Compact Low-Profile Circularly Polarized Metasurface Antenna for 6 GHz IoT Applications

DOI

10.2991/978-94-6239-628-9_22How to use a DOI?

Keywords

Circular polarization; metasurface antenna; FR4 substrate; IoT applications; gain enhancement; axial ratio; microstrip patch; single-feed antenna

Abstract

The design and electromagnetic analysis of a small single-feed circularly polarized (CP) antenna for sub-6 GHz Internet-of-things (IoT) wireless devices are covered in this work. In Internet of Things communication devices encounter different orientations, multipath reflections, and fluctuating channel conditions, circular polarization is particularly advantageous. By radiating orthogonal field components of equal magnitude and 90° phase difference, CP ensures orientation-independent connectivity, reduced polarization mismatch, and enhanced link reliability compared to linearly polarized antennas.

The proposed antenna employs a two-layer FR-4 structure of total thickness 4 mm, comprising an upper meta-surface superstrate and a lower slotted radiating patch. In order to improve broadside gain and re-radiate in phase, the upper FR-4 layer (h₁ = 3.5 mm) creates a metasurface with dimensions of Wₘ = 35 mm × Lₘ = 24 mm. A rectangular patch with a slot of length Lₛ = 22 mm and width Wₛ = 2.5 mm is carried by the lower FR-4 substrate (h₂ = 0.5 mm). This slot generates a 90° phase quadrature that generates strong right-hand circular polarization (RHCP) by upsetting the degenerate TM₁₁ modes of the patch.

A 3 dB axial-ratio (AR) bandwidth between 5.8–6.2 GHz, a peak realized gain of 6.1 dBi at 6.0 GHz, and |S₁₁| < –10 dB from 5.5–7.0 GHz are confirmed by full-wave simulations. The antenna radiates a stable broadside RHCP beam with cross-polarization levels below –15 dB and ~80% efficiency. The combination of metasurface-assisted gain enhancement and slot-induced circular polarization yields wideband impedance matching, improved polarization purity, and excellent radiation efficiency — all within a low-cost, single-feed FR-4 design. The proposed antenna therefore provides a robust, orientation-insensitive, and compact solution for IoT sensors, portable RF platforms, and smart-device communication modules.

Copyright

© 2026 The Author(s)

Open Access

Open Access This chapter is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/), which permits any noncommercial use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made.

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TY  - CONF
AU  - Nishant Kumar
AU  - Rashmi Sinha
PY  - 2026
DA  - 2026/03/31
TI  - Compact Low-Profile Circularly Polarized Metasurface Antenna for 6 GHz IoT Applications
BT  - Proceedings of the International Conference on Recent Trends in Intelligent Computing, Manufacturing, and Electronics (rTIME 2025)
PB  - Atlantis Press
SP  - 243
EP  - 251
SN  - 2352-5401
UR  - https://doi.org/10.2991/978-94-6239-628-9_22
DO  - 10.2991/978-94-6239-628-9_22
ID  - Kumar2026
ER  -