfaces (RIS) are a key enabler of various new applications in 6G smart radio environments. By utilizing an RIS prototype system, this paper aims to enhance self-interference (SI) cancellation for in-band full-duplex (FD) communication systems. SI suppression is a crucial requirement for FD communication as the SI severely limits the performance of a node by shadowing the received signal from a distant node with its own transmit signal. To this end, we propose to assist SI cancellation by exploiting an RIS to form a suitable cancellation signal in the analog domain. Building upon a 256-element RIS prototype, we present results of RIS-assisted SI cancellation from a practical testbed. Given an initial analog isolation of 44 dB provided by the antenna design, we are able to cancel the leaked signal by an additional 59 dB in the narrowband case, resulting in an overall SI suppression of 103 dB without additional digital cancellation. The presented case study shows promising performance to build an FD communication system on this foundation.

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