The Research Of Miniaturized And High-performance Multiplexers

Modern wireless communication systems demand for multi-function and high performances due to lack of spectrum resource and complex electromagnetic environment. More researchers focus on multiplexers that can combine or separate signals. It can be used to optimize spectrum resource, protect channels and improve communication performance. Moreover, the circuits need to meet the demands such as high integration, miniaturization and high performance. So the study of miniaturized and high-performance multiplexer has very important significance. The main researches of this dissertation are arranged as follows:1. By using the capacitance loaded dual-mode loop resonator and dual-mode SIW resonator, two diplexers are proposed. By analyzing the dual modes of resonator, the proper perturbation or circuit coupling structure can be used for the design of filters and multiplexer. It can realize the miniaturization of multiplexer because of reducing the number of resonators. Due to the inherent characteristics of dual-mode resonator, it can produce two transmission zeroes at each side of passband, which can improve the selectivity and realize high isolation.2.Defected ground structure has band gap properties and slow-wave effect, which can be used to design multiplexer. A defected spiral resonator(DSR) is proposed for designing a diplexer and a triplexer. Due to using DSR, the diplexer and triplexer have good performance such as miniaturization, high isolation and wide stopband. Moreover, using distributed coupling technique instead of matching network can further reduce the size of diplexer and triplexer. It can also reduce loading effect between each channel and enhance the flexibility of design.3.By optimizing the circuit topology and simplifying the design process of multiplexer, it makes the circuit more easily to be realized. A diplexer is proposed by using multi-mode resonator loading an opening stub and a short stub instead of traditional matching networks. The two resonant frequencies of resonator can be controlled independently by adjusting the lengths of the opening stub and short stub, respectively. The two channels of diplexer can be matched and designed independently by using the multi-mode resonator, which can reduce the interactive effect between the two channels. Based on diplexer, a quadruplexer can be realized by using distributed coupling technology to add two channels while there is little effect on other channels.