Varicap-tuned narrowband filters with extended rejection band based on U-shaped microstrip Resonators
- 25 Downloads
A resonance equation for the first unwanted resonant frequency of tunable microwave U-shaped loop-type resonator with variable capacitance has been derived. This frequency does not depend on the variable capacitance value; it is invariable and proportional to λ-type oscillations. The ascertained feature makes it possible to determine the ratio of the first unwanted resonant frequency to the frequency of the main resonance and control the rejection bandwidth of tunable filters with U-shaped resonators. A narrowband (2%) varicap-tuned filter with extended rejection band has been built and its experimental data are presented. The experimental four-resonator filter could be tuned in the frequency range 225–400 MHz. The filter rejection band in terms of the attenuation level of –40 dB was located in the frequency range 420–1290 MHz, i.e., f max /f min = 3.07. Varicap-tuned filters with microstrip U-shaped resonators are shown to have a good potential for their practical use.
Unable to display preview. Download preview PDF.
- 4.B. Kapilevich, “A varactor-tuned filter with constant bandwidth and loss compensation,” Microwave J., No. 4, 106 (2007). URI: http://www.microwavejournal.com/articles/4575.Google Scholar
- 7.J. Nath, D. Ghosh, J.-P. Maria, A. I. Kingon, W. Fathelbab, P. D. Franzon, M. B. Steer, “An electronically tunable microstrip bandpass filter using thin-film Barium-Strontium-Titanate (BST) varactors,” IEEE Trans. Microwave Theory Tech. 53, No. 9, 2707 (2005). DOI: 10.1109/TMTT.2005.854196.CrossRefGoogle Scholar
- 14.http://www.dovermpg.com/polezero.Google Scholar
- 17.E. A. Guillemin, Synthesis of Passive Networks (Wiley, 1957).Google Scholar
- 18.G. Matthaei, E. M. T. Jones, and L. Young, Microwave Filters, Impedance-Matching Networks, and Coupling Structures, Vol. 2 (Artech Microwave Library, 1980).Google Scholar