Microstrip Wideband Bandpass Filter Based on Square Ring Loaded Resonator

Abstract

Abstract-In this paper, a compact microstrip wideband bandpass filter (BPF) based on square ring loaded resonator (SRLR) is proposed. The SRLR is formed by loading a pair of bent open-stubs outside the diagonal corners of a square ring, which generates three split degenerated modes. The first two split modes form a dominant wideband passband. By introducing another pair of loaded open-stubs, the third split mode is moved into the passband to achieve an extra bandwidth for the wideband passband. Measured results show that this proposed BPF has a 3 dB fractional bandwidth of 69%, and the insertion loss of the BPF is less than 1.0 dB.

A Ultra Compact Wideband Bandpass Filter Using a Quadmode Stub-Loaded Resonator

“…In [1], a lowpass filter and highpass filter in a cascade connection are used to design a wideband filter, and wideband BPFs using this kind of method have relatively large circuit size. In [2], a compact microstrip wideband BPF based on a square ring loaded resonator (SRLR) is proposed, which is formed by loading a pair of bent open-stubs outside the diagonal corners of a square ring, which generates three split degenerated modes. In [3,4], a method of signal interaction of two transmission paths is employed to design a wideband filter, and wideband BPFs using this kind of method have relatively broader bandwidth and better selectivity, but the design processes are relatively complex.…”

“…So far, as an intensively studied topic, there are several approaches reported in the literature to design integrated wideband BPFs [1][2][3][4][5][6][7][8][9][10][11][12]. In [1], a lowpass filter and highpass filter in a cascade connection are used to design a wideband filter, and wideband BPFs using this kind of method have relatively large circuit size.…”

A Novel Compact Wideband Bandpass Filter Using Rotational Symmetric Loaded Structure

“…The resonator is an important part to constitute a microwave bandpass filter (BPF). Many different types of resonator have been proposed in recent years, typically multiple modes resonator (MMR) [1][2][3][4], and the MMR is commonly used due to several attractive features, such as compact size, additional modes for wide band or UWB operation, and wide upper stopband. Traditionally, λ/4 resonators and λ/2 resonators are used to constitute a wide-band bandpass filter [5][6][7], but the bulky size is a fatal disadvantage.…”