Ku波段编码式电控超薄周期单元设计与验证

编码式电控周期单元通过加载电子控制器件使周期结构具有编码式的电可调特点. 本文利用PIN二极管, 设计实现了一种工作在Ku波段的超薄平面电控单元结构. 当外加电压控制二极管导通或截止时, 该结构的反射相位呈现出180°的相位差, 并且具有较低的反射损耗. 因此, 当对周期排列的单元外加不同的电压时, 可等效为用不同组合的“1”, “0”对结构进行编码, 从而可以获得不同的电磁功能. 为验证单元的编码特性, 从“场”与“路”两个角度考虑, 设计了实际的偏置电路, 制作了单元样品, 并基于波导法测试了其性能. 实验结果表明: 在加载不同的控制电压时, 制作的单元结构实现了设计的低损耗和相位差; 实验与仿真符合良好. 提出的周期单元形式简单, 厚度超薄, 其电控编码式特性在主动式隐身表面或波束捷变天线设计等许多方面都有潜在应用.

Design and verification of an electronically controllable ultrathin coding periodic element in Ku band

The coding periodic element is able to achieve coded reconfigurable electromagnetic (EM) responses by loading controllable electronic devices. In this work, an electronically controllable ultrathin planar periodic element structure in Ku band is implemented with one PIN diode. When the PIN diode turns ON or OFF by applying a proper biasing voltage, the resonant property of the element changes correspondingly, and hence a 180° phase difference between the two states is obtained. By optimizing the geometrical parameters, the reflection loss less than 0.5 dB is achieved by the proposed element. Therefore, using a proper biasing voltage control network, the PIN diodes of the proposed elements in a periodic arrangement are set at different states, which may be denoted by a binary string with "1"s or "0"s, and the whole array of elements operates as a binary coding periodic structure and exhibits controllable EM functionalities. In order to verify the coding property of the proposed element, the general principle for the biasing circuit design is given. An optimized biasing circuit is thoroughly studied using both field distribution analysis and equivalent circuit theory. Simulated results show that the specially designed biasing hardly affects the element reflection performance. Finally, a group of element prototypes are fabricated with welded PIN diodes and measured using the standard waveguide test method. The difference in mirror image between the waveguide test and the desired periodic arrangement is also discussed. The experimental results validate that the proposed element successfully achieves good coding EM performance by controlling its biasing voltage. The reflection loss of the element is very low, and well distributed phase difference between the two element states is observed. The simulation and experiment results agree well, and the deviation between them is analyzed in detail. The proposed element possesses distinctive favorable features such as coded controllable EM functionalities, simple structure and ultrathin profile, thus exhibiting the promising prospects in tunable stealth surface, agile antennas, and many other applications.