A fast design approach of compact microstrip multiband bandpass filters

Abstract

A simplified technique is used to design multiband bandpass filters using a compact ultrawideband (UWB) microstrip bandpass filter with spiral‐shaped λg/2 resonators, spaced apart by λg/4.Pairs of transmission zeros are generated on predefined locations in the UWB to create dual‐, triple‐, or quad‐band bandpass filters, as desired. The bandwidth and location of the sub‐bands can be easily controlled by the locations of the transmission zeros. These are generated by inserting additional resonators with predicted lengths. Highly selective quasielliptic multiband controllable responses can be achieved. Equations for fast calculations of filter dimensions are derived. Measurements show excellent agreement with the simulations. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1075–1079, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26742

Multiband bandpass filters with suppressed harmonics using a novel defected ground structure

“…The multiband filter, discussed in a previous work , had the main drawback of out‐of‐band spurious responses, originally existent in this type of UWB basic filter. To improve the performance of this multiband filter class, the out‐of‐band spurious responses might be suppressed in some way to a sufficient level and safe frequency range.…”

A quad‐band bandpass filter using sept‐mode double square‐ring loaded resonator

“…Moreover, owing to the advantages of lower cost, easier fabrication, and flexible multiband design approach, the microstrip quad‐band BPF based on the hybrid substrate has attracted much attention as the focus of a large number of studies . For example, Reference proposes a microstrip quad‐band BPF constructed by introducing improved coplanar waveguide (CPW)‐fed and the DGS via dual‐mode perturbations with dual‐mode double square‐ring resonators to achieve high out‐of‐band rejection and low IL.…”

“…For example, Reference proposes a microstrip quad‐band BPF constructed by introducing improved coplanar waveguide (CPW)‐fed and the DGS via dual‐mode perturbations with dual‐mode double square‐ring resonators to achieve high out‐of‐band rejection and low IL. In Reference , a fast design approach using spiral‐shaped λ g /2 resonators and spaced apart by λ g /4 was employed to implement quad‐band BPF with the merit of flexible multiband design, ultrawide band, and controllable TZs. As two common resonators employing to achieve multiband design, stub‐loaded resonator (SLR) and SIR were also utilized in the quad‐band BPF implementation.…”

A Compact Quad-Band Bandpass Filter Using Multi-Mode Stub-Loaded Resonator

“…Very few researches on quad-band BPF design have been reported [8][9][10][11][12][13][14][15][16][17]. In [8], dual-behavior resonator has been applied to split a wide passband into multiple passbands. However, it is difficult to independently manipulate the frequency response of each passband in this technique.…”