• Journal of electromagnetic engineering and science
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• v.2 no.2
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• pp.124-127
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• 2002

A RF tunable bandpass filter using dielectric resonators and varactor diodes is redesigned to improve the passband flatness. Since the tunable liters are generally of narrow bandwidth and the Q value of the varactor diode is usually very low, the passband flatness is strongly deteriorated by sizeable distortion loss. To remedy this problem, we construct modified Chebyshev type filter by use of network synthesis techniques. The key of modified Chebyshev type filter is the rearrangement of the passband poles to improve the passband flatness. To maintain the constant passband bandwidth, design techniques of input/output stage and coupling windows are also applied. Experimental results show that the passband flatness can be improved by purposed method without any additional RF amplitude equalizer.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.1
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• pp.8-13
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• 2010

In this paper, a new hairpin type strip-line BPF(Band Pass Filter) improving the suppression performance of unwanted frequency signal is studied. A modified hairpin filter is designed by classical hairpin filter design methodology and is realized by newly placing structure of designed filter. And a newly formed coupled-line effects between modified bilateral symmetry structures make the transmission zeros. Each transmission zeros can shift its frequency to wanted frequency by tuning a certain part of filter. To investigate the validity of this novel technique, an order-5 Chebyshev BPF centered at 9.2 GHz with a 15 % FBW(fractional bandwidth) were used. According to design and measurement results, a good performance of insertion loss of 0.8 dB and unwanted signal suppression of maximum 50 dB is achieved at full input/output ports.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.7
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• pp.36-42
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• 1995

In this paper, the CAD program for designing the microwave waveguide narrow-band bandpass filters has been developed by the passband correction method with filter synthesis for the MDR(Microwave Digital Relay) system. Here, the modified double E-plane structures are employed in the filter structure which is analyzed by the variational method. Using the developed CAD program, 0.01dB equi-ripple chebyshev type 6-section bandpass filters used in the MDR system operating nationally is designed at the center frequency of 11.0GHz, fabricated with tunable type and then measured by tuning process. The experimantal results show good agreements with the theoretical results.

• Journal of electromagnetic engineering and science
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• v.3 no.1
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• pp.35-38
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• 2003

In this paper, compact lumped-element low-pass filter structure with two transmission zeros at second and third harmonics is presented. The use of lumped-elements and transmission zeros can provide the advantages of compact size, sharp cutoff and wide stop-band frequency response. The proposed low-pass filter is a modified Chebyshev low-pass filter type and is implemented by the use of low temperature co-fired ceramic (LTCC) technology. This filter has been verified by both simulation and experiment. The simulated and experimental results agree very well.