Coupled Microstrip Transmission Lines Research Articles

On the Design of a Stepped Mixed Signal Transmission Line with Defected Microstrip Structure for High-Frequency PCB Traces

The paper addresses the challenge of crosstalk in neighboring paths on PCBs, emphasizing its growing importance with the advancement of electronic circuits in terms of speed and frequency. The proposed solution involves the introduction of a novel W-shaped Defected Microstrip Structure (DMS) on a step-shaped coupled transmission lines to mitigate near-end crosstalk (NEXT) and far-end crosstalk (FEXT) using mixed signal input. A novel W-shaped defective microstrip structure (DMS) that is etched on step-shaped coupled transmission lines. The proposed technique focuses on minimizing the electromagnetic coupling strength with a minimum spacing of one time the width of the trace. It optimizes the ratio of capacitive coupling and inductive coupling between the coupled microstrip transmission lines to improve crosstalk. The frequency domain simulation, conducted using Computer Simulation Technology (CST), indicates promising results. The insertion loss (|S21|), near-end crosstalk (|S31|), and far-end crosstalk (|S41|) of the suggested structure are reported as 1.425dB, <25dB, and <25dB, respectively, over the frequency range of 0 to 10 GHz. Eye diagram characterizations are done and measured in terms of eye height, eye width, jitter and data rate are reported as 0.942V, 695.5ps, 6.69ps and 1.4Gbps respectively.

Design of a Retransmitted Chipless Tag based on Multi-state Resonators

In order to increase the encoding capacity and reduce the size of the tag, this paper proposes the frequency sharing method to design a retransmitted chipless tag, which is composed of N resonators, a coupled microstrip transmission line, and the orthogonal transmitting antenna and receiving antenna. A pair of the same size resonators is placed symmetrically on both sides of the coupled microstrip transmission line. M open-ended stubs (OES) with different combinations are embedded in each resonator to obtain different resonance frequencies. The frequency sharing multi-state resonators’ chipless tags are designed where N=6, M=4, and the dimension of the tag is 46 mm × 30 mm, which can generate about 212 codes. Simulation and measurement results show good agreement and feasibility of the tag design. The chipless tag is small in size, has large encoding capacity and is easy to print. This kind of tag has no silicon chip so the cost is low. It can be widely used in logistics, supermarkets and other fields to replace the barcode.

Performance Evaluation of Broadband Characterization of Coupled Transmission Lines Even- and Odd-Mode Propagation Constants Using Differential and Common Mode S-Parameters

This work encompasses some relevant issues that arise when using a broadband method to characterize the even and odd mode propagation constants of symmetric microstrip coupled lines using four-port pure-mode differential and common mode S-Parameters. Correct excitations of differential and common modes play a significant role in experimental results. From these 4-port measurements, parameters corresponding to the even and odd modes can be extracted from the multi-mode generalized S-parameters obtained by the vector network analyzer. Differential and common mode sub-matrices are considered as two independent equivalent 2-port transmission lines. The method will be applied to extract the propagation constants of even and odd modes of coupled microstrip transmission lines. A discussion is included on ensuring the correct excitation of the modes in the structure and avoiding possible unwanted effects such as radiation, that negatively affects the final estimation, both in phase and attenuation. Two figures of merit are defined to evaluate how transitions affect the performance of the method. These figures of merit allow a reasonable estimation of how the final experiment is affected by selected excitation of modes. To assess the theory presented, two sets of seven lines of different lengths are manufactured. The experimental results show an excellent agreement, both with electromagnetic simulations and with the analytical model used, for the phase constant in the improved case of 30° bends, and an improvement in the useful bandwidth of the attenuation constant. This fact verifies the correct functioning of the method. In addition, the measurements are presented in the range of 0.01–67 GHz, which represents a significant advance in bandwidth for this type of structure.

Features of the implementation of fixed phase shifters on coupled microstrip transmission lines with a stub

Fixed phase shifters with a phase-shifting channel based on coupled transmission lines of class II with a stub have a number of advantages in comparison with previously known structures for similar purposes. However, their practical implementation causes difficulties associated with the topological features of the structure, which, in turn, leads to a deterioration in frequency characteristics. In this regard, a numerical analysis of inhomogeneities in a class II structure with a stub and an assessment of their influence on the frequency characteristics of fixed phase shifters is required. In this work, circuitry and electrodynamic modeling of class II structure elements has been carried out, which showed that the greatest parasitic effect on the frequency characteristics of the phase shifter has a nonzero coupling coefficient of single transmission lines and an inhomogeneity localized at the junction of the short-circuited stub and the output arms of the associated transmission lines. A fixed phase shifter with a phase-shifting channel based on a smoothly stepped structure with a stub has been developed. The presented results of the study of fixed phase shifters based on microstrip coupled transmission lines of class II with a stub can be useful to scientific and technical workers engaged in the development of functional devices for the phase shift of microwave signals.

Circularly Polarized SIW DRA Fed by Ridge Gap Waveguide for 60 GHz Communications

A compact planar dielectric resonator antenna (DRA) is designed based on the substrate integrated waveguide (SIW) technology for 60 GHz communications. The proposed antenna is constructed from a multilayered dielectric substrate separated by metallic sheets. A dog-bone shaped DRA is formed by perforating the upper dielectric substrate with air holes surrounding the dog-bone structure. The DRA is surrounded by metallic vies connecting two metal sheets above and below the substrate containing the DRA. The DRA is fed through a slot coupled microstrip transmission line printed below the slot. The ridge-gap waveguide technology (RGW) is used in the feeding layer to suppress the surface wave surrounding the microstrip transmission line and improve the peak gain. The RGW unit-cell structure has stop-band of 46–95 GHz. The SIW DRA introduces impedance bandwidth from 59.4 to 60.4 GHz (1.67% referenced to 60 GHz) with peak gain of 6.78 dBi. The circular polarization (CP) is achieved by the rotation of the dog-bone shaped DRA by 45° with respect to the feeding slot. It produces left-hand CP with a bandwidth of 0.22 GHz (0.36%). A 2 × 1 SIW-DRA elements are designed with sequential rotation and phases for CP bandwidth enhancement. The peak gain increases to 9.1 dBi, and a broadband AR of 4.8 GHz (8%) is achieved. 2 × 2 SIW-DRA elements with 90° orientation rotation angle and phases of 0, 90°, 180°, and 270° are designed. An improvement in the peak gain of 11 dBi is produced with wide AR bandwidth of 10.8 GHz (18% from 54.2 GHz to 65 GHz) for 60 GHz communications.

Dual-band devices based on coupled striplines for different power distribution in the frequency bands

The approach to the development of dual-band power distribution devices with different power division ratios in different frequency bands, based on the method of a dual-frequency equivalent replacement, is considered in the article. For its implementation, an equivalent four-terminal network based on a section of coupled microstrip transmission lines is proposed in addition to the T- and P-type circuits. Relations for calculating the electrical parameters of the circuit elements of these four-pole devices are obtained. The relations allow replacing the transmission line section with different values of the wave impedance in different frequency bands. The electrical length of such a section can vary and be different from p/2. Examples of modeling of non-equilateral power distribution devices with unequal branches such as two-channel balanced dividers and a ring divider (ring coupler) with power division coefficients of 2.0 and 1.0 in frequency bands with center frequencies of 2.0 and 3.6 GHz are given. Experimental measurement of characteristics of the designed models of the two devices showed good agreement between the experiment and the simulation results.

Neighboring-Metallic-Layer-Induced Nonreciprocal Wave Propagation in a Thin Metallic Ferromagnetic Film

Nonreciprocal spin wave propagation, induced by placing a neighboring metallic nonmagnetic layer, has been studied in metallic ferromagnetic thin films. The structure consists of a set of coupled microstrip transmission lines acting as antennas placed over a thin Ni80Fe20 layer. Nonreciprocal propagation of magnetostatic surface waves (MSSWs) has been observed. The nonreciprocal effect is evaluated by the amplitude ratio and the phase difference of the MSSWs traveling in opposite directions. By investigating the correlation between the device structure and the nonreciprocal effects, a maximum of −26.0 dB of the amplitude ratio and −180.0° phase difference were obtained. These results can be applied to optimize the nonreciprocal device.

Modelling and validation of a simple and compact wide upper stop band ultra‐wideband bandpass filter

A compact ultra-wideband (UWB) bandpass filter (BPF) is proposed based on end coupled microstrip transmission line, defected ground structure and defected microstrip structure. The experimental filter shows a fractional bandwidth of 110% at a centre frequency, with two observable transmission zeros (attenuation poles) at 2.1 and 11.7 GHz. Measured results exhibit an UWB passband from 3.02 to 10.6 GHz with mid-band insertion loss of 1.8 dB and group delay variation <0.45 ns. The BPF achieves a wide stopband with < −18 dB attenuation up to 20 GHz.

Nonreciprocal Magnetostatic Wave Propagation in Micro-Patterned NiFe Thin Films

Nonreciprocal magnetostatic wave propagation in micro-patterned ${\rm Ni}_{80}{\rm Fe}_{20}$ thin film has been investigated. The nonreciprocal devices consist of a set of coupled microstrip transmission lines acting as antennae on the top of the micro-patterned ${\rm Ni}_{80}{\rm Fe}_{20}$ films. The ${\rm Ni}_{80}{\rm Fe}_{20}$ films were structured into an array of rectangular prisms. Nonreciprocal wave propagation was observed in the patterned ${\rm Ni}_{80}{\rm Fe}_{20}$ film. Compared to the control device with a continuous ${\rm Ni}_{80}{\rm Fe}_{20}$ film, the micro-patterned ${\rm Ni}_{80}{\rm Fe}_{20}$ films led to a weaker non-reciprocity.

Crosstalk in Coupled Microstrip Lines With a Top Cover

In this paper, we investigate the influence of the excitation of improper radiating modes (leaky modes) in the propagation characteristics of coupled microstrip transmission lines. We calculate the crosstalk noise excited in the victim line and evaluate the impact of the presence of a metallic top cover due to the circuit packaging. The time domain propagation of pulses of different widths and rise times are computed in order to study the effect of the separation between the coupled strips on the crosstalk noise currents. We show that both even and odd leaky modes can be simultaneously excited on the covered microstrip structure at low frequencies. This can seriously compromise the signal integrity on the line because of the appearance of effects such as radiation, power loss, and interference, which are usually found in microstrip transmission lines at high frequencies. Our results are compared with those provided by a conventional analysis based on the quasi-TEM approximation and transmission line theory. For an open microstrip structure, we have found that the transmission line model accounts properly for the crosstalk current on the victim line. However, on covered coupled microstrip lines with a sufficiently low top-cover height, the crosstalk noise is higher than expected and cannot be accurately predicted by the transmission line model, even at frequencies where the cross section of the line is much smaller than the wavelength.

THE FREQUENCY CHARACTERISTICS OF COUPLED MICROSTRIP LINES / SUSIETŲJŲ MIKROJUOSTELINIŲ LINIJŲ DAŽNINĖS CHARAKTERISTIKOS

The article deals with the use of the finite difference time domain method and uniaxial perfectly matching layer for analysis of frequency characteristics of coupled microstrip transmission lines. It describes calculation techniques for voltage, current, characteristic impedance and effective dielectric constant of each signal conductor. Besides, it analyses the frequency dependencies of characteristic impedance and the effective dielectric constant. Article in Lithuanian. Santrauka Straipsnyje aptariamas baigtinių skirtumų laiko srities metodo taikymas ir absorbuojančio sluoksnio taikymas susietųjų mikrojuostelinių linijų analizei. Sudaryti ir išnagrinėti baigtinių skirtumų laiko srities metodu grįsti susietųjų mikrojuostelinių linijų matematiniai modeliai. Pateikiamos kiekvieno iš laidininkų įtampos, srovės, charakteringojo impedanso ir efektyviosios dielektrinės skvarbos skaičiavimo metodikos. Aptariami skaičiavimo metodikų pranašumai, trūkumai, pateikiamos jų tobulinimo kryptys.

Novel electronic tuner using varactors for tunable RF front-ends

This paper presents a novel electronic tuner with high power handling capability utilizing varactors based on the asymmetric bilateral coupled microstrip transmission line. Through varying the bias voltage of the varactor at the Ultra High Frequency (UHF) band, the performance of the tuner is demonstrated according to simulated and measured results from several cases with the return loss (S11) below −20 dB and the insertion loss (S21) within ±0.5 dB. Compared with tuners using π and τ network, electronic tuner of this paper shows superior frequency agility as well as wide impendence coverage. Advanced biasing structure has been developed to improve power handling for high power level applications. It is expected that the novel tuner would be part of intelligent Radio Frequency (RF) front-ends system and cognitive wireless system in the future.

Modeling of bandpass filter using defected ground structure and defected microstrip structure

In this present work a novel concept for designing of tunable bandpass filter has been introduced with the help of end coupled microstrip transmission line, defected ground structure (DGS) and defected microstrip structure (DMS). Utilizing this concept, one bandpass filter of 8 GHz center frequency with 30 % fractional bandwidth (FBW) at ?3 dB has been implemented for the applications of X-band communication systems. The structure has been simulated with Method of Moment (MoM) based IE3D EM simulator and Measured with Agilent make vector network analyzer of model N5230A. Finally, the simulated result and measurement result provides good agreement between them.

Analysis and characterisation of coupled transmission lines loaded with complementary spiral resonators

In this study, the behaviour of coupled microstrip transmission lines loaded with complementary spiral resonators (CSRs) is analysed in depth. CSRs are constitutive elements for the synthesis of metamaterials with negative effective permittivity which allows the suppression of undesired signals at a given frequency band. Several test prototypes have been characterised and modelled for transmission, crosstalk interference, isolation and signal integrity (SI). Experimental results reveal that CSRs provide a good solution to reduce crosstalk between parallel transmission lines in the radio frequency band with a low impact in terms of the SI. A design methodology based on the equivalent circuit model for the description of the proposed structures, including transmission lines and coupling parameters, is provided.

Miniature antennas based on printed coupled lines emulating anisotropy

The author presents small antennas that exploit a new class of slow-wave modes. These modes were originally observed in anisotropic volumetric media and were recently realised using a pair of coupled microstrip transmission lines (TLs) printed on a uniform substrate. The simplicity of the coupled printed lines and slow-group velocity of the photonic crystal modes provided an avenue for designing small conformal antennas. The author reviews the degenerate band edge (DBE) mode antennas and extends their bandwidth by supporting dual resonances. This is done by inserting lumped elements along and between the printed TLs. The resulting coupled double loop (CDL) antenna has 14.7% bandwidth and is as small as λ0/9.8×λ0/9.8 (λ0/16 thick) in footprint. Alternatively, magnetic photonic crystal (MPC) mode is realised using the same DBE-printed structure and by inserting small ferrite sections within the otherwise uniform substrate. This new MPC antenna was realised on a high-contrast (ɛr=10.2) dielectric section and attained a gain of 3.1 dB (73% efficiency) and 8.1% bandwidth on a footprint as small as λ0/9.8×λ0/10.4 (λ0/16 thick).

THE EFFECT OF AN EXTERNAL ELECTROMAGNETIC FIELD ON ORTHOGONAL COUPLED MICROSTRIP TRANSMISSION LINES

The response of a two-layer structure of orthogonal coupled microstrip transmission lines illuminated by an external electromagnetic fleld has been studied. A simple model for the crosstalk region using lumped capacitance and inductance elements is used. The efiect of the external EM fleld on the microstrip lines will be obtained using the method taking into account the EM fleld in order to reach transmission line equations along the lines. The model is flnally validated using the full wave analysis simulator, HFSS. Voltage and current along the lines obtained by the present method are in good agreement with the results of the full wave analysis (HFSS). The proposed model has been used for voltage and current in terminal ports up to 10GHz. This method can be developed simply for multilayer structures.

Circular symmetric coupled Microstrip transmission lines

Circular symmetric coupled Microstrip transmission lines

Microwave Parametric Frequency Dividers With Conversion Gain

A novel active parametric frequency divider configuration using coupled microstrip transmission lines and two balanced pseudomorphic HEMTs (pHEMTs) is presented. The analysis of the divide-by-2 circuit presented applies the principles of subharmonic generation using a nonlinear reactance to an active semiconductor device such as a pHEMT. A 2-1-GHz active analog frequency divider is designed and fabricated, with measurements showing a 20% bandwidth, 13.5-dB conversion gain, and harmonic rejection levels of more than 22 dBc. A maximum conversion gain of 18 dB is also achieved. These higher conversion efficiencies and the ability to cascade dividers allow for higher order division ratios to be achieved with the same topology.

DETERMINATION OF CAPACITANCE AND CONDUCTANCE MATRICES OF LOSSY SHIELDED COUPLED MICROSTRIP TRANSMISSION LINES

Laplace’s equation is solved analytically for lossy shielded coupled microstrip transmission lines. The solution is represented in fourier series expression and is being used to determine the capacitance and conductance matrices of the structure. The method is examined using some examples and then some results are obtained.

Bi-directional coupling between two coupled transmission lines

Coupled mode theory including backward coupling is employed to investigate the bi-directional coupling mechanism in two symmetrical coupled microstrip transmission lines. Analytical scattering parameter expressions for the case of matched terminations are presented. Reflections and near-end crosstalk is attributed to the combined effects of distributed backward coupling and interference between discrete reflections caused by termination mismatches at two ends.