Parallel-coupled Microstrip Lines Research Articles

Synthesis and design of miniaturized poly-phase differential phase shifters with filtering function

In this paper, a class of miniaturized poly-phase differential phase shifters with filtering function is proposed, synthesized and developed. The proposed design is constructed by using parallel-coupled microstrip lines as the phase-shifting element in all branches. Operational mechanisms for these parallel-coupled microstrip lines are given. Closed-form formulas of insertion phase and phase slope are derived to guide a practical design procedure for phase shifters with arbitrary shifted phases and minimized phase errors. Benefitting from the compact size of those parallel-coupled microstrip lines, the proposed design is much smaller when compared with state-of-the-art works. To validate the proposed concept and synthesis method, a class of five-way poly-phase (ΔΦ = 45°, 90°, 135°, and 180°) differential phase shifter centered at 3 GHz is designed, fabricated, and measured. Measured results indicate that, achieved relative phase shifts are 45° ± 2.7°, 91° ± 2.9°, 135° ± 3.2°, and 181° ± 3.9° within a 33 % fractional bandwidth, with amplitude imbalances smaller than 0.2 dB among different ways.

Wideband filtering power dividers with/without notch band

AbstractLow loss and compact wideband filtering power dividers (WB‐FPDs) with/without notch band are proposed. The WB‐FPDs are designed using wideband bandpass filter based on asymmetric stepped‐impedance resonator (SIR). Parallel coupled microstrip lines are used to create both wideband filtering characteristic and two additional transmission poles. A notch band can be generated at upper passband edge by using open‐circuited stubs on the SIRs. The WB‐FPDs with/without notch band are successfully designed, fabricated, and tested. The wide passband is centered at 4 GHz with the fractional bandwidth (FBW) of 51.1%, while the notch band is at 5.56 GHz with the FBW of 3.1%. Good agreement between the simulated and measured results is observed.

Linear programming solve-predict for tunable couplers with coupling and phase differences

The demands for high flexibility in signal phase modulation, operating frequency, and amplitude modulation in contemporary wireless communication systems present challenges for reconfigurable devices. To address this issue, two tunable couplers have been designed, which consist of two parallel microstrips couplers with one-eighth wavelength and phase-shift networks composed of two varactors and coupling lines. Adjusting the even-odd mode impedances of one-eighth wavelength parallel coupled microstrip lines has been established as a means to control the coupling. The alteration of the capacitance of the varactors allows for manipulation of the phase differences in the couplers. Considering the disparities among simulation, manufacturing, and theoretical models, to get the capacitance combinations corresponding to the specific phase differences more quickly and accurately, the linear programming solve-predict method is introduced to this design. Finally, the errors between the predicted values and the theoretical values for the actual values are compared. The relative errors of the theoretical values are not less than 31.76 %, and the maximum errors of the predicted values are not more than 12.5 %, which shows the effectiveness of the method. For demonstration, two couplers operating at 2.4 GHz with different tuning ranges were designed and fabricated, work-1 with a tuning range of 45–135° and work-2 with a tuning range of 0–180° degrees. Based on the standard of 10 dB return loss and 1 dB unbalanced coupling, the relative bandwidths of work-1 and work-2 are not less than 42 % and 25 %. The relative bandwidths of phase differences effective modulation (±5°) are 20.1–42 % and 6–25%, respectively.

Compact Parallel Coupled Line Microstrip BPF Design for 5G Applications

A compact parallel coupled line microstrip bandpass filter (BPF) for sub-6 GHz fifth generation (5G) applications is designed operating between edge frequencies of 3.40 and 3.80 GHz. The design is designed and simulated by means of the Advanced Design System (ADS) software using the flame retardant-4 (FR-4) board as the substrate. The BPF design applies the insertion loss method (ILM) to generate a parallel coupled line filter structure that performs passband permission and unwanted noise attenuation below 3.40 GHz and above 3.80 GHz, respectively. Consistent and relevant performances in terms of matching impedance, return loss (S11), insertion loss (S21), voltage standing wave ratio (VSWR), far field radiation pattern, gain, directivity, and radiated efficiency promise the microstrip BPF design has a potential for sub-6 GHz 5G applications.

Design, Modeling, and Implementation of Dual Notched UWB Bandpass Filter Employing Rectangular Stubs and Embedded L-Shaped Structure

Targeting the range defined by the FCC (Federal Communication Commission) in 2002 for ultra-passband bandpass filters, i.e., 3.1 to 10.6 GHz, this article presents a simple compact multipoles ultra-wideband bandpass filter (range starting from 2.9 GHz and end at 11.5 GHz with central frequency 7.2 GHz) using parallel coupled microstrip line and multimode resonator with controllable double narrow notched bands at 3.5 GHz and 7.5 GHz by embedded a spur line structure and rectangular stub resonator coupled to the middle section of the multimode resonator to eliminate the interference with the existing radio signals falls in the range of 3.1 to 10.6 GHz, respectively. After optimization of the proposed filter, some attractive features were obtained, i.e., a compact size 21 mm × 5.2 mm, simple topology, good reflection coefficient lower than −18 dB, good passband transmission coefficient –1.1 dB over the entire fractional bandwidth of about 119.4%, and four transmission poles at 3.4 GHz, 4.6 GHz, 6.5 GHz, and 10 GHz, respectively, can be seen which improves the performance of the filter. Finally, the fabricated filter was tested, and the results obtained demonstrated an excellent agreement.

A compact S-band band-pass filter with ultra-wide stopband

Abstract A novel compact S-band band-pass filter (BPF) with ultra-wide stopband is presented. The proposed filter mainly consists of three parts, a novel crossed resonator, parallel-coupled microstrip lines, and defect ground structures (DGSs). The resonator is constructed by three capacitive open stubs, while a defect is etched in the center stub to eliminate high frequency harmonics. The parallel-coupled microstrip lines are mainly used to improve the passband and the roll-off rate (the ratio of height to width of the filter transition band). And the DGSs are utilized to improve the stopband performances. The proposed BPF has the merits of compactness, good insertion loss and good stopband characteristic. The measured 3 dB operating band is 1.80–4.03 GHz (76.5% at f 0 = 2.92 GHz), The upper out-of-band suppression was better than 20 dB for the frequency up to 20 GHz (6.33f 0), and the upper roll-off rate reaches 75.59 dB/GHz.

The measurement of water level based on parallel-coupled lines with capacitance compensation

This paper aimed to measure the water level using parallel-coupled microstrip lines with capacitor compensation. The design and implementation were parallel coupled microstrip lines with capacitor compensation to measure the water level. The technique of parallel-coupled microstrip lines had a coupling coefficient of – 10 dB. The center frequency was 200 MHz, and the compensated capacitor was positioned at ports 3 and 4. The water level was adjusted from 0 to 20 cm in the experiment. The frequency response of the coupling factor was measured from 300 kHz to 2 GHz. The coupling coefficient at 200 MHz was – 11.45 dB at 0 cm water level, where a shift of frequency decreased continuously. This technique was simple to follow, as the sensor was small and inexpensive.

Quintuple‐mode wideband bandpass filter based on stub‐loaded circular resonator

In this paper, novel compact wideband filters have been implemented using a stub-loaded microstrip resonator based on a circular open-loop configuration for the first time. To offer an alternative wideband filter configuration, the quadruple−/quintuple-mode wideband bandpass filters (BPFs) using stub-loaded circular microstrip resonator (SLCMR) and parallel-coupled microstrip line (PCML) feed configuration are proposed. They are realized by employing a single open stub and two open stubs, respectively. A half-wavelength λ / 2 circular microstrip resonator (CMR) loaded with two open stubs excites three resonant modes, while the one with a single stub produces two resonant modes. One of the modes is odd-mode generated by a λ / 2 CMR, the others are even-modes excited by the two loading stubs. The PCML with enhanced input/output (I/O) coupling degree excites also two modes in the passband. Two loading stubs not only creates transmission poles in the passband, they also create two transmission zeros in the lower and upper stopbands. The quadruple−/quintuple-mode wideband BPFs with fractional bandwidths FBW of 60% and 62% are successfully realized by using the SLCMR and PCML feed configuration together. Both filters are designed, fabricated, and tested where excellent agreement between simulated and measured results is observed.

Design of Microstrip Parallel-Coupled Lines with High Directivity using Symmetric-Centered Inductors

A technique for directivity improvement of the microstrip parallel-coupled lines using symmetric-centered inductors is presented in this paper. The design procedure of the symmetric-centered inductors using the closed-form equations is given. The proposed technique was performed with a design at the operating frequency of 0.9 GHz on an FR4 substrate. Validity of the proposed technique is verified by simulations and measurements in comparisons with conventional parallel-coupled lines. The measured results exhibit the isolation of -30.10 dB and directivity of 19.28 dB at the operating frequency of 0.9 GHz. The directivity from the measured results is improved by more than 4 dB at 0.9 GHz and more than 6 dB at 1.05 GHz compared with the conventional parallel-coupled lines. In addition, the proposed technique for the microstrip parallel-coupled line can achieve a high directivity with the compact size (21.0 mm x 4.70 mm). The novelty of this paper is by introducing the proposed and closed-form design equations for the compact symmetric-centered inductors with high directivity.

A high-selectivity double-mode SIW bandpass filter utilizing the modified parallel coupled microstrip lines

ABSTRACT In this article, a high-selectivity double-mode substrate integration waveguide bandpass filter utilizing modified parallel coupled microstrip lines (MPCML) is presented. The designed method is analyzed in detail. Six metal vias are designed to perturb TE-101 mode and TE-103 mode. The resonant frequency of the perturbed TE-101 mode is shifted to high frequency, close to that of TE-102 mode, which caused the formation of passband. The resonant frequency of the perturbed TE-103 mode is shifted to high frequency, improving out-of-band performance. Simultaneously, the coplanar waveguide structure is used to adjust the external quality factor. Two rectangular slotlines are introduced to adjust center frequency and bandwidth slightly. Two rectangular stubs are designed for better source and load matching. Three transmission zeros (TZs) are obtained to improve the selectivity. The designed MPCML promotes the generation of TZs. Another TZ is obtained by the coupling between TE-102 mode and TE-103 mode. The designed filter operates at 14.4 GHz with bandwidth of 800 MHz. The measured return loss is better than 15 dB, and the minimum insertion loss is 1.60 dB. The measurement is agreed with the simulation.

Multi mode Resonator based Concurrent Triple band Band pass Filter with Six Transmission Zeros for Defence Intelligent Transportation Systems Application

A compact and highly selective triple-band bandpass filter (BPF) is designed and presented in this paper. Proposed filter offers low insertion loss, and passband characteristics is achieved by using two coupled MMR multi-mode resonators (MMR1 and MMR2) and an inverted T and circular shape MMRs. The filter operates at frequency 2.43 GHz (Vehicular Communication), 5.91 GHz (ITS band), and 8.86 GHz (satellite communication band). The simulation and measurement results show a minimum insertion loss of 1.6 dB, 0.73 dB, and 2.8 dB for triple-band BPF. The return loss is found to be greater than 13.06 dB, 28.6 dB, and 21.55 dB. It is noted that measurement results are in accordance with the result of electromagnetic simulation. Desired triple-band multi-mode resonators (MMRs) filter characteristics are achieved with six transmission zeroes (TZs). The filter comprises of MMRs which provide small size and control over the spurious frequency. By using a parallel-coupled microstrip line, the first and third passbands are realised. Whereas by using an end-coupled microstrip line, the second passband is recognised. At the input and output ports, the resonator coupling technique is used. By using the anti-parallel microstrip line arrangement, the transmission zero is acquired. The dimensions of the designed filter are 25×16 mm 2.

A Compact Bandpass Microstrip Filter for Wireless Communication Applications

A design of Compact Bandpass Microstrip Filter is proposed for wireless communication applications like Bluetooth, Wi-Fi, and 5G. Filter is constructed using parallel-coupled Microstrip lines to form 5th order filter of an inverted C structure. Ground slotted technique is used to enhance the bandwidth with dielectric constant of 9.9. The designed filter is simulated at a center frequency of 5.87GHz and bandwidth of 1.9GHz with an insertion loss of -0.5dB, return loss of greater than 12dB. The proposed filter has a compact size, good increased bandwidth and cost-effective. These results are verified with the theoretically designed values and good agreements are recorded. Hence the proposed compact filter will provide a platform for designing and development of compact filters for the microwave regime.

WITHDRAWN: A Miniaturized Bandpass Filter using Microstrip Lines

Abstract This paper presents a design and simulation of a Miniaturized Bandpass Filter (MBF) at center frequency 8.05 GHz and bandwidth 1.80 GHz with insertion loss −0.3 dB. Filter is designed and constructed by reconfiguring hairpin filter, using parallel coupled microstrip lines, with six cascading coupled lines and two ports. Flame Retardant (FR4) substrate is used with dielectric constant 4.4 and thickness 715 µm for cost effectiveness. Proposed filter is miniaturized to 20% reduction in size, good enhanced bandwidth and cost effective with the targeted filter. In this way a miniaturized and wide bandpass filter is achieved with measurements and analysis of miniaturized structure. Main advantages of MBF are lighter in weight, compact in size, less expensive in cost, much useful in most of wireless applications.

Design of A Dual-Wide Band BPF Utilizing Parallel Coupled Microstrip Lines and A Centered Arrow-Shaped Resonator

This paper presents a dual wide-band band pass filter (DWB-BPF) by using two parallel, symmetrical micro-strip lines loaded by a centered resonator, consisting of a T- and a triangle-shaped geometry, attached at the lower and upper ends, respectively. The filter reveals good performance and both the passbands can be independently controlled by adjusting specific parts of the filter. The proposed BPF is simulated by using CST microwave studio package and the simulated result is verified experimentally with good agreement between the two results. The fabricated prototype BPF demonstrates two passbands located at 2.3 GHz and 6.35 GHz center frequencies with 39% and 23.6% of 3-dB fractional bandwidth (FBW), respectively and a good insertion and return losses. The designed BPF can be targeted for wireless local area network (WLAN), WIFI and satellite communication systems.

A Six-Port Dual-Function RF Device With Four-Element MIMO Antenna Array and Bandpass Filter Operations

This article presents a dual-function RF device, with four antenna ports and two filter ports, which behaves either as a multiple-input multiple-output (MIMO) antenna array or a bandpass filter. It consists of four parallel-coupled microstrip lines as the dual-function part and two feed parts for the two channels. The former part simultaneously performs wideband array radiator and fourth-order filter resonator characteristics. For MIMO antenna array operation, the parallel-coupled microstrip line structure is equivalent to a traditional patch, which is divided into four strips with three slots. Based on such a configuration, wide antenna impedance bandwidth is achieved. With regard to the filter operation, it features a conventional fourth-order microstrip parallel-coupled filter typology. As a result, high circuit integration is achieved, and although the two channels share the common part, the bandwidth improvement for both the channels is realized. For demonstration, the proposed dual-function device is implemented and fabricated. As an MIMO antenna array, the center frequency and the measured impedance bandwidth is 4.5 GHz and 27.3%, respectively. The isolation between the two channels in this band is more than 23.6 dB. In addition, it features ±45° continuous beam scanning capacity with less than 3 dB gain reduction. With respect to the bandpass filter operation, the center frequency and measured impedance bandwidth is 0.55 GHz and 15.6%, respectively. The measured in-band insertion loss is 2.12 dB and channel isolation is more than 58 dB.

A Compact Wide Bandpass Filter for Satellite Communications with Improved Out-of-Band Rejection

This paper presents a compact C-band bandpass filter with improved out-of-band rejection. It consists of a symmetric three-pole parallel coupled line microstrip loaded with complementary split ring resonators (CSRRs) and slot resonators. Enhancements regarding the filter responses are obtained by etching these two parasitic shapes successively. When, CSRRs are introduced in the ground plane, exactly in the back of the transmission line of 50 -Ohms , improvements on the filter selectivity level are achieved. Whereas, the slot resonator elements are implemented on the feed line to permit the suppression of the second harmonics. To reduce the second harmonics of 11:1-13GHz, the parasitic elements are both combined, widen the filter rejection of 5:81%. The surface current distribution together with the equivalent circuit are also studied in order to demonstrate the slots and the CSRRs effect parameters on the behavior of the proposed filter. A prototype of the optimal filter is fabricated and measured.Theory and experiment results prove the validity of the new design procedure.

A new dual‐band single‐ended‐to‐balanced filtering power divider

This article proposes a new dual-band single-ended-to-balanced (SETB) filtering power divider (FPD), which shows the excellent characteristics of wideband common-mode (CM) suppression and good selectivity. By employing the structure of double-sided parallel-strip line with a mid-inserted conductor and a T-shaped defected ground structure etched in the mid-inserted conductor, out-of-phase behavior and high CM suppression can be achieved successfully. Besides, to realize dual-wideband filtering performance and high selectivity, two pairs of step impedance stubs (SIS) loaded quarter-wavelength central line-terminal-shorted three parallel-coupled microstrip lines structure are adopted. Meanwhile, two pairs of resistors are introduced so as to realize excellent isolation. To verify effectiveness of the design method, a prototype of dual-band SETB FPD which operates at 3.2 and 4.9 GHz is designed, fabricated, and tested. Final results exhibit that the new dual-band SETB FPD possess high selective dual-band differential mode response, wideband CM suppression, and excellent isolation between the balanced output ports.

Series-Fed Dual-Polarized Single-Layer Linear Patch Array With High Polarization Purity

In this letter, a novel dual-polarized 1 × 4 patch array using proximity feed technique is presented. The proposed single-layer antenna consists of four square patch elements, two short-terminated parallel coupled microstrip lines, and a rat-race incorporated in the feed network. The patches are placed at the inner space between the two parallel microstrip feedlines. Horizontal and vertical polarizations of the patch array are excited by the even and odd modes of the two microstrip lines, respectively. The rat-race structure is used to provide in-phase and 180° out-of-phase feeds for the two modes. A prototype operating at 3.5 GHz is fabricated and measured. The measured overlapping bandwidth of the two ports is 81 MHz, also with port isolation higher than 40 dB. Owing to the symmetry of the structure and balanced excitations, the measured cross polarizations are all below -29 dB in E- and H-planes.

Modeling a Planar Coupled Microstrip Lines using various Wavelets and Method of Moments

In this paper, we apply a several wavelets basis functions to the method of moments to modeling the parallel-coupled microstrip lines. The first set of equations is for the shielded microstrip line solved with moment’s method and wavelets. The Green’s function is obtained from the theory of images. The second set are for the parallel-coupled microstrip lines operating in the TEM mode or when the analysis can be based on quasi-static approximation, the properties of coupled lines can be determined from the self- and mutual inductances and capacitances for the lines. To demonstrate the effectiveness and accuracy of the proposed technique, numerical results of even- and odd-mode characteristic impedances, coupling coefficient, percentage sparsity achieved in the impedance matrix, the CPU Time to reverse impedance matrix, and error relative for Daubechies, Coiflets, Biorthogonal and Symlets wavelets are presented. Numerical results are in good agreement with those in previous publications.

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.