Band Bandpass Filter Research Articles

Dual band bandpass filter based on substrate integrated waveguide loaded with mushroom resonators

AbstractThis article presents a dual band bandpass filter by loading two cascaded mushroom resonators inside the cavity of a rectangular substrate integrated waveguide (SIW). The passbands are generated by exciting TE101 and TE201 modes of dual mushroom structures loaded inside SIW cavity. The fundamental mode, that is, TE101 of the entire filter structure is utilized to create the first passband and the next higher order mode, that is, TE201 of the filter structure is employed for the generation of second passband. Due to the incorporation of mushroom resonators into SIW, which are composite right/left handed transmission lines, the anticipated frequency response represents highly selective passbands with three transmission zeros (TZs) and an improved out‐of‐band response beyond the second passband. The effects of some structural parameters of the filter on the control over coupling parameters (k101 and k201) and quality factor (Q) are studied. This modified SIW based dual bandpass filter is fabricated and measured to verify two passbands centered at 2.25 and 4.1 GHz with 12.9% and 10.8% fractional bandwidth (FBW) and minimum insertion loss of 0.86 dB and 1.6 dB, respectively. Mobile satellite communications, weather radar systems and Wi‐Fi technology are the actual fields where such bandpass filters can be thoroughly applied.

Multilayer triple band bandpass filter with a floating U-shaped SIR and split ring resonator

A multiple band bandpass filter (BPF) is designed using multilayer arrangement. The bandpass filter has three passbands having centre frequencies at 2.45 GHz, 4 GHz and 5 GHz. First a single band BPF is designed which includes a pair of coupled resonator and a split ring resonator in a multilayer arrangement. This geometry of the filter structure is studied and validated by fabrication and measurement. The initial single band filter structure is further improved to provide triple band BPF. All these bands are realized by a stub loaded U-shaped step impedance resonator (SLU-SIR). However, to improve the response of the second and third band a modified split ring resonator and a pair of open stubs are used. Each passband can be controlled individually. A mathematical analysis is done to study the proposed SLU-SIR using transmission line model. The proposed filter provides compactness and low insertion loss. A prototype is measured using vector network analyser (VNA) and shows a good matching with the simulated result.

Design of compact tri and quad band band-pass filters using stub loaded resonators for wireless applications

A compact tri and quad band band-pass filters (BPFs) utilizing stub loaded resonators is presented for wireless applications. The proposed resonator has been designed and analyzed using even–odd mode analysis due to its symmetrical geometry. Open-ended stubs are loaded at an appropriate position in the dual-mode resonator to achieve tri and quad passbands. To reduce the circuit size and create transmission zeros at our desired frequencies, a symmetrical meandered shape resonator is loaded with open-ended identical stubs which are bent towards each other. The proposed BPFs are tune to operate at GSM (900 MHz), LTE (2300 MHz), WiMAX (3.5 GHz), and WLAN (5.4 GHz) bands. Significant improvements are observed in terms of circuit size, 3-dB fractional bandwidth, insertion loss, and transmission zeros. To check the validity of the proposed tri and quad BPFs, these are simulated, fabricated and measured. The simulated and measured results are compared and strong agreement is observed. The proposed filters can be prospective candidates for wireless communication applications.

Dual band Stepped Impedance Interdigital Microstrip Filter for LTE Bands

In this paper, a dual band microstrip bandpass filter has been proposed utilizing three edge coupled resonators, interdigital stubs and DGS technique. To enhance the coupling degree, two interdigital coupled feed lines are employed in this filter. The suppressing cell consists of stepped impedance ladder type resonators, which provides a wide stopband. The proposed suppressing cell has clear advantages like low insertion loss in the passband and suitable roll off. The frequency response of the filter looks like a standard dual band band-pass filter. The filter exhibits a dual passband with resonant frequencies at 2.2GHz and 3.45GHz covers LTE1 and LTE22 bands.

Dual band Stepped Impedance Interdigital Microstrip Filter for LTE Bands

In this paper, a dual band microstrip bandpass filter has been proposed utilizing three edge coupled resonators, interdigital stubs and DGS technique. To enhance the coupling degree, two interdigital coupled feed lines are employed in this filter. The suppressing cell consists of stepped impedance ladder type resonators, which provides a wide stopband. The proposed suppressing cell has clear advantages like low insertion loss in the passband and suitable roll off. The frequency response of the filter looks like a standard dual band band-pass filter. The filter exhibits a dual passband with resonant frequencies at 2.2GHz and 3.45GHz covers LTE1 and LTE22 bands.

Compact tunable dual/Tri‐band bandpass filters with multiple zeros

Here, compact dual/tri-band bandpass filters (BPFs) with tunable passbands are proposed. The multiband BPFs are designed by combining a BPF with tunable passband and a BPF with fixed passband using a common external coupling line. The former consists of a dual-mode resonator loaded with varactors (DMVLR) and the latter is composed of a quad-mode resonator (QMR). The classical analysis method of odd/even mode is employed to analyse the characteristics of the resonators. The centre frequency (CF) of the tunable passband can be easily tuned by varying the voltage imposed on the varactors. A constant absolute bandwidth (CABW) is obtained over the whole tuning range of frequency by properly adjusting loading positions of the varactors. The single and dual-passband BPFs with fixed passband are obtained by designing the parameters of QMR appropriately. Simulation and measurement results show that the proposed BPFs are of high selectivity, and the resultant filters are of compact size. In addition, the proposed multiband BPFs have four transmission zeroes (TZs). There are two self-adaptive TZs on both sides of the tunable passbands, which are generated by the multipath coupling structure.

Compact triple band bandpass filters design using mixed coupled resonators

In this paper a study on designing Triple Band (TB) Bandpass Filter (BPF) by exploiting Triple Mode Resonator (TMR) is presented. By connecting stepped impedance and radial stubs in a categorical manner, a TMR can be obtained which is the basic component for designing this TB BPF. Microstrip lines are tapped over the resonator to work as feed lines and also to generate transmission zeros. The TMRs are Mixed Electric and Magnetic Coupled (MEMC) which help in generating additional Transmission Zeros (TZs) around passbands. As verification, a TB BPF is designed, fabricated and measured. In the designing process, first, a Dual Band (DB) BPF is designed and analyzed completely with the help of even-odd mode analysis. Extraction of lumped component model for the DB BPF is done in order to study the circuit model of the filter. Then the work is extended to design a Triple Band-Band Pass Filter. The fabricated filters offer an advantage in terms of compact size, low insertion loss, good inter band isolation and harmonic suppression.

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.

Dual Band BPF Based on Parallel Coupled Lines Loaded by Open Stubs for Ku-Band Satellite Applications

This paper presents a dual band Band Pass Filter (BPF) operating at both the downlink and uplink frequency bands for Ku-band satellite applications. The commonly used frequency band in mobile communications satellites is the Ku-band. These mobile satellite systems help connect remote regions, vehicles, ships, people and aircraft to other parts of the world and/or other mobile or stationary communications units, in addition to serving as navigation systems. The structure of the proposed filter is based on parallel coupled microstrip lines and four sections are used. Tuning the two operational bands can be achieved using two open-circuited stubs at the first and last sections of the parallel coupled microstrip lines. The proposed filter is adjusted to operate at 12.54 GHz and 14.14 GHz for downlink and uplink bands, respectively. The proposed dual band BPF is fabricated, measured, and good agreement is obtained between simulated and measured results.

A compact ultra wide band bandpass filter with dual band notch designed based on composite right/left‐handed transmission line unit cell

In this article, we propose an ultra wide band (UWB) bandpass filter with dual notch characteristics. The proposed filter is designed based on composite right/left handed (CRLH) transmission lines. The filter is having a compact size of 2.4 mm × 8.78 mm and printed on FR4 material with relative permittivity 4.4 with thickness 1.6 mm. The filter is constructed by series of strip lines, which forms interdigital capacitance and shunt inductors allowing both low and high frequencies of the UWB to pass. The selectivity in lower and higher parts of the UWB is achieved by the slots etched from the ground plane. The dual band notch is obtained at 4 GHz and 7 GHz using the L-shaped strip lines on both sides of the filter. The comparative analysis of the proposed UWB band pass filter without and with notch characteristics is presented with the help of the S11 and S21 curves.

Ultra-Wide-Band Band-Pass Filters Using Plasmonic MIM Waveguide-Based Ring Resonators

In this letter, different types of plasmonic ultra-wide band band-pass filters (UWB-BPFs) have been studied and numerically analyzed. The filters have been designed based on the angular ring resonators (ARRs) and square ring resonators (SRRs) connected with a coupled feed line. The UWB can be realized by suitably adjusting the coupling gaps both sides of the resonator. Based on the ideal characteristics of the proposed ARRs and SRRs, all miniaturized UWB-BPFs are operating at THz frequencies. Multiple transmission zeros are generated to improve the selectivity of the filter. All simulated results have been studied using CST Microwave studio suite. The transmission performance is explained by the resonance condition, which agrees well with the numerical simulation or theoretical calculation. This letter provides a promising application for plasmonic UWB-BPFs and plasmonic integrated optical circuits.

New Compact Microstrip Filters Based on Quasi Fractal Resonator

This paper presents new microstrip devices as single band bandpass and multi band bandstop filters. The proposed filters use slotted patch microstrip resonator based on quasi fractal geometry, simulated by AWR12 software package. Both filters have quasi elliptic frequency response, designed at centre frequency of 2.437 GHz for bandpass filter and at band frequencies of 2.434, 4.032, 4.976 and 5.638 GHz GHz respectively, for multi bandstop filter. All filters are employed using RT/Duroid 6010.8 LM substrate of dielectric constant and 1.27 mm dielectric thickness. Simulation results show that the designed quasi fractal bandpass filter has very narrow fractional bandwidth of 0.38 % which is very rare in microstrip filter design. On the other hand, the projected bandstop filter offers multi narrow rejection bands that is useful in broadband wireless schemes influencing from fixed interferences. Both filters present satisfactory S11 and S21 responses besides smallness properties that stand for interesting features of the newest wireless applications. The simulated and measured frequency responses for both designed filters are in good agreement.

Quad Band Waveguide Bandpass Filter Using Slot Ring and Complementary Split Ring Resonators

In this paper, a combination of slot ring and complementary split ring resonators has been proposed to achieve quad band bandpass filter response in waveguide. The resonators have been formed on a Roger RO 4350 substrate with their common centre at the middle of the substrate. Two such structures have been placed on the transverse plane of a WR–90 waveguide at a distance of 8.41 mm to achieve the dual pole quad band response. Necessary simulations have been carried out using Ansoft HFSS (version 14). Measured result shows a quad band bandpass response with centre frequencies at 8.51/9.46/10.47/12.05 GHz and 3-dB bandwidth 0.256/0.2287/0.445/0.755 GHz, respectively. Approximate equivalent circuit of the filter is also proposed. The filter is 10 mm long.

Multistub multimode resonating structure for microwave multiband band‐pass filtering applications

AbstractThis article proposes a design, analysis, and characterization of multistub resonator with its multimode characteristics for band‐pass filtering applications. First, the principle of resonating structure is explained with related mathematical explanations. Next, the proposed multimode structure is introduced with simple technique to analyze resonating frequency behavior by related mathematics. Through mathematical analysis, it has been presented that the number of resonating frequency and their position can be individually controlled by structural parameter. As a result, the proposed resonating structure can be utilized to design different microstrip band‐pass filters (BPFs). For validating the concept, an ultra wide band (UWB) BPF with −3 dB impedance bandwidth of 4.6 GHz (1.9–6.5 GHz) and a dual band BPF with −3 dB impedance bandwidth of approximately 1.5 GHz (2.7–4.3 GHz) for the first band and around 2.1 GHz (6.2–8.3 GHz) for the second band; have been implemented on Neltec substrate with dielectric constant 3.38, thickness 1.52 mm, and loss tangent 0.0016 and characterized on Keysight vector network analyzer N9918A. All the measured and simulated results are in good agreement with each other.

Reduced size dual band pass filters for RFID applications with excellent bandpass/bandstop characteristics

This paper presents the design of two reduced size dual-band metamaterial bandpass filters and its simulation followed by measurements of proposed filters. These filters are supporting different frequency bands and primarily could be utilize in radio frequency identification (RFID) application. The filter includes three cells in which two are symmetrical and both inductively coupled with the third cell which is present in between them. In the proposed designs, three different metamaterial composite right/left handed (CRLH) cell resonators have been analysed for compactness. The CRLH cell consists of an interdigital capacitor, a stub/meander line/spiral inductor and a via to connect the top of the structure and ground plane. Finally, the proposed dual band bandpass filters (using meander line and spiral inductor) are showing size reduction by 65% and 50% (with 25% operating frequency reduction), respectively, in comparison with reference filter using stub inductor. More than 30 dB attenuation has been achieved between the two passbands.

An Analysis of Dual Band bandpass Filters using with Arbitrary Band Ratios

An Analysis of Dual Band bandpass Filters using with Arbitrary Band Ratios

A compact broadside coupled dual notched band UWB-BPF with extended stopband

This manuscript describes a compact multi notched band ultrawide band (UWB) bandpass filter (BPF) based on broadside coupling of microstrip and co-planar waveguide (CPW). Initially, a meandered CPW embedded in ground plane is optimized efficiently to allocate the resonant modes equi-spaced within the UWB passband (3.1–10.6 GHz) and later, the tight coupling of the transition of microstrip with the CPW ensures a smooth passband. Four open ended stubs are appended with the microstrip patches on top to attenuate dual passband frequencies and improve higher stopband performance. An approximate equivalent circuit model of the prototype is developed and its circuit response is compared with full wave EM simulation data. The compact prototype measures only 13 × 7 mm2.

A Compact UWB BPF with a Notch Band using Rectangular Resonator Sandwiched between Interdigital Structure

This paper presents a compact design of an ultra wide band bandpass filters with a notch band using interdigital structure. The aim of the design is to reduce the size of filter, reduce the complexity of the design, and improve the performance of filter response. The proposed filter comprises of a rectangular resonator sandwiched between Interdigital structures, with rectangular slot as defected microstrip structure at the input and output ports. This design has been used for the first time to achieve the above aim. The advantage with this design is that, it does not use any via or defected ground structure. The insertion loss of proposed filter, in passband between 3.1 GHz to 10.8 GHz, is less than 0.7dB, and for the notched band it is 21.5 dB centred at 7.9 GHz. The proposed filter is fabricated, tested and compared with simulated results. The proposed design was small in size with less complexity, and shows performance better than the other designs available in the literatures at this dimension.

Dual band bandpass filter using meander split loop resonator

AbstractBased on meander split loop resonator (MSLR), dual band filter with wide bandwidth, low insertion loss and compactness is investigated and fabricated. Embedded spiral coupled line (ESCL) is added not only to enhance coupling between two split stubs, but to adjust transmission zeros (TZs) and form dual band response. Through transformation among ABCD‐matrix, Y‐matrix, and S‐matrix, TZs of proposed filter can be analyzed. Utilizing direct connection of feed line and MSLR, low insertion loss is achieved.

Scattering of electromagnetic waves by a metal lattice placed at the interface of two media

Simple formulas for determination of components of the scattering matrix of a plane electromagnetic wave incident along the normal onto a thin infinite 2D metal lattice with square windows placed at the interface of two media are derived for the first time. Frequency responses (FRs) of this structure calculated with the use of these formulas agree well with responses obtained by the numerical electromagnetic analysis of a 3D model in the case when the lattice period is less than one-half of the wavelength. The capability of efficient control of the FR of the analyzed structure by means of variation in the width of conductors and the lattice period enables application of this lattice for fabrication of a reflector with prescribed reflectivity. Such reflectors at interfaces of dielectric layers are required, for example, in the design of multilayer sufaces radio transparent in a specified frequency band or optical bandpass filters.