频分复用器既可以用作频率合成器，也可以用作频率分离器，在超宽带通信系统中有着广泛的应用。目前的频分复用器基本设计在传统通信频段（<10GHz），根据其结构特点可以分为多支管类型、混合耦合类型、环形器耦合类型和定向滤波类型。为了获得更宽的频带和几十亿位每秒的数据传输速率，通信系统朝着毫米波的方向发展。其中，60、74、84和94 GHz附近的频段因尚未被利用而受到广泛关注。然而，目前很少有这些频段的频分复用器被报道。传统的多支管、混合耦合、环形器耦合结构在高频有较高的损耗，而定向滤波结构虽然损耗低，但是单通道带宽窄。申请人拟开发可对60、74、84和94GHz进行频率合成和分离的7通道频分复用器，该结构由一个基于新型定向滤波器的4通道频分复用器和一个4通道多支管频分复用器级联而成，可以在单通道内实现3%-15%的可调带宽，并实现低损耗和低反射，为未来的超宽带毫米波通信提供支持。

Frequency division multiplexer (FDM) can work as frequency combiner or separator, and addresses massive applications in ultra-wideband (UWB) communication systems. So far, most of the FDMs have been designed at traditional communication frequencies, i.e., <10 GHz. According to the structure, FDMs can be classified into four categories: manifold type, hybrid-coupled type, circulator-coupled type and directional filter type. To obtain wide bandwidth and tens of gigabyte per second data transmission rate, communication systems are moving towards millimeter wave frequencies, where 60, 74, 84, and 94 GHz have gained tremendous interest due to their unlicensed bands. However, FDMs have seldom been reported within these bands. At such high frequencies, manifold, hybrid-coupled and circulator-coupled FDMs typically have large insertion loss. As an alternative, directional filter FDMs can provide low insertion loss, but have narrow bandwidth for each channel. We propose developing a seven-channel FDM to combine and separate 60, 74, 84, and 94 GHz, which consists of a four-channel DFM based on novel directional filters and a four-channel manifold FDM. The proposed FDM can provide tunable bandwidth from 3% to 15% for each channel as well as low insertion loss and reflection, promising great potential for future UWB communication systems.