Compact Dual-band Bandpass Filter Research Articles

Fabrication of compact substrate integrated waveguide dual band bandpass filter using complementary split-ring resonators for C and X band applications

This article presents a compact dual-band Bandpass Filter(BPF) based substrate integrated waveguide(SIW) used for C and X band applications. Complementary split-ring resonators(CSRR) are loaded into the waveguide surface to obtain more advantages of compactness and good performance. The SIW cavity undergoes initial optimization utilizing the powerful genetic algorithm, renowned for its robustness in solving complex problems, before proceeding to simulation with Ansys HFSS software with loaded CSRRs. The filter displays two passbands: the first has a bandwidth of 2 GHz and resonates at 6.8 GHz, while the second has a bandwidth of 5,55 GHz and resonates at 10.3 GHz. Moreover, with two resonance frequencies, the developed BPF has the benefit of low insertion loss(S21=-1.7dB and -1.9 dB) and improved return loss: (S11=-24dB and -22 dB) respectively. Furthermore, the proposed combination not only allows the implementation of a forward-wave passband propagating below the characteristic cutoff frequency of the waveguide but also exhibits good rejection, demonstrated by the presence of two transmission zeros with rejection of -16 dB and -19 dB, attained at 7.4 GHz and 14.8 GHz respectively. The proposed SIW BPF was designed using a 0.6mm thick FR4 dielectric substrate measuring 13mm × 15mm. The filter is manufactured to validate the concept and the measured results agree well with the simulation. With all these advantages: compact size, high rejection, and good filtering response, the proposed SIW BPF became suitable for microwave applications.

Compact on-chip dual-band bandpass filter with wide out-of-band suppression based on hybrid coupling technique

A compact dual-band bandpass filter (BPF) with wide out-of-band suppression based on a hybrid coupling technique is proposed. This BPF consists of two hybrid spiral coupled resonators, in which the electrical coupling and magnetic coupling between resonators can generate two transmission paths for dual bands. This dual-band BPF has wide out-of-band suppression. Moreover, its passband frequency and bandwidth can be readily controlled. To illustrate its working principle, an equivalent circuit with even- and odd-mode analysis is presented. This dual-band BPF is fabricated using a silicon integrated passive device (IPD) technology. The fabricated dual-band BPF has a compact size of 1.6 mm × 0.54 mm × 0.23 mm and is measured. The measured results show that this dual-band BPF can generate two bands at 2.45 GHz and 6.15 GHz. In addition, more than 20 dB of suppression is achieved from 7.8 to 20 GHz (8.16f0). The simulated and measured results exhibit good agreements.

Miniaturized independent controllable dual-band bandpass filter by using transversal signal interference concepts

Abstract This paper presents and validates a compact dual-band bandpass filter with independent controllable passbands and isolation. The proposed filter is constructed by two transmission paths from input port to output port. Based on the transversal cancellation mechanism of two transmission paths, dual passband with independent controllable characteristics can be approached. The transversal cancellation techniques yield extra transmission zeros, which are located at 2.56 GHz, 3.58 GHz and 4.43 GHz respectively. Therefore, two passbands centered at 2.25/3.9 GHz are divided by triple transmission zeros. These transmission zeros also improve the out-of-band suppression performance of proposed filter. The designed prototype filter is implemented and tested, the measured 3 dB passband fractional bandwidths are 12.4 % and 7.5 %, respectively, and the minimum insertion losses are 0.48 dB and 0.88 dB respectively. Additionally, the dual-band transversal filter only occupies 0.012 λ g 2 ${\lambda }_{g}^{2}$ , which λ g is the guided wavelength at 50 Ω microstrip line at 2.25 GHz.

A novel compact microstrip dual-band bandpass filter with independently controlled center frequencies based on dual-mode resonators concept

This letter presents a novel ultra-compact microstrip dual-band bandpass filter (DBBPF) with independently controlled center frequencies, and high Q-factor. The recommended DBBPF is realized by combining two different microstrip dual-mode resonators. One is a short-end stub-loaded resonator used to produce the first passband and the other one is an open-end stub-loaded resonator operating at the second passband which serves as part of the feed lines for the lower passband. To validate the performance of the proposed configuration, a novel compact DBBPF with center passband frequencies of 2.4 and 3.55 GHz is designed, simulated, fabricated and tested. A good agreement has been found between the simulation and measurement results. The designed microstrip DBBPF occupies a small area which is only about 0.19 λg × 0.15 λg. The presented microstrip DBBPF has many advantages in terms of compact size, low insertion loss, good frequency selectivity, easy fabrication, and high selectivity.

Двошаровий Т-подібний навантажений шпильковий резонатор для двоcмугового смугопропускного фільтра з покращеними параметрами

В статті розроблено простий високоефективний компактний двосмуговий фільтр на основі багатошарового Т-подібного навантаженого шпилькового резонатора T-SLHR (T-shape loaded hairpin resonator). В схемі розробленого фільтра використано дві підкладки. На заземленій площині першої підкладки реалізовані два резонатори T-SLHR, які електрично зв’язані через просторовий зазор S, завдяки чому досягається необхідна подвійна смуга пропускання. На другій незаземленій підкладці розташовується заземлений шпильковий шлейф, вхід/вихід якого з’єднується з T-SLHR для отримання необхідної характеристики фільтра. Для перевірки запропонованої концепції реалізовано двосмуговий смуго-пропускний фільтр BPF (bandpass filter) для системи багатоканальної бездротової мережі, що працює на центральних частотах 2,4 ГГц і 3,5 ГГц. Крім того, на основі теорії непарних і парних мод аналізується можливість генерації заданих частот за допомогою T-SLHR. Також, представлена блок-схема за допомогою якої пояснюється механізм зв’язку та очікувані характеристики фільтра. Крім того, змодельований фільтр був виготовлений, і отримані результати вимірювань і моделювання порівняні та проаналізовані. Виготовлений фільтр має досить малу площу менше 126 мм2, високу вибірковість завдяки високій крутизні скатів характеристики фільтра та високий рівень смуг загородження.

Compact dual-band balanced bandpass filter using CRLH resonator with intrinsic common-mode suppression and multiple transmission zeros

In this paper, a newly composite right-/left-handed (CRLH) resonator is presented and applied to constitute a compact dual-band balanced bandpass filter (BPF). The proposed CRLH resonator contains two spiral coupled line segments. By imposing the differential-mode (DM) and common-mode (CM) excitation, the DM and CM equivalent circuits of the presented resonator and their lumped-element circuit models are built for investigating the resonant property. The CRLH resonator has two DM resonances and are adopted to design two DM passbands. Also, the CM resonances are all far away from DM resonances, achieved intrinsic desirable CM rejection within DM frequency range without any auxiliary elements. Attributing to the mixed electric and magnetic coupling between two coupled resonators and the introduced source-loaded coupling, multiple transmission zeros are obtained and therefore enhance the selectivity and attenuation in stopband. Finally, a well-designed dual-band balanced BPF is fabricated. Verification of the presented structure and design method’s validity is evidenced by the measured results, which are in agreement with the simulations.

Design of High Selectivity Compact Dual-Band Bandpass Filter With Seven Transmission-Zeros for GPS and WiMAX Applications

A miniaturized Y-shaped dual-band bandpass filter with multiple transmission zeros/poles is presented in this work. The proposed filter configuration comprises series coupled lines, shunt cascaded coupled line and parallel open stubs, and stepped impedance resonators. Analysis of the proposed filter is executed using a circuit simulator, and the magnitude and bandwidth variations have been studied. Equations for transmission zero frequencies have been derived and verified based on lossless transmission line theory and even-odd mode analysis to validate the proposed filter configuration. A prototype operating at 1.38 GHz (GPS) and 3.4 GHz (Wi-Max) applications is fabricated and experimented. The final prototype occupies a compact area of 0.33λg × 0.20λg, where λg is the guided wavelength at the first band (1.38GHz). The experimental results show that the roll-off rate for the first and second passbands is 212.5 and 188 dB/GHz, respectively, indicating high selectivity. The insertion loss is better than 20 dB indicating good isolation between the two passbands.

Dual-Band Dual-Channel Bandpass Filters Using High Quality Factor Dielectric Resonators

Compact dual-band dual-channel bandpass filters (BPFs) with different and identical frequency allocations are presented in this paper. Because of the magnetic boundary condition, four resonant modes are excited in the dielectric resonator (DR). The excitation and coupling scheme are analyzed and therefore dual-passband with different frequencies and bandwidths are obtained in each channel. Moreover, benefiting from the two pairs of orthogonal degenerate modes and excitation principle, the high isolation between the two channels is guaranteed. For verification, two dual-band dual-channel BPFs are designed. With only two DRs and two sets of probes, low insertion loss and high isolation better than 38 dB are achieved in the dual-band dual-channel BPF with the same passbands. It demonstrates that the proposed method would replace four conventional BPFs in the massive input massive output communication systems and the volume and number of resonators could be remarkably reduced.

Compact dual-band narrowband bandpass filter with small frequency ratio

Abstract A compact but very simple dual-band bandpass filter (BPF) based on just five pairs of coupled lines is designed in this paper. It can be examined using the even- and odd-mode method because of its symmetry structure. Six transmissions zeros (TZs) can be obtained and calculated by using input impedance analysis. For demonstration, a dual-band narrowband BPF example with center frequencies at 0.94 and 1.12 GHz is fabricated and measured. The 3-dB fractional bandwidths of two passbands are 2% (0.93–0.95 GHz) and 3.4% (1.1–1.14 GHz), whose frequency ratio of upper-band to lower-band is very small. The measurement results agree with the simulation results, confirming the design process.

Realization of a novel dual-band bandpass filter with coupled series gaps and stepped impedance complementary split ring resonators

In this article, a bandpass filter (BPF) is proposed by etching stepped impedance complementary split ring resonators (SICSRRs) pairs in parallel with series gaps on the top side of a coplanar waveguide (CPW). The Nicolson-Ross-Weir (NRW) method is used to analyze the left-handed (LH) behavior of the filter. The effects of the resonators parameters on the left-handed BPF are studied. The parameters and number of the resonators are adjusted properly to obtain the desired filter characteristics. Split ring resonators (SRRs) are magnetically coupled to the BPF to realize a novel left-handed dual-band bandpass filter. Besides, The dual-band filter is described by means of the lumped-element equivalent circuit model. Also, the quasi-static analysis is used to obtain the equations for the resonant frequencies of the resonators. The efficient electrical size of the dual-band filter is 0.51λg × 0.42λg where λg represents the guided wavelength at the first passband center frequency. The prototype of the compact dual-band BPF is fabricated and measured. The measured results reveal low insertion loss and high return loss at the passbands along with wide upper stopband attenuation. The measured result is in a good agreement with the corresponding simulation result.

Multi-band propagation of spoof surface plasmon polaritons by its high-order modes

Compact dual-band and tri-band bandpass filters (BPFs) based on high-order modes of spoof surface plasmon polaritons (SSPPs) are proposed. By using the meander line technique, the electrical size of the proposed SSPP structure was reduced by 68% compared with the traditional rectangular-grating SSPP structure. The high-efficiency passbands are excited by high-order modes of SSPPs. Therefore, dual-band and tri-band BPFs are designed by using two and three high-order modes of SSPPs, respectively. In addition, a notched band is obtained by loading three complementary split-ring resonators (CSRRs) on the bottom layer of the tri-band BPF. Thus, a quad-band BPF is achieved.

A Compact Dual-Band Bandpass Filter Using Coupled Microstrip Lines

In this paper, a new compact dual-band bandpass filter (DB-BPF) is proposed using parallel coupled lines. The design method is based on introducing transmission zeros (TZs) in the frequency response of a single-wideband filter. In the proposed structure, three coupled lines and a multi-mode resonator are used to realize the wide bandpass filter. Meanwhile, two coupled lines that are connected at the end and loaded by an open-circuit stub are employed to make a new notch filter. The proposed DB-BPF is designed and fabricated on Rogers RO3210 substrate for Wireless Local Area Networks (WLANs) applications. The simulation results show good agreement with measurements. The measured results exhibit two passbands centered at 2.4 and 5.2 GHz, having an insertion loss of less than 0.1 dB and 0.9 dB, respectively. Low insertion loss, compact size, and high attenuation between two passbands are the main advantages of the proposed DB-BPF.

Compact Dual-Band Bandpass Filter Based on SSL-SIR With Sharp Roll-Off

A compact dual-band bandpass filter (DB-BPF) is studied and implemented by using shorted stub-loaded stepped impedance resonator (SSL-SIR) and 0∘∘feed structure in this paper. The resonance frequencies of SSL-SIR can be analyzed and explained by odd−-even mode analysis method and it is used in the design of BPF I. Then, the BPF II is created using the theory of 0∘∘feed structure. Finally, the two structures are combined together to form a DB-BPF by reasonably adjusting the coupling between them and the position of the feed points. The simulation results suggest that the center frequencies of the two passbands are 3.45 and 5.2 GHz, respectively, which are suitable for modern wireless communication systems like 5G and WLAN. Compact size, strong passband isolation, and large stopband bandwidth are all advantages of the proposed DB-BPF filter. A prototype is created and constructed to validate this. The simulated results are in good agreement with the measured results.

Compact dual-band balanced bandpass filter based on circular SIW cavity

Abstract A compact dual-band balanced bandpass filter with high frequency selectivity and adjustable passband based on the perturbed circular substrate integrated waveguide cavity is firstly proposed in this paper. Two pairs of metallic vias are located at 45°direction of cavities to separate a pair of degenerate modes (TM110 modes) to achieve the differential-mode (DM) dual-band response. Moreover, the perturbation vias can also be used to control the center frequency of the second DM passband while the first one still stays unaffected. The introduction of source-load coupling makes the filter exhibit excellent selectivity. And four controllable transmission zeros appear near two DM passbands. Finally, good common-mode suppression has been got owing to the proposed balanced structure. The measured results are in accordance with the simulated ones well.

Compact dual‐band bandpass filter with flexible passband frequencies and sharp skirt using cross coupling and mixed magnetic and electric coupling

This paper presents the design of a compact dual-band bandpass filter (DB-BPF) with flexible passband frequencies and sharp skirt. A pair of stub loaded stepped-impedance resonators (SL-SIRs) together with two different tri-section stepped-impedance resonators (TS-SIRs) constitute this DB-BPF. The low impedance sections of two SL-SIRs and one TS-SIR are realized by ring structure, on the one hand to acquire two independent resonant modes of SL-SIRs, and on the other hand to let the harmonic mode of TS-SIR be away from the upper passband. The cross coupling, the canceling effect of mixed electric and magnetic coupling (MEMC), and the virtual ground introduce the TZs, resulting in the sharp skirt property of proposed DB-BPF. Step-to-step design process is given to guide the DB-BPF design. As an example, a 0.9 / 1.8 GHz DB-BPF is designed and fabricated. The fabricated sharp skirts DB-BPF has a compact size of 0.079λg × 0.193λg, low passband loss of 0.84 / 0.98 dB and high band-to-band rejection of better than 40.6 dB.

A new compact microstrip dual bandpass filter using stepped impedance and λ /2 bended resonators

In this paper, a compact dual-band bandpass filter (DB-BPF) is implemented by using a pair of coupled stepped impedance resonators (SIRs) and a pair of λ/2 bended resonators for the modern wireless communication systems such as WiMAX and WLAN (3.4 and 5.4-GHz). The physical layout is presented and explained the establishment of an LC equivalent circuit. Moreover, the second passband of the proposed dual-band bandpass filter can be independently controlled by inserting the open-circuited stubs at the end of the λ/2 bended resonators without increasing the circuit size. Simulation results show that the second passband can be ranged from 5.6 to 4.8-GHz with the bandwidth of 400 ± 96-MHz, whereas the first passband is fixed with the bandwidth of 280 ± 8.5-MHz. The measured results exhibit the insertion losses (S21) lower than 1.2 and 1.4 dB, and the return losses (S11) of −23 and −32 dB at the first and second passbands, respectively, which show a good agreement with simulation results. The dual-band microstrip filter is fabricated on RT/Rogers 4003 substrate with a compact size of 0.24λg × 0.25λg.

Compact dual‐band bandpass filter using coupled lines and shorted stubs

A compact dual-band bandpass filter (BPF) based on parallel coupled lines and shorted stubs has been presented in this Letter. The transmission and reflection coefficients of the proposed dual-band BPF are straightforwardly derived via the input impedances using odd- and even-mode analysis methods. Four transmission poles in the two passbands and nine deep transmission zeros (TZs) in the stopband can be realised. The centre frequencies and bandwidths of the two passbands can be tuned by controlling the impedance parameters of the coupled lines and shorted stubs. For demonstration, a prototype example of this dual-band BPF with a small size is experimentally characterised. The measured results show that it has high-frequency selectivity with multiple TZs at the stopband.

Implementation of a compact dual-band bandpass filter using signal interference technique on paper substrate

This paper exhibits the design and implementation of a compact dual-band bandpass filter on paper substrate. The proposed filter which works on the principle of signal interference technique has a parallel combination of short-circuited coupled line and an H-shaped network of transmission lines with open stubs. Due to the superposition of signals of the two transmission paths, a second order dual-band bandpass response with four transmission zeroes is achieved. To validate the proposed design, theoretical analysis using the lossless transmission line model is carried out and acknowledged. The developed dual-band filter prototype with center frequencies 1.17 GHz and 4.06 GHz has 3-dB fractional bandwidths of 82.56% (0.69–1.656 GHz) and 20.59% (3.645–4.481 GHz), respectively. The simulated and experimental results are in good congruence with each other. The proposed dual-band bandpass filter can be used in various wireless applications, for example, Global System for Mobile Communications (880–915 MHz), Aircraft surveillance (960–1215 MHz), Indian Regional Navigation Satellite System (1.164–1.188 GHz), Amateur radio (1.24–1.30 GHz), Global Positioning System (1.559–1.61 GHz), Satellite phones (1.616–1.626 GHz), and Satellite communication (3.7–4.2 GHz).

Dual-Band Differential Bandpass Filters Using Quadruple-Mode Stubs-Loaded Ring Resonator With Intrinsic Common-Mode Suppression for 5G

A novel quadruple-mode stubs-loaded ring resonator (SLRR) is presented in this letter, which can achieve compact dual-band differential bandpass filters (BPFs) with intrinsic common-mode suppression. The differential-mode (DM) equivalent circuit and common-mode (CM) equivalent circuit of the SLRR are given and investigated by using the even-/odd-mode theory. Two DM resonances of the SLRR can be adjusted independently and are used to construct two DM passbands. Due to the magnetic-dominated coupling between two SLRRs, the intrinsic CM suppression characteristics are achieved in the differential passbands without using any additionally loaded elements. And by loading the different short-circuited coupled lines (SCCLs) at the parallel-coupled feed-line of differential BPF separately, two transmission zeros (TZs) are introduced on both sides of the DM passbands, which improves the selectivity of dual differential passbands. Furthermore, to realize the desired external Q values for two DM passbands, hybrid feeding line structure including tapped and coupled-line feeding structures is used to produce the valid excitation for the differential BPF. At the same time, the open stubs are attached to the inside of the ring resonator to reduce the filter size. Finally, two dual-band differential BPFs with central frequencies of 3.5 GHz and 4.9 GHz are designed and fabricated for fifth generation of mobile communications (5G). The measured minimum CM suppression of the two DM passbands are 31.0 dB and 34.8 dB.

Compact dual‐mode dual‐band HMSIW bandpass filters using source–load coupling with multiple transmission zeros

Compact dual-mode dual-band bandpass filters (BPFs) with multiple transmission zeros (TZs) using over-mode half-mode substrate integrated waveguide (HMSIW) resonators are presented. Each passband built by TE001 or TE201 has three TZs introduced by source–load coupling and low-/high-order mode cross-coupling between TE001 and TE201 to improve the frequency-selectivity. The equations that determined the TZs are built. Perturbation slots realise the independent-control of frequency ratio. Dual-mode dual-band BPFs are designed, fabricated and measured, and the simulated results agree with the measured results well.