Direct-Write Laser-Induced Graphene Microstrip Patch Antennas on Medium-Density Fiberboard
Elsa M. Materón, Faustino Reyes Gómez, Desirée Tamara Scheidt, Beatriz Bastos Assis, Cecilia de Carvalho Castro e Silva, Edwin J. Ortiz-Riaño, Gustavo M. Sousa, Emanuel Carrilho, Osvaldo N. Oliveira, Luciano Leonel Mendes, Jorge Ricardo Mejía-SalazarAbstract
Laser-induced graphene (LIG) has been used in flexible and wearable antennas fabricated on polymeric substrates and paper; however, these materials are not ideal for seamless integration into rigid indoor structures. Antennas integrated into such structures would represent a sustainability advantage over conventional technologies. In this work, we report LIG microstrip patch antennas fabricated directly on medium-density fiberboard (MDF), a ubiquitous wood-derived material used in indoor furniture and architectural fixtures, enabling unobtrusive radiators that can be integrated into ordinary wooden objects. MDF substrates were pretreated with sodium tetraborate and patterned via CO2-laser scribing to form a porous conductive layer with sheet resistance of approximately 9 Ω/sq, without cleanroom processing. Two inset-fed patch geometries, rectangular planar and circular conformal, were produced and validated. Impedance matching with return loss S11 ≤ −10 dB was achieved over 3.19–4.12 GHz and 5.95–7.49 GHz for the rectangular antenna, and 2.98–3.84 GHz and 5.50–7.96 GHz for the circular antenna, in good agreement with full-wave simulations. The measured radiation patterns were consistent with the simulated modes, and the peak realized gain was approximately −2.5 dBi, limited primarily by MDF and conductor losses. With these results, the LIG-on-MDF approach is demonstrated as a scalable route to furniture-integrated antennas for short-range sub-6-GHz indoor connectivity.