A closed electromagnetic resonant chamber (RC) is a highly favorable artificial environment for wireless communication. A pair of antennas within the chamber constitutes a two-port network described by an impedance matrix. We analyze communication between the two antennas when the RC has perfectly conducting walls and the impedance matrix is imaginary-valued. The transmit antenna is driven by a current source, and the receive antenna is connected to a load resistor whose voltage is measured by an infinite-impedance amplifier. There are a countably infinite number of poles in the channel, associated with resonance in the RC, which migrate towards the real frequency axis as the load resistance increases. There are two sources of receiver noise: the Johnson noise of the load resistor, and the internal amplifier noise. An application of Shannon theory yields the capacity of the link, subject to bandwidth and power constraints on the transmit current. For a constant transmit power, capacity increases without bound as the load resistance increases. Surprisingly, the capacity-attaining allocation of transmit power versus frequency avoids placing power close to the resonant frequencies.

中文翻译：

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谐振腔中无线通信的香农理论


封闭的电磁谐振室（RC）是非常有利于无线通信的人工环境。室内的一对天线构成由阻抗矩阵描述的双端口网络。当 RC 具有完美导电壁且阻抗矩阵为虚值时，我们分析了两个天线之间的通信。发射天线由电流源驱动，接收天线连接到负载电阻，负载电阻的电压由无限阻抗放大器测量。通道中有无数个极点，与 RC 中的谐振相关，随着负载电阻的增加，极点会向实际频率轴迁移。接收器噪声有两个来源：负载电阻的约翰逊噪声和内部放大器噪声。香农理论的应用产生了链路的容量，受到传输电流的带宽和功率限制。对于恒定的发射功率，容量随着负载电阻的增加而无限制地增加。令人惊讶的是，发射功率与频率的容量获得分配避免了将功率放置在靠近谐振频率的位置。