With the advancements of electronics, information, and communication industries, the radio communication systems accomplished fast growth and the quality of human life is improving rapidly under benefit of various informations. However, the improved techniques and increased using frequencies cause unwanted noises in systems and equipments. So filters are used in systems,equipments, and circuits that can be operated exactly by filtering the noise.
A filter is one of the components indispensable for microwave and millimeter wave system. Various kinds of filters have been studied and developed. The filter with better characteristics is needed for qualitative elevation of microwave system. In this thesis,a band pass filter with good characteristics was realized and miniaturized by designing the filter using open loop resonator. To solve and prove the theory of microstrip slow-wave open loop resonator in the some case of traditional filters, open loop resonator has been used by reciprocally, because it is to be assumed that the open loop resonator must satisfy the reciprocal condition.
The two pole BPF was designed and fabricated. For miniaturized design, the open loop resonator was divided by 4 sections and 2 sections with 1/4 wavelength which have different line impedances where Powell's least square method was adopted. The characteristics of the proposed BPF were improved by using two pole open loop resonator. The characteristic impedance values of each section were obtained by Powell's least square algorithm where differentiations are not needed.
This paper presents a novel design method of open loop resonator using Powell's least square algorithm and utilizes to band pass filters. The filters are not only compact size due to the open loop resonator, but also have good skirt characteristics. The measured results showed a good agreement with the theoretical results as well as ADS simulation.