Shuanglin Yuan

Compact box-section bandpass filter with enhanced stopband characteristics

A compact bandpass filter (BPF) with enhanced stopband characteristics is presented in this paper. The proposed BPF consists of four improved stepped impedance resonators (SIRs), which implements into a box-section structure. To improve the frequency selectivity and the stopband characteristics, additional transmission zero (TZ) was introduced by mixed electric and magnetic (EM) coupling. A new filter with 31.2% fractional bandwidth (FBW) has been designed and fabricated to verify the validity of the proposed method. The filter has two transmission zeros, where TZ1 is located in 0.4 GHz with 78.7 dB rejection and TZ2 is located in 2.7 GHz with 50.2 dB rejection. Measured results are in good agreement with the electromagnetic simulation.

Compact Bandstop Filter with Multiple Rejection Zeros

This paper presents a compact band stop fllter (BSF) based on the dual metal plane conflguration with multiple rejection zeros (RZs). Quasi-lumped technique with novel patch-via-spiral dual mode resonator is applied to the design of the proposed fllter. Multiple rejection zeros are introduced by open-end stubs for high selectivity. Design equations are obtained by using a lossless transmission line model. The calculated results show that the lower and upper rejection zeros can be easily tuned by the coupling capacitor and the open- end stubs respectively. By using the Microstrip-Coplanar-Waveguide (CPW) structure, the size of the proposed fllter can be reduced to 12:8mm £ 9mm (i.e., 0:24‚g £ 0:17‚g), where ‚g denotes the guided wavelength at center frequency.

Design of compact bandpass filter with enhanced stopband characteristics

A compact third-order bandpass filter (BPF) with enhanced stopband characteristics is proposed in this paper. The filter consists of two stepped impedance resonators (SIRs) and a new resonator named closed loop SIR. The closed loop SIR which is embedded into the other two resonators for compact size is not the real structure of SIR, but it is similar to the conventional λ/4 SIR in some characters. Cross coupling is introduced into the proposed filter to generate extra transmission zero (TZ) near the passband for sharp frequency selectivity. By adjusting the strength of the mixed cross coupling, the location of the extra transmission zero can be controlled. A new filter centered at 1.77GHz has been analyzed, simulated and fabricated to verify the validity of the proposed method. The measured results show that there are three finite transmission zeros near the passband, which are located at 1.4GHz with 54.2dB rejection, 1.58GHz with 35.9dB rejection, 3.72GHz with 48.5dB rejection, respectively. And, the spurious frequencies of the upper-stopband are suppressed below 30dB from 2.5 GHz to 8.0 GHz.

Design of a Compact Enhanced Stopband Bandpass Filter with Embedded Coupled Stubs

Abstract A compact bandpass filter with an enhanced stopband using stepped-impedance resonators is presented in this article. The proposed filter consists of two quarter-wavelength stepped-impedance resonators with a circular structure for compact size. To improve the upper stopband of the proposed filter, embedded coupled stubs are employed. Owing to the mixed electric/magnetic coupling and the embedded coupled stubs, four transmission zeros can be generated in the stopband for improved selectivity and a wider upper stopband. A new bandpass filter centered at f0 (1.38 GHz) has been designed and fabricated to demonstrate the validity of the proposed method. Measured results show that four finite transmission zeros are located at 0.91, 3.01, 4.90, and 7.20 GHz. The spurious frequencies of the upper stopband are suppressed better than 30 dB up to 6.10 f0. The circuit size of proposed filter only occupies 0.09λg × 0.09λg.

Design of ultrawideband planar monopole antenna of C shape

A novel planar monopole with enhanced impedance performance across an ultrawideband operation bandwidth of 3.1-10.6GHz is proposed. With trimmed ground, this gradient CPW fed antenna is characterized by the rotated notch on the traditional ring monopole. By simply embedding this notch, the bandwidth of the ring monopole is widened remarkably from 2.3 to 16.8GHz. Notch related parameters analysis is carried out. Finally, experimental verification of the fabricated antenna for its impedance bandwidth is carried out, showing agreement with the simulated date.

Design of enhanced stopband bandpass filter with mixed electric and magnetic coupling

A new compact bandpass filter(BPF) with improved out-of-band performance is presented in this paper. The proposed BPF consists of two non-adjacent stepped impedance resonators (SIRs), which shared a common grounded via-hole. To improve the stopband characteristics, a π type capacitive circuit is introduced in the filter. The location of the transmission zeros can be controlled by adjusting the strength of the mixed electric and magnetic (EM) coupling. Simulated results show that good performance of proposed BPF at 1.38GHz has been achieved.

Compact tri-band bandpass filter using tri-section stepped impedance resonators

A compact tri-band bandpass filter (BPF) using tri-section stepped impedance resonators (SIRs) with short loaded stubs is presented. In this letter, the second passband frequency of the tri-band filter can be flexibly controlled by tuning the tri-section SIRs, and the first and the third passband frequencies of the tri-band filter can be obtained by adjusting the parameters of the tri-section SIRs and the short loaded stubs. To validate the design, a tri-band bandpass filter is fabricated and measured. The measured results are in good agreement with the electromagnetic simulation. The circuit only occupies 0.11λg×0.12λg, where λg is guided wavelength at the lower passband center frequency.

Cascaded fourth-order mixed-coupled bandpass filter with good frequency selectivity

A compact fourth-order bandpass filter with good frequency selectivity is presented. The proposed BPF consists of four cascaded stepped impedance resonators (SIRs). Mixed electric/magnetic (E/M) coupling are introduced in the proposed filter to generate transmission zeros (TZs) near the passband for sharp frequency selectivity. The method on the generation of transmission zeros caused by mixed coupling introduced in the filter is analyzed. A new filter with 15.4% fractional bandwidth (FBW) has been designed and fabricated to verify the validity of the proposed method. Three TZs are introduced near the passband, which is at 1.21GHz, 1.72GHz, 3.03GHz. Measured results are in good agreement with the electromagnetic simulation.

Compact bandpass filter with improved stopband characteristics using S-L coupling

A compact bandpass filter (BPF) with improved stopband performance using mixed electric/magnetic (E/M) coupling and Source-Load (S-L) coupling is presented. Due to the cancelling effect of the mixed coupling, a transmission zero (TZs) is employed near the passband. The design is implemented to a circular structure to achieve compact size. For realizing wide stopband characteristic, an extra transmission zero is achieved in the upper stopband owing to the S-L coupling introduced between the input and output port. A new filter centered at 1.08 GHz has been analyzed, simulated and fabricated to verify the validity of the proposed method. The measured results show that there are three finite transmission zeros near the passband, which are located at 0.78 GHz with 53.8 dB rejection, 1.86 GHz with 67.6 dB rejection, 3.01 GHz with 53.6 dB rejection, respectively. The out-of-band rejection better than 30 dB is up to 6 GHz. And the circuit only occupies 13.5×11.5 mm2.

Compact Box-Section Bandpass Filter with Improved Frequency Selectivity

Abstract A compact box-section wideband bandpass filter with improved frequency selectivity is presented, and good performance has been achieved. The proposed bandpass filter consists of four folded stepped-impedance resonators that shared a common grounded via-hole. Mixed electric and magnetic coupling is introduced in the proposed filter to generate an extra transmission zero near the passband for sharp frequency selectivity. By adjusting the strength of the mixed electric and magnetic coupling, the location of the extra transmission zero can be controlled. A new filter with 31.4% fractional bandwidth has been designed and fabricated to verify the validity of the proposed method. Measured results are in good agreement with the electromagnetic simulation.