High-Order Miniaturized Narrowband Bandpass Filter with Wide Stopband Characteristics

Abstract

The invention discloses a high order miniature narrowband bandpass filter with wide stopband character. The high order miniature narrowband bandpass filter with wide stopband character comprises a micro-strip medium substrate (1), a metal grounding plate (2), a quarter-wave resonator (3), an input-output feeder line (4), and a grounding hole coupling wire (5). The quarter-wave resonator (3) consists of four stepped impedance resonators (31, 32, 33, 34), and the four stepped impedance resonators (31,32,33,34) are annularly distributed on the micro-strip medium substrate (1); the first stepped impedance resonator and the second stepped impedance resonator are connected through the grounding hole coupling wire (5); the second stepped impedance resonator and the third stepped impedance resonator, the third stepped impedance resonator and the fourth stepped impedance resonator, as well as the first stepped impedance resonator and the fourth stepped impedance resonator are all energy coupled through gaps. The high order miniature narrowband bandpass filter with wide stopband character can greatly reduces the dimension of the high order filter, increasing the selectivity of the filter, and is applicable to wireless communication systems.

Description

technical field [0001] The invention belongs to the technical field of electronic devices, and in particular relates to the design of a microstrip bandpass filter, which can be used for a radio frequency front end of a wireless communication system. Background technique [0002] With the rapid development of modern wireless communication, the spectrum occupation is becoming more and more intensive, resulting in the problem of spectrum congestion becoming increasingly prominent, and the requirements for wireless communication electronic equipment are also increasing. Filter is an important device in modern radio frequency communication system, its performance and size will affect the design of the whole system. Therefore, how to design high-performance and miniaturized microwave filters is one of the key research focuses of modern wireless communication systems. [0003] The main indicators of traditional bandpass filters are: bandwidth, center frequency, insertion loss, ret...

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Problems solved by technology

[0004] In response to these problems, in October 2003, Jen-Tsai Kuo and others published a high-order filter designed with a parallel coupled line over-coupling structure in the IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS journal, although the high-order harmonics were suppressed to a certain extent , and no additional structure is added, but its size and stop band width are not ideal, and the insertion loss is large; in July 2005, Yo-Shen Lin et al. published a set of The cross-coupled bandpass filter designed by the total K converter achieves good selectivity while reducing the overall size of the filter, but its stopband and insertion loss characteristics are not ideal, and the overall size is too large; 2014 In January, Shih-Cheng Lin published a cross-coupled filter designed with connection coupling and parallel coupling lines in the IEEE MICROWAVE AND WIRELESS COMPONENTSLETTERS journal. Although this coupling structure greatly reduces the size of the filter, it realizes the size of the overall structure Reduced, and the insertion loss is small, but there is still a shortcoming that the stop band is too narrow

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