Compact Dual-band Bandpass Filter Research Articles

Design and analysis of a compact dual‐band bandpass filter using V‐ and W‐shaped microstrip open lines

AbstractIn this article, a compact dual band bandpass filter using V‐ and W‐shaped microstrip open lines is developed and analyzed. An equivalent lumped elements circuit, derived from the designed structure is presented and its elements are calculated based on its transfer function. The obtained equivalent circuit is interpreted with the geometric tuning results in particular the transmission zero relocations. The measurement results of the fabricated prototype agree with the simulations and confirm the design theory. The design can suit WLAN application.

Design of Dual-Band Bandpass Filter With Multiple Transmission Zeros Using Transversal Signal Interaction Concepts

In this letter, a compact dual-band bandpass filter (BPF) based on the transversal signal interaction concepts is presented. The center frequencies of dual-band BPF are centered at 3.8 and 4.8 GHz with 3-dB fraction bandwidths of 11.3% and 10.7%, respectively. Transversal filtering structure is introduced in the proposed dual-band BPF, which provides two signal propagation paths from input to output. Thus, a dozen of transmission zeros are yielded to obtain wide stopband suppression ranging from 5.2 to 16 GHz. To validate the design scheme, a dual-band BPF with high selectivity, compact size, independently controllable bandwidth, and wide stopband suppression is fabricated and measured.

A compact dual-band bandpass filter for 2.4/5.2 GHz WLAN application

A compact dual-band bandpass filter for 2.4/5.2 GHz WLAN application

Compact dual-band bandpass filter and diplexer using hybrid resonant structure with independently controllable dual passbands

In this article, a compact dual-band bandpass filter (BPF) is developed using a hybrid resonant structure, which consists of a microstrip stub-loaded dual-mode resonator and a slotline stub-loaded dual-mode resonator. These two resonators, both having two controllable resonant modes and one transmission zero (TZ), are analyzed and used to construct two desired passbands of a dual-band BPF. Multiple TZs are generated by introducing a source-load coupling, thus improving the selectivity of the passbands. Then, the dual-band BPF is reshaped to configure a compact diplexer. The inherent TZs of the two proposed resonators are designed to improve the frequency property and port isolation of the diplexer. Finally, a dual-band BPF and a diplexer with the lower and upper passbands centered at 2.45 and 3.45 GHz, respectively, are designed, fabricated, and measured to verify the proposed structure and method.

A Novel Dual-Band Controllable Bandpass Filter Based on Fan-Shaped Substrate Integrated Waveguide

A compact dual-band bandpass filter with controllable center frequencies based on the 90° fan-shaped substrate integrated waveguide resonator (FSSIWR) is first proposed in this letter. Dual-band response is achieved by the fundamental mode (TM101 mode) and high mode (TM201 mode) of the FSSIWR, respectively. In this design, two pairs of the posts are loaded at the 45° direction of FSSIWRs, which produce perturbation to adjust the center frequency of the first passband. In order to control the second-passband center frequency, the complementary split-ring resonators (CSRRs) are etched on the surface of the resonator. The etched CSRRs can not only adjust the second-passband center frequency by changing the locations of the CSSRs but also produce a transmission zero (TZ) in the upper stopband of the second-passband. In addition, other five TZs are obtained by introducing source–load coupling, which highly improve the frequency selectivity. Finally, the proposed filter is fabricated and measured. The measured results agree well with the simulated ones.

Compact Dual-band Parallel Coupled T-shaped SIR Filter for WLAN Applications

In this article, a new compact dual-band bandpass filter was introduced. The filter utilized two operating bands centered at 2.45 GHz and 5 GHz widely used for wireless local area network applications. The filter consists of T-shaped sections of step impedance resonator. The structure is an even symmetrical around electrical or magnetic wall, so the operation mechanism of the filter can be analyzed by an even- and odd-mode transmission line theory. The resonator structure is parallel coupled to a pair of 50 Ω input/output ports. Proper feeding and coupling structures can realize at least two transmission zeros around each of the operating band. To enhance the spurs rejection in the out of the band response of the filter, additive transmission zero at 10 GHz was created by adding stub of quarter guided wavelength at a selected distant from the output port edge. The filter is designed and optimized using the full wave Electromagnetic simulator. The center frequency of the designed bands can be easily refined by the filter dimensions. The overall dimension of the filter is (where is the guided wavelength at the frequency of 2.45 GHz) corresponding to 14.3 mm x 22 mm.

Compact dual-band bandpass filter based on signal-interference techniques

To realize good isolation between two signal passbands, a dual-band bandpass filter (BPF) in this article was presented using signal-interference techniques, in which five open loop resonators are adopted. The proposed filter topology is made up of two signal transmission paths in parallel, under signal-interference principles, overlap section of two original passbands, decided respectively by two different transmission paths, is selectively removed from the combined passband, as a result, two aim passbands are realized. In addition, good isolation between two aim passbands is established due to two new transmission zeros, produced by adopted signal-interference techniques. At last, good agreement can be observed between simulation and measurement.

Compact dual bandpass filter for terrestrial radio and GSM applications

A Compact Dual Band-Bandpass Filter (DB-BPF) with wide stopband rejection is proposed in this article. The basic tools used in the structure are Short Circuited Stepped Impedance Resonators (SCSIR), Open Stub Resonators (OSR). First, a Single Band-Bandpass Filter (SB-BPF) is designed with wide stopband rejection, and then it is modified to DB-BPF. Both the SB-BPF and DB-BPFs have similar type of construction except for an additional SCSIRs used in DB filter. The structure of the filters, use the source-load coupling and OSR to generate transmission zeros, which suppresses harmonics and achieves wide stopband. The use of SCSIRs make the SB and DB bandpass filters size compact to 0.099λg×0.094λg and 0.118λg×0.092λg, where λg is guided wavelength with a wide stopband upto 6.85f0 with 22 dB suppression for SB-BPF and 2.78f1/7.57f0 with 22 dB suppression for DB-BPF, where f0 and f1 are centre frequencies of first and second passbands respectively.

Miniaturized dual-band filter with return loss bandwidth and transmission zero control

In this paper, a compact dual-band bandpass filter (DB-BPF) using new dual-mode resonator-loaded resonators (DM-RLRs) is presented and investigated to simultaneously achieve controllable return loss (RL), bandwidth (BW) and transmission zeros (TZs), and the simple strategy for this type of filter design is proposed. The DB-BPF consists of two high-flexibility DM-RLRs with separated electric and magnetic coupling (SEMC). Specifically, the proposed DM-RLR provides the DB-BPF with center frequency control as well as RL control, and SEMC is utilized for the BW and TZ control. To facilitate the design, a simple optimization-based design strategy is proposed and employed, resulting in an example layout. Finally, the example filter, with center frequencies of 1.57 GHz (channel 1 for GPS) and 3.5 GHz (channel 2 for WiMAX), is fabricated and measured. The measurement insertion loss and RL are 0.9/0.9 and 17/20 dB. The fabricated DB-BPF also exhibits a compact size of 0.12λg × 0.08λg at 1.57 GHz.

Compact single/dual band BPF with harmonic suppression using open‐loop resonator and L‐shaped coupling arm

A new approach is presented to design a widestopband single and dual-band bandpass filter (BPF) using L-shaped coupling-arm and open-loop resonators (OLRs). Non-uniform gap between the L-shaped coupling-arm and OLR and the length of the coupling-arm lead to the selective and collective suppression of higher order harmonics. Using voltage wave analysis, it is shown that the coupling-coefficient reduces to zero for certain harmonics. To demonstrate the application of the proposed technique single and dual-band BPFs is designed and fabricated. Second- and fourth-order single-band BPFs are fabricated for the centre frequency of 2.24 GHz. Harmonic suppression up to 5.8 fo with the suppression level >30 dB is achieved in second-order BPF. One more second-order BPF is designed and fabricated using stub-loaded stepped impedance OLR. This BPF displays widestopband up to 8.4 fo with the suppression level of 30 dB. Further a compact dual-band BPF is also designed and fabricated. The response shows the harmonic suppression up to 5.3 fo. The measured results are in good agreement with the full-wave simulation performed by high-frequency structure simulator.

Compact Dual-band Bandpass Filter Based on HMSIW and DS-CSRR

AbstractA compact dual-band bandpass filter (BPF) based on a half-mode substrate integrated waveguide (HMSIW) and double-side complementary split-ring resonators (DS-CSRR) is investigated in this paper. The proposed DS-CSRR consists of two complementary split-ring resonators (CSRRs) with different sizes. One is etched on the top surface of HMSIW, the other is on the ground. By changing the parameters of DS-CSRR, both the center frequencies and the bandwidths can be controlled independently, respectively. In order to validate its practicability, a dual-band BPF centered at 3.5 GHz/5.2 GHz is designed and demonstrated. The simulated and measured results are in good agreement with each other.

Design of ultra compact dual-band bandpass filter using L-shaped resonator

A compact dual-band microstrip bandpass filter (BPF) is presented for application at the frequencies 2.4 and 5.84 GHz. The proposed main resonator consists of two L-shaped resonators. To improve the upper-stopband of the proposed filter, modified U-Shaped resonators are accepted. The operation mechanism of the filter is investigated based on proffered equivalent-circuit model and transformation function. The sketched dual-band BPF attends the insertion loss less than 0.1 and 0.4 dB Also the return loss is 26 and 28 dB at 2.4 and 5.84, respectively. This proffered filter structure is proper for Bluetooth and wireless local area networks and other wireless communication systems. An overall good agreement between measured and simulated results is observed.

Compact dual‐band BPF with wide stopband using stub‐loaded spiral stepped‐impedance resonator

A compact dual-band bandpass filter (BPF) with wide stopband performance using stub-loaded spiral short-circuit λ/4 stepped-impedance resonator is proposed. Spiral configuration has been used for compactness of filter. Both passbands can be controlled individually by changing the geometric parameters of resonator. Multiple transmission zeros provide high selectivity to both passband and extend stopband up to 3 GHz. The filter has compact size of 0.06λg × 0.09λg. A dual-band BPF has been designed and fabricated for terrestrial trunked radio (TETRA) band and global system for mobile communication applications.

Planar dual-mode dual-band bandpass filter using a modified rectangular split-loop resonator loaded by an open-circuited stub

A compact planar dual-band bandpass filter using a new microstrip dual-mode resonator has been proposed in this article, which is based on a modified rectangular split-loop resonator loaded by an open-circuited stub. The implemented filter with two passbands has shown an excellent performance, including three transmission zeros disturbed nearby the two passband edges and between the passbands, by which a high selectivity is obtained for the proposed filter. Also, the measured results agree well with the simulated ones.

Compact dual‐band balanced bandpass filter based on double‐layer SIW structure

A compact dual-band balanced bandpass filter with high common-mode (CM) suppression is proposed. Two layers of substrate are vertically stacked to realise the miniaturisation. The first differential-mode passband can be obtained by the dominant modes and the second can be achieved by utilising the higher-order modes. The desired coupling coefficients of both bands are achievable by properly setting positions and sizes of the coupling slots etched on the layer interface. Meanwhile, four slotlines are etched on the bottom layer of the substrate to improve CM suppression and band-to-band isolation. A four-order prototype is designed for demonstration. Good agreement between simulated and measured results is obtained.

Compact dual‐band bandpass filters using complementary split‐ring resonators with closely spaced passbands

Two compact dual-band bandpass filters based on open complementary split-ring resonators (OCSRRs) with stub loaded are presented. Both of the stub-loaded open-loop resonators can achieve two resonant modes, and each of the resonators generate a passband. Thus, a small ratio of two passbands central frequencies can be obtained. Moreover, the two resonant modes of the outer ring are λ /4 resonators, so the OCSRR exhibits a compact size. Meanwhile, the characteristics of dual-mode resonators can be discussed by using even-/odd-mode analysis. The proposed filters exhibit four transmission zeros, one or two of which can be introduced between the two passbands. To verify the theory, two filters with zeros of different locations are designed, fabricated and measured. The test results indicate good agreement with simulated ones.

Miniaturized Dual-Band Waveguide Filter Using TM Dielectric-Loaded Dual-Mode Cavities

In this letter a class of very compact dual-band band-pass filters based on TM dual-mode cavities loaded with high permittivity dielectric is presented. Filters consist of cascaded doublets resulting in in-line structures with a high degree of design modularity where each doublet is designed separately. Each doublet provides two poles and two transmission zeros resulting in a filter with an equal number of poles and zeros. Zeros can be placed in both the lower and upper stop-bands as well as between the two pass-bands to increase their insulation. The feasibility of the proposed approach is demonstrated through the design and manufacturing of a 6th order dual-band filter with central frequencies at 4.25 and 4.55 GHz having six transmission zeros.

Compact dual-band bandpass filter using uniform-impedance resonators and dual-mode resonator

This article presents a compact dual-band bandpass filter (BPF) using a pair of one-end shorted uniform-impedance resonators (SUIRs) and a single dual-mode resonator (DMR). A pair of SUIRs with mixed electric and magnetic coupling (MEMC) not only realizes the lower passband but also serves as the feeding lines with source-load coupling to excite the DMR to produce the upper passband. Four transmission zeros due to the cancelling effect of MEMC, harmonic effect, source-load coupling, and inherent property of DMR improve the passband selectivity, band-to-band isolation, and out-of-band rejection. As an example, a dual-band BPF operating at 1.57/2.4 GHz with compact size of 0.1λg × 0.127λg is designed and fabricated. The simulation agrees very well with measurement. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1537–1540, 2016

Perturbed Sierpinski carpet resonator and its usage in compact dual and triple band bandpass filters

In this paper, perturbed Sierpinski carpet fractal shaped resonator is characterized and applied in the design of multiband band pass filters (BPFs). The route to achieving compact multimode resonators starting from the Sierpinski carpet fractal shaped resonator is detailed. The proposed resonators are used to demonstrate two topologies of dual band bandpass filters with passband center frequencies at 3.5 GHz as well as 5.5 GHz, respectively. Both the designs exhibit nearly identical passband bandwidth. In the second design, it is observed that the second passband gets slightly shifted towards 5.85 GHz. However, with edge loading this shift is nullified. A scaled down version of the same resonator is designed and three such resonators are interdigitally coupled in conjunction with complementary split ring resonators to exhibit a novel technique of achieving compact triband bandpass filter. All designs have acceptable passband insertion loss in the respective bands. Accessories are used to improve passband selectivity in all designs and also a wide stop band till 10 GHz is obtained. Fabrication prototypes for all the variants are realized with simulated and measured results in good agreement. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:418–425, 2016.

Compact dual-band bandpass filter using open stub-loaded stepped impedance resonator with cross-slots

A compact dual-band bandpass filter using stub-loaded stepped impedance resonator (SLSIR) with cross-slots is presented. The symmetric SLSIR is analyzed using even- and odd-mode techniques. Design equations are derived and they are used to guide the design of the circuits. Two passbands can be easily tuned by cross-slots and open stubs. Transmission zeros among each passbands are created, resulting in high isolation and frequency selectivity. An experimental circuit is fabricated and evaluated to validate the design concept. The fabricated filter is compact with 19.76 × 12.7 mm2. The measurement results are in good agreement with the full-wave simulation results.