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本文提出了一种带通滤波器的精密设计。这种滤波器是把TE_(01δ) 模环形介质谐振器同轴地放在TE_(01δ) 模截止圆波导内构成的。在用模匹配技术进行严格分析的基础上,根据结构对称平面短路和开路时的两个谐振频率f_(sh) 和f_(op)的计算,精确决定了谐振器间的耦合系数。对于TE_(01δ)环形谐振器来说,谐振频率f_0、温度系数τf、无载Q值Q_u以及其它谐振也以同样的方法精确计算。由这些计算釆确定,当F_r=fr/f_0保持恒定时获得最大Q_u的最佳尺寸,这里f_r为下一个更高谐振频率。采用低损耗陶瓷 ((?)_r=24.3,tanδ=5 x 10~(-5)) 的环形谐振器在12GHz时的Q_u=16800,而τ_f=0.1±0.5 x 10~(-6)/℃,但棒形谐振器有Q_u=14700。利用这类谐振器制成在f_0=11.958GHz时波纹为0.04dB和等波纹带宽为27.3MHz的四级切贝谢夫滤波器,测得的频率响应与理论完全相符。插入损耗为0.9dB,相当于Q_u=9800。
This paper presents a sophisticated design of band-pass filters. This filter is constructed by placing the TE_ (01δ) mode ring dielectric resonator coaxially within the TE_ (01δ) mode cut-off circular waveguide. Based on the rigorous analysis of the die matching technique, the coupling coefficient between resonators is precisely determined according to the calculation of two resonant frequencies f sh and f op in the symmetrical plane short circuit and open circuit. For the TE_ (01δ) ring resonator, the resonant frequency f_0, the temperature coefficient τf, the unloaded Q value Q_u, and other resonances are also exactly calculated in the same way. It is determined by these calculations that the optimum size of maximum Q_u is obtained when F_r = fr / f_0 remains constant, where f_r is the next higher resonant frequency. The ring resonator with a low loss ceramic ((?) _r = 24.3 and tan? = 5 x 10 ~ (5)) has Q_u = 16800 at 12 GHz and τ_f = 0.1 ± 0.5 x 10 -6 / ° C , But the rod resonator has Q_u = 14700. Using this type of resonator, a four-stage Chebyshev filter with a ripple of 0.04 dB and an equiaxed bandwidth of 27.3 MHz at f_0 = 11.958 GHz is produced, and the measured frequency response is in good agreement with the theory. The insertion loss is 0.9dB, which corresponds to Q_u = 9800.