We consider the class of wireless links whose propagation characteristics are described by a dipole model. This comprises free-space links between dipole antennas and magneto-inductive links between coils, with important communication and power transfer applications. A dipole model describes the channel coefficient as a function of link distance and antenna orientations. In many use cases the orientations are random, causing a random fading channel. This paper presents a closed-form description of the channel statistics and the resulting outage performance for the case of i.i.d. uniformly distributed antenna orientations in 3D space. For reception in AWGN after active transmission, we show that the high-SNR outage probability scales like $p_\mathrm{e} \propto \mathrm{SNR}^{-1/2}$ in the near- or far-field region, i.e. the diversity exponent is just 1/2 (even 1/4 with backscatter or load modulation). The diversity exponent improves to 1 in the near-far-field transition due to polarization diversity. Analogous statements are made for the power transfer efficiency and outage capacity.

中文翻译：

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随机定向偶极子之间的通道：近场和远场的统计和中断

我们考虑其传播特性由偶极子模型描述的无线链路的类别。这包括偶极天线之间的自由空间链接以及线圈之间的磁感应链接，具有重要的通信和功率传输应用。偶极子模型将信道系数描述为链路距离和天线方向的函数。在许多使用情况下，方向是随机的，从而导致随机的衰落信道。本文对3D空间中iid均匀分布的天线方向的情况，给出了信道统计信息以及由此产生的中断性能的闭式描述。对于主动传输后在AWGN中的接收，我们表明在近场或远场区域中，高SNR中断概率像$ p_ \ mathrm {e} \ propto \ mathrm {SNR} ^ {-1/2} $ ， IE 分集指数仅为1/2（使用反向散射或负载调制时甚至为1/4）。由于极化分集，在近场转换中，分集指数提高到1。对功率传输效率和停电容量做出类似声明。