Closed-form Model for Radiation Pattern of Pinching Antennas

TL;DR

This paper introduces a closed-form analytical model for the radiation pattern of pinching-antenna systems, enabling more accurate system-level analysis by capturing their directional radiation characteristics.

Contribution

It develops a novel, physically motivated radiation pattern model for pinching antennas using coupled-mode theory and radiation integrals, validated against simulations.

Findings

The model accurately reproduces the directional radiation pattern of PASS.

Neglecting the directional behavior leads to performance degradation in wireless scenarios.

The closed-form model can be integrated into system-level PASS analyses.

Abstract

In this article, we develop an analytical radiation-pattern model for pinching-antenna systems (PASS) based on a two-dimensional dielectric slab waveguide. The model is derived in two steps. First, we employ coupled-mode theory (CMT) to derive a closed-form expression for the field coupled into the pinching antennas (PAs). Second, we use this analytical field profile as a scattering source model and derive the far-field radiation pattern via a two-dimensional radiation integral. We validate the proposed model against full-wave finite-element simulations performed in COMSOL Multiphysics, showing that it accurately reproduces the directional radiation characteristics of PASS. In contrast, most existing works model PAs as omni-directional point radiators, which simplifies system-level analysis but does not accurately capture the underlying electromagnetic radiation mechanism. Because the proposed model is given in closed form, it can be easily integrated into existing system-level PASS models to replace the assumed omni-directional pattern with a physically motivated directional radiation pattern. Finally, numerical simulations quantify the performance degradation that arises when the directional behavior of PAs is neglected in a representative wireless communications scenario.