Dual-wideband Bandpass Filter Research Articles

Design of a miniaturized multi resonance resonator based highly selective dual wideband bandpass filter

This paper presents the design of a highly selective dual-wideband bandpass filter. The filter is designed by using multi-resonance resonator consisting of two stub-loaded step impedance resonators separated by an inter-digital capacitor. The inter-digital capacitor generates capacitive coupling, resulting in multiple resonating modes. The proposed filter generates two passband frequencies centered at 5.75 GHz and 11.5 GHz. Experimental measurements show that the maximum insertion loss in the passbands is 0.83 dB and 0.87 dB, while the reflection losses are better than 10.8 dB and 12.6 dB, respectively. The resonant frequencies can be adjusted by changing the length of the loaded stubs. The proposed dual-wideband bandpass filter offers improved out-of-band rejection and selectivity by generating seven transmission poles and seven transmission zeros around both passbands. The experimental results confirm the effectiveness of the proposed filter. Furthermore, the filter has a compact size of (0.61×0.66)λg, making it suitable for integration into microwave sensing devices.

Dual-wideband sandwich coupled three-lines bandpass filter based on modified open-stub loaded stepped impedance resonator with improved second harmonic for 5G wi-fi/ ku-band applications

A modified open-stub-loaded three sections stepped impedance resonator (OSL-TSIR) is analysed in this paper. Based on the even- and odd-mode analysis technique, it can be easily achieved that the proposed OSL-TSIR have the advantage of improving spurious resonant mode frequencies. Besides, more degrees of freedom are provided to control the location of harmonics. A third order Chebyshev dual-wideband bandpass filter composed of cascade parallel sandwich coupled three-lines sections of types SC/CS and OSL-TSIR which act as multi-mode resonator was developed and the design procedure is described. To demonstrate the efficiency of the design process, DB-BPF operating at 5.15/12.58 GHz (2.45 f0) and FBW of 19/5.7% for 5G Wi-Fi/Ku-band Applications is designed and simulated. Three transmission zeros are created, resulting in the excellent band-in-band isolation and high selectivity. The filter has a miniaturized size of 27 mm × 18 mm.

A dualband bandpass filter with tunable bandwidths for automotive radar and 5G millimeter-wave applications

A compact dual wideband bandpass filter for automotive radar (AR) and 5G millimeter-wave (mmWave) applications with adjustable bandwidths is presented in this work. The filter is based on microstrip dual-mode edge-coupled stub-loaded resonators (SLR). The novelty of this configuration is that it allows independent control of the bandwidths which is not obvious for many reported SLR-based filters. To achieve an overall size of 1.23λ_g× 2.02λ_g, these resonators are coupled and bent int o U-shape, T-shape, and E-shape. The U-shaped resonator, based on a quarter-wavelength transmission line, is coupled to the T-shaped element which constitutes the main feed line to obtain the dual-band response. Having a symmetrical structure, the design i s studied using the even-odd mode analysis. The layout is made using the Ansys high-frequency structural simulator (HFSS) and fabricated on Rogers RO3010 with a thickness of 1.28 mm, a dielectric constant of 10.2, and a loss tangent of 0.0022. The measured bandwidths are 660 MHz and 880 MHz at central frequencies of 23.92 GHz and 28.38 GHz respectively. The measured insertion losses are less than 3.9 dB and the return losses are greater than 17 dB in both bands. A good agreement is obtained between simulate d and experimental results.

A Dual-Wideband Balanced Bandpass Filter Based on Branch-Line Structure With Controllable Common-Mode Suppression

In this paper, a novel dual-wideband balanced bandpass filter (BPF) based on branch-line structure is proposed. For analysis, the equivalent circuits of differential-mode (DM) and common-mode (CM) of the filter are built based on the even- and odd-mode method. With a proper synthesis design of DM bisection, dual passbands with a multi-order filtering response can be obtained. Additionally, three open-circuited stubs are centrally loaded on the CM bisection and six controllable transmission zeros are therefore generated. Thus, two stopbands are formed and then a favorable CM suppression within DM passbands is obtained. For demonstration, a third-order dual-wideband balanced BPF is designed with two passbands operating at 2.54 and 4.62 GHz. Good agreement between the simulated results and measured results is obtained, which verifies the validity of the proposed design method.

Microstrip Dual-Band Bandpass Filter With Wide Bandwidth Using Paper Substrate

This work presents the design and analysis of a novel dual-wideband bandpass filter (BPF) using the transversal filtering section (TFS), coupled lines (CLs), and stepped impedance stubs (SISs). Initially, a dual-band BPF employing TFS and CLs is designed. To enhance the bandwidth and selectivity, SIS units and quarter wavelength transmission lines are attached at the input and output ports. This novel filter's frequency response has six transmission zeros in the stopband and four transmission poles in each passband. A prototype with center frequencies of 1.17 and 2.4 GHz is realized on a biodegradable substrate and tested. The tested and simulated results are in high congruence, validating the proposed design circuit and theory.

High‐conductivity graphene‐assembled film‐based bandpass filter for 5G applications

This article presents a compact 5G dual-wideband bandpass filter (DBPF) based on high-conductivity graphene assembled films (GAFs), which can meet the requirements of the sub-6 GHz bands, high integration and high information transmission rate for 5G wireless communication. The GAF DBPF consists of two folded open-loop stepped-impedance resonators with a compact size of 21.9 mm × 22.5 mm × 0.53 mm. The measured results show that the presented GAF DBPF has two passbands with 3 dB fractional bandwidths of 15.95% and 12.72% at center frequencies of 2.14 and 3.5 GHz, respectively. In addition, the filter exhibits an attenuation level greater than 20 dB up to 7.52 GHz.

Design of A Dual-Wide Band BPF Utilizing Parallel Coupled Microstrip Lines and A Centered Arrow-Shaped Resonator

This paper presents a dual wide-band band pass filter (DWB-BPF) by using two parallel, symmetrical micro-strip lines loaded by a centered resonator, consisting of a T- and a triangle-shaped geometry, attached at the lower and upper ends, respectively. The filter reveals good performance and both the passbands can be independently controlled by adjusting specific parts of the filter. The proposed BPF is simulated by using CST microwave studio package and the simulated result is verified experimentally with good agreement between the two results. The fabricated prototype BPF demonstrates two passbands located at 2.3 GHz and 6.35 GHz center frequencies with 39% and 23.6% of 3-dB fractional bandwidth (FBW), respectively and a good insertion and return losses. The designed BPF can be targeted for wireless local area network (WLAN), WIFI and satellite communication systems.

Dual-/Tri-Wideband Bandpass Filter with High Selectivity and Adjustable Passband for 5G Mid-Band Mobile Communications

The design and implementation of the filters for the fifth-generation (5G) mobile communication systems are challengeable due to the demands of high integration, low-cost, and high-speed data transmission. In this paper, a dual-wideband bandpass filter (BPF) and a tri-wideband BPF for 5G mobile communications are proposed. The dual-wideband BPF consists of two folded open-loop stepped-impedance resonators (FOLSIRs), and the tri-wideband BPF is designed by placing a pair of folded uniform impedance resonator inside the dual-wideband BPF with little increase in the physical size of the filter. By employing a novel structural deformation of a stepped-impedance resonator, the FOLSIR is achieved with a more compact structure, a controllable transmission zero, and an adjustable resonant frequency. The measurement results show that the working bands of the two filters are 1.98–2.28/3.27–3.66 GHz and 2.035–2.305/3.31–3.71/4.54–5.18 GHz, respectively, which are consistent with the full-wave EM simulation results. The implemented filters have a compact size and the results show low loss, good out-of-band rejection, and wide passbands covering sub-6 GHz bands of 5G mobile communications and a commonly used spectrum.

A Compact Dual-Wideband Bandpass Filter Based on Open-/Short-Circuited Stubs

A dual-wideband bandpass filter is proposed and analyzed, which is based on loaded open-/short-circuited stubs. The dual-band filter consists of a second-order bandpass filter and a third-order bandpass filter, which can be designed separately. The bandwidth of two passbands can be adjusted by tuning the impedance and the length of the stubs. A dual-band bandpass filter prototype operating at 2.4/5.2 GHz is designed for demonstration. It shows a low insertion loss of 0.3 dB and wide bandwidth of 51.9% at 2.4 GHz and 23.3% at 5.2 GHz. The filter structure is simple without narrow coupling gap between resonators, which is easy for fabrication.

Design of Equal-Ripple Dual-Wideband Bandpass Filter With Minimum Design Parameters Based on Cross-Shaped Resonator

A novel quarter-wavelength cross-shaped resonator (CSR) is presented in this brief for the design of equal-ripple dual-wideband bandpass filter (DWB BPF) with minimum design parameters. The proposed CSR is composed of a pair of parallel-coupled lines (PCLs) with short- and open-ended stubs. To extract the transmission poles and zeros, rigorous scattering-parameters and ABCD -matrix theories with even-odd-mode analysis method are used. After theoretical analysis, it is found that two passbands with equal-ripple responses can be realized on both sides of the operation frequency. In contrast to the reported DWB BPFs with complex structures, the proposed one is only formed by a quarter-wavelength CSR and featured as minimum design parameters. To verify this, a prototype is designed and fabricated. The measured results are in good agreement with the simulated ones, verifying a simple design approach of equal-ripple DWB BPFs.

Dual‐wideband filter with wide high‐rejection band using composite resonators

A new type of dual-wideband bandpass filter using composite series and shunt resonators is proposed in conjunction with its direct synthesis and design theory. By making use of the transmission pole (TP) and the transmission zero of the composite resonators flexibly, a dual-wideband filter with a wide range of frequency and bandwidth ratios as well as a wide stopband can be realised. With a shunt capacitor introduced at each I/O port, extra TPs either in the low passband or in the high passband can be created, leading to more filter design options. To give a direct design procedure, a lumped-element prototype is first synthesised based on a target filtering function and a dedicated circuit extraction process. The filter layout can be realised using semi-distributed circuits and chip capacitors. Two practical schemes are introduced to suppress spurious resonances for a wide high-rejection stopband. Two filter examples are designed with a small and a large frequency ratio and a wide band suppressed spurious resonances. The unique filter response and good agreement between the designed and measured results demonstrate the superior performance of the proposed filter structure and the effectiveness of the synthesis and design theory.

Size-Reduction of Dual-Wideband Bandpass Filters Using Bridged-T Coils

In this paper, reduced-sized dual-wideband bandpass filter designs using bridged-T coils are proposed. The bridged-T coil can be designed as a wideband lumped-element equivalent of the transmission line, and it is used to replace all or part of the transmission line sections in a conventional dual-wideband bandpass filter for very efficient circuit size reduction. The tradeoff between circuit size and insertion loss is investigated, and practical design examples are presented to demonstrate the filter performance.

Design of dual wideband bandpass filter using stub loaded multi‐mode resonators

AbstractIn this paper, a novel dual wideband microstrip bandpass filter is proposed. The designed filter is constructed by two different stub loaded resonators located at the upper and bottom sides of the coupling line. The coupling transmission line is also connected to input and output (IO) ports. The upper resonator creates a wide passband, whereas the bottom resonator is used to create two transmission zeros in the passband. Thus, a wide passband can be divided into dual wide passbands. The bottom resonator is also utilized to improve the insertion and return losses in the passband. The designed filter is fabricated and tested in a very good agreement with the simulated results. The measured fractional bandwidths (FBWs) of the passbands are 44.6% and 24.2% at the center frequencies of 3.4 GHz and 5.51 GHz, respectively. The measured insertion losses in the passbands are 0.51 dB and 1.13 dB.

A dual-wideband bandpass filter using open/shorted coupled lines

AbstractA compact dual-wideband (DWB) bandpass filter utilizing open-shorted coupled lines (OSCL) is proposed in this paper. The introduction of the folded structure not only reduces the overall size but also contribute to the split of the transmission zero (TZ), which improves the selectivity effectively. Six transmission poles and five TZs are realized utilizing the shorted-circuit stub and OSCL. The characteristic of the flexible adjustment method of TZs guarantees an independently wide adjustable range of the bandwidth. For demonstration, a DWB filter (3 dB bandwidth 120 and 28%, respectively) is designed and fabricated. The filter is compact and has the characteristics of extraordinary wide bandwidth, low insertion loss, as well as high selectivity.

Compact dual-wideband bandpass filter for wireless applications

In this paper, a compact dual-wideband bandpass filter with two reflection zeros in both passbands and two transmission zeros in the stopband, based on a signal interference technique is presented. The proposed filter is formed by a transmission line connected in parallel with a series connection of transmission lines and a short circuited edge coupled line. A simple lossless transmission line model is used to derive the condition for transmission zeros. To validate the theoretical predictions, a compact dual-wideband bandpass filter has been fabricated to operate at GPS and INSAT Satellite bands. The measured 3 dB passband fractional bandwidths are 82.16% and 41.52%, respectively.

Dual-wideband bandpass filter with independently controllable center frequencies and wide stopband

In this paper, a dual-wideband bandpass filter (BPF) with independently controllable center frequencies (CFs) and wide stopband suppression is presented using a new quintuple-mode resonator (QMR). By applying the classical odd-/even-mode analysis method, the resonant characteristics of the new QMR have been analyzed. It shows that five modes can be excited, and two of them can be employed to form the lower passband, while the other three modes contribute to the higher passband. For verification, a dual-wideband BPF using the new QMR is designed, fabricated, and tested. Experimental results show that the CFs of the dual-wideband BPF centered at 2.96 GHz and 5.695 GHz with 3 dB fractional bandwidths of 27.7 and 23.4%, respectively. In addition, 20-dB suppression in upper-stopband ranges from 2.23 to 4.04f0, where f0 is the center frequency of the first passband. The measurement results are in good agreement with the prediction results.

Dual‐wideband band pass filter using folded cross‐stub stepped impedance resonator

AbstractIn this letter, a dual‐wideband band pass filter (DW‐BPF) using cross‐stub stepped impedance resonator (CS‐SIR) was simulated, fabricated, and measured accordingly. The CS‐SIR was used to replace the conventional half‐wavelength open stub resonators. Compare to the conventional resonator, the CS‐SIR resonator has a wider fractional bandwidth and ease of fabrication. Furthermore, the DB‐BPF was fabricated on microstrip with ɛr = 4.4, h = 0.8 mm, and tan δ = 0.0265. The DW‐BPF with CS‐SIR achieves transmission‐coefficients/fractional‐bandwidth of 0.22 dB/94.19% and 1.87 dB/33.52% at 1.14 GHz and 2.31 GHz, respectively. In order to reduce the filter size, a folded CS‐SIR (FCS‐SIR) was also proposed. As a result, this BPF size was reduced to 53%, with the BPF size of 0.30 λG2 and 0.14 λG2 for DW‐BPF with CS‐SIR and DW‐BPF with folded CS‐SIR, respectively. The λG is the wavelength at the first frequency. Further, the DW‐BPF with FCS‐SIR achieves transmission coefficients/fractional bandwidth of 0.19 dB/89.08% and 1.29 dB/31.90% at 1.21 GHz and 2.41 GHz, respectively. Measured results are in a very good agreement with the simulated results.

분산 CRLH 전송선로 4중 모드 공진기를 이용한 이중-광대역 대역통과 여파기 설계

본 논문은 CRLH (composite right/left handed) 전송선로 구조의 4중 모드 공진기를 이용하여 높은 대역간 격리도를 갖는 이중-광대역 대역통과 여파기를 설계하는 방법을 제안한다. CRLH 전송선로 구조를 해석하여 4중 모드 공진기의 s-패러미터와 공진 주파수를 유도하였다. 유도된 s-패러미터를 이용하여 새로운 구조의 이중-광대역 대역통과 여파기를 설계, 제작하였다. 측정 결과는 2.8-5.52 GHz, 9.68-12.26 GHz의 이중 통과대역에서 각각 1.08 dB, 2.01 dB의 삽입손실을 갖고, 6.34-8.42 GHz의 중간대역에서 38dB의 대역 격리도를 가져 설계 결과와 잘 일치하는 특성을 보여 주었다. This paper presents a dual-wideband bandpass filter (BPF) with high band-to-band isolation and skirt selectivity using distributed composite right/left-handed (CRLH) transmission line (TL) quad-mode resonators (QMRs). The results of the proposed distributed CRLH TL unit cell analysis are used to establish the scattering parameters and the resonance frequencies of the QMR constituting the dual-wideband BPF. A novel dual-wideband bandpass filter is designed and fabricated, using the derived scattering characteristics. The measured results show that the fabricated dual-wideband bandpass filter has an insertion loss of less than 1.08dB in the lower band, and of 2.01dB in the upper band, a bandwidth of 2.8-5.52GHz and 9.68-12.26GHz, and a band-to-band isolation of more than 38dB, from 6.34-8.42GHz.

Highly selective dual-wideband bandpass filter using quad-mode resonators for WLAN and WIMAX applications

A highly selective dual-wideband bandpass filter (BPF) using quad-mode resonators (QMRs) is presented. The proposed QMR loaded with two folded open-ended stubs and a T-shaped stub exhibits not only four transmission poles but also two transmission zeros, which results in a wider bandwidth and sharper cut-off responses. The dual-band performance is realized with two QMRs sharing a common input and output. Four transmission zeros are found located at 2.09, 2.67, 3.18, and 4.14 GHz, with an attenuation level that is less than −20 dB. The measured center frequencies of the two operation passbands are 2.4 (WLAN) and 3.5 GHz (WiMAX), and the minimum insertion loss of the two passbands are 0.87 and 1.4 dB, with 3 dB fractional bandwidths of 17.5% and 16%, respectively. The stopband suppression is greater than 20 dB from 4.2 to 6.5 GHz. Good agreement between the simulated and measured results demonstrates the validity of the proposed BPF. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1417–1423, 2015

A NOVEL COMPACT DUAL-WIDEBAND BANDPASS FILTER WITH MULTI-MODE RESONATORS

A novel compact dual-wideband bandpass filter (BPF), with two multi-mode resonators (MMRs), a quad-mode one (QMR) and a triple-mode one (TMR), is proposed in this paper. The first passband is generated by a QMR loaded with a short-ended stub and two open-ended stubs, and the second one is realized by a TMR loaded with a square ring and a short-ended stub. Each passband can be tuned separately by controlling the corresponding resonator. The classical even-/odd-mode analysis is applied to characterize the presented MMRs due to their symmetric configurations. In order to validate the design methodology, a dual-wideband BPF prototype centered at 2.34 and 3.46 GHz with fractional bandwidths of 25.6% and 21.4% for WLAN and WiMAX applications is designed, fabricated and measured. Measurements have good agreement with simulations.