Modern space communication systems often need high-power low-frequency (UHF, L-, S-, and C-band) low-pass filters (LPFs) with wide stopbands extending to Ka-band and beyond. Current design approaches frequently fail to meet these requirements completely. This paper proposes a new coaxial LPF concept and design methodology. The LPF consists of an array of cavity elements, which operate with transverse electromagnetic mode (TEM) and transverse magnetic (TM)-coupled resonances, and thus achieve a frequency response with a reflection zero at DC and transmission zeroes at targeted stopband locations. The design method is based on positioning the cavities in a quasi-periodic order, which efficiently spreads the transmission zeroes over the stopband, while keeping the characteristic impedance matched to the input/output interfaces over the passband. This design concept yields an ultra-wide, continuous and modal spurious-free stopband, while maintaining a low insertion loss, high peak power capacity, and low sensitivity to production tolerances.

现代空间通信系统通常需要高功率低频（UHF、L、S 和 C 波段）低通滤波器 (LPF)，其具有扩展到 Ka 波段及以上的宽阻带。当前的设计方法经常不能完全满足这些要求。本文提出了一种新的同轴 LPF 概念和设计方法。LPF 由一组空腔元件组成，它们以横向电磁模式 (TEM) 和横向磁 (TM) 耦合谐振运行，因此实现了频率响应，在 DC 处反射为零，在目标阻带位置处传输为零。该设计方法基于以准周期顺序定位空腔，从而有效地在阻带上扩展传输零点，同时在通带上保持与输入/输出接口匹配的特性阻抗。