Microstrip Directional Coupler Research Articles

Multiobjective Optimization Design of Microstrip Directional Coupler With Generalized Coupling Slots

Multiobjective Optimization Design of Microstrip Directional Coupler With Generalized Coupling Slots

Compact Microstrip Directional Coupler with Topology Layout on Multilayer PCB

Compact Microstrip Directional Coupler with Topology Layout on Multilayer PCB

An Ultrawideband GaAs MMIC Microstrip Directional Coupler With High Directivity and Very Flat Coupling

By introducing an adaptive lumped bridged-T amplitude equalizer into the microstrip directional coupler, this article realizes a 2.2 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times1.3$ </tex-math></inline-formula> mm ultrawideband GaAs monolithic microwave integrated circuit (MMIC) directional coupler with high directivity and very flat coupling by using the GaAs integrated passive device (IPD) process. The experimental results show that the proposed directional coupler exhibits more comprehensive radio frequency (RF) performance than the reported directional couplers due to the use of an adaptive bridged-T amplitude equalizer. In the ultrawide working frequency range from 2 to 20 GHz, the insertion loss of the coupler is less than 1.5 dB, the return loss is better than −20 dB, the coupling flatness is within ±0.3 dB, the isolation is higher than 40 dB, and the directivity is more than 20 dB, which are basically consistent with theoretical predictions. The microstrip directional coupler using the adaptive bridged-T amplitude equalizer shows great potential in the high-performance broadband communication system.

Broadband Directional Coupler with High Isolation

A novel wideband microstrip directional coupler operating at 1 to 5 GHz with high isolation is presented in this paper. Parallel coupling lines replace the traditional coupling transmission lines, providing broadband characteristics. The rectangular defected ground structure (DGS) on the RF ground on the back increases the isolation. The coupler was designed using 3D electromagnetic simulations. FR4-type dielectric substrate has been used due to its low cost. Simulation results prove that the proposed directional coupler provides an isolation of at least 20 dB on the full frequency band from 1 to 5 GHz, and reaches 66 dB at 2.89 GHz. The coupling degree is about 12 dB. Moreover, the proposed design can also achieve wide operating bandwidth (approximately 139% fractional bandwidth).

Three‐line microstrip directional coupler with high directivity

AbstractThis article proposes a novel microstrip directional coupler with high directivity. The proposed coupler was configured using three coupled transmission lines and two reflectors to cancel the leakage components in the isolation ports. To demonstrate the validity of the proposed coupler, we designed and fabricated the microstrip directional coupler with 15 dB coupling at 5.8 GHz. The measurement showed the directivity of 50.0 dB at 5.83 GHz, which was improved by 35.9 dB compared with that of conventional one.

Introductions about Microstrip Couplers and Power Splitters

Microstrip couplers and power splitters are widely used electrical components in the field of microwave technology, which has the function of dividing one wave into multiple waves with same magnitudes but different phases. In this essay, 5 typical types of couplers and power splitters are introduced, with their applications, layout designs, effect on the wave, advantages and weaknesses. Couplers and power splitters are labelled with their output wave phase differences and their voltage magnitude transfer ratio. In this essay, all the couplers introduced are 3dB couplers, which means that the output voltage is decreased by 3dB. The Wilkinson power splitter has an output phase difference of 0 degree, the monolithic multilayer 2-line microstrip directional coupler, the Lange coupler, the microstrip branch-line coupler have output phase difference of 90 degrees, and the planar Marchand balun has output phase difference of 180 degrees. The microstrip rat-race coupler has 2 divider modes and 1 combiner mode, where in the divider mode the phase difference could be set as 0 degree or 180 degrees. Therefore, in the design of microwave circuits, the type of coupler should be carefully chosen according to the working characteristics, the structure features and the working conditions of couplers.

전류 경로 보상을 이용한 높은 격리도를 갖는 마이크로스트립 방향성 결합기 설계

This paper proposes new microstrip directional couplers with high directivity using current path detour to compensate for unequal even- and odd-mode phase velocities in the U-NII upper band (5.725~5.850 GHz). The proposed method involves matching the phase velocities of even and odd modes by designing a longer current path for the odd mode, whose phase velocity is faster than that of the even mode. The proposed idea is demonstrated by the design of two directional couplers: one is a directional coupler with triangular edges on each side of the coupling area, and the other is a coupler with circular patterns in the coupling gap. The measurement results of the proposed two directional couplers exhibited an isolation of more than 38.6 dB and 46.0 dB, respectively, and a directivity of more than 25.7 dB and 29.7 dB, respectively. Compared to the conventional structures, the directivity of the proposed structures was enhanced by more than 10.8 dB and 14.8 dB, respectively.

Differential Bi-Level Microstrip Directional Coupler with Equalized Coupling Coefficients for Directivity Improvement

In this paper, a bi-level microstrip differential directional coupler has been investigated. It has been shown that the equalization of coupling coefficients can be successfully made with the use of appropriate dielectric stack-up and conductor geometry. The application of additional top dielectric layer can ensure proper equalization of coupling coefficients by lowering the value of capacitive coupling coefficient to the value of the inductive one. The theoretically investigated coupled-line section has been used for the design of a 3-dB differential directional coupler. The measurement results are compared with the theoretical ones.

30 dB microstrip coupler with high directivity

Due to the inhomogeneous structure of microstrip directional couplers, i.e. partly dielectric substrate, partly air, they mostly present property of poor directivity and low coupling level. The high directivity is achieved by a capacitive compensation by gap coupling of open stub formed in a sub-coupled line. Nevertheless, these couplers have the advantage of easy fabrication, lightweight, and incorporation with other microwave devices and are validated via design using Sonnet software. The main goal was to obtain coupling around -30 dB, meaning that almost all power is passed to the output, with a wide band; from around 3.5GHz to nearly 9GHz. Desired values have been obtained, including isolation and input match reaching -70 dB.

COMPACT DIRECTIONAL COUPLERS USING COMBINATION OF MICROSTRIP AND SLOT LINES

Context. Transition of modern electronics to higher frequencies is directly related with an extremely important problem of miniaturization of microwave integrated circuits. Conventional planar structures such as microstrip directional couplers have the feature – their linear dimensions are defined by the wavelength in the transmission lines, so the use of such structures for miniaturization of microwave integrated circuits becomes problematic. Objective. Using 3D-structures on combinations of transmission lines to study frequency properties of two possible implementations of quarter-wave directional couplers based on a combination of microstrip and slot transmission lines. Obtaining simple analytical expressions for calculating the electrophysical parameters of these directional couplers and confirm their properties by rigorous electrodynamic calculation. Methods. An even-odd mode decomposition technique and the scattering matrix theory were used to derive simple analytical formulas for calculating impedances of transmission line segments that define the topology of couplers considered. Results. Electrodynamic modeling of proposed couplers with dispersion and losses in the lines showed that the proposed constructions have better frequency characteristics in comparison with traditional three-branch microstrip directional couplers. It is also shown that the considered designs of couplers have great potential in the selection of the desired electrical characteristics of devices. Conclusions. The presented compact couplers can find a broad range of applications in mobile communication systems for decoupling of channels, division of power and frequency conversion. The method of transition from planar to three-dimensional structures used in the development of directional couplers on combinations of transmission lines permits not only to create compact devices with desired characteristics but also paves the way for significant decrease in the size and costs of the broad range of electronic equipment utilizing such couplers.

Compact Broadband High-Directivity Microstrip Directional Coupler

Abstract The difference between phase velocities of the odd and even modes in inhomogeneous microstrip coupled lines makes the microstrip directional coupler a poor device regarding directivity. In this work, this issue is successfully compensated by the addition of a matching network at the ports of coupled lines. Furthermore, the proposed matching network, composed of a single segment of microstrip line, was extensively studied providing significant insights for the design of a compact and broadband device. As result, simple design equations based on coupled lines S-parameters are obtained, as well as the achievable operation limits of the proposed matching network. Finally, in order to validate the proposed design methodology, a compact microstrip directional coupler is constructed to operate with directivity higher than 30 dB and coupling of 17 dB over a 600-MHz bandwidth.

Tightly Coupled Directional Coupler Using Slotted-Microstrip Line

This paper presents the theory and implementation of a novel microstrip directional coupler (DC) with a high coupling coefficient that can achieve the value of 0 dB. The coupling region is a slotted-microstrip line that supports two modes, even and odd. The geometry of the slotted-microstrip line facilitates the phase velocity compensation, which improves the isolation and directivity. A 3-dB coupler is fabricated and characterized. Measurements and electromagnetic simulations are in a good agreement with the theoretical predictions. They show that the proposed DC has 52% ±1 dB coupling coefficient fractional bandwidth centered around 2.4 GHz with isolation and return loss better than 25 dB.

Integrated Microstrip-to-Waveguide Transition With Microstrip Directional Coupler

In this letter, a novel design of microstrip-to-waveguide transition integrated with a microstrip directional coupler (MDC) is presented. This integration was designed, so that the MDC not only does not add extra loss to the main signal but also provides high directivity. The measurement results of the proposed structures, designed at 5.8 GHz, demonstrate less than 0.25-dB insertion loss, about 38-dB coupling factor, and greater than 20-dB return loss as well as 15-dB directivity for 20% fractional bandwidth. This structure can be therefore seen as a suitable candidate for high-power transmitter modules for which insertion loss at the output stage is a critical issue and a high coupling factor is required.

Design of a Low-Cost Microstrip Directional Coupler with High Coupling for a Motion Detection Sensor

A coupled-line coupler based on the asymmetric cascade connection of two coupled line sections is used to achieve a high coupling factor using low-cost material and technology in the X frequency band, and its performance is compared with a standard quarter-wave, coupled-line coupler, showing an increase in the coupling factor of about 3 dB. The proposed coupler can be effectively used in a Doppler motion detection sensor, due to its strong coupling and relatively high isolation. The coupler is designed through a simple, yet rigorous, equivalent circuital model. Then, an optimization procedure was performed using the commercial software Ansys HFSS in order to compensate for losses and second order effects. A prototype of the designed coupler was realized, and the measured data show very good agreement with simulations.

DESIGN OF MULTILAYER AND MULTILINE MICROSTRIP DIRECTIONAL COUPLER WITH CLOSED FORM RELATIONS

Design, simulation, implementation and measurement results of multiline and multilayer microstrip directional couplers are given with closed form relations. Step-by-step design procedure reflecting ...

High‐performance tight coupling microstrip directional coupler with fragment‐type compensated structure

In this study, a design scheme for high-performance tight coupling microstrip coupler is proposed by adding a fragment-type compensated structure between two loosely coupled lines. Owing to its flexibility and adaptability, the fragment-type compensated structure can not only provide a quarter-wavelength phase shift for coupling enhancement, but also compensate the difference in the phase velocities of the even- and odd-modes for high directivity. Design of the fragment-type compensated structure can be implemented by multi-objective optimisation searching with several design objectives characterising tight coupling couplers. A high-efficiency optimisation searching strategy by using two-dimensional median filtering operator is employed to improve the efficiency of multi-objective optimisation. For demonstration, a high-performance 3-dB tight coupling directional coupler operating at 2 GHz is designed. The measurement data demonstrates a maximum directivity of 47 dB, above 25 dB directivity in a 21.5% bandwidth, a maximum variation of 0.3 dB in the coupling level and a maximum power division ratio of 0.6 dB, which indicate the overall performance better than the previously reported 3-dB couplers. In addition, a simplified theoretical analysis of the proposed coupler and full-wave simulated results are provided for better understanding of the fragment-type compensated structure.

UHF and SHF Micro-strip Directional Couplers

The paper gives a review to analyse the outcomes achieved in the field of micro-strip directional couplers within 2010 – 2017. Considers design features of over twenty original or modified quadrature micro-strip directional couplers within ultrahigh (UHF) and super-high frequency (SHF) bands. The focus is on the ways to reduce overall dimensions of traditional loopback, printed and coupled couplers, enhance their use in several frequency bands, suppress higher order harmonics up to the sixth, provide broad-banding operation frequency to several octaves, change a type of the laterally-coupled coupler directionality from the counter-directional to the co-directional and trans-directional ones. The results obtained are achieved due to the following: the change of the quarter-wave line segments for their equivalent micro-strip “П”- and “T”- like structures and their combinations, the quasi-fractal topological implementation of devices, the use of composite transmission lines with the properties of meta-materials, the use of defects of various shapes in the ground plane, the samples in the signal layer of metallization, the low-pass filters in combination version of high-resistance and low-resistance lines, the use of special-form coupling apertures in a multilayer response which allows to compensate for the differences in phase lengths of the segments of connected lines for the even- and odd-order modes, thereby enabling significant improvement of coupler characteristics. The paper briefly describes coupler topologies, equivalent circuits and device layouts. Shows amplitude-frequency and phase-frequency characteristics simulated in computer-aided design systems. Also presents measuring results of the fabricated mock-ups of micro-strip directional couplers. The results obtained may be of interest to the creators of SHF devices and those involved in further investigation to seek and improve couplers of known designs.

Design and Implementation of a Novel Directional Coupler for UHF RFID Reader

The directional coupler is applied to isolating RX from TX because of low cost and simplicity compared to the circulator in the radio-frequency identification (RFID) reader. Because of unequal phase velocity between odd and even mode, the drawback of the traditional microstrip directional coupler is poor isolation. In this paper, to obtain a good isolation between RX and TX, a novel directional coupler is proposed to be applied to the UHF RFID system with a single antenna. Measurement result shows that the proposed directional coupler possesses a good isolation of -35dB in operating frequency band.

Analysis and Comparison of Sensors for Measurements of Partial Discharges in Hydrogenerator Stator Windings

In order to measure electrical signals produced by partial discharges in hydrogenerators stator windings, capacitive couplers are regularly used. They are electrically connected to the windings and therefore, require undesired insulation intrusion. For avoiding such an intrusion, a microstrip directional coupler is used, which is experimentally and numerically investigated in this work. This electromagnetic field sensor is analyzed initially via computer simulation using the finite-difference time-domain method. This numerical analysis is fulfilled considering the coupler placed over a stator bar. Experimental high-voltage tests with generator windings were also performed. We compare the results of the measurements obtained by using various sensors and show that the microstrip directional coupler has some important advantages over traditional capacitive sensors such as complete conductive insulation from the windings and the capacity of detecting shorter PD pulses due to their wider bandwidth.

Design of High-Directivity Wideband Microstrip Directional Coupler With Fragment-Type Structure

A novel design for a microstrip wideband directional coupler is proposed by using fragment-type structures. The use of a fragment-type structure may provide satisfactory flexibility and excellent performance. For a given design space, a fragment-type wideband coupler can be designed by first gridding the space into fragment cells and then metallizing the fragment cells selected by a multi-objective optimization searching algorithm, such as a multi-objective evolutionary algorithm based on decomposition combined with enhanced genetic operators. For demonstration, a 20-dB wideband microstrip directional coupler is designed and verified by test. A 45% bandwidth centered at 2 GHz has been measured in terms of maximum variation of 0.5 dB in the 20-dB coupling level. In the operation band, the designed coupler has directivity above 37 dB, and a maximum directivity of 48 dB at 2 GHz. In addition, some technique aspects related to multi-objective optimization searching, such as effects of design space, control of coupling level, and efficiency consideration for optimization searching, are further discussed. Fragment-type structures may also be used to design high-performance wideband directional couplers of tight coupling level.