A typical network analyzer can measure s parameters over a large frequency range. Principles of rf and microwave measurements lecture notes and experiments for ecen 46345634 by. Alternative approaches are proposed in 14 and 15, where the coupling between microstrip lines is successfully exploited, in 16, where the three branch line. For double symmetry circuits like two coupled lines the 16 sparameters of the scattering matrix of the fourport reduce to 4 independent sparameter values. The quadrature property of the coupled lines is a subset of the amazing properties of lossless, symmetric fourport microwave circuits with or without coupling. Improvement of the bandwidth and scattering parameter.
Pdf we introduce a branchline coupler using discontinuous microstrip. So, lets take a look at a particular coupler that is able to provide us with a plus or minus 90degree phase shift and also split our signal into two pieces. Based on this concept, a 43% size miniaturization is achieved as compared with a classical microstrip branchline coupler prototype. Measured sparameters for the newsolid and the conventionaldotted branch line. Its scattering matrix ideally has the symmetric solution for a matched, lossless, reciprocal 4port device. The 3d coupler structure in cst studio s parameters results are presented in fig. In a backward coupler port 4 is the coupled port and. Compact planar microstrip line branchline and ratrace coupler article pdf available in ieee transactions on microwave theory and techniques 5110. In waveguide couplers, where coupling between main and auxiliary line is accomplished through holes or slots, vswrcanbeheldtoverylowlevels,oftennogreaterthan that resulting from a typical flange mismatch.
We assume there is no incident waves on any other ports, i. Procedure get the fabricated branch line coupler from your lab instructor. This work was partially supported by the ministry of science and higher. Its called the branchline coupler and it is shown here. Make measurements of s 11, s 21, s 31, s 41, s 14 and s.
Branchline coupler calculator online branchline coupler. A transmission line and its lshaped equivalent branchline couplers, lange. The coupler is connected to a vector network analyzer vna through four soldered sma connectors. The design consists of one single layer with implementation of two stubs and two slots to maintain the performance of the coupler. The measured s parameters confirm the proposed concept of the reconfigurable 36 db branch line coupler. For the branch line coupler plot the s parameters in the range 0. Influence of a directional coupler s parameters on the results of forward and reflected power measurements white paper products. Design of miniaturized 10 db wideband branch line coupler. Design of compact dualband branch line coupler the geometric graph of the proposed branch line coupler is shown in fig. Specifically, the 90 degree hybrid coupler is utilized in the handset infrastructure because it offers lowloss, high isolation, and exceptional phase and amplitude balance. S 21 p 1 c2 s 31 c s 41 0 s 11 s 22 s 33 s 44 0 for both ideal forward and backward couplers the re ection coe cients are zero. The measurement is direct and only involves measurement of relative quantities such as the swr or the. Miniaturization is one of the most important issues that should. Print version of this book pdf file a branchline coupler outputs from the coupled port pin 3 a fraction of the power presented at the input pin 1.
Directional coupler is a 4port waveguide junction consisting of a primary main waveguide and a secondary auxiliary waveguide. Next, consider the s parameters of an ideal directional coupler. Design methods for broadband 3 db branchline and rat. This calctown calculator calculates the various parameters related to a branchline coupler circuit. The 90d hybrid coupler is a 4port device, otherwise known as the quadrature coupler or branchline coupler. The scattering matrix of branchline coupler has the following form see. Pdf a compact branchline coupler using discontinuous. S 11 is the ratio of the reflected wave to incident. Abstract this paper deals with analysis of s parameters for microstip branchline coupler for frequency ranging from 4 to 6 ghz.
Design and simulation of branch line coupler using mems. The reverse travelling wave goes into port 2 and out of port 1. Branch line hybrid is 3 db directional couplers with a 90. The coupler has parameters that indicate the performance such as. The second part shows the set of proposed merit parameters. Finally, a compact dualband branch line coupler is optimally designed, fabricated and measured. Design and simulation of microstrip butler matrix elements. The advantage of using branch line coupler includes. Pdf modified double box branchline coupler with reduction. The size decreasing of the structure is depending on the replacement of branched transmission. The device can be used for a single antenna transmitterreceiver system or an iq signal splittercombiner. In the table the frequencies, length, thickness, width and materials are varied and the model is designed. The branch line coupler is designed for various parameters. Analysis also includes a shielded enclosure with metal lid 100 mils above the surface of the alumina substrate.
How does the artwork you generated from the computer program compare to this layout. In this paper, a new idea of reconfigurable 3 6 db branch line coupler is proposed. The s parameters of the ideal directional forward coupler are as follows. The measured results agreed well with the simulation. The remainder of the power is passed through to the output port pin 2. The parameters in the table of chapter 4 are used to design the branch line coupler. The objective of this model is to compute the sparameters and to observe the matching. For microstrip quasitem mode couplers and nontem mode structures. Microwave engineering directional couplers tutorialspoint. The following figure shows the image of a directional coupler.
Directional couplers an overview sciencedirect topics. Based on this concept, a 43% size miniaturization is achieved as compared with a classical microstrip branch line coupler prototype. Characterization of the branchline and ratrace ideal. Design of microwave hybrid couplers using intercoupled resonators by shani lu a thesis submitted to the university of birmingham for the degree of master of philosophy school of electronic, electrical and computer engineering the university of birmingham april 2012. Pdf compact planar microstrip line branchline and rat. The branchline the simplest type of quadrature coupler, since the circuitry is entirely planar.
Abstract this paper presents a novel design of branch 3db coupler, it is designed and simulated by using fr4 substrate at the operating frequency 2. Compact and performance evaluation of branchline hybrid. Improvement of branch line coupler isolation in s band. Design method for quasioptimal multiband branchline couplers. Keywords branch line coupler, microstrip lines, asymmetric coupled microstrip. So, let us start with let us say we are giving the input at port 1. The s parameters of the lumped element model of branch line coupler 8. The conventional branchline coupler is composed of four quarter wavelength. The s parameters can be measured by embedding the twoport network the deviceundertest, or, dut in a transmission line whose ends are connected to a network analyzer.
S parameters are easier to measure at high frequency. The branch line couplers providing an equal power divi. The demand for a smaller 90degree hybrid coupler with a broader bandwidth is. Design of miniaturized 10 db wideband branch line coupler using. Since the coupler is a lossless passive element, the sum of the signals power at ports 1 and 2 equals to the input signal power. Pdf compact cascaded branch line coupler using tsections. The proposed coupler is tuned through a simple open and short circuit at the coupler s branches edges. This example shows a microstrip branchline coupler on alumina er 9. An ideal branchline crossover theoretically has no coupling between the two paths through it. We find the s parameters for the system through the standard definition of incident and reflected waves. In coaxial couplers the proximity effects, end effects and capacitive effects from the coupling bars employed generally result in higher. A ideal singlebox branchline coupler is shown below. This kind of coupler is frequently performed in microstrip technology or. As a prototypes, two blcs are designed, analyzed and tested at the on and off states at 2.
Let us just see first the concept part and then we will try to complete the s matrix for this 3 db coupler. Return loss, power coupling, insertion loss and isolation characteristic in this thesis, the research was conducted to investigate the effects of optimization dimension to the isolation value of the branch line coupler. The measured s parameters present a return loss of 25. Directional coupler is used to couple the microwave power which may be unidirectional or bidirectional. In this paper two branchline directional couplers are investigated, i. Couplers dividers branch line coupler wilkinson coupler modified wilkinson coupler ratrace coupler gain block low noise amplifier oscillator 3.
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