Microwave Ring Circuits and Related Structures phần 3

Chế độ phân chia cộng hưởng địa phương, như thể hiện trong hình , là vui mừng bằng cách thay đổi trở kháng của một khu vực hình khuyên vòng hình khuyên ngành highor trở kháng thấp sẽ xây dựng một điều kiện ranh giới địa phương cộng hưởng để lưu trữ hoặc chia tách các năng lượng các chế độ cộng hưởng khác nhau. | 64 MODES PERTURBATIONS AND COUPLING METHODS OF RING RESONATORS FIGURE Four types of split modes a coupled split mode b local resonant split mode c notch perturbation split mode d patch perturbation split mode. Local Resonant Split Modes The local resonant split mode as shown in Figure is excited by changing the impedance of one annular sector on the annular ring high-or low-impedance sector will build up a local resonant boundary condition to store or split the energy of the different resonant modes. Figure illustrates a coupled annular ring element with a 45 high-impedance local resonant sector LRS . According to the standing-wave pattern analysis only the SPLIT RESONANT MODES 65 FIGURE Power transmission of an asymmetric coupled annular ring resonator. FIGURE Layout of the symmetric coupled annular circuit with 45 LRS. resonant modes with mode number n 4 m where m 1 2 3 and so on have integer multiple of half guided-wavelength inside the perturbed sector. This means that these resonant modes can build up a local resonance and maintain the continuity of the standing-wave pattern inside the perturbed region. The other resonant modes that cannot meet the local resonant condition will suffer energy loss due to scattering inside the perturbed sector. According to the analysis of the standing-wave pattern it is expected that only the fourth mode will maintain the resonant condition and the other modes will split. The theoretical and experimental results illustrated in Figure agree very well. The test circuit was built on a RT Duroid substrate with the following dimensions 66 MODES PERTURBATIONS AND COUPLING METHODS OF RING RESONATORS a Theory Experiment FIGURE Resonant frequency vs. mode number for 45 LRS. Substrate thickness mm Line width mm LRS line width mm Coupling gap mm Ring radius 6 mm Following the standing-wave pattern analysis the mode phenomenon for the 45 LRS is found to be the .