Measurement of the Dielectric Properties of Tropical Wood Species for Application to Millimetre-Band Antennas

Abstract

The purpose of this article is to determine the dielectric characteristics of wood species from Central African forests at microwave frequency for use as patch antenna substrate. The measurements were carried out on dried wood at frequencies of 930 MHz and 2.48 GHz. The suitability of the wood as a printed microwave antenna substrate will be determined by the values taken by the complex parameters “permittivity” ε^′, loss tangent “tanδ,” and “permeability” μ = 1. The measurement method chosen in this work is the method of small disturbances in a cylindrical cavity operating in the TM₀₁₀ mode. The values obtained for each species confirm the anisotropic nature of the wood. These measurements will also confirm that losses, which are the main criterion for selecting wood as substrate, increase with the wood species category and its density. The design and simulation results at 28 GHz of a travelling wave antenna on a wood substrate show that antennas can radiate with these materials in the millimetre band.