Design And Implementation Of Wideband Directional Coupler Based On Low Temperature Co-fired Ceramic

With the rapid development of modern telecommunication technology, people's requirements for communication equipment have changed from "A communication device” to "A lightweight, compact device". As one of the most important components in microwave circuits and systems, the miniaturization of directional coupler is a very important step in realizing the miniaturization of mobile communication equipment.Among these technologies which can realize the miniaturization of microwave components, Low Temperature Co-fired Ceramic (LTCC)technology has a three-dimensional multi-layer circuit structure. This structure can effectively reduce the area and the volume of the microwave components. Now, LTCC technology has become the preferred way to improve the miniaturization and integration of microwave circuits and systems.This paper is based on the design and research of the wideband directional coupler using the LTCC technology. Here are the main study points:1. The equivalent circuit of the directional coupler is analyzed using the microwave network analysis method, and the obtained scattering matrix is applied to the design of the directional coupler model. Then, the working principle and the corresponding characteristic impedance of the coupling transmission line under different excitation modes are studied.2. In order to meet the requirement of the directional coupler in the wideband frequency range, the directional coupler model is established using the electromagnetic simulation software HFSS and LTCC technique.Finally, comparing the model of the miniaturized directional coupler with a commercial directional coupler, the results show that the performance of the model is more excellent under the wideband frequency.3. The effects of some physical parameters on the performance of the directional coupler are studied by simulation. The coupled line spacing has an obvious effect on the coupling. The smaller the line spacing is, the greater the coupling is. The line width of the coupled line will affect the isolation, greater line width will create better isolation in the high frequency domain and worse isolation in the low frequency domain; the length of the coupling strip line also affects the performances of several indicators at the same time. Finally, a conclusion has been drawn that the design of a model needs to take a number of performance indicators inside, in order to take reasonable balance.