Miniaturization of Microstrip Branch-Line Coupler With Dual Transmission Lines

The dual transmission lines are proposed to replace conventional quarter-wavelength transmission lines for a compact microstrip branch-line coupler in this study. The developed coupler can be easily fabricated on the printed circuit board without lumped element; moreover, its size is greatly reduced compared to the conventional branch-line coupler. Furthermore, simulated and measured frequency responses match well to validate the proposed coupler with dual transmission lines.     

Polarization independent narrow channel wavelength divisionmultiplexing fiber couplers for 1.55 μm

A polarization-independent narrow-channel (PINC) wavelength division multiplexing (WDM) coupler for operation at 1.55 μm has been designed based on the birefringent properties of fused single-mode couplers. These couplers are made from both conventional single-mode fiber (SMF) and dispersion shifted fiber (DSF). The couplers are designed so that the coupling-coefficient-length products for the two orthogonal polarizations are π out of phase. As a result of the long coupling lengths required, these couplers have very small cross-sectional dimensions, typically on the order of 10 μm     

Novel Rat-race Hybrid Coupler for RF Front-end Module

In this paper, a novel compact rat-race hybrid coupler incorporating an improved beeline compact microstrip resonant cell(IB-CMRC) is presented firstly. The size of the coupler is reduced by 46.5% than conventional one due to IB-CMRC’s excellent slow-wave effect. The novel coupler possesses strong ability of high-order harmonic suppression (above 30 dB) in addition. The measured insertion loss is comparable to that of a conventional microstrip hybrid coupler. Great potential applications of this IB-CMRC can be explored in MICs and MMICs to reduce the circuits size, suppress harmonics and improve the overall performance of the RF front-end module.     

Microstrip Spiral Directional Coupler

A new microwave directional coupler with a spiral-shaped construction is described. This coupler is named the spiral coupler and is formed by coiling two edge-coupled lines. Therefore, the size of the coupler can be greatly miniaturized. Furthermore, this coupler can achieve tight coupling much easier than the conventional coupler with edge-coupled lines on account of the multiconductor structure. The spiral couplers with a total length of a quarter-wave were fabricated on alumina ceramic substrates and resulted in 3.5-dB maximum conpling for a 40-mu m strip spacing. The size of the coupler was about one-sixth of the conventional one. The spiral coupler with a total length of three quarter-waves theoretically showed 2.5-dB coupling for a 95-mu m strip spacing on an alumina substrate. The achieved coupling is due to the skillful construction of the spiral. An experimental coupler fabricated on a Teflon substrate confirmed the usefulness of this approach.     

Size reduction and harmonic suppression of rat-race hybrid coupler using defected ground structure

In this letter, a defected ground structure (DGS) is applied to design a compact microstrip rat-race hybrid coupler. The proposed structure can achieve both a significant reduction of size and harmonic signal. By embedding the DGS section, it is observed that the resonant frequency of the hybrid coupler is significantly lowered, which can lead to a large amount of size reduction for a fixed frequency operation. Besides, the third harmonic signal is suppressed to -30 dB with respect to a conventional rat-race hybrid coupler. In this case, the measured insertion loss is comparable to that of a conventional hybrid coupler.     

A novel compact-size branch-line coupler

A novel compact-size branch-line coupler without any implementation of lumped-elements, bonding wires, and via holes is proposed. In this study, the size of the proposed coupler occupied only 45% of the conventional branch-line coupler at 2.4GHz. The performances of the circuit can be competed with the conventional coupler. The element sizes of this coupler can be realized easily by using simply standard printed-circuit-board etching processes. It is very useful for applications in the wireless communication systems.     

A Compact Slow-Wave Microstrip Branch-Line Coupler With High Performance

One compact slow-wave microstrip branch-line coupler is presented. The new structure not only effectively reduces the occupied area to 28% of the conventional branch-line coupler at 2.0 GHz, but also has high second harmonic suppression performance. The measured results indicate a bandwidth of more than 200 MHz has been achieved while the phase difference between S₂₁ and S₃₁ is within 90deg plusmn 1deg. Furthermore, the measured insertion loss is comparable to that of a conventional branch-line coupler. The new coupler can be easily implemented by using the standard printed-circuit-board etching processes and is very useful for wireless communication systems.     

一种带有反相单元的小型化宽带双面平行带线混合环

本文研究了一种利用双面平行带线(Double-Sded Parallel Strip Line,DSPSL)反相器和加载微带分支电路来设计的混合环.文中首先介绍了设计理论和思路,并给出了设计实例和测试结果.结果表明:该混合环的尺寸可缩小为常规混合环的11%,相对带宽达到了82%,中心频率点处反射损耗在-20dB以下,通...     

Fused couplers function in a broad range of wavelength

There is specific V value around which a fused coupler can function as a directional coupler in a broad range of wavelengths. This V value is too small to be achieved by a conventional fused coupler     

Polarising fibre coupler with high extinction ratio

Fused polarising fibre couplers have been fabricated using single-polarisation single-mode fibres. When circularly polarised light is fed into the coupler, one of the two orthogonal polarisation modes suffers strong attenuation, and only one polarisation mode couples in the fused biconical taper region. The extinction ratio of the coupler is 41 dB at a wavelength ? = 1.3 ?m with a coupling ratio of 48:52.     

Multiple Branch-Guide Directional Coupler Using TE/sub 01/-Mode Semicircular Waveguide (Short Papers)

This short paper describes experimental results derived from a newly devised branch-guide directional coupler using a TE/sub 01/-mode semicircular waveguide. The length of an experimental 0-dB coupler is about 150 mm, which is one-third shorter than the conventional coupled wave-type 0-dB coupler, and the loss is decreased in proportion to the reduction in length. Using this coupler, it is possible to manufacture more compact millimeter-wave diplexers with reduced insertion loss.     

L波段小体积微带监测耦合器设计研究

提出了一种用于1/8监测网络的微带线定向耦合器,该微带线定向耦合器结构在传统的微带线定向耦合器两端加入补偿电容,具有高定向性,给出了物理模型,对该结构进行了理论分析,并设计制作和测量了该种耦合器。测量结果表明,该定向耦合器的耦合度为26dB,工作频带为1.2～1.4GHz,隔离度超过-53dB,性能指标明显优于传统结构的微带线定向耦合器。同时减小了微带线定向耦合器的尺寸。     

High performance polarisation splitting fibre coupler

Presents an original design of a polarisation splitting coupler based on stress release in polished birefringent single-mode fibres within orthogonal orientation. 1.55 μm was used for coherent telecommunication applications and the best result was 25 dB of selectivity     

Compact Rat-Race Coupler Using Shunt-Stub-Based Artificial Transmission Lines

In this letter, a compact rat-race coupler is developed using shunt-stub-based artificial transmission lines (SSB ATLs). A conventional quarter-wavelength microstrip can be equivalent to an SSB ATL realized by two series high-impedance microstrips with the high-impedance branch-type shunt stubs. The circuit configuration of the SSB ATL is beneficial to miniaturize the circuit size using the folding technique. By integrating six SSB ATLs, a compact rat-race coupler can be implemented with a 3.9% circuit size of the conventional one. The measured results of the developed rat-race coupler are in a good agreement with the simulated results by full-wave electromagnetic simulator.      

Grating assisted waveguide-to-waveguide couplers

A new radiation-type waveguide-to-waveguide coupler is proposed. The coupling is realized through gratings embedded on the dielectric waveguides involved. Compared to the conventional hybrid-mode coupler, this type of coupler has advantages in that the two waveguides can be quite dissimilar as well as being separated by large distances. It is demonstrated that the coupling performance of this radiation-type coupler can be enhanced significantly by using photonic bandgap (PBG) structures     

基于微带倒相器的新型宽带3dB分支线耦合器

设计了一种宽带的微带线3dB分支线耦合器,并给出了理论分析。该模型结构简单,易于实现,通过级联两级分支线耦合器及加入超宽带微带倒相器,增加了带宽。仿真结果表明,在0.7~1.26GHz频带范围内,该耦合器回波损耗大于20dB,隔离度大于19dB,两平分端口幅度不平衡性小于1.23dB,相位不平衡小于,具有良好的性能。实验结果与仿真结果相符。     

Adiabatic fused tapered couplers

Pre-fattening of one fibre is shown to be a vehicle for achieving wavelength independent adiabatic fused tapered couplers. Compared with the conventional pre-tapered fused tapered coupler, this adiabatic coupler has a significant improvement in its ease of manufacture     

Miniaturized fractal rat-race, branch-line, and coupled-line hybrids

In this paper, space-filling curves have been used to realize a family of miniaturized hybrids. The large surface area occupied by a conventional structure has been significantly reduced through the use of space-filling curves having the same electrical characteristics. Several space-filling curves have been studied and implemented in different designs. The second-iteration Moore rat-race coupler occupies only 12.6% of the conventional coupler's area, while the area of the second-iteration Sierpinski branch-line coupler is 24.7% of the conventional case. On the other hand, a nine-section Minkowski coupled-line balun is confined in 60% of the conventional balun's area. However, the effective size reduction depends on the used space-filling curve, compression ratio, and associated coupling between segments. The performance of the proposed space-filling hybrids is as good as that of the corresponding conventional structures, and even better in some cases. The design and simulation of the proposed space-filling hybrids have been performed using a moment-method-based full-wave electromagnetic simulator. Measurements of one fabricated coupler prototype are in good agreement with simulation results.     

一种紧缩型的SOI 3-dB多模干涉耦合器

采用线锥形结构,在silicon-on-insulator (SOI)材料上设计并实现了一种新的紧缩型3-dB多模干涉耦合器(MMI).与普通的矩形结构3-dB MMI耦合器相比,该器件长度减少了40%.耦合器输出均衡度为1.3dB,过剩损耗为2.5dB.