arXiv subjects

William Whittow

Publications and source records attributed to William Whittow.

4 recordsLinked to original sources

arXiv2026

A Superposition-Based Framework for Rapid Estimation of Arbitrary Antenna-Array Patterns

Antenna array theory is a well-established field. However, a systematic approach for fast pattern estimation in arrays with arbitrary antenna locations and orientations has not yet been developed. In this paper, based on simulated (or measured) radiation patterns of a single element, we present a Superposition-Based Framework (SBF) for numerically computing array radiation patterns in which the positions and orientations of the antenna elements can be readily modified. To validate the framework, a compact dual-layer circularly polarized patch antenna at 5.02 GHz (ESA's Celeste frequency) is designed and used as an array element in an 8-element ring antenna. Using the proposed framework and the single-element far-field pattern, the array radiation pattern is computed in 13s (excluding single-element simulation time), which is at least 50 times faster than the corresponding full-wave simulation while maintaining comparable accuracy. Comparisons with CST simulations show a peak E-field error of less than 0.5% for the intended polarization. Full-wave simulations are memory- and energy-intensive, and hence, impractical for larger arrays. The proposed SBF requires low computational power, making it energy-efficient and sustainable.

physics.app-ph↗

arXiv2026

Computational Microwave Imaging Relying on Orbital Angular Momentum Transmitarrays for Improved Diversity

This work proposes the use of orbital angular momentum (OAM) waves to improve the performance of a computational imaging (CI) system. Specifically, in contrast to a solely frequency-diverse operation, leveraging multiple OAM waves leads to a significant increase in the diversity of the measurement modes of a CI system. This significantly reduces the frequency bandwidth required to achieve high-quality image reconstructions. A proof-of-concept prototype working at Ka-band frequencies is used to validate the proposed approach. The prototype consists of two metalized three-dimensional (3D) printed cavities, with fully-dielectric transmitarrays inside that generate OAM waves. Imaging results from various targets reveal that the CI system achieves superior imaging quality when multiple OAM waves are considered, compared to when it solely relies on frequency-diversity. This is specially noticeable in the case of complex distributed targets, which can only be reconstructed with the prototype when multiple OAM waves are used. Furthermore, it is shown that accurate image reconstructions can be obtained employing only one eighth of the operational bandwidth of the frequency-diverse system.

physics.ins-det↗

arXiv2025

Analysis of Frequency-Diverse and Dispersion Effects in Dynamic Metasurface Antenna for Holographic Sensing and Imaging

Dynamic metasurface antennas (DMAs) represent a novel approach to programmable and affordable electromagnetic wave manipulation for enhanced wireless communications, sensing, and imaging applications. Nevertheless, current DMA designs and models are usually quasi-narrowband, neglecting the versatile frequency-diverse manifestation and its utilization. This work demonstrates the frequency-diversity and dispersion operations of a representative DMA structure at the millimeter-wave band. We demonstrate flexible dispersion manipulation through dynamic holographic reconfigurability of the meta-atoms in a DMA. This effect can create distinct radiation patterns across the operating frequency band, achieving flexible frequency diversity with enhanced scanning range within a compact, reconfigurable platform. It eliminates the need for wideband systems or complex phase-shifting networks while offering an alternative to frequency-scanned static beams of traditional leaky-wave antennas. The results establish fundamental insights into modelling and utilization of dispersive effects of DMAs in next-generation near-field and far-field holographic sensing and computational holographic imaging applications.

eess.SP↗

arXiv2024

Structural Morphing Metasurface for Electromagnetic Beam Manipulation

The paper presents a novel concept of a 3D structural metasurface with mechanically morphing capability that can be used as a transmit- or reflect-array to manipulate electromagnetic beams for applications in RF sensing and communications for both space and ground stations. They can be controlled using low-power actuators to deform the surface profile which is then utilised as a lens or a reflector for beamforming and steering. The proposed simulated structural metasurfaces can be used for either beam-steering or to generate bespoke contour beams for satellite communication and sensing.

physics.space-ph↗