Reflex klystron or gunn diode characteristics and basic microwave parameter measurement such as vswr, frequency. In this work, voltage standing wave ratio vswr was measured in a global system for mobile. Vswr stands for voltage standing wave ratio, and is also referred to as standing wave ratio swr. The gss7725 is suitable for operation only in a typical office or laboratory environment. A similar version of this article appeared in the october 2012 issue of power. A similar version of this article appeared in the october 2012 issue of power systems design magazine. Final worksheet 4 1 what is meant by vswr vswrvoltage. To make the students to design, experiment, analyze, interpret in the core field with the help of. Data sheet lda602q lda602q lab brick 4 channel digital. The main purpose of this lab is to study the gunn oscillator for square wave modulation and calculating the modulation depth. This is needed to find swr relationship, described by the formula. The voltage standing wave ratio vswr is defined as ratio between maximum and minimum field strength along the line. Voltage standing wave ratio vswr is a way to measure transmission line imperfections.
The hpv laboratory of the chronic viral diseases branchcdc periodically refines these laboratory methods. Set the message signal of amplitude 10 vpp and frequency 500 hz. Should take only the lab manual, calculator if needed and a pen or pencil to the work area. It is reliable power source with very high regulation and low ripple contents. Keep all the control knobs as it is, move the probe to the next minimum position. The radius of the vswr circle is equal to the magnitude of the load reflection coefficient. Operators manual general purpose water baths 110031 vwren version. Voltage standing wave ratio vswr is defined as the ratio between transmitted and reflected voltage standing waves in a radio frequency rf electrical transmission system. The lab brick lms series of signal generators bring affordability, functionality, reliability and simplicity to the microwave test bench. After the conclusion of environmental lab testing, four filters will be mounted on a shelf in the nose of one of ttcis facility for accelerated service testing fast locomotives. Cmrit 1 list of experiments 1 tdm of two band limited signals.
After the completion of experiment, before going to switch off the mains keep all the. Measure the frequency by frequency meter and detune it. While doing the experiment ensure that the beam voltage and beam current. If the reflection coefficient is given by, then the vswr is defined by the following formula. The voltage standing wave ratio, vswr is defined as the ratio of the maximum to minimum voltage on a lossless line. Keep the range db switch of vswr meter at 50 db position with gain control full.
Like in eplane tee, the signal fed through first port of h plane tee will be. Pdf simulation and measurements of vswr for microwave. Just remember to divide the larger impedance by the smaller impedance, because vswr is. Data sheet lda203 vaunix technology corporation 7 new pasture road newburyport, ma 01950 9786627839. As vswr is an important aspect associated, especially with feeders and antennas, it can be helpful to know the different relationships and formulas for calculating vswr.
Any level can be set through variable attenuator and gain control knob of vswr meter. For example, a trans mitting antenna with a vswr of 10. Do not apply any bias to pin diode throughout the experiment. Microwave and digital communication lab hence directivity d db ic 10 log 10 p2p1 main line vswr is swr measured, looking into the mainline input terminal when the matched loads are placed at all other ports. In an emc lab where many of the tests are very broadband in nature, a vswr of 2. In this lab you will learn how to characterize and use a 50ohm slotted line, crystal detector, and standing wave ratio swr meter to measure an unknown. Ece 584 microwave engineering laboratory notebook college of. The resulting ratio is normally expressed as a ratio, e. Vswr meter theory a directional coupler is a device with which it is possible to measure the incident and reflected waves separately. Remote troubleshooting for voltage standing wave ratio. A mismatch in the system causes reflections that will increase the vswr and lead to losses in transmission. To measure the standing wave ratio and reflection coefficient in a. Introduction to smith chart and its application for unknown impedance measurement requirement. For cases where z l is real, with a little algebra youll see there are two cases for vswr, calculated from load impedance.
Announcement vacancies tenders notices other announcements seminar conference workshop. Set the carrier signal of amplitude 2 vpp and frequency 2 khz. Microwave lab manual mahaveer institute of science. Recall this is a complex function, the magnitude of which expresses the magnitude of the sinusoidal signal at position z. Let it be p3 then the attenuation value of variable attenuator for particular position of micrometer reading of will be p1p3 db. Optical and microwave lab department of ece, velammal college. A screw or probe inserted at the top of wave guide. Measuring output vswr for an active levelled source. Adjust the vswr meter gain control knob or variable attenuator until the meter indicates 1. Experiment 2 low, medium and high vswr measurements. To measure the standing wave ratio and reflection coefficient in a microwave. Vswr voltage standing wave ratio, is a measure of how efficiently radiofrequency power is transmitted from a power source, through a transmission line, into a load for example, from a power amplifier through a transmission line, to an antenna. Vswr is a more common term used in radio engineering. There will be two bench setups for each of three experiments on any given lab day, so two lab groups will start with lab 1, and the other two groups will start with either lab 2 or lab 3.
Department of electronics and communication engineering name. Transmission lines in communication systems labvolt. Reduction of vswr by attenuation transmission line attenuation improves the vswr of a load or antenna. Energize the gunn oscillator or klystron amplifier for maximum output at desired frequency. Under ideal conditions, when the load is perfectly matched to the source, the vswr will be 1. Vswr is denoted by s and is given as where zl is the load impedance, z0 is characteristics impedance. Site vswr set with spm1 manual site vswr positioner 3 4 3 4 x m10 x 50 hexagon socket for mounting the tube base 1 x allen key, 6 mm 4 different length and amount, depending on the test volume height flight case manual and certificates base plate mounting material pod antenna set tube connector hvconnector tube base tubes4 pod holder. Eagle technologies r8000 3ghz rf bridge, accessories and calibration kit. Chronic viral diseases branch division of highconsequence pathogens and pathology. This tutorial defines vswr and explains how it is calculated. Vswr is a function of the reflection coefficient, which describes the power reflected from the antenna. Vswr calibration techniques the broadcasters desktop.
Finally, an antenna vswr monitoring system is shown. Obtain full scale deflection at vswr meter with variable attenuator. Read through the lab experiment to familiarize themselves. Tune the frequency meter knob to get a dip on the vswr scale and note down the frequency directly from frequency meter. When you key the transmitter, it develops a radio fre. Books indent form school kits and lab manual exemplar problems laboratory manuals 50 years of ncert results framework document. Measure a voltage standing wave ratio vswr to quantify. Power splitter 9 khz 6 ghz, vswr voltage standing wave ratio vswr is defined as the ratio between transmitted and reflected voltage standing waves in a radio frequency rf electrical transmission system.
On the klystron power supply, vswr meter and cooling fan for the klystron tube. From equation 4 it is seen that swr is a real number such that, where implies a matched. General dynamics r8000 with tracking generator and spectrum analyzer esa options. List of publication epub flipbook pdf ixii state uts ebook. Page6 guidelines to students equipment in the lab for the use of student community. Vswr meters, frequency meters and other detector devices. Just remember to divide the larger impedance by the smaller impedance, because vswr is always greater than 1. Not only does a high vswr mean that power is being wasted, the reflected power can cause problems such as heating cables or causing amplifiers to foldback. Vswr is a measure of the reflected power on a transmission line. Data sheet lda602eh lda602eh lab brick high resolution. It is a measure of how efficiently rf power is transmitted from the power source, through a transmission line, and into the load.
Voltage standing wave ratio definition and formula maxim i. Tune the probe for maximum deflection in vswr meter. The best way to easily understand swr is by example. Optical and microwave lab department of ece, velammal.
The laboratory scheme used for vswr measurement in. It is the responsibility of the user to contact the person listed on the title page of each write up before using the analytical method to find out whether any changes have been made and w hat revisions, if any, have been incorporated. To design and demonstrate the working of tdm and recovery of two band limited signals of pam signals. Each lab group will take two consecutive lab periods to complete each of the six lab experiments. It is the responsibility of the user to contact the person listed on the title page of each writeup before using the analytical method to find out whether any changes have been made and what revisions, if any, have been incorporated. Vswr specs specifications are introduced, along with formulas for mismatch loss and return loss in relationship to vswr. Vswr is a function of the characteristic impedance of the transmission line and the impedance of the antenna. Switch on the klystron power supply, vswr meter, cro and cooling fan. Klystron power supply skps 610 the model klystron power supply skps610 is general purpose laboratory power supply which is specially designed to use for reflex klystron tubes of s to x band frequency range. Swr is sometimes called vswr, for voltage standing wave ratio, by the technical folks. Auxiliary live vswr is swr measured in the auxiliary line looking into the output terminal.
Need for transmission lines, types of transmission lines, characterization in terms of primary and secondary constants, characteristic impedance, general wave equation,loss less propagation,propagation, propagation constant, wave reflection at discontinuities, voltage standing wave ratio, transmission line of finite length. The normal way of expressing a vswr is in terms of a ratio. In case the variable attenuator change the micro meter reading and record the vswr meter or cro reading. The voltage standing wave ratio vswr is one of the parameters in rf systems that measures the impedance mismatch. Students have to bring the lab manual cum observation book, record etc along with them whenever they come for lab work. Input vswr input vswr attenuator x db load vswr load example 1. The data is accurately organized in table 1, table 2 and table 3, provided below results and discussionsin the lab manual we are provided voltagefrequency dependence plot, see figure 7. Contents i experiment7 directional coupler 5 1introduction 7. Advanced communication laboratory manual 06ecl67 department of telecommunication engg. In the typical ham station setup, a transmitter is connected to a feed line, which is then connected to the antenna.
The wave guide components are based on rectangular waveguide equipped with rectangular flange. Move the probe along the slotted line to get maximum deflection in vswr meter. Students need to maintain a proper decorum in the computer lab. Hence, vswr can be expressed in terms of reflection coefficient as follows. Jul 25, 2015 ec 707 advanced communication laboratory dept. This is an ideal situation that rarely, if ever, is seen. Calculation of the vswr in a lossless line in terms of the reflection coefficient at the load. It consists of two transmission lines, the main arm and the auxiliary arm. Obtain the reading at the vswr meter at the receiving antenna and record it. Transmission lines and wave guides tlwg pdf notes sw. Download pdf september 2014 among the important ways to keep an fm transmitter happy is to ensure the match to the transmission line and antenna is optimal, as measured by the voltage standing wave ratio vswr.
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