The Design Of Dual Band Band-pass Filter Based On DGS

Microwave filter can suppress out-of-band noise, equalize the amplitude and phase characteristics effectively. With the diversification of communication model, single frequency communication is difficult to meet the needs of this change. For example in WiMAX, WLAN, GPS equipment, receiver should launch and receive multiple frequency signals at the same time. As an important device in the RF system, dual band band-pass filter plays an important role in the communication system. It has vital significance to study the dual band band-pass filter.In this paper, theoretical analysis is proposed in the first three chapters. Chapter 1 describes the research background and significance of the dual band band-pass filter, then the analysis of the research status and progress of the double band-pass filter is proposed. Chapter 2 introduces the DGS structure and enumerates several typical DGS structures. The extraction principle of the DGS equivalent circuit is introduced through the analysis of the dumbbell DGS structure. Then it is extracted by the simulation software. Chapter 3 introduces the general theory of the filter, compares the several low-pass filter prototype response and introduces the principles of the filter frequency transformation at last.The designs and the results are analyzed in Chapter 4. The frequency characteristic of the ring resonator is analyzed at first. Then the arrowhead DGS structure and the ring resonator are combined to design a dual band band-pass filter which works in WiMAX and WLAN bands. Then the arrowhead DGS structure is replaced by the C-shaped DGS. The simulated and measured results show better frequency selectivity. Finally this chapter discusses some problems which should be paid attention to in the processing and testing procedure of filter. Chapter 5 draws some conclusions and gives expectations.