- Title
- Novel M-shaped defected ground structure for spurious suppressed dual mode bandpass filter design
- Creator
- Lau, J. W.; Lum, K. M.
- Relation
- Progress in Electromagnetics Research Symposium (PIERS 2012). Progress in Electromagnetics Research Symposium Proceedings (Kuala Lumpur, Malaysia 27-30 March, 2012) p. 583-587
- Relation
- http://piers.org/piersproceedings/piers2012KualalumpurProc.php?start=100
- Publisher
- Electromagnetics Academy
- Resource Type
- conference paper
- Date
- 2012
- Description
- This paper presents a spurious suppressed microstrip dual mode bandpass filter (BPF). High selectivity and good adjacent channel interference rejection are required of modern transmitting and receiving devices. Conventionally, square resonator with orthogonal input and output feedlines is employed to achieve a quasi-elliptic type of bandpass response with two transmission zeros near its passband edges. However, this resulted in spurious response of unwanted harmonics at higher frequencies. The proposed spurious suppressed dual mode BPF utilized novel M-shaped defected ground structures (DGS) etched in the ground plane beneath a square resonator input and output feedlines to attain spurious suppressed bandpass responses. The presence of DGS leads to the increment in the current path and effective permittivity, and also decrement of the effective phase velocity and effective wavelength. In addition, DGS of different sizes, patterns and positioning, equivalent L-C ratio, coupling coefficients and other electrical parameters will result in various spurious suppression responses. It can be represented by a parallel tuned circuit arranged in series with the main circuit transmission line to which it is coupled. The prototyped BPF is fabricated on a Ro4003C substrate with relative permittivity of 3.38 and loss tangent of 0.0021. The center frequency is 2.55 GHz. The best measured S₁₁ is obtained at 2.58 GHz with a value of -23.76 dB and the corresponding S₂₁ is -3.7 dB which is slightly lower as compared to the simulated response. This is mainly due to fabrication tolerance and misalignment loss. One transmission zero is obtained at 2.25 GHz and 2.85 GHz respectively. The lower and upper stopband attenuation is greater than 20dB/GHz. The bandwidth of the passband response at -3 dB level is 3.2%. Validation of the BPF design is obtained via good agreement between the simulated and measured results.
- Subject
- bandpass filters; coupled circuits; defected ground structures; permittivity; resonators
- Identifier
- http://hdl.handle.net/1959.13/1308441
- Identifier
- uon:21645
- Identifier
- ISBN:9781934142202
- Language
- eng
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