Parallel-coupled Bandpass Filter Research Articles

Parallel-coupled bandpass filters with directly coupled input and output resonators

A novel method for modifying input and output coupling in the parallel-coupled bandpass filters, which allows for direct connection of source and load to the outer resonators, is proposed. In the filter modification a coupled-resonator approach is utilized, which allows one for calculating both the impedance of the introduced new quarter-wave section and the necessary coupling modification of the first and second resonators. The proposed filter modification allows for realization of wider bandwidth filters by removing the necessity of narrow gap realization. Further the following gap in the filter is also enhanced, what helps in wide band filter realization. The presented theoretical approach has been confirmed by theoretically calculated responses of three- and seven-resonator filters. The theoretically investigated filter modification has been confirmed with the experiment in which a seven-resonator modified bandpass filter has been fabricated and measured. The presented measurement results confirm the theoretical predictions and prove the proposed design method.

Bandwidth Enhancement of 5G Parallel Coupled Line Band Pass Filter Using Patterned Ground Structure Technique

This paper presents the design of parallel coupled line band pass filter with 10 GHz operating frequency that will be used in 5G applications. As 5G application requires big data usage and to cater the applications, the bandwidth of 5G devices need to be wider enough to support it. Thus, to improve the bandwidth performance of the designed filter, patterned ground structure (PGS) technique is implemented into it. The result shows that the bandwidth of the designed filter has been improved from 0.25 GHz to 4.98 GHz when PGS is implemented.

First order parallel coupled BPF with wideband rejection based on SRR and CSRR

In this paper a new approach for first order Chebyshev parallel coupled Bandpass filter resonant at 1 GHz is presented to obtain better results (wideband rejection, high selectivity and low bandpass insertion loss) compared to conventional design. The proposed filter (a tri-formation consisting of CSRR, SRR and stubs of stepped impedance are loaded microstrip resonator) can be configured, by laying split ring resonator (SRR) and complementary split ring resonator (CSRR) with 50 Ω microstrip lines, in addition to effect of loading two stubs of stepped impedance around center of midline microstrip with impedance line 55.36 Ω of parallel coupled. The proposed filter produces high selectivity from passband to stopband transition equals to 307.5 dB/GHz and an excellent wide stopband performance extend from 1.22 GHz to 5 GHz (harmonics repression till for 5 ƒ0); all are bellow -20 dB excepting one transmission zero of -19 dB, that can be eliminate the harmonic superior frequencies without using any external Bandstop filter. Also, enhancement low bandpass insertion loss level, where it reaches 0.25 dB at fundamental centered frequency (ƒ0 = 0.96 GHz) with 21% bandwidth. The proposed filter is designed and simulated with computer aided of Ansoft HFSS software package which ordinarily used in microwave application.

Spurious harmonic suppression in compact coupled-line bandpass filter with asymmetric perturbations

ABSTRACTPresent article exhibits the design of a third-order compact parallel-coupled line bandpass filter at 5.25 GHz having asymmetric perturbations to suppress the second harmonic. Initially, the effects of compactness on filter characteristics have been studied by synthesising the distributed filter network into its equivalent circuit model. The design has been initiated by computing the unit cell model, which leads to the first-order and third-order design instances with an improvement in compactness over the traditional parallel-coupled line filter. In contrary, compactness in the filter characteristics degrades the second harmonic level subject to enhanced imbalances among the odd- and even-mode velocities at the coupled lines. Subsequently, the improvement in the harmonic suppression of 53 dB and 58 dB has been achieved by incorporating different non-uniform perturbations to the outer and coupled edges of the compact filters. Accordingly, compactness of 58% and 71% have been obtained subject to the folded and in-line designs over the conventional layout.

Design of the Filtering Power Divider With a Wide Passband and Stopband

The planar power divider with a wide passband/ stopband and filtering characteristics is proposed in this letter. In order to increase the slope rate around the passband skirt, the modified parallel-coupled bandpass filter is adopted. Moreover, utilizing the stub-loaded resonator within the filter, a wide passband can be achieved. Furthermore, the stopband bandwidth and attenuation can be extended with the stepped-impedance coupled lines. An exemplary design of the filtering power divider operated at 2 GHz is presented. In addition, the measured fractional bandwidth at 3 dB and attenuation in the stopband are 57.1% and 40 dB, respectively.

Compact Inkjet-Printed Flexible MIMO Antenna for UWB Applications

In this paper, a miniaturized fully inkjet-printed flexible multiple-input-multiple-output (MIMO) antenna for ultrawideband (UWB) application is proposed, occupying a compact size of $22\times 31\times 0.125$ mm3. In the proposed antenna, two half-planar radiators are introduced to minimize the antenna size. Moreover, a modified T-shaped stub is employed on the ground plane to improve the impedance performance. In addition, a slot is etched on this modified T-shaped ground stub to further enhance the isolation. By doing so, the proposed antenna can operate from 2.9 to more than 12 GHz with the mutual coupling less than −15 dB. Furthermore, to address the out-of-band characteristic drawback that existed in most of the previous UWB antenna, a parallel coupled band-pass filter with stepped impedance transformation and defected ground structure is incorporated in the feedline of the antenna to achieve sharp rejection at the edges of the UWB band. The measurements indicate that the proposed filter-antenna can cover from 3.43 to 10.1 GHz, with the envelope correlation coefficient below 0.3 and the channel capacity loss below 0.4 bit/s/Hz, which ensures its good MIMO performance.

Design of a compact symmetricalc-Band Micro Strip Band Pass Filter with Periodic Saw tooth Grooves

Design of a miniaturized symmetrical band pass filter (BPF) using parallel-coupled half-wavelength micro strip resonators with improved stop band characteristics and 2nd harmonic suppression is presented. The proposed filter is designed at a center frequency of 5.25 GHz with a stop band insertion loss greater than-10dB at 5.15 GHz and fractional bandwidth of 20% (4.74–5.80GHz). The conventional parallel-coupled line band pass filter structure has been folded symmetrically about the horizontal plane and consecutive saw tooth periodic grooves are introduced to the parallel lines. Thus there has been a significant improvement in 2ndharmonic suppression to almost-34.51dB. Size reduction of 46.73% is accomplished with respect to the conventional filter.

Design of compact multiband bandpass filter with suppression of second harmonic spurious by coupling gap reduction

In this paper, we describe a method to implement compact multiband bandpass filters with suppression of second harmonic frequency. This filter design approach is based on decreasing the coupling gap between adjacent resonators of a parallel-coupled-line bandpass filter in order to achieve both the desired multiband frequency response and the spurious suppression. We present the theoretical analysis of the proposed structure that consists of modeling the frequency dependence of the even- and odd-mode characteristic impedances as well as due to the different phase velocities of the parallel-coupled microstrip lines. As an example, a compact tri-band parallel-coupled-line bandpass filter with suppression of second harmonic frequency was implemented operating at 1.9/3.2/4.6 GHz to cover PCS1900, WiMAX, and C-band applications. A three-pole Chebyshev parallel-coupled microstrip bandpass filter was designed at a center frequency of 3.2 GHz and used as the basis to validate the gapping effect on the filter response which also achieves a narrower bandwidth for the second harmonic. Finally, the filter performance with minimized coupling gap is compared to a filter enhanced by the insertion of apertures in the ground plane. Generally speaking, good agreement was accomplished between simulated, calculated, and measured results.

Design of Microstrip Triplexer Using Common Dual-Mode Resonator with Multi-Spurious Mode Suppression for Multiband Applications

A triplexer is an important component for channel separation in microwave front-end systems. This paper proposes a triplexers designed with common dual mode resonator sections have been proposed. By exploiting the variable frequency response of the stepped-impedance resonator, resonators can be shared by the three filter channels of the desired triplexer if their fundamental and the first spurious resonant frequency are properly assigned. Triplexer design method for suppressing spurious responses in the stopband by choosing the constitutive resonators with the same fundamental frequency, but staggered higher order resonant frequencies. The design concept is demonstrated by three of third order parallel-coupled bandpass filters. The bandpass filter is composed of three different stepped impedance resonators for which a general design guideline had been provided in order have the same fundamental frequency and different spurious frequencies. The measured results are in good agreement with the simulated predictions, whereby the spurious responses in the upper stopband can be suppressed below-25dB up to 14 GHz, which can be quite useful for multiband and multiservice applications in future wireless communication systems.

A Passive Front End of Radio Transceivers for LTE Bands

ABSTRACT Software defined radio implementation is required for LTE radio transceivers. An SDR consists of an rf front end and a digital processor platform DSP. This paper is devoted to the design and implementation of the passive part of the front end; the antennas and bandpass filters. It presents the design of two microstrip patch antennas and a third order parallel coupled band pass filter with defected ground structure that can be used in cellular communication applications, especially in LTE . The two antennas cover LTE network bands 1, 2, 3, 4, 9, 10, 23, 25, 33, 34, 35, 36, 37, and 39[1]. The antennas and filter were printed using FR-4 substrate material with dielectric constant of ɛ r =4.4, thickness of h = 1.6 mm and loss tangent tan δ = 0.025. The overall dimensions of the first antenna is 39 mm * 37mm * 1.6 mm with 50 Ω impedance. This antenna operates between 1666 MHz and 2239.5MHz for return loss of less than - 6 dB and covers LTE network bands 1, 2, 3, 4, 9, 10, 23, 25, 33, 34, 35, 36, 37, and 39. The simulation results suggest that the antenna gain and directivity value are 1.7dB and 2.5 dBi with omnidirectional radiation pattern. The overall dimension of the second antenna is 25 mm * 21mm * 1.6 mm with 50 Ω impedance. This antenna operates between 1896MHz and 2015.8MHz for return loss of less than - 6dB and covers LTE network bands 1, 2, 25, 33, 36, and 37. The simulation results suggest that the antenna gain and directivity value are 1.4dB and 1.7dBi with omnidirectional radiation pattern. The parallel coupled filter with over all dimensions of 45 mm * 25 mm achieves centers frequency of 1.95 GHz and band width of 80 MHz and covers LTE network bands 36 or 1. The order of the proposed band pass filter is three and three defected ground structure are used. The devices are analyzed using Computer Simulation technology (CST) and Zeland IE3D. They are fabricated with photolithographic techniques and their scattering parameters are measured by using Vector Network Analyzer (VNA) E8719A. Measurements and simulations show good agreement.

Coupled-Line Filters With Stub-Embedded Resonators Using Accurate Admittance-Transformer Feeds for Flexible Terminations

Accurate admittance-transformer (Y-TF) feeds along with short-circuited stub-embedded resonators (SCSERs) are proposed in this study to design the improved parallel coupled-line (PCL) filters with structure-inherent transmission zeros (TZs). The proposed Y-TF feeds for flexible terminations are thoroughly analyzed and found more accurate than conventional approximate tapped-line feedings. Specifically, two basic parallel-coupled bandpass filters with conventional λ/2 stepped-impedance resonators are first successfully implemented to validate the proposed Y-TF feedings. The ideal frequency responses of the two filters by a circuit simulator are compared with those transformed from the coupling matrix. Furthermore, an SCSER-based filter with multiple TZs is designed to verify the feasibility of the described design procedure. The adopted resonating components are composed of two short-circuited stepped-impedance stubs and multiple open-circuited ones all extended from a common joining point. The interstage couplings of the filter are achieved by the short-ended PCLs, while the input/output couplings are realized by the proposed Y-TF feedings. Through the fabrication of the proposed filters, the measured results along with the simulated ones validate the theoretical derivations.

Design of the Parallel Coupled Microstrip Bandpass Filter

A design method of microstrip filter with good isolation is presented. In the paper, the design method of microstrip bandpass filter is introduced, and one example filter with 3.075GHz center frequency, 9% relative bandwidth is given. With the aid of microwave HFSS software, the microstrip filter is simulated. The result of simulation shows the microstrip filter has an excellent frequency response.

A New Feed Line of Parallel-Coupled Bandpass Filters with Out-Stopband Rejection

A new design of feed lines, called 'U Corner', is proposed in order to improve the rejected bandwidth of a compact microstrip filter topology. The first spurious resonance frequency can be conveniently suppressed by the use of two identical U corners at the input and output of the filter. After the derivation of design rules, a two-pole filter based on Parallel-Coupled Filter was designed for a proof-of-concept. The working frequency was chosen equal to 1 GHz with a 21.4 % fractional bandwidth. Measurements and simulations are in very good agreement. A wide stopband up to more than six times the working frequency was achieved. The insertion and return losses in the passband are 1.2 dB and 16 dB respectively. Index Terms-Microstrip bandpass filter, parallel-coupled line.

On the Design of Laser Structured Ka Band Multi-Chip Module

The rapid prototyping of millimeter wave (MMW) multi-chip module (MCM) on low-cost ceramic-polymer composite substrate using laser ablation process is presented. A Ka band MCM front-end receiver is designed, fabricated and tested. The complete front-end receiver module except the IF and power distribution sections is realized on the single prescribed substrate. The measured receiver gain, noise figure and image rejection is 37 dB, 4.25 dB and 40 dB respectively. However, it deduced from the experimental results of the two front-end modules that the complex permittivity characteristics of the substrate are altered after the laser ablation process. The effective permittivity alteration phenomenon is further validated through the characterization and comparison of various laser ablated and chemically etched Ka band parallel-coupled band-pass filters. A simple and experimentally verified method is worked out to utilize the laser ablation structuring process on the prescribed substrate. It is anticipated that the proposed method can be applied to other laminated substrates as well with the prescribed manufacturing process. DOI : http://dx.doi.org/10.11591/telkomnika.v12i2.3775

Study the Effect of SRRs on Broadband Microwave Parallel-Coupled Band-Pass Filters

 Abstract—  In this paper, broadband microwave parallel-coupled band-pass filters for wireless microwave technology are presented. Two designs of filters with center frequency of 10.5GHz and 9.5GHz are proposed. A metallic split ring resonator (SRR) as a basic building block for planar filters with dual-band band-pass frequency response, which exhibits simultaneously negative permittivity and permeability as a metamaterial without resorting to additional metallic wires is numerically investigated. The effect of SRRs on these filters to get new two metamaterial dual-band microwave filters is also presented. The dimensions of the second filter are reduced compared to the first filter with better results. Numerical results for all designs are obtained, then the filters are simulated using computer aided design (CAD) in microwave applications (Ansoft HFSS) and implemented on the Roger RT/duroid 6010, Metamaterials (MTMs) are defined as artificial (fabricated by human), effectively homogeneous (p << λg) and exhibiting highly unusual properties (er, µ r < 0) not readily available in nature, where p is the average cell size and it is much smaller than the guided wavelength (λg) (4). Split-ring resonators (SRR) were one of the first particles proposed for metamaterial construction. Metallic metamaterials comprising double split-ring resonators (SRRs) are the main artificial structures to realize magnetic responses at an electromagnetic spectrum above gigahertz frequencies (5)-(8). The realization of backward wave propagation using split ring resonator (SRR) and thin wire (TW) and several other electrically small resonators was considered by Pendry (5), ( 9). The split ring resonator shown in Fig. 2 is used to obtain a negative value of effective permeability over a desired frequency range.

Enhancement of Stopband Attenuation Bandpass Filter Using Complementary Split Ring Metamaterial Resonators

In this paper, a simple parallel-coupled band pass filter with a metamaterial complementary split ring resonator is introduced for improvement of the filter stopband attenuation. The theoretical concept of the complementary split ring resonator is introduced. The designed filter has been examined theoretically using circuit modelling and electromagnetic full wave simulation. The results demonstrate that the reported filter can enhance the stopband attenuation three times compared to conventional filter with maintaining typical linear phase response and constant group delay. Moreover, these results have been obtained using only one unit cell for the sake of filter compactness and simplification.

Compact parallel-coupled line bandpass filter using double complementary split ring resonators

A novel compact parallel-coupled line bandpass filter (BPF) with complementary split ring resonators (CSRRs) is presented in this letter.The proposed BPF, with a combination of CSRRs and parallel-coupled lines, has the advantages of compact size and simpler design procedure compared with conventional CRSS BPFs. The prototype filter achieves the measured insertion loss of 1.4 dB at 3.6 GHz. The implementing area is 0.35 λg × 0.14 λg, where λg is the guided wavelength at the resonant frequency. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:506–509, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27373

A Low Loss Fully Embedded Stripline Parallel Coupled BPF for Applications using the 60 GHz Band

This paper presents a low loss fully embedded bandpass filter (BPF) using low temperature co-fired ceramic (LTCC) for multilayer System-in-Package (SiP) and Multi-Chip-Module (MCM) applications, e.g. wireless applications for the unlicensed 60 GHz band. The measured insertion loss was 1.5 dB at the center frequency 58 GHz, and a return loss of less than −10 dB was achieved, including two grounded coplanar waveguide transmission line (CPWg) to stripline transitions. The four layers BPF has a 3 dB bandwidth of about 11 GHz which supplies e.g. broadband and high data rate applications. The whole BPF requires a substrate area of 5.6 × 2.1 × 0.42 mm3 with transitions and a shielding via fence. This BPF suits well for V-band applications in a LTCC package because of the compact dimensions and the good performance.

Microstrip Bandpass Sensor Based on Distributed Capacitors

A microstrip bandpass filter with rectangular patch coupled resonator is presented. The filter is designed to be more affected by the dielectric layer above the conductors compared to the same type of parallel-coupled bandpass filter. The filter is designed to operate between 1 GHz to 3 GHz and this can be a sensor base on distributed capacitors. The agreement between the circuit simulator and measured results is excellent and gives a very good prediction for the filter characteristics. The aim of this prototype filter is to show insertion loss (IL) at the bandpass transmission response when a dielectric material is above or near the conductors. A large study around the sensibility and the effect of the dielectric layer is done in order to evaluate its performance in detection and dielectric characterization.

Small-sized quasi-elliptic parallel coupled band pass filter using microstrip discontinuity corrections and multilayer-technique

In this article, we present a new technique to obtain a sharp symmetric response with lower losses for microstrip coupled-line bandpass filters using the discontinuities correction method.The technique is verified by measurements and simulations. Simulated and measured results of the proposed filters are presented and show good agreements. Additionally, based on this work it will be shown that a new idea with the help of U-resonators and multilayer-technique may be used in the future to reduce more the size and to suppress the second harmonic in reject band of the structure. We think that the filter structure can be applied to improve the stopband and passband performances of other microwave circuits as well as other types of filters. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2433–2438, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26262