Research And Design Of Microwave Multi-frequency Power Dividers

With the development of modern wireless communication technology, spectrum resource is more and more limited. In order to make full use of the resource, multiple frequency components arise at the proper moment. As an important part of radio frequency system, power splitter which can work in multiple frequency bands at the same time can lead to improvements of system integration and spectrum utilization.This dissertation mainly studies the design of the microwave multi-frequency power splitters. The main work carried out can be summarized as follows:1. Three kinds of dual-band Wilkinson power splitters have been designed, including stepped impedance type, double lines type, two section coupled lines type. The stepped impedance type can achieve larger working frequency ratio and keep a smaller overall size at the same time. Then, dual-band power splitters with working frequency ratio of 5.2 and 7.5 are designed and tested, respectively, and the experimental results agree well with the simulation. For double lines type, a ring structure composed of the quarter-wave transmission line arm loaded with a folded section line is proposed, which may have some filtering function. Based on the structure, a dual-band filtering power divider with working frequency ratio 2.2 is designed. For two section coupled lines type, a dual-band power splitter with work frequency ratio of 5.8 is designed, which has compact structure and good simulation performance.2. Three kinds of tri-band Wilkinson power splitters have been designed, including improved ? structure, improved ? structure, loaded combination of stubs. Improved ? structure with center frequency at 1.5/3.0/4.5GHz and improved ? structure with center frequency at 1.58/3.8/6.0 GHz are designed respectively. But for the tri-band power splitters based on these two kinds of structure, only two work bands can be controlled freely and the third band can be determined by the known two bands, which has limited the function of tri-band power splitters. To avoid the above shortcomings, a new tri-band power splitter with combination of stubs is proposed, of which the three center frequencies can be controlled and working bandwidth can be adjusted to some extent. Then, a tri-band power splitter with center frequency of 1.5/2.7/3.5GHz, suitable for GPS, WCDMA, WIMAX, is fabricated to verify the design idea.3. Based on quad-frequency impedance converters composed of quarter-wave transmission line arms loaded with three sets of combination of stubs, a quad-band power splitter with center frequency at 0.9/2.1/3.5/5.2GHz is designed. The working bandwidth of every center frequency can be adjusted. Meanwhile, it shows good filtering characteristics and has excellent isolation between four working bands. The power splitter can be applied in GSM, IMT, WIMAX and WLAN, which can realize the function of filtering and power dividing, simultaneously.