Design Of The Hairpin And DGS Microwave Filter For Wireless Communications

With the fast development of the mobile communications, especially the rapid spread of the 3G technology, as the key component of the communication system equipments becomes high-performance and miniaturization. This paper is mainly analyzed the hairpin structure band-pass filter and DGS low-pass filter, and designed the new structure microwave filter. The major work of this paper is the following aspects:Firstly, briefly reviewed the development history of microwave filters, and basic theories are summed up. According to relevant theoretical analysis, a five-order hairpin band-pass filter is designed and simulated.Secondly, the development and design technology status of the DGS are summed up, and the equivalent circuits are analyzed. Much and deeply research on DGS is made in this paper, emphatically analyzed the influence of variation of parameters on the performance. Then, the parameters of the dumbbell-shaped, circle-shaped and semicircle-shaped filters are deeply analyzed.Thirdly, low-pass filters of semicircle defected ground structure with H-shape open stubs are proposed. Single, two-cascaded and three-cascaded new semicircle shape DGS low-pass filters are designed and simulated. The resonant characteristic of the new two-cascaded semicircle shape DGS low-pass filter shows its advantages of compact size, high selectivity, low insertion loss and excellent pass-band performance. The frequency response of the three-cascaded semicircle shape DGS low-pass filter presents the advantage of compact size, high selectivity; low insertion loss, better pass-band performance and high out-band suppression.Finally, in order to validate the simulated analysis, single, two-cascaded, and three-cascaded new semicircle shape DGS low-pass filters are fabricated and measured. The measured results show a good agreement with the simulated result. Compared with the traditional filter, the performance of the new designed DGS low-pass filter has significantly increased. Because of its compact size, it can be used in the actual microwave equipments.This work was supported by the National Natural Science Foundation of China under Grant 61072136.