This paper proposes a narrowband fully-analog $N$-antenna transmitter that emulates the functionality of a narrowband fully-digital $N$-antenna transmitter. Specifically, in symbol interval $m$, the proposed fully-analog transmitter synthesizes an arbitrary complex excitation vector $\boldsymbol{x}[m]\in\mathbb{C}^N$ with prescribed total power $\|\boldsymbol{x}[m]\|_2^2=P$ from a single RF tone, using only tunable phase-control elements embedded in a passive interferometric programmable network. The programmable network is excited through one input port while the remaining $N-1$ input ports are impedance matched. In the ideal lossless case, the network transfer is unitary and therefore redistributes RF power among antenna ports without dissipative amplitude control. The synthesis task is posed as a unitary state-preparation problem: program a unitary family so that $\boldsymbol{V}(\boldsymbol{\varphi}[m])\boldsymbol{e}_1=\boldsymbol{c}[m]$, where $\boldsymbol{c}[m]=\boldsymbol{x}[m]/\sqrt{P}$ and $\|\boldsymbol{c}[m]\|_2=1$. We provide a parameter-minimal realization and a closed-form programming rule: a balanced binary magnitude-splitting tree allocates the desired per-antenna magnitudes $|c_n|$ using $N-1$ tunable split ratios, and a per-antenna output phase bank assigns the target phases using $N$ tunable phase shifts. The resulting architecture uses exactly $2N-1$ real tunable degrees of freedom and admits a deterministic $O(N)$ programming procedure with no iterative optimization, enabling symbol-by-symbol updates. Using representative COTS components, we model the compute-excluded RF-front-end DC power of the proposed fully-analog transmitter and compare it against an equivalent COTS fully-digital array. For $N\le 16$, the comparison indicates significant RF-front-end power savings for the fully-analog architecture under a common delivered antenna-port power normalization.

翻译：本文提出一种窄带全模拟$N$天线发射机，其功能等效于窄带全数字$N$天线发射机。具体而言，在符号间隔$m$内，所提出的全模拟发射机利用单个射频音调，仅通过嵌入在无源干涉可编程网络中的可调相位控制元件，合成具有指定总功率$\|\boldsymbol{x}[m]\|_2^2=P$的任意复激励矢量$\boldsymbol{x}[m]\in\mathbb{C}^N$。该可编程网络通过一个输入端口激励，其余$N-1$个输入端口实现阻抗匹配。在理想无损耗情况下，网络传输矩阵为酉矩阵，因此无需耗散性幅度控制即可实现天线端口间的射频功率重新分配。该合成任务可视为一个酉态制备问题：编程一个酉族使得$\boldsymbol{V}(\boldsymbol{\varphi}[m])\boldsymbol{e}_1=\boldsymbol{c}[m]$，其中$\boldsymbol{c}[m]=\boldsymbol{x}[m]/\sqrt{P}$且$\|\boldsymbol{c}[m]\|_2=1$。我们提供了一种参数最小化实现方案及闭式编程规则：通过平衡二进制幅度分割树，利用$N-1$个可调分束比分配所需各天线幅度$|c_n|$；通过各天线输出相位库，利用$N$个可调相移分配目标相位。所得架构精确使用$2N-1$个实值可调自由度，并采用确定性$O(N)$编程流程（无需迭代优化），支持逐符号更新。基于代表性商用现货（COTS）组件，我们建模了所提全模拟发射机不含计算单元的射频前端直流功率，并与等效COTS全数字阵列进行对比。对于$N\le 16$，在通用天线端口功率归一化条件下，对比表明全模拟架构可显著节省射频前端功耗。