煤矿巷道是无线信号传输受限的特殊空间，当前井下无线通信系统设计面临着天线布局难以优化的挑战，巷道信号覆盖特性与天线工作频率及位置密切相关。现有井下电磁波传输特性研究存在以下关键问题：第一，当前多数研究将发射天线置于巷道断面中心位置进行建模和测试，这一假设不符合巷道实际情况。第二，针对弯曲巷道的研究场景过于单一，缺乏对T型岔道等关键区域电磁波传播特性的系统分析。因此，本文针对矩形直巷道、T型岔道场景分析工作频率、天线位置等因素对无线传输及电波覆盖特性的影响。

首先，针对煤矿井下典型的喷射混凝土运输大巷，采用入射及反弹射线法（Shooting and Bouncing Ray tracing, SBR）构建符合实际的三维煤矿巷道模型，从传输距离（一维）、纵向切面（二维）和空间分布（三维）多尺度系统分析0.9 GHz、2.4 GHz和3.5 GHz频段在宽5 m高3.4 m巷道中的功率衰减规律，并研究天线水平位置及高度对传输的影响。结果显示：0.9 GHz传输特性优于其他两个频段，不同传输距离的纵向切面功率均值较2.4 GHz和3.5 GHz分别高出6.60至9.17 dBm和10.49至12.63 dBm；天线最佳水平位置为距巷壁0.01至0.1 m，紧贴侧壁（0.01 m）部署时，功率空间分布呈非对称特性，发射天线同侧邻壁区的接收功率比对侧高1至4 dBm；收发天线高度差小于0.5 m时可获得稳定且较强的接收信号，收发端高度差0.5至1.2 m时，接收功率有所衰减，但差异不大，在实际应用中可作为备选高度方案。

其次，针对现有弯曲巷道仿真场景单一的研究局限，构建三维混凝土T型岔道模型，运用“线-面-体”多层次研究思路分析T型岔道电磁场分布规律，在直行与右转巷道区域，通过5个纵向特征切面和6条动态接收路线，系统分析收发天线距离、工作频段、发射天线水平位置、收发端高度差、移动波源等关键因素对岔道内接收功率的影响情况。结果表明：0.9 GHz频段在T型岔道中仍旧展现出显著传输优势，其功率分布在五个典型切面较2.4 GHz和3.5 GHz分别高出7.881至13.478 dBm和12.124至21.835 dBm；当天线水平位置距左侧巷壁0.1 m时，可实现直行与右转巷道的最佳信号均衡，此时右转巷道平均接收功率较中心或右侧布置方案提高3至4 dBm；收发天线高度一致时的接收功率均值均比存在高度差时的均值高出0.5至1 dBm；发射天线距岔道口中线2.5 m时，右转巷道区域完全进入视距传输范围，电磁波以直射方式覆盖整个岔道区域。

研究成果可用于指导矿井应急通信系统、矿井移动通信系统、矿井人员定位系统的工作频率选择，为进一步探索和优化矿井巷道通信中基站设置和天线布局提供了参考依据，有助于开发更有效、可靠的井下通信系统。

Coal mine roadways represent a unique confined space where wireless signal transmission is significantly constrained. The current design of underground wireless communication systems faces challenges in optimizing antenna placement, as signal coverage characteristics are closely related to both operating frequency and antenna positioning. Existing research on electromagnetic wave propagation in underground roadways exhibits two critical limitations: firstly, most studies assume the transmitting antenna is positioned at the center of the roadway cross-section, which deviates from practical deployment scenarios; secondly, research on curved roadways remains overly simplistic, lacking systematic analysis of electromagnetic wave propagation in critical areas like T-junctions.

The research investigates the impact of operating frequency and antenna positioning on wireless transmission and coverage characteristics in both straight rectangular roadways and T-junction scenarios. First, adopting the Shooting and Bouncing Ray (SBR) method, a realistic 3D model of a typical shotcrete transportation roadway is established. Through multi-scale analysis encompassing transmission distance (1D), longitudinal cross-sections (2D), and spatial distribution (3D), power attenuation patterns for 0.9 GHz, 2.4 GHz, and 3.5 GHz frequencies in a 5m×3.4m roadway are examined, while evaluating the effects of antenna horizontal position and height. Key findings include: 0.9 GHz demonstrates superior performance, with mean power levels exceeding 2.4 GHz and 3.5 GHz by 6.60-9.17 dBm and 10.49-12.63 dBm respectively across different distances; optimal horizontal positioning is 0.01-0.1m from the wall, with wall-proximal (0.01m) deployment creating asymmetric power distribution (1-4 dBm stronger on the antenna side); height differences below 0.5m yield optimal signal stability, while 0.5-1.2m differences remain viable alternatives with moderate attenuation.

Second, addressing the simplification in curved roadway research, a 3D concrete T-junction model employing a "line-plane-volume" analytical framework is developed. Through five characteristic cross-sections and six dynamic reception paths in both straight and turning segments, systematic evaluation is conducted on how transmission distance, frequency band, antenna position, height difference, and mobile sources affect received power. Results indicate: 0.9 GHz maintains significant advantages in T-junctions, outperforming 2.4 GHz and 3.5 GHz by 7.881-13.478 dBm and 12.124-21.835 dBm respectively; positioning antennas 0.1m from the left wall optimizes coverage balance, improving turning-segment reception by 3-4 dBm versus central placement; uniform antenna heights enhance received power by 0.5-1 dBm versus height differences; positioning transmitters 2.5m from the junction centerline ensures line-of-sight coverage throughout the turning segment.

These findings provide practical guidance for frequency selection in mine emergency communication systems, mobile networks, and personnel positioning systems, while offering valuable references for base station deployment and antenna configuration optimization to develop more robust underground communication solutions.

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