tailieunhanh - Microwave Ring Circuits and Related Structures phần 6

Qc, Qd, và QR cá nhân Q-giá trị liên quan đến dây dẫn, điện môi, và thiệt hại bức xạ, tương ứng [14]. Đối với các bộ cộng hưởng vòng và tuyến tính cùng chiều dài, tổn thất điện môi và dẫn đều bình đẳng và do đó Qc và Qd đều bình đẳng. Sức mạnh bức xạ, WR, là cao hơn cho các cộng hưởng tuyến tính. | RING BANDPASS FILTERS WITH TWO TRANSMISSION ZEROS 181 f nc 4114Ẽf and n 1 3 5. where f is the frequency eeff is the effective dielectric constant n is the mode number c is the speed of light in free space and f1 and f2 are the frequencies of the two transmission zeros corresponding to the tapping positions of the lengths of l1 and l2 on the resonators. At the transmission zeros S21 0 and there is maximum rejection. Figure shows the measured results for different tapping positions on the hairpin resonators in Figure . The filter was designed at the fundamental frequency of 2 GHz and fabricated on a RT Duroid substrate with a thickness h 25 mil and a relative dielectric constant er . Table shows the measured and the calculated results for the transmission zeros FIGURE Measured results for different tapping positions with coupling gap 51 38 . Permission from IEEE. TABLE Measured and calculated results of the hairpin resonators for different tapping positions 38 . Permission from IEEE. Measurements Calculations 11 l2 l 2 mm No passband at 2 GHz f1 f 2 GHz l1 mm l2 mm f1 GHz f2 GHz f1 GHz f2 GHz l1 mm l2 mm f1 GHz f2 GHz f1 GHz f2 GHz 182 FILTER APPLICATIONS corresponding to the different tapping positions. Inspecting the results the measurements agree well with the calculations. Figure shows the filter using two open-loop ring resonators 38 . This type resonator with two folded arms is more compact than the filter in Figure . This filter has the same dimensions as the filter in Figure except for the two additional 45-degree chamfered bends and the coupling gap g mm between the two open ends of the ring. Figure shows the measured results for the different tapping positions on the rings. The measured locations of the transmission zeros are listed in Table . Comparing with Table the locations of the transmission zeros of l 11 12 .