Research on Ultra Narrow Size Microstrip Multiband Antenna Suitable for Wireless Repeaters in Mine Tunnels with Different Cross-Sections
Yun Li
,
Peng Chen
and
Bo Yin
Through the analysis of experimental data, it is found that the optimal communication frequencies of mine tunnels with different cross-sections are different. These optimal operating frequency bands (580-600 MHz, 806-826 MHz, 1427.9-1447.9 MHz, 2401.5-2481.5 MHz, 5150-5600 MHz) are not only numerous, but also wide-ranging. Meanwhile, because the wireless repeater in the mine tunnel has great restrictions on the antenna size, the antenna has to be designed in a very small range of transverse size. In this paper, an ultra-narrow sized multi-frequency dipole (0.41λ × 0.04λ) is proposed to cover the optimal communication bands of underground mine tunnels with different cross-sections. This multibranch dipole consists of three main parts: lateral long branch, middle short branch, and end-loaded reverse branch. By adjusting the length of the two lateral long branches and utilizing the high harmonics, the antenna covers the lowest and highest operating bands that differ by a factor of seven. The middle short branch is one of the contributors to 1.4 GHz band. Meanwhile, the performance of the antenna at high frequencies is optimized by adjusting the distance between branches. The bandwidth of 1.4 GHz band is expanded by the loaded reverse branches. The test results are in good agreement with the simulation data, and the antenna covers all the optimal communication frequencies of underground mine tunnels with different cross-sections. Its peak gain at the resonance point is greater than 0 dBi, and the structure is simple.