Design Of Dual-band Filter Research Articles

Design and development of dual-band superconducting filter with a novel structure

In this paper, a novel design structure of a dual-band filter is proposed. The core of the structure is to form a dual-band filter by connecting two sub-filters through a matching network. The matching network can not only improve the flexibility of the design, but also minimize the influence between the two sub-filters. Two sub-filters are designed separately, one of which is composed of interdigital resonators and the other is composed of hairpin resonators. The center frequency and bandwidth of the two passbands are flexible and controllable. Finally, a dual-band high-temperature superconducting (HTS) filter is designed and successfully fabricated on a DyBa2Cu3O7 (DyBCO) thin film on thickness of 0.5 mm LaAlO3 wafer, and the measured results are in good agreement with the simulation results.

Generative Model for Dual-Band Filters Based on Modified Complementary Split-Ring Resonators

This article presents a generative model for the inverse design of dual-band filters based on a type of modified complementary split-ring resonator (CSRR). It consists of a series of convolutional neural networks that incorporate the conditional deep convolutional generative adversarial network (GAN) technique. The filters are designed by etching the modified CSRRs on the surface of substrate-integrated waveguides. This design allows us to achieve two passbands with a compact size. In this GAN-based generative model, the CSRRs are represented as two-dimensional matrices. Each matrix corresponds to a training sample of the designed filter, and its S-parameters are extracted through an HFSS simulation. Both the matrices and the S-parameters are fed into the model as the training datasets. Different CSRRs with various sizes are employed for a wider applicable frequency band. Normalized matrices and normalized S-parameters are utilized to simplify the complex generative model resulting from the variations in CSRR sizes. The effectiveness of the generative model is validated through four design examples of dual-band filters, with their center frequencies located within 5 to 18 GHz. The inference time for each design is approximately 18.5 min. The measurement results of the fabricated filters are in good agreement with the simulation ones.

Design of dual-mode dual-band filter based on multilayer groove gap waveguide

This paper presents a novel dual-mode dual-band filter (DBF) based on multilayer groove gap waveguide (GGW). Unlike other published planar GGW filters, the proposed filter achieves a vertically stacked duplicate topology by introducing a rectangular aperture in the common wall and traditional inductive irises on the same layer, with perfect central symmetry in the overall structure. This reduces machining difficulty while having a smaller size. By optimizing the dimensions of the coupling structure and rectangular cavities, dual-mode resonators (DMRs) including even mode and odd mode are used to accomplish dual-bandpass response. Additionally, an efficient transition is presented and applied to achieve a good impedance matching from rectangular waveguide (RW) to GGW. To better demonstrate, a multilayer DBF with working center frequencies of 67.9 and 69.8 GHz is designed, fabricated and measured. Good consistency can be observed between the simulation result and the measurement result.

Design of a dual-band filter with high selectivity and wide stopband

ABSTRACT This paper proposes a design of dual-band bandpass filter with a high selectivity and a wide stopband, by using two ring type hairpin resonators. The equivalent circuit of the used resonator is analyzed through the analysis of odd and even modes. The designed filter can achieve dual passbands at 2.4 GHz and 3.65 GHz for wireless local area network (WLAN) and 5 G communication systems, with transmission zeros at 2.9 GHz and 5.1 GHz, realizing high selectivity. With a wideband bandstop filter on the input port, a wide stopband from 4.6 GHz to 17.3 GHz is realized.

Topology Assessment for Dual-Band Filters Based on Acoustic Wave Resonators

This work assesses three different approaches to the design of dual-band filters with single-ended input and output based on acoustic wave (AW) technology together with the filter synthesis methodology behind each structure. First, the straightforward option, already on the market, is to connect two standalone ladder filters in parallel. This work provides a synthesis view to this option and also describes its strong limitations regarding achievable isolation. Nonetheless, departing from the classical ladder, an innovative topology is proposed in which series and shunt resonators of different sub-bands are concatenated forming a double-ladder topology. Although this latter structure is able to achieve better isolation levels, this work describes the particular constraints arising from this innovative solution in terms of response and technology requirements. Finally, the conventional ladder structure with a single signal path is proposed as a strong candidate to accommodate dual-band filtering responses for the first time. All three structures are discussed from a filter synthesis perspective, describing the particular constraints behind each topology. Also, each structure is reviewed and compared in technological terms to highlight its main advantages and disadvantages.

Dual-band filter design based on hourglass-shaped spoof surface plasmon polaritons and interdigital capacitor structure

In this paper, a dual passband filter with spoof surface plasmon polaritons (SSPPs) and interdigital capacitance structure loaded on a coplanar waveguide (CPW) is proposed. First, the hourglass-shaped SSPP unit-cell structure and the interdigital capacitor structure are introduced on the coplanar waveguide transmission line to obtain high fractional bandwidth and low insertion loss passband characteristics. Then, a dual passband filter is formed by loading the interdigital capacitor loop resonator to excite the trapped waves. The simulation results show that the proposed dual passband filter has excellent upper sideband rejection and dual passband filtering performance. The fractional bandwidths of the two passbands of the design are 46.8% (1.49–2.40 GHz) and 15.1% (2.98–3.63 GHz), respectively, which can achieve more than –40 dB rejection in a range of 4.77–7.48 GHz. The upper cutoff frequency and lower cutoff frequency of the two passbands can be independently regulated by changing the structural parameters of the proposed filter. In order to gain a more in-depth understanding of the operating principle of the dual passband filter, the corresponding dispersion curves and electric field distribution, LC equivalent circuit analysis are given. Finally, the prototype of the designed filter is fabricated according to the optimized parameter values. The experimental results are in good agreement with the simulation ones, indicating that the proposed dual-passband filter is of great importance in implementing microwave integrated circuits .

Design and Implementation of Microwave Dual-Band Pass Interdigital Filter Using an Analytical Approach

In this paper, benefiting from frequency transformation between the normalized frequency domain of low-pass prototype frequencies and the real frequency domain of the filter, a purely analytical procedure for dual-band filter design is used. The coupling matrix of the filter is analytically extracted, without the need to perform numerical optimization. The procedure also includes finding the equivalent circuit for these types of filters. The frequency transformation formula is verified through an example. The equivalent circuit and the coupling matrix are also analytically deduced through the same example. Using an electromagnetic structure simulator, an interdigital dual-band filter is designed and simulated. The simulation results fulfill the specifications of the given filter example, and the simulation results verify the possibility of achieving the required specifications of the filter frequency response. The designed and simulated filter has been implemented and measured using a Scalar Network Analyzer. The measurement results confirm the simulation results and the efficiency of the synthesis procedure.

Miniature Dual-Band Absorptive Bandstop Filters With Improved Passband Performance

In this paper, a miniature dual-band absorptive bandstop filter (ABSF) design with improved lower passband performance is proposed. Specifically, a stepped-impedance short-circuited stub is introduced to a bridged-T coil-based dual-band ABSF design, such that the insertion loss around the desired passband center frequency can be largely reduced while the absorptive stopband performance remains intact. This also helps equalize the lower passband insertion loss response and achieve a flatter passband, which is especially advantageous when cascading multiple ABSFs for improving the stopband rejection or increasing the number of stopbands. Closed-form design formulas are established to facilitate the synthesis of proposed dual-band ABSF. As an example, a 4.8/9.6-GHz dual-band ABSF in GaAs is realized with a measured insertion loss within 0.85± 0.12 dB from dc to 2.6 GHz. The circuit size is only 1.6 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 1.84 mm, and the corresponding electrical size is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.013\lambda _{0} \times 0.015\lambda _{0}$ </tex-math></inline-formula> at the designated passband center frequency of 2.4 GHz. Application of the proposed dual-band ABSF for the passband performance improvement of cascaded ABSF designs is also demonstrated, and good performance is obtained.

Switched Dual-Band SAW Filters Using Hybrid and Monolithically Integrated Vanadium Oxide Switches

This article presents design and implementation of switchable dual-band filters using surface acoustic wave (SAW) resonators and vanadium oxide (VO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) switches imbedded within the filter using both hybrid and monolithic integration. The switched dual-band filter has two channels and four switching states: transmission only of the lower channel, transmission only of the upper channel, transmission of both the channels, and no transmission. The experimental results are presented for the first switchable dual-band filter of order 5 with two discrete VO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> switches strategically integrated within the proposed filter’s structure using hybrid integration. The five-pole dual-band filter demonstrates a measured insertion loss of 3.7 and 3.9 dB in the transmission states at 765 and 935 MHz, respectively. To improve the overall performance of the proposed switched dual-band filter, a second seven-pole filter with six VO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> switches, three for each channel, is designed and fabricated. VO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> switches are monolithically integrated with SAW resonators on the same substrate using a four-mask in-house fabrication process. The article also presents experimental results to study the impact of the monolithically integrated VO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> switches on the linear and power-handling performance of SAW resonators. VO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> monolithically integrated switched dual-band filter has two channels at 600 and 725 MHz. It exhibits a measured insertion loss of 3.23 and 3.22 dB for the two channels. Depending on the number of detuned resonators in the OFF state for each channel, an isolation of 20–40 dB is demonstrated. The monolithic integration of VO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> switches results in improved performance of the filter along with significant size reduction.

Design of dual-band pass filter with two end-to-ends T-shaped resonator and open ended stubs for wireless LAN applications

Design of dual-band pass filter with two end-to-ends T-shaped resonator and open ended stubs for wireless LAN applications

Design of coaxial dual‐band filter with high stopband rejection

This paper proposes a design of dual-band coaxial filter with high stopband rejection. By setting the half-window coupling structures and loaded resonators, the stopband rejection of the dual-band coaxial filter can be significantly improved. An L band coaxial dual-band filter is designed and measured as an example. The stopband rejection of the design is increased from 2.7 times to 3.52 times the center frequency of the filter, which verifies the proposed method.

Novel Cross-Coupled Dual-Band Bandpass Filters With Compact Size Based on Dual-Mode Isosceles Right-Angled Triangular Resonators

Novel cross-coupled dual-band bandpass filters (BPFs) with compact size are proposed based on dual-mode isosceles right-angled triangular (IRAT) resonators. The dominant mode in the IRAT resonator is the TM100Z mode. By introducing posts in the resonators, an LC resonant unit is formed, which resonates at a lower frequency than the TM100Z mode. In the design of novel dual-band filters, the LC mode constitutes the first passband while the TM100Z mode produces the second passband. As cross-coupling is applied, two and eight transmission zeros (TZs) are produced in the responses of third-order and fourth-order dual-band BPFs, respectively. Two third-order cross-coupled dual-band BPFs with altered passbands and one fourth-order cross-coupled dual-band BPF are fabricated and measured. The measured results agree very well with the simulated results, demonstrating attractive advantages of the proposed BPFs such as compact size and decent performance.

Dual‐band filter based on one single circular patch resonator with highly improved bandwidths and compact size

In this Letter, a new design of dual-band patch filter is proposed with greatly improved bandwidth and miniaturised size based on one single modified circular patch resonator. In this design, a metallic via is introduced in the centre region of the patch to develop the modified resonant TM01 mode (TM′01 mode), while two types of slot perturbations are adopted to separate a pair of degenerate modes of TM11 (TM11A and TM11B) and control another pair of degenerate modes of TM21 (TM21A and TM21B), respectively. Thus, two passbands with one transmission zero (TZ) can be attained by elaborately exploring these resonant modes (the TM′01 and TM11A modes form up the lower passband while TM11B and TM11A modes constitute the upper passband, and TM21B mode is responsible for the TZ). For verification, one prototype is implemented. Results indicate that the novel dual-band filter (centred at 3.7 and 5.3 GHz) exhibits not only relative compact size (0.36 λ g × 0.36 λ g), but also much larger 3-dB fractional bandwidths (27 and 13%), nice return loss (better than 21 dB) and insertion loss (better than 1.0 dB), compared with other reported patch filters.

Dual-band passband terahertz filter based on multilayer metamaterial

We have theoretically verified the design of dual-band passband terahertz filter using multilayer metamaterial. The top and bottom layers are composed of periodically branching structure metallic patterns, which are exactly the same. The middle layer consists of a periodically metallic square aperture. The three metallic layers are separated by two thin dielectric layers. An equivalent circuit model is used to simplify the design procedure of the proposed structure. The performance of the terahertz filter is analyzed via equivalent circuit model together with the full wave CST method. The results show that the proposed structure provides two passbands. One is the center frequency of 0.32 THz with -3dB bandwidth of 164 GHz, and the other is the center frequency of 0.74 THz with -3dB bandwidth of 176 GHz.

Synthesis and design of SIW dual-band narrow-band bandstop filter

ABSTRACT In this letter, a general approach to synthesize arbitrary order dual-band narrow-band bandstop filter (BSF) is proposed. Simple formulas are derived to calculate the design parameters for the filter. To validate the method, a third-order dual-band BSF using substrate integrated waveguide (SIW) technology is fabricated. Taking the advantage of the high Q SIW resonators, the fabricated filter shows good stopband suppression. The measured center frequencies of the filter are 6.81 and 7.213 GHz, and the corresponding relative 3-dB bandwidths are 4.6% and 4.1%.

Single-Layer Mode Composite Coplanar Waveguide Dual-Band Filter With Large Frequency Ratio

A dual-band filter of a large frequency ratio is proposed, studied, and developed in this article, which is based on mode composite coplanar waveguide (MCCPW). Both low and high bands of the dual-band filter can be designed independently with a high degree of design freedom. The filter can achieve more than ten times the frequency difference between the two bands, which is usually hard to accomplish by conventional dual-band filter design techniques. All harmonics between the two bands can be suppressed by a cascaded low-pass filter and impedance matching structure to form a qualified dual-band frequency response. The characteristic of the proposed MCCPW dual-band filter makes it a promising candidate for multiband systems, especially in 5G communication systems. The demonstrated MCCPW dual-band filter is fabricated with a single-layer substrate. Measured results are in good agreement with simulated results, which validate the feasibility and superiority of the proposed filtering technique.

Design of Dual Band and Tri-band Bandpass Filter (BPF) with Improved Inter-band Isolation Using DGS Integrated Coupled Microstrip Lines Structures

A novel approach to design dual-band as well as a triple-band BPF with improved isolation is ventured in this paper. In dual-band filter, dual mode property of coupled line filters is utilized to obtain resonant frequencies at 2.4 GHz and 7.4 GHz suitable for WLAN and WiMAX application respectively. Additionally a rectangular-ring DGS element is introduced within the coupled line filter to obtain a separate mid-band resonance at 5.2 GHz. The frequency shifting property of the pass bands due to cross-coupling between the microstrip line resonators and the DGS element is mostly eliminated by implementing stepped impedance open stub (SIOS) technique. All filter configurations are fabricated, measured and compared with the simulated models to validate the practical effectiveness. Stop band isolation > 40 dB and insertion loss (IL) < 0.8 dB is attained in all the filter configurations.

Design of a compact ultra-narrow band dual band filter for WiMAX application

A novel narrow-band bandpass filter with two fully controllable passbands is proposed in this letter. The filter is designed through a systematic, yet simple approach, in which two independently-controllable passbands are realized using two different coupling paths. Each passband can be tuned independently only by changing one parameter of the filter. The measured and simulated results are in good agreement, showing, two passbands cantered at 3.5 and 5.8 GHz with fractional bandwidths of 0.8% and 1%, respectively. The return loss in the first and second passbands are better than 19 dB. The filter exhibits a very good out of band rejection performance, suppressing spurious bands up 16 GHz. The demonstrated filter has a compact size of 0.21λg × 0.13λg, where λg is the guided wavelength at 3.5 GHz.

Design of Concurrent Dual-Band Filters for GSM Application

In this paper, concurrent dual band filters are designed and stimulated using CST software. This system has Notch filter with an operating range 720MHz to 920MHz and Dual-band Band pass filter with an operating range of 700MHz to 1.8GHz. Dual bands are obtained between 0.98-1.02 GHz and 1.47-1.57GHz. The Notch and the Band pass filter are both designed with the help of microstrip structure with a material called FR4 with relative dielectric constant 4.4 and order 2. Band pass filter is designed using two step impedance resonator. And Notch filter structure is designed by placing a single stub between the load of the microstrip and its source. The change in the filter output with the change in the length as well as width if the stub is noted. The band of the filters changes according to the dimensions of the stub. Thus, the range of the filters can be adjusted accordingly by changing the stub dimensions.

Design of Micro-strip Symmetrical Dual-band Filter Based on Wireless Sensor Network Nodes

The micro-strip antenna filter design of wireless sensor network nodes is usually used to improve the out-of-band suppression and frequency selectivity by increasing the order of the filters, but the filters are usually single band, not only the size is large, but also the in-band characteristics of the filters are not ideal. This paper proposes a method to design a micro-strip symmetric dual-band filter in wireless sensor network nodes. Firstly, the coupling matrix of single-passband filter is obtained by using the synthesis method of generalized Chebyshev filter function. Then, the coupling matrix of the dual-passband filter is generated according to the reflection zeros and the transmission zeros. Finally, the S parameters response curve is drawn by mapping the normalized frequency domain of the dual-passband to the actual frequency domain. According to the data analysis and experimental results, the method is feasible and effective to design a micro-strip symmetrical dual-band filter. It can not only provide a more guiding design method for the joint design of antenna and RF front-end circuit, but also realize the spread of single-passband filter to multi-frequency for a wireless sensor network node antenna.