Angular Sensing by Highly Reconfigurable Pixel Antennas with Joint Radiating Aperture and Feeding Ports Reconfiguration

TL;DR

The paper addresses accurate 3D angle-of-arrival sensing in compact devices by introducing the Highly Reconfigurable Pixel Antenna (HRPA), which jointly reconfigures the radiating aperture and feeding ports. It develops an equivalent multi-port circuit model and a radiation-pattern formulation $\mathbf{E}(\mathcal{F},\mathbf{g},\Omega)$, then minimizes the angular CRLB $\mathbf{C}_{\mathrm{RPA}}(\mathcal{F},\mathbf{g},\Omega)$ via an alternating optimization framework and a codebook of area-specific configurations. A genetic-algorithm–based search selects $N$ active ports among $M$ and binary pixel-load states to realize a design that provides reliable angular sensing across the full 3D sphere, outperforming a conventional UPA by roughly $>50\%$ in angle-estimation error. The results demonstrate HRPA’s potential to enable compact, integrated sensing and communications for 6G ISAC, with best gains at endfire directions and a practical pathway toward real-time reconfiguration and prototyping.

Abstract

Angular sensing capability is realized using highly reconfigurable pixel antenna (HRPA) with joint radiating aperture and feeding ports reconfiguration. Pixel antennas represent a general class of reconfigurable antenna designs in which the radiating surface, regardless of its shape or size, is divided into sub-wavelength elements called pixels. Each pixel is connected to its neighboring elements through radio frequency switches. By controlling pixel connections, the pixel antenna topology can be flexibly adjusted so that the resulting radiation pattern can be reconfigured. However, conventional pixel antennas have only a single, fixed-position feeding port, which is not efficient for angular sensing. Therefore, in this work, we further extend the reconfigurability of pixel antennas by introducing the HRPA, which enables both geometry control of the pixel antenna and switching of its feeding ports. The model of the proposed HRPA, including both circuit and radiation parameters, is derived. A codebook is then defined, consisting of pixel connection states and feeding port positions for each sensing area. Based on this codebook, an efficient optimization approach is developed to minimize the Cram\acute{\mathrm{\mathbf{e}}}r-Rao lower bound (CRLB) and obtain the optimal HRPA geometries for angular sensing within a given area. Numerical results show that the HRPA reduces the angle estimation error by more than 50% across the full three-dimensional sphere when compared with a conventional uniform planar array of the same size. This demonstrates the effectiveness of the proposed approach and highlights the potential of HRPA for integrated sensing and communication systems.

Figures (8)

• Figure 1: Illustrative examples of MIMO antennas of (a) conventional UPA and (b) HRPA with $N=4$.
• Figure 2: (a) General architecture and (b) digitally controllable feeding port selection module of HRPA.
• Figure 3: MIMO sensing receiver diagram using HRPA.
• Figure 4: Equivalent circuit model of $\left(M+Q\right)$-port network for HRPA with $N$ activated feeding ports, $M-N$ muted feeding ports and $Q$ loaded ports.
• Figure 5: Radiation patterns of the proposed HRPA with the optimized geometry configurations for optimal sensing at broadside angle $\theta=90^{\circ}$ and $\phi=0^{\circ}$ using $N=8$ activated feeding ports.