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.

翻译：封闭电磁谐振腔（RC）是一种极具优势的人造无线通信环境。腔内的天线对构成一个由阻抗矩阵描述的双端口网络。我们分析了当谐振腔具有理想导电壁且阻抗矩阵为纯虚数时，两天线间的通信特性。发射天线由电流源驱动，接收天线连接至负载电阻，其电压通过无限阻抗放大器测量。信道中存在可数无穷多个与谐振腔共振相关的极点，这些极点随负载电阻增大向实频率轴迁移。接收机噪声包含两类：负载电阻的约翰逊噪声和内部放大器噪声。应用香农理论可得出该链路在发射电流带宽与功率约束下的信道容量。对于恒定发射功率，信道容量随负载电阻增大而无界增加。令人惊讶的是，实现容量的发射功率-频率分配方案会避免在谐振频率附近集中功率。