The Design And Applications Of Transdirectional Coupled-line Couplers

Directional couplers are directional power distribution devices, which are widely used in microwave communication. Traditional coupled-line directional coupler is difficult to achieve strong coupling, and in some applications it may increase circuit complexity, then generate parasitic effects. Trans-Directional couplers are proposed in recent years as a new type of directional coupler, the device is able to achieve strong coupling by loading other components, and can effectively avoid the traditional coupled-line directional couplers cross-cutting issues,reduce parasitic effects,achieve DC blocking in active circuit,compared with traditional coupled-line directional couplers, it has superior performance in some applications. So studies of the Trans-Directional couplers become more popular.The paper discussed the transmission condition of Trans-Directional couplers by microwave network theory. We proposed different method to design Trans-Directional couplers by even-odd theory. By different loading schemes we improved the directivity,and reduced the size of the Trans-Directional couplers, which is more advantageous for device integration. While considering the problem that loading periodically can not achieve weak cross-coupling, we proposed a method to solve it. Then list some practical applications using Trans-Directional couplers, and compared with traditional transmission directional coupler with the host advantage.Based on the even and odd mode theory, by using different loading programs to realize arbitrarily coupling. While maintaining the basic premise of constant performance, we effectively reduced the size off by 55%. At the same time, we proposed new applications based on the characteristics of the Trans-Directional couplers.