BASIC CHARACTERISTICS OF A QUARTER-WAVELENGTH CPW RESONATOR WITH TAP-FEED STRUCTURE AND ITS APPLICATION TO A BANDPASS FILTER WITH ATTENUATION POLES

Properties of a quarter-wavelength coplanar waveguide resonator such a s resonant Frequency external quality factor (Q(e)) are characterized by a theoretical approach and verified by the experiment. The unloaded quality Factor (Q(0)) of the resonator is also examined experimentall y. After new types of combline bandpass filter (BPF) made of these res onators are realized, their transmission and reflection characteristic s are examined theoretically and experimentally. A new combline BPF ha ving attenuation poles are also realized. A simple method to produce t wo-port equivalent circuit of these BPF is presented in this paper. Th e transmission characteristics including such as the control of attenu ation poles of these filters are explained by the created equivalent c ircuit with the concept of even and odd modes. A new method of describ ing attenuation poles is established.