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A. Bage & S. Das
Table 2. Comparison of the characteristics of the proposed ¯lter with few other similar bandpass ¯lters.
Source |
f0 (GHz) |
TZs location (GHz) |
IL (dB) |
RL (dB) |
Length (mm) |
Ref. 4 |
9/11 |
— |
1.95/1.85 |
20/20 |
12.18 |
Ref. 5 |
8.15/9.66/11.67 |
— |
1.8/1.4/1.15 |
16.5/24/18 |
10 |
Ref. 11 |
10/10 |
6/4 |
1.7 |
17 |
20.42/10.8 |
Ref. 12 |
10 |
6 |
0.58 |
20 |
19.875 |
This work |
8.81/10.9 |
6 |
1/1.15 |
19/17 |
10 |
|
|
|
|
|
|
and compared in Fig. 17. The ¯gure shows a good agreement between them which validates the simulations. The simulated result shows that the ¯lter operates at 8.81 GHz and 10.9 GHz with the respective 3 dB bandwidths of 0.28 GHz and 0.4 GHz and the TZs at 8.02, 8.5, 9.46, 10.13, 11.53 and 12 GHz. Measured result shows that the ¯lter operates at 8.82 GHz and 10.91 GHz with the respective 3 dB bandwidths of 0.28 GHz and 0.39 GHz and the TZs at 8.18, 8.46, 9.45, 10.11, 11.5 and 12 GHz. Comparison of the characteristics of the proposed ¯lter with few other similar ¯lters is tabulated in Table 2.
5. Conclusion
This paper presents a dual-pole, dual-band bandpass ¯lter with multiple TZs using stub-loaded C-shaped resonators and asymmetrical slot resonators. The ¯lter allows independent control of the center frequencies and TZs. The ¯lter also uses a simpli¯ed geometry of the planar inserts as compared to the other reported planar insert-loaded ¯lters with adjustable TZs. The length of the ¯lter is 10 mm which makes it compact and light-weight. Therefore, the proposed ¯lter may ¯nd applications in aeronautical radio navigation/radiolocation (8.75–8.85 GHz) and ¯xed satellite (10.7–10.95 GHz) systems.
In the proposed work, the coupling analysis between the planar resonators has not been done. Therefore, future work may be focused on the coupling analysis between the planar resonators to better understand the operation of the ¯lter. In addition, more modi¯cations may be incorporated in the resonator to achieve more bands (triple-band or quadband).
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A Dual-Band Waveguide Bandpass Filter with Adjustable Transmission Zeros
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