An Adjusted Waveguide Antenna with A Woodpile-Shaped EBG for Eucalyptus Wood Moisture Content Measurement
Authors: Naktong Watcharaphon , Puangnak Korn , Phanthuna Nattapong , Prapakarn Sawitree , Prapakarn Natthapong , Wattikornsirikul Natchayathorn 
Published: May 2024

A rectangular waveguide antenna was tested for eucalyptus wood moisture content (MC) measurement before being used. To improve the moisture content measurement of the rectangular waveguide antenna, a woodpile-shaped Electromagnetic Band Gap (EBG) was installed by Transverse Electric (TE) arrangement. This antenna is responsible for receiving and transmitting signals which are converted from electrical energy into radio frequency energy transmitted through the air. In this research, we take advantage of the wave propagation of antennas in the air and use them to propagate waves through wood materials. To compare signal transmission power to determine moisture content in wood and the benefit of the EBG is that it acts like a convex lens to increase the strength of the waves so that they can penetrate the wood more efficiently. The results showed that woodpile-shaped EBG could increase the efficiency of receiving and transmitting signals, reduce working hours for farmers and reduce costs by about 90 %. When this antenna was tested and actually used, it was found that the frequency band that responded best to the moisture content value was 2.20 GHz. This antenna was built with an aluminum material of size 9×4×15 cm3 and 2×6 units woodpile EBG on a 9.54×4 cm2 Polyester Mylar base plate. There was a gain of 7.81 dBi from the original structure, or by 20 %. At a radius of 4 cm, the values ​​of moisture content ranged from –9.46 to –42.19 dBm. At a radius of 6 cm, the values ​​were –9.41 to –42.89 dBm. At a radius of 8 cm, the values ​​ranged from –9.39 to –43.01 dBm, respectively. All 3 values ​​were found to be efficient. The size was not less than 84 % compared to the general standard meter.
HIGHLIGHTS
A rectangular waveguide antenna was tested for eucalyptus wood moisture content (MC) measurement before being used. To improve the moisture content measurement of the rectangular waveguide antenna, a woodpile-shaped Electromagnetic Band Gap (EBG) was installed by Transverse Electric (TE) arrangement. This antenna is responsible for receiving and transmitting signals which are converted from electrical energy into radio frequency energy transmitted through the air. In this research, we take advantage of the wave propagation of antennas in the air and use them to propagate waves through wood materials. To compare signal transmission power to determine moisture content in wood and the benefit of the EBG is that it acts like a convex lens to increase the strength of the waves so that they can penetrate the wood more efficiently. The results showed that woodpile-shaped EBG could increase the efficiency of receiving and transmitting signals, reduce working hours for farmers and reduce costs by about 90 %. When this antenna was tested and actually used, it was found that the frequency band that responded best to the moisture content value was 2.20 GHz. This antenna was built with an aluminum material of size 9×4×15 cm3 and 2×6 units woodpile EBG on a 9.54×4 cm2 Polyester Mylar base plate. There was a gain of 7.81 dBi from the original structure, or by 20 %. At a radius of 4 cm, the values of moisture content ranged from –9.46 to –42.19 dBm. At a radius of 6 cm, the values were –9.41 to –42.89 dBm. At a radius of 8 cm, the values ranged from –9.39 to –43.01 dBm, respectively. All 3 values were found to be efficient. The size was not less than 84 % compared to the general standard meter.
GRAPHICAL ABSTRACT