A Novel Dumbbell-Shaped Defected Ground Structure With Embedded Capacitor and Its Application in Low-Pass Filter Design

Chen, Zhiyong; Li, Lin; Chen, Sisi

doi:10.2528/pierl15042006

Cited by 3 publications

(1 citation statement)

References 9 publications

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“…In [1,2], low pass filters (LPFs) employing complimentary split ring resonator (CSRRs) structures in the ground planes are proposed to achieve a sharp rejection response. Defected ground plane LPFs with dumb-bell shaped [3], Hilbert curve ring shaped [4] and metal loaded structures [5] are suggested to reduce the size of the filter and attain a sharp cutoff frequency response in the stopband. UDSRC (unipolar double spiral resonant cell) [6], multiband meandered slotted ground plane resonator [7], and quarter wave stepped-impedance resonator [8] are also used to achieve sharprejection in LPF.…”

Section: Introductionmentioning

confidence: 99%

Design and Development of Recessed Ground Microstrip Line Low Pass Filters

Jaiswal¹,

Abegaonkar²,

Koul³

2019

PIER Letters

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The design of conventional stepped-impedance microstrip line low pass filter (LPF) is based on high (Z H) to low impedance (Z L) ratio. The width of Z H line, for Z H > 100 Ω, becomes critical and challenging, especially on high dielectric constant substrates. A concept of air-filled recessed ground plane below a microstrip line is introduced in this paper. The effect of dimensions of recessed ground on characteristic impedance, attenuation, and propagation constant of a microstrip line are first studied. This simple approach is utilized to design the Z H line of stepped-impedance microstrip line LPFs. Prototypes of recessed ground stepped-impedance microstrip line LPFs with Z H /Z L (keeping Z L constant as 20 Ω) ratio in the range 6 to 10 are designed and developed on Rogers 4350B of height 0.508 mm with ε r = 3.66 at 3 GHz. For LPF with Z H /Z L = 10, the measured 3-dB cutoff frequency (f c) is achieved at 3.12 GHz with return loss (RL) > 12 dB and insertion loss (IL) < 0.28 dB in its passband whereas the stopband attenuation (SBA) is better than 38 dB. In comparison to recessed ground LPF, the simulated results of conventional LPF with Z H /Z L = 10 (critical width of Z H line =) are as follows RL > 10 dB and IL < 1.07 dB in passband at f c = 3 GHz. The size of recessed ground LPF is reduced by 25%, when Z H /Z L is increased to 10 from 6. The approach of recessed ground microstrip line avoids the fabrication issues, reduces size, and improves the performance of LPF, which in turns confirms the advantages of recessed ground over conventional microstrip line.

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