Coupled Microstrip Lines Research Articles

Signal-Integrity Optimization for Complicated Multiple-Input Multiple-Output Networks Based on Data Mining of S-Parameters

In this paper, an efficient signal-integrity analysis and optimization method for complicated multiple-input multiple-output (MIMO) networks is proposed, in which data mining is applied to discover the concealed information in black-box S-parameter models. Instead of performing a number of circuit simulations, data mining employs mathematical search algorithm directly into the model, which can save significant analyzed time and improve the efficiency. An optimized mining flow is presented for large scale data set, where the data processing and data mining are performed simultaneously, and thus it is unnecessary to save large extracted data. The proposed data mining method consider both the interconnect structure and the stimulated pattern of a MIMO system, which can perform thoughtful analysis and optimization with high efficiency. Two examples, signal-integrity analysis of two coupled microstrip lines and noise coupling among multiple signal vias through a power-ground plane pair, are presented to demonstrate the efficiency of the proposed data mining method in signal-integrity optimization design.

Compact wideband microstrip bandpass filter with wide upper stopband based on coupled-stub loaded resonator

A novel wideband microstrip bandpass filter BPF based on a coupled-stub loaded resonator CSLR is presented in this article. The CSLR is constructed by attaching one short-circuited parallel coupled microstrip line PCML in shunt to a high impedance microstrip line. The filter bandwidth can be conveniently controlled via reasonable adjusting of the impedance of PCML. Moreover, new defected microstrip structures DMSs introduced in the PCML functions as a means of adjusting the positions of transmission zeros, created by the PCML. The resonant mode and transmission zero chart are given, indicating that the higher modes could be suppressed by the transmission zeros. Finally, to validate the proposed method, two wideband BPF filters with and without DMSs centered at 3 GHz with 3 dB fractional bandwidth of 87% are designed and fabricated. The measured results show that both the return losses are better than 15.8 dB, while the BPF with DMSs has a -19.4 dB isolation wideband from 1.57 f0 to 4.23 f0. The measured results are in excellent agreement with full-wave electromagnetic simulation results. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:122-128, 2015.

Narrowband Bandpass Microstrip Filter Design

This paper analyzes the basic theory of the microstrip narrow-band filter design and accomplishes the design of narrow band-pass filter whose center frequency is on L-band with the help of the Agilent ADS simulation software. The filter adopts Chebyshev’s prototype structure and consists of coupled microstrip line. Its fluctuation is less than 0.5dB and attenuation is less than 1.5dB between 1.9GHZ and 2.1GHZ .Its port Reflection coefficient less than-15dB and attenuation is greater than 20dB at 1.72GHZ and 2.3GHZ. Layout simulation meets the requirement of filter design.

Broadband dielectric loaded parallel coupled microstrip quadrature coupler

ABSTRACTIn this article, a wideband dielectric loaded coupled line microstrip 90° hybrid coupler is proposed. The effect of changing the effective dielectric constant of substrate by dielectric loading is capitalized to tune the even‐ and odd‐mode velocities of coupled line to achieve wideband performance. Two different designs are perturbed by dielectric loading to achieve minimum amplitude and phase imbalance with good isolation. The simulated and measured results exhibit a coupling of 3 ± 0.7 dB across the band 3.5–10 GHz. The return loss and isolation are found to be better than 15 dB with 3° phase imbalance over the ultrawideband band. The designed coupler has compact size with a dimension of 30 × 20 mm2. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1694–1697, 2014

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.

Reduced Order PEEC Modeling for EMC Problems via Mixed Arnoldi Algorithm and Padé Approximation

The Partial Element Equivalent Circuit (PEEC) method is a 3-D full-wave modeling method suitable for combined electromagnetic and circuit analysis, and now is one of the promising numerical methods for Electromagnetic Compatibility (EMC) modeling. Model order reduction (MOR) techniques provide a feasibility to approximate complex circuit models with compact reduced-order models, and have great potentials to improve the computational efficiency for complex modeling problems. An effective MOR technique basing on mixed Arnoldi algorithm and Padé approximation for the PEEC modeling is introduced in this paper. Numerical simulations of a typical coupled micro-strip line EMC problem indicate the effectiveness of the proposed methods.

Symmetric reflection line resonator and its quality factor modulation by a two-dimensional electron gas

We have designed and fabricated a half-wavelength reflection line resonator that consists of a pair of coupled microstrip lines on a GaAs/AlGaAs heterostructure. By changing the top gate voltage on a small square with a two-dimensional electron gas under the resonator, the quality factor was tuned over a large range from 2700 to below 600. Apart from being of fundamental interest, this gate modulation technique has the potential for use in on-chip resonator applications.

The Intrinsic Impedance and Its Application to Backward and Forward Coupled-Line Couplers

The even-odd-analysis of a reciprocal and twofold symmetrical four-port provides four eigenimpedances. A method for the derivation of the intrinsic impedance of the network from these eigenimpedances is shown. Once the conjugate complex of its intrinsic impedance is presented to the external ports of the network, it will be a quadrature coupler. The usefulness of the intrinsic impedance is shown exemplarily by two detailed examples: the improvement of the directivity of microstrip coupled-line couplers and the development of forward coupled-line couplers. Approaches for the broadening of the bandwidth are shown. All couplers presented achieve superior performance regarding directivity, return loss, and bandwidth.

COMPACT MICROSTRIP BANDPASS FILTER IMPROVED BY DMS AND RING RESONATOR

In this paper, complementary split ring resonators (CSRRs) as band-stop elements are used in combination with coupled microstrip lines as high and low pass elements to design and fabricate very compact bandpass fllter (BPF) having controllable characteristics. The proposed fllter provides several advantages such as compactness (occupying area less than 0:1‚g £ 0:1‚g in which ‚g is calculated at center frequency of pass band), sharp rejection, suitable insertion loss (IL 3-dB bandwidth of roughly 2GHz from 0.7GHz to 2.7GHz, i.e., more than 115% FBW), good return loss (RL less than i8:5dB in all of the bandwidth) and low cost. Defected Microstrip and Ring Resonator Structures have been used for eliminating the created spurious pass band in upper frequencies. The simulation results have been done with full-wave softwares, i.e., CST MWS and ANSYS HFSS by time and frequency domain solvers, respectively. Also, the equivalent lossless lumped circuit of total structure has been obtained and simulated by ADS software. These simulated results show good agreements with experimental ones.

Miniaturized High-Isolation Dual-Frequency Orthogonally Polarized Patch Antenna Using Compact Electromagnetic Bandgap Filters

A miniaturized dual-frequency dual-polarization microstrip patch antenna with high isolation between receiving and transmitting ports (operating at 2.1 GHz for receiving and at 2.5 GHz for transmitting) is presented in this paper. The proposed antenna consists of a modified rectangular radiating patch, two 50 Ω microstrip feed lines, and two EBG filters. Two coupling microstrip lines are employed to excite two orthogonal fundamental modes (TM10and TM01). The high isolation is achieved by embedding two novel EBG filters underneath two feed lines to reject the incoming signal from the opposite line. Multilayer configuration, miniaturized EBG filters, and modified rectangular radiation patch contribute to size reduction. The total size is 0.67λ × 0.67λ × 0.03λ , only quarter of the multilayer rectangular radiation patch antenna (1.33λ × 1.33λ × 0.03λ) using common EBG filters with the same performance. Measured results on the reflection coefficients, isolations, and gains for the two frequencies are provided, which agree well with the numerical simulations. Also, measured isolations and radiation patterns at both two resonant frequencies are compared with the antenna without filters. The results show that the proposed method improves isolation by more than 20 dB with little influence on the radiation patterns.

Nonreciprocal and magnetically scanned miniaturized leaky-wave antennas using coupled transmission lines

This paper presents a new class of magnetically scanned leaky wave antennas (LWAs), incorporating ferrite (or possibly magnetoelectric composite), for wide angle beamsteering. Using the ferrite’s tunable permeability beamsteering is achieved by controlling the external bias field. This is unlike most leaky-wave antennas requiring frequency modulation to steer the beam. Our first design is based on coupled microstrip lines on a biased ferrite substrate with nonreciprocal radiation properties, specifically a 5 dB contrast between the measured transmit and receive gain in the E-plane was achieved. However, it was found that inhomogeneities in the bias field limited its scanning performance. To alleviate this issue, a new class of miniaturized metamaterial based LWA was considered and presented here. This new design is based on coupled composite right left handed (CRLH) transmission lines (TLs) and has a unit-cell length of only λ0/20. For validation, a 15-unit-cell prototype was manufactured and its TX/RX beams were scanned in the E-plane 80° by changing the bias field within a range of ±50 Oe. We found that the associated antenna gain varied between 3.5 dB and 5 dB at 1.79 GHz as the beam was scanned. In the above design, scanning was realized by changing the distance between the bias source and the LWA. Thus, future work will be focused on LWAs tuned by biasing a magnetodielectric layer placed below the ferrite substrate.

A MODIFIED COUPLED-LINE SCHIFFMAN PHASE SHIFTER WITH SHORT REFERENCE LINE

A coupled-line circuit structure is proposed in this paper to design a modified Schiffman phase shifter with short reference line. Based on the traditional transmission line theory and ABCD parameters, closed-form mathematical equations for electrical and scattering parameters are obtained. Obviously, this proposed coupled-line phase shifter has several advantages such as arbitrary phase difference, easy implementation, and analytical design method. Finally, two examples of microstrip coupled-line phase shifter, which have fractional bandwidth over 45%, are fabricated and measured. Good agreements between the simulated and measured results verify our design.

Optically Controlled Coupled Microstripline Microwave Power Attenuator

This paper presents an optically controlled coupled microstripline microwave powerattenuator on a high resistivity silicon substrate in the 3GHz-7GHz frequency band. The structure is based on the10dB microstrip directional coupler. Attenuation control is performed by optical control of the open end resistances. The open end act as a variable resistance under sufficient optical illumination conditions. The attenuator has been designed for 10dB and 25dB attenuation control for one-port and two port optical illuminations respectively. The analysis has been carried out for one port illumination using a 30mW, 850nm laser diode and two ports illumination using two 20mW, 650nm laser diode. The attenuator has been modeled by the Computer Simulation Technique's Micro Wave Studio (CST MWS) 3D EM simulator. At 5GHz, the structure provides a continuous variation of S41 between 0 and 25dB with both open end illumination.

Random-Space Dimensionality Reduction for Expedient Yield Estimation of Passive Microwave Structures

A methodology is presented for the expedient statistical analysis of the electromagnetic attributes of passive microwave structures exhibiting manufacturing uncertainty in geometric and material parameters. In the proposed approach, the computational complexity stemming from the high dimensionality of the random space that describes the uncertainty in the electromagnetic analysis of the structure is mitigated by employing a principal component analysis with sensitivity assessment in combination with an adaptive sparse grid collocation scheme. The method exploits the inherent dependencies between random parameters to reduce the number of simulations needed to extract the statistics of the desired output response. This leads to the expedient estimation of production yield by means of the cross-entropy algorithm, which provides for fast calculation of the failure probability for a given functionality criterion. The proposed methodology is demonstrated through its application to the analysis of crosstalk in coupled microstrip lines exhibiting manufacturing variability and the investigation of the variation the bandwidth characteristics of a bandpass filter in the presence of uncertainty in geometric and/or material parameters.

A 10-Gb/s Adaptive Parallel Receiver With Joint XTC and DFE Using Power Detection

A 10-Gb/s adaptive parallel receiver with joint crosstalk canceller (XTC) and decision-feedback equalizer (DFE) is presented. A differentiator-based XTC and a one-tap DFE are adapted to cancel far-end crosstalk (FEXT) and inter-symbol interference (ISI), respectively. When the lengths of the coupled microstrip lines change, an FEXT detector measures and compares the powers of FEXT and XTC to digitally update the XTC coefficient. Then, an ISI detector measures and compares the powers of the received data and recovered data to digitally update the DFE coefficient. This adaptive parallel receiver was fabricated in a 40-nm CMOS technology. The maximum power consumption is 17.55 mW from a 1.3-V supply, and the core area occupies 0.0352 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . For a 10-Gb/s PRBS of 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> -1 passing through 15-in FR4 printed-circuit-board traces with 8-mil spacing, the measured rms and peak-to-peak jitter of recovered data are 5.56 and 30.2 ps, respectively. The measured bit error rate is less than 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-12</sup> . The measured total calibration time is 2.424 μs.

Triple-Band Marchand Balun Filter Using Coupled-Line Admmittance Inverter Technique

This study presents the first reported design and implementation of triple-band Marchand balun filter. The novel balun filter is constructed from the short-circuited coupled line with a triple-band resonator to demonstrate the triple-band admittance inverter characteristic. To improve the amplitude and phase responses within three passbands, the compensation techniques for phase-angle, impedance-matching, and susceptance-slope discrepancies are employed in the balun filter design. Four types of triple-band balun filters with significantly different bandwidths and passband separations are designed and the results are consistent with the specifications. The design procedure for the triple-band Marchand balun filter is established to obtain the amplitude and phase balances in three operating bands with arbitrarily controlled center frequencies and fractional bandwidths. The proposed Marchand balun filter realized by the microstrip coupled-line sections and the defected ground structure stubs is measured and a good agreement among equivalent-circuit calculation, full-wave simulation, and measurement is observed, demonstrating the validity and versatility of the proposed design methodology and balun filter configuration.

Compact Microstrip Dual-/Tri-/Quad-Band Bandpass Filter Using Open Stubs Loaded Shorted Stepped-Impedance Resonator

This paper presents a new class of dual-, tri- and quad-band BPF by using proposed open stub-loaded shorted stepped-impedance resonator (OSLSSIR). The OSLSSIR consists of a two-end-shorted three-section stepped-impedance resistor (SIR) with two identical open stubs loaded at its impedance junctions. Two 50- Ω tapped lines are directly connected to two shorted sections of the SIR to serve as I/O ports. As the electrical lengths of two identical open stubs increase, many more transmission poles (TPs) and transmission zeros (TZs) can be shifted or excited within the interested frequency range. The TZs introduced by open stubs divide the TPs into multiple groups, which can be applied to design a multiple-band bandpass filter (BPF). In order to increase many more design freedoms for tuning filter performance, a high-impedance open stub and the narrow/broad side coupling are introduced as perturbations in all filters design, which can tune the even- and odd-mode TPs separately. In addition, two branches of I/O coupling and open stub-loaded shorted microstrip line are employed in tri- and quad-band BPF design. As examples, two dual-wideband BPFs, one tri-band BPF, and one quad-band BPF have been successfully developed. The fabricated four BPFs have merits of compact sizes, low insertion losses, and high band-to-band isolations. The measured results are in good agreement with the full-wave simulated results.

Nonreciprocal Leaky-Wave Antenna Based on Coupled Microstrip Lines on a Non-Uniformly Biased Ferrite Substrate

Previous work demonstrated that nonreciprocal slow waves can be guided on a pair of coupled transmission lines printed on a magnetic substrate. This was done by designing the unit-cell geometry to exhibit spectral asymmetry near the band edge ($K = pi$) frequency in its dispersion (K-ω) diagram. In this effort, the same concept is adapted to attain nonreciprocal radiation by operating the coupled lines in the fast wave region (|β| <; k <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ) of the K-ω diagram. To validate the nonreciprocal radiation, an 8-unit-cell leaky-wave antenna (LWA) was constructed and tested in presence of a non-uniform external magnetic field. Specifically, 5 dB contrast was observed between the measured transmit and receive gain in the E-plane. Importantly, good agreement was observed between measurements and simulations once non-uniformities in the magnetic field were taken into account. We note that the external magnetic field can be changed to achieve beam scanning. This is unlike traditional LWAs that achieve beamscanning via frequency control.

Common-Mode Noise Reduction Schemes for Weakly Coupled Differential Serpentine Delay Microstrip Lines

This paper proposes design schemes to reduce the common mode noise from weakly coupled differential serpentine delay microstrip lines (DSDMLs). The proposed approach is twofold: we leverage strongly coupled vertical-turn-coupled traces (VTCTs) instead of weakly coupled VTCTs (conventional pattern) and add guard traces. Time-and frequency-domain analyses of the proposed schemes for reducing the common-mode noise are performed by studying the transmission waveform and the differential-to-common mode conversion using the circuit solver HSPICE and the 3-D full-wave simulator HFSS, respectively. Compared to the conventional design of the weakly coupled DSDMLs, the proposed solutions yield a reduction of about 54% of the peak-to-peak amplitude of the common-mode noise, while the differential impedance remains matched along the complete length of the DSDML. Moreover, the range of frequencies, over which the magnitude of the differential-to-common mode conversion is now significantly reduced, is very wide, i.e., about 0.3-10 GHz. Furthermore, the differential insertion and reflection loss introduced by the newly proposed designs are almost the same as the ones achieved by using the conventional design. Finally, a favorable comparison between simulated and measured results confirms the excellent common-mode noise reduction performance of the proposed schemes.

Comments on Reply to Comments on "Wideband coupled-line microstrip filters with high-impedance short-circuited stubs"

In this short communication we want to discuss the reply given in [1] to our comments in [2]. In [2], we analyzed and corrected the equation proposed in [3] to compute the equivalent characteristic impedance of a short-circuited coupled-line section [Fig. 1(a)], but in [1], the same authors maintain that theory in [3] is correct. Therefore, in this work the analytical equation obtained in [2] is assessed and compared to the equation given in [1], [3] with the help of an electromagnetic solver based on the method of moments.