Key Technique Studies On Passive Components In Microwave Receiver

Microwave receiver and passive components including filters and microstrip-to-waveguide transition are studied. Several schemes for wide-stopband lowpass filters (LPF), ultra-wide band (UWB) filters, and dual-mode dual-band filters are proposed. Besides, a novel minimized waveguide-to-microstrip transition is designed which necessary in millimeter-wave receivers. All these passive components have merits of compact size, improved performances, and easy integrated, which can be used widely in future receiver systems.In chapter 1, the basic principle of microwave receiver and the background and the progresses of microwave filters are introduced, including wide-stopband LPF, ultra-wide band filter, and dual-mode dual-band filter. The stopband characteristics of the defected ground structures (DGS) and patch loaded slotline (PLS) are also mentioned in this chapter.In chapter 2, systematic research on the design theory of filters. Different types of lowpass prototype filters are introduced and element transformations for lowpass prototype to highpass, stopband, and bandpass responses are given. Besides, synthesis methods of transfer function and general coupling matrix for chebyshev filtering functions are also discussed in this chapter.In chapter 3, a parallel stepped impedance resonators (SIR) loaded hairpin resonator is proposed. The equivalent LC circuit and transmission matrix of the new resonator used in LPF design is given. Several LPFs with wide stopband are designed using this resonator and improved ones. Comparing with other LPFs reported in open literatures, the new LPFs designed in this chapter have merits of decreased size, wide-stopband, and improved stopband.In chapter 4, several classic characteristics of DGS and PLS are studied, such as stopband and slow-wave characteristics. A novel resonator with high Q factor is proposed and filters using the new resonator are designed. A UWB filter with DGS is investigated and it has a minimized size and a very wide stopband comparing with conventional ones. Furthermore, the DGS loaded UWB can avoid a disadvantage which the periodic bandgap (PBG) structures loaded UWB will met with that the line is too narrow to be fabricated.In chapter 5, characteristics of stub loaded dual-mode resonator are studied. A new kind of dual-mode dual-band filter using this resonator is designed and two passband of it can be adjusted separately. The new dual-mode dual-band filter is compact and has excellent stopband performances with the second harmonic was completely compressed.In chapter 6, the background of microstrip-to-waveguide transition is simply presented. A new kind of microstrip-to-waveguide transition is proposed using slot antenna, which has high gain, narrower beam, and wide radiation band. The new transition has compact size, small ripples and low insertion losses in the passband. Because of these characteristics, this transition is fit for practical circuit.In chapter 7, a summary of the whole dissertation and potential research topics are given.