基于耦合波理论和相位匹配技术，对准光辐射器的传统设计方法进行了改进，使其适用于低阶模式的设计.通过调节耦合时模式间的相位，在切口处实现了具有高斯场分布的理想模式组合.利用这一方法，优化设计了一个94 GHz, TE5,3回旋管准光辐射器.数值模拟结果表明，设计的辐射器在切口处形成了一个良好的束斑，边馈电平达到-30 dB，口径场高斯含量高于98%.

Based on the coupled-wave theory and the phase-matching technique, an improved method for low-order quasi-optical mode launcher is presented. Adjusting the phase difference between the working mode and its satellite modes, an ideal mixture mode with the features of Gaussian field distribution was obtained. Using the proposed method, a 94 GHz TE5,3 quasi-optical mode launcher was synthesized. The numerical calculation shows that the difference between the edge and peak values of field intensity reaches 30 dB. A well-focused field at the aperture with a Gaussian mode content of more than 98% can be obtained，which will reduce drastically the diffraction losses and reflection of power from the cuts.