Slot-coupled Directional Coupler Research Articles

Improving isolation of slot‐coupled directional couplers with weak and tight couplings

A suitable method for improving the isolation of slot-coupled directional couplers with elliptical-shaped slot and patches is introduced. It is shown that the even- and odd-mode phase velocities depend on the width of the patches and slot of the slot-coupled directional couplers. For couplers with tight couplings, the even- and odd-mode phase velocities can be effectively equalised by cutting some parallel slots into the patches, while for couplers with weak couplings, the even- and odd-mode phase velocities can be equalised by cutting some teeth into exterior part of the slot in the common ground plane. For various slot lengths and tooth depths, various design graphs are derived by sweeping some dimensions of the coupler. On the basis of the design graphs, three couplers with tight, moderate and weak couplings are designed and simulated. The designed coupler with tight coupling is also constructed and tested. The results show that by employing the proposed method, the isolation of the slot-coupled directional couplers has improved significantly.

Improving isolation of slot‐coupled directional couplers

A suitable method is introduced to improve the isolation of slot-coupled directional couplers. The proposed coupler consists of two trapezoidal-shaped patches that are coupled through a trapezoidal-shaped slot in a common ground plane. The inherent phase velocity differences between the even- and odd-modes of the slot-coupled directional coupler are compensated around the centre frequency of the coupler by introducing some slots to the trapezoidal-shaped patches. A design graph is derived by sweeping some dimensions of the coupler. A hatched area is also added to the design graph that indicates the appropriate coupler dimensions which lead to the equal even- and odd-mode phase velocities around the centre frequency. To demonstrate the effectiveness of the proposed coupler, an 8 dB coupler operating from 1 to 3.3 GHz is designed and constructed. The measurement results are in good agreement with the simulation results. The results show that the isolation of the designed coupler has improved significantly in comparison with the other designed coupler with no cut slots in the patches.

Slot-Coupled Multisection Quadrature Hybrid for UWB Applications

We present a three-section quadrature hybrid based on slot-coupled directional couplers, which operates over a bandwidth from 3.1 to 10.6 GHz. A prototype has been fabricated which exhibits a return loss better than 20 dB, isolation around 20 dB, an amplitude imbalance between output ports of less than plusmn0.75 dB and a phase imbalance between +1deg and -3deg across the 3.1-10.6 GHz band. This design outperforms previously reported results for ultra wide band operation.

A NEW ULTRA-WIDEBAND BEAMFORMING FOR WIRELESS COMMUNICATIONS IN UNDERGROUND MINES

In this paper, a novel ultra-wideband switched-beam antenna system based on 4×4 two-layer Butler matrix is presented and implemented to be used in hostile environment, such as underground mines. This matrix is based on the combination of a broadband two- layer slot-coupled directional coupler and a multilayer slot-coupled microstrip transition. With this configuration, the proposed matrix was designed without using any crossovers as used in conventional Butler matrices. Moreover, this new structure is compact and offers an ultra-wide bandwidth of 6 GHz. To examine the performance of the proposed matrix, experimental prototypes of the multilayer microstrip transition and the Butler matrix were fabricated and measured. Furthermore, a three 4-antenna arrays were also designed, fabricated and then connected to the matrix to form a beamforming antenna system at 3, 5.8 and 6 GHz. As a result, four orthogonal beams are produced in the band 3-9 GHz. This matrix is suitable for ultra- wideband communication systems in confined areas.

Novel butler matrix using CPW multilayer technology

In this paper, a novel 4 times 4 two-layer Butler matrix based on a broad-band two-layer slot-coupled directional coupler is presented and implemented at 5.8 GHz using coplanar waveguide technology. With the slot-coupled directional coupler, the proposed matrix was designed without using any crossovers as used in conventional Butler matrices, which leads to significant size reduction and loss minimization. To examine the performance of the proposed matrix, experimental prototypes of the multilayer directional coupler and the Butler matrix were fabricated and measured. Furthermore, a four-antenna array was also designed and fabricated at 5.8 GHz and then connected to the matrix to form a beamforming antenna system. As a result, four orthogonal beams at -45deg, -15deg, 15deg, and 45deg are produced. Measured results on the entire system agree well with the theoretical predictions, validating the proposed design

Design of a new directional coupler using CPW multilayer technology

In this paper, a novel 3-dB CPW multilayer slot-coupled directional coupler is presented and implemented. The coupler has two CPW lines coupled through a hexagonal slot etched on a common ground plane located between these lines. To increase the coupling between these CPW lines, a slot with sharp edges is used. The proposed directional coupler showed promising results, especially in terms of bandwidth (∼6 GHz). The simulated results are also compared with the measured data, and a good agreement is reported. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 471–474, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21381

CPW multilayer slot-coupled directional coupler

A new 3 dB CPW multilayer slot-coupled directional coupler between two CPW lines coupled through a rectangular slot etched on a common ground plane located between these lines is presented. The proposed directional coupler showed promising results, especially in terms of bandwidth (/spl sim/80%). The simulated results are compared with the measured data, and good agreement is reported.

Design of a broadband directional coupler using microstrip-like multilayer technology

An improved 3 dB broadband double-sided slot-coupled directional coupler has been designed and implemented. The slot is modified by trimming the sharp rectangular edges and the coupled microstrip lines in the coupling region. The performance of the coupler shows good agreement with the simulated frequency response. The main improvement is in the significant reduction of ripple amplitude in the design bandwidth. Insertion loss of the novel coupler has also been reduced compared to the conventional rectangular slot coupler. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 23: 273–275, 1999.

Simple design formula of a slot-coupled directional coupler between double-sided microstrip lines

Simple design formula of a slot-coupled directional coupler between double-sided microstrip lines

Arbitrarily-Shaped Slot-Coupled Microstrips and Their Applications in Microwave Integrated Circuits and Antennas

Abstract The mixed-potential integral equation (MPIE) is solved by the method of moments in order to investigate arbitrarily-shaped slot-coupled microstrip discontinuity problems. A concise expression of the mutual coupling matrix element is utilized to assure numerical efficiency and accuracy. Comparison between this MPIE and other moment methods (such as MFIE and EFIE) is also carried out and discussed. In order to validate this modeling tool, a circularly polarized dual slot-coupled patch antenna and a single slot-coupled directional coupler arc investigated. Good agreement between numerical results and measurement is achieved. Two examples of dual slot-coupled patch antenna and annular ring slot antenna with microstrip line feed arc designed to provide desired circularly polarized radiation. In addition, a weak coupling slot-coupled directional coupler is designed by utilizing a pair of circular slots. Good performance for directivity, isolation, and return loss is obtained.

Analysis and design of slot-coupled directional couplers between double-sided substrate microstrip lines

The characteristics of a slot-coupled directional coupler between two microstrip lines coupled through a rectangular slot in the common ground plane are studied. Conformal mapping techniques are used to obtain analytic closed-form expressions for the coupler's even and odd-mode impedance and propagation constants for any coupler configuration. Using the spectral domain approach, a full-wave analysis is performed to determine the dispersion properties of coupler parameters. Theoretical and experimental results for a 10-dB coupler at 10 GHz are presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Slot-coupled directional couplers between double-sided substrate microstrip lines and their applications

A slot-coupled microstrip directional coupler and its application to a planar multiport directional coupler (MDC) are described. This coupler can be applied to both loose coupling (e.g. 10 dB) and tight coupling (e.g. 3 dB). A four-port planar MDC fabricated by combining these couplers is described. Measured and calculated results are in agreement for both couplers.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Discussion on “Broad-band slot-coupled microstrip directional couplers”, “The application of printed-circuit techniques to the design of microwave components” and “Re-entrant transmission-line filter using printed conductors” before the Radio and Telecommunication Section, 13th November, 1957

Discussion on “Broad-band slot-coupled microstrip directional couplers”, “The application of printed-circuit techniques to the design of microwave components” and “Re-entrant transmission-line filter using printed conductors” before the Radio and Telecommunication Section, 13th November, 1957

The author's reply to the discussion on “Broad-band slot-coupled microstrip directional couplers”, “The application of printed-circuit techniques to the design of microwave components” and “Re-entrant transmission-line filter using printed conductors”

The author's reply to the discussion on “Broad-band slot-coupled microstrip directional couplers”, “The application of printed-circuit techniques to the design of microwave components” and “Re-entrant transmission-line filter using printed conductors”