e. Return Loss and Mismatch Loss Calculator. vswr-rl変換する計算ツールです。 イノベーションtop; 研究開発の実績; 博士の電波講座; アンテナ作りのこだわりVSWR Calculator. 504pF. As an example of common VSWR values, a VSWR of 3. 8. 0 0. The VSWR/return loss calculator from Pasternack will find VSWR, return Loss, mismatch loss, and the reflection coefficient given any one of. 많은 초심자들이 대체 왜 return loss란 지표와 VSWR이란 지표가 혼용되는지 이해하기 어려워 하는 경향이 있다. comThere are many antenna parameters out there. In some cases, users require a custom impedance value. 000:Return Loss (RL) and Voltage Standing Wave Ratio (VSWR) are related through a mathematical relationship. This can be built into a FLEXI-BOX and a transmission line (50 Ohm track) PCB is available which easily adapts for this circuit with one simple trimming. The corresponding value in the right column is the return loss value. 1 Return Loss. voltage standing wave ratio. The VSWR to RL Calculator employs this formula to convert VSWR values into RL values. net I(RL) V1. Mismatch Loss: Reflected Power Through Power (dB) Coefficient, VSWR is defined as the maximum voltage of the standing wave (E max) to the minimum voltage of the standing wave (E min ). Just enter the value and click calculate. multiplier m=1 RL=50*1 multiplier n=-4 XL=40*-4 multiplier k=2 Z0=50*k Q2: An antenna with a load, ZL=RL+jXL, is connected to a lossless transmission line Z0? What is the phase angle of the reflection coefficient in degrees toRelated Calculators. Return loss can be measured by using microwave and RF test equipment such as a signal generator, directional coupler along with a spectrum analyser or power meter, or alternatively by using a. In either case, the resulting VSWR is 1. Yoni Calculator Online Test System Configurator ezSample. 5. Voltage Measured Along a Transmission Line. Step 4. Home. If the power incident on a load is Pi P i and the power reflected by the load is Pr P r, then the return loss in decibels is [6, 7] RLdB = 10 log Pi Pr (2. 4. But the meter at the transmitter will show a VSWR of 1. Example 2. (also called insertion loss). Lower VSWR means lower reflection power (good impedance matching); thus, power transfers to load will be high. The isolation S23 is exactly -20 dB at the center frequency, while the output match is also degraded to about -13. 064 36. S21 is the transmission coefficient of Port 2. A commonly required conversion is between return loss and VSWR, and some values are tabulated in chart, along with a graph of these values for quick reference. 0708,min,max = =A VSWR value of 2 or under is typically acceptable for antennae in communications systems. - Applied attenuation. voltage standing wave ratio 020710. Note that we have a VSWR calculator that will allow you to convert between VSWR, mismatch loss and return loss!. This configurator will generate a bill of materials for a Constellation power delivery system. Noise Conversion Calculator. Return Loss Vs. Calculate the VSWR to 1 decimal place. Stripline Impedance calculator Smith charts VSWR/Return loss converter Wavelength calculator Wilkinson splitter designer. 92 dB 0. VSWR is a measure of the reflected power on a transmission line. VSWR Calculator:(by using RL) return loss(RL)= VSWR = RF Coax Cable Assembly Designer: Most Viewed Companies MegaPhase, LLC. Definition and BackgroundVSWR return loss calculator The voltage standing wave ratio (VSWR), reflection coefficient (Τ), return loss and mismatch loss are all dependant on one or the other, as can be seen by the equations below. How to improve the Return. Skin Depth Calculator. VSWR is the ratio of maximum voltage to minimum. Clear. This is because the parasitics of lumped elements tend to kill the frequency response as you go higher in frequency. For series combinations of components such as RL and RC combinations, the. Note: The historical definition of return loss results in a negative sign. Fairview Microwave's Waveguide Calculator provides the cutoff frequency, operating frequency range and closest waveguide size for a rectangular waveguide based on the custom inputted broad wall width. VSWR (voltage standing wave ratio, sometimes pronounced "viswar"), is the ratio of the maximum standing wave amplitude at one node to the minimum amplitude at another node in a system. A perfect match would be 1:1, meaning that the peak amplitude of the signal is always the same (i. RG-8 and RG-213 (50 ohm); and RG-11 (75 ohm) are about 0. Now let's look at the response. But, for a practical system, there will be a small impedance. The return loss at the input and output ports can be calculated from the reflection coefficient, S 11 or S 22, as follows: RL IN = 20log10|S 11 | dB. 1. 405 inch. On the other hand, you calculate VSWR by using the maximum and minimum voltage levels of the standing wave pattern on a transmission line. Pasternack's RF Calculators and Conversions section provides engineers valuable and easy-to-use tools ranging from complex mathematical formulas to simple conversions. Fill in the input field and select the input type and click the "calculate" button to show the values. 707. This is actually a general way to express impedance, but it requires an understanding of complex numbers. This calculator computes the VSWR, reflection coefficient, return loss and matching loss in a transmission line. This formula is used to calculate the VSWR from the given return loss. voltage standing wave ratio 020710. 1) RL dB = 10 log P i P r. Calculate. Free Online Engineering Calculator to quickly convert a Return Loss (dB) into a VSWR. (3) ea 90°E-Bend - 1. The VSWR to RL Calculator employs this formula to convert VSWR values into RL values. If VSWR is known, then the reflection coefficient (Γ), return loss (RL), and mismatch loss (ML) is calculated by using following formulas. This online reflection coefficient to VSWR calculator calculates the VSWR by entering the reflection efficient Γ (= value between 0 & 1). You can also use LTSpice to calculate S-parameters as well, which is a bit of a hidden trick. The ratio of the input to the reflected signal is. The result is an antenna VSWR or return loss measurement corrected for cable loss. Since directivity is a ratio of power densities, it is unitless. The limit of transmitter power for cable power dividers is 250 watts. A return loss conversion table is used to quickly convert VSWR values into return loss values. p65 Author: barbara Created Date:Return Loss is the portion of a signal that is lost due to a reflection of power at a line discontinuity. dBm to Milli Watts Calculator. This is an online calculator that calculates Return Loss based on VSWR. Free Online. Both decimal point and comma are ok. 045 foot length of this part in smaller units: 0. For example, an efficiency of 0. comThere are many antenna parameters out there. If VSWR is known, then the reflection coefficient (Γ), return loss (RL), and mismatch loss (ML) is calculated by using following formulas. Antenna). The VSWR is a measure of the efficiency of a transmission line and is used to determine how well the line is matched to the impedance of the. 0 or the results don't mean anything!). S11 is the reflection. 3. R = 10log 10 (P incident /P reflected) and. VSWR is the ratio of voltage applied. long or about 1. 0 is the minimum. Just enter the value and click calculate. On the other hand, VSWR and the reflection coefficient are connected by the equation: VSWR = (1+|Γ. 예를 들어 Return loss가 10dB 정도라면, VSWR은 2:1 이하가 되어서 입력매칭이 비교적 잘된 경우로 평가하며, Return loss가 14 dB 정도가 되면 VSWR은 1. VSWR (:1) Return Loss (dB) Reflection Coefficient (Γ) Mismatch loss (dB) Reflected Power (%) Through Power (%) VSWR Calculator. The below step by step solved example problem may helpful for users to understand how the input values are being used in such calculations to find the ratio of load impedance matching to the transmission line or wave guide characteristic impedance (Z 0). VSWR indicates matching condition of source (i. VSWR can be generated by Network Analysers. Electric fieldrms 5 conductivity 1 mass density 13E03 13 x 10 3. cdn-anritsu. If a complex plane is used with resistance along the real axis then the reactances of the capacitor and inductor are treated as imaginary numbers. Because the reflection coefficient Γ < 1, then the return loss will have a positive dB value. A calculator designed to compute the VSWR,return loss and matching loss in a transmission line. The Smith Chart achieves this by superimposing a grid on S11 that maps load impedance. Return Loss (RL) = 10 * log(Pr/Pi) Return Loss (RL) in dB = -20* log(Γ) Lesser value of return loss indicates higher impedance matching and vice versa. 009. Please Support RF Cafe by purchasing my ridiculously low−priced products, all of which I created. Online SWR Calculator. used to calculate the various values of impedances, voltages, currents, and SWR values that exist in the operation of a par-ticular transmission line. This is described in more detail on a separate page. VRMSF and VRMSR are measured and the return loss is back calculated. Mismatch Loss: Reflected Power Through Power (dB) Coefficient,VSWR is defined as the maximum voltage of the standing wave (E max) to the minimum voltage of the standing wave (E min ). The VSWR value range from 1. Step 3. Use the S11 value in the calculator above to find the equivalent VSWR. 64/100) = ±0. 000:Calculate SWR and return loss from impedance values. Upon arriving back at the source, part of the reflected wave is coupled back. This general RF calculator provides path loss, VSWR and wavelength as well as conversions between many common measurements used in the wireless industry. Return Loss. 8. 045 foot length of this part in smaller units: 0. It is specified in dB. Reflection -3dB: half of the RF energy is being reflected, and thus half of the energy is being received by the device. Voltage standing wave ratio (VSWR) is a way to measure transmission line imperfections. VSWR calculator: Isolation between circuit stages (mentioned above) is a way to minimize the voltage standing wave ratio (VSWR) and, in this way, improve impedance matching. Port 4 is the port which provides the reflected measurement (Return Loss/ VSWR), when the device is configured with the DUT connected to Port 2. 43. The ratio of the input to the reflected signal is called the Voltage Standing Wave Ratio (VSWR). The relationship between composite return loss and individual return loss in the constructive condition of identical mismatches is that the composite VSWR is the the square of the individual VSWRs. It converts the following units: • VSWR • Reflection • Return Loss • Prefl (Power reflection) • Reflections, Reflectionl to Mismatch Uncertainty Enter a value in any field, and all the other values are calculated and displayed. VSWR Calculator. RL OUT = 20log10|S 22 | dB This calculator computes the VSWR, reflection coefficient, return loss and matching loss in a transmission line. VSWR: RL (dB) 1. 091 25. In the above. Understanding VSWR and Return Loss. coefficient of Port 1 (also called return loss), and. S11 then would be the reflected power radio 1 is trying to deliver to antenna 1. In summary, return loss is the loss of signal power due to signal reflection or return by a discontinuity in a fiber-optic link or transmission line. vary with frequency). VSWR/Return Loss Frequency Band VSWR Return Loss (dB) 680–800 MHz 1. g. The VSWR can then be calculated from the return loss (RL) with the following equation. A known return loss is applied to the RF OUT port. Calculate VSWR and Return Loss from Zload (or Yload or S11) and Zo; Calculate Vmax, Vmin, Imax, Imin for lossless line from Zload (or Yload) and Zo; Calculate transmission line Matched Line Loss from Rin of o/c or s/c resonant section; Calculate luminous flux (lm) from luminous intensity (cd) and apex angle (°) Calculate irradiance flux (W/m^2. The voltage standing wave ratio (VSWR) is defined. This can be built into a FLEXI-BOX and a transmission line (50 Ohm track) PCB is available which easily adapts for this circuit with one simple trimming. As an added bonus, the results are modifiable and can calculate the other values. III. Title: dg03-110. Individual calibration is generally recommended to account for manufacturing process variation. complimentary copy of the "RF Calculator" at . Fairview Microwave's Waveguide Calculator provides the cutoff frequency, operating frequency range and closest waveguide size for a rectangular waveguide based on the custom inputted broad wall width. 6 dB of mismatch loss). This online reflection coefficient to return loss calculator calculates the return loss (dB) by entering the reflection efficient Γ (= value. Radio Frequency Engineering Calculator. Where, RL = Return loss in dB. (under "Support" and "Technical Application Notes" tabs). 2%) = ±3. 특히 Return loss와 VSWR의 대략적 값의 관계정도는 암기해두는게 편리할 때가 많다. In addition, the calculation takes into account the effect of signal attenuation in the transmission line. Moreover, return loss is the relationship between both the reflection coefficient (Γ) and the. 15. Please Support RF Cafe by purchasing my ridiculously low−priced products, all of which I created. 8. 6 dB of mismatch loss). RG-8 and RG-213 (50 ohm); and RG-11 (75 ohm) are about 0. Voltage standing wave ratio (VSWR), or often given as just standing wave ratio (SWR), is the ratio between the transmitted and reflected voltage standing waves at a signal chain element incident node. Finally, an antenna VSWR monitoring system is shown. com +1 (718) 934 4500 +1 (800) 654 7949. 224 X=-14. การใช้งาน vswr: หน้าที่หลักของ vswr : เสาอากาศส่งสัญญาณ: อัตราส่วนคลื่นนิ่งของแรงดันไฟฟ้า (vswr) เป็นตัวบ่งชี้จำนวนค่าที่ไม่ตรงกันระหว่างค่า ante nna และ. At 100 MHz, the loss is 0. The table below converts between VSWR, return loss, reflection coefficient, mismatch loss, reflected power and through power. We want a small return, so a large loss on the return “echo” is good. VSWR is the voltage standing wave ratio it used to measure the all-types waves (example: antenna waves) during transmission. so, for instance “. Therefore, a VSWR of less than 1. Consumers; Contact Us;Return Loss is a measure of the amount of energy that is reflected back at a discontinuity in a Radio Frequency Circuit . It also shows the percentage of forward to reflected power. A table of convenient values are presented at the bottom. This calculator converts between return loss (RL), voltage standing wave ration (VSWR), and reflection coefficient (Γ). In terms of the reflection coefficient: If VSWR = 1, G 0 = 0 (no reflection) = vp f, vp= c r 0 100 200 300 400 500 600-1. Note: If you select a waveguide size from the dropdown below, the broad wall width will be automatically calculated along with the other results. It varies from 1 to (plus) infinity and is always positive. Figure 6. VSWR. 3. Introduction to VSWR. 12 VSWR max. Return Loss Vs. Figure 13. I have already calculated the cascaded VSWR and RL using the RSS method (very similar result to simply multiplying each components VSWR as Itay mentioned), but the problem is that the result is not even close to the measured value of return loss. For series combinations of components such as RL and RC combinations, the. 64/100) = ±0. Usually this is the threshold when most devices are considered. The return loss & VSWR is related by the following formula, from which we can calculate return loss for a given VSWR. As an example, input power of 100 W (50 dBm) and output of 50 W (47 dBm) yields a cable. The view of any reflected voltage wave alone so see the reactive part would need the reflected current to plot the ratio, so it is not used. Title: dg03-110. Return loss = 10 log (Pr / Pi) = 20 log (Er / Ei) For example, if a load has a return loss of -10 dB, then 1/10 of the incident power is reflected. 3 800–960 MHz 1. How to Use? Using the VSWR to RL Calculator involves the following steps: Enter VSWR Value: Input the VSWR value that you want to convert into RL. 2 times the minimum voltage along that line, if the line is at least one half wavelength long. Fortunately, there’s a very easy way to analyze complex loads using graphical methods and it’s called the Smith Chart. e. Where, RL = Return loss in dB. Do y. 011. Formula is:: reflection coefficient (Γ)=. Unwrapped phase and reference plane extensions. A power meter may also be used to calculate cable loss. com . The term ‘forward power is synonymous with powered deliver to the load, or thru power. For support with the MatchCalc tool, contact [email protected] 24. When you look at a graph of a return loss formula, the negative sign is often omitted and is sometimes used interchangeably with the S11 parameter. Forward Power (W) Reverse Power (W) VSWR. Advanced Control Components. 5:1 VSWR is equivalent to -13. Calculates the resistor values, attenuation, 'impedance', reflection coefficient, VSWR and return loss of a Pi attenuator. Directivity and VSWR Measurements. This can be achieved by regulating the inner and outer diameter of the coaxial cable, along with the. —and calculates both the typical system return loss along with the worst case return loss. These measurements show the user the match of the system. VSWR | Return Loss | Reflection Coefficient Conversion Calculator: This Javascript calculator converts between return loss (RL), voltage standing wave ration (VSWR),. 13 24. This can be built into a FLEXI-BOX and a transmission line PCB is available which easily adapts for this circuit with one simple trimming operation. Reflection -10dB: 1/10 th of the RF energy is being reflected. The power reflected back from an antenna is specified using either the voltage standing wave ratio (VSWR) or the reflection coefficient (also referred to as return loss). Return Loss (dB) VSWR. Power Density Calculator is designed to give the power density, in Watts per square meter, at a given distance, output power and antenna gain. Figure 14. be used to add or subtract an arbitrary number of power, to convert power and voltage units from the linear to the logarithmic. Despite Equation [Math Processing Error] 10. Measure the power levels at the input and output of your cable, convert to units of dBm, and calculate the difference. Forward Power (dBm)Skin depth calculator Stripline Impedance calculator Smith charts VSWR/Return loss converter Wavelength calculator Wilkinson splitter designer. Stripline Calculator. The load can be an antenna, filter or other equipment connected to a transmission line. Reflections propagate back and forth in a line, but most assessments only consider the effects of the initial reflection because the back and forth energy attenuates until it is untraceable. Complex Impedance for RL and RC. Suitable for higher power (~1800 watts) at HF. Mismatch Loss (dB) 3. 7145 VSWR 6 Directivit y of directiona l coupler 23 dB 0. This tutorial defines VSWR and explains how it is calculated. Milli Watts to dBm Calculator. Suppose the wave is not matched with load and signal there is some unwanted signals are interrupted or signal loss is occurred. ,100 % power transferred from a source to a load via a transmission line/cable). 098Ω resistor in parallel with a 306. The table below converts between VSWR, return loss, reflection coefficient, mismatch loss, reflected power and through power. Fill in the input field and select the input type and click the "calculate" button to show the values. VSWR Calculator The VSWR Calculator is a program for reflection unit conversion. ZL = RL + jXL, load impedance. is of particular concern in the implementation of Gigabit Ethernet (1000BASE-T) The value of impedances at the ends of the link must be equal to the characteristic impedance of the link. A Forward and Reflected Power to VSWR Calculator is a tool that helps to determine the Voltage Standing Wave Ratio (VSWR) of a transmission line by using measurements of the forward and reflected power. The Voltage Standing Wave Ratio (VSWR) is defined as the ratio of the maximum amplitude to the minimum magnitude of the voltage standing wave at an input port of an antenna. A ratio of 2:1 indicates that reflections have resulted in a standing wave with a maximum amplitude that is twice as large as its minimum amplitude. Knowing the VSWR value allows engineers to determine the amount of signal loss that occurs due to reflection and calculate the return loss for the system. Step 2. Conclusion: In summary, RL and VSWR formulas and calculators are valuable tools that enhance the efficiency, accuracy and consistency of RF engineering tasks such as measurement, analysis, troubleshooting and system design. Definition and Background. 09 = 1. The return loss at that point has degraded by approximately 5 dB. VSWR = Voltage standing wave ratio. Definition of VSWR. 1. Enter. transmitter) with the load (i. Free Online Engineering Calculator to quickly convert a Voltage Standing Wave Ratio into Mismatch / Return Loss. At 1000 MHz, the S11 (dB) = -RL (dB) = -15 dB. 405 inch. Return Loss VSWR Reflection. Return loss can be measured by using microwave and RF test. So a perfect match can be represented by the range 0. This calculator allows you to calculate the input impedance of a transmission line, as well as the VSWR, return loss, and mismatch loss at the input point. 5 1 1. A VSWR of 6 or more is pretty high and will generally need to be improved. 0 is the minimum. e. Custom. 223:1 VSWR (It is slightly improved because of Component A having more insertion loss than. Summarizing: Directivity is ratio of power density in a specified direction to the power density averaged over all directions at the same distance from the antenna. Polar or rectangular grids only allow direct reading of S11. 98 dB return loss. Pout is the output power or signal level. 41:1 with a return loss of 15. 5, the corresponding value of. S21 is the transmission coefficient of Port 2. 5 0. Formally, S11 is the negative of return loss and has. 98 dB. Click here for RL to VSWR CalculatorKnowing Return Loss (RL), calculate voltage reflection coefficient Rho= 10^(-RL/20). See the relationship between VSWR and return loss. Conversion Formulas. 1) (2. VSWR table of return loss vs. By Marki Microwave, Posted Wed May 19 2010. Vswr To Rl Formula. If “V” is used, then the ratio is defined to voltage level of a standing wave at a line. 19. The calculated value is MUCH worse. Our RF calculators and converters will provide the figures you need for your radio frequency engineering needs. These multiple solutions are possible because each contributor is a vector having both. This VSWR / Return Loss calculator allows you to compute corresponding VSWR, Return Loss, Reflection coefficient and Mismatch Loss values for the entered input value and input type. VSWR (Voltage Standing Wave Ratio) is a measurement of how well matched a radio transmitter and transmission line is to a load such as an antenna. Visit Return Loss to VSWR converter>> RF Calculator #5 :Effects of Cable Loss in VSWR and Return Loss Measurements By Jim Norton Bird Technologies Group Applications Engineer 1 | Bird Technologies Group 866. Interactive Tools & Calculators. S-parameters, S11 and S21. Any other value indicates that a portion of the energy is reflected. 특히 Return loss와 VSWR의 대략적 값의 관계정도는 암기해두는게 편리할 때가 많다. A similar version of this article appeared in the October 2012 issue of Power Systems Design magazine. If VSWR is known, then the reflection coefficient (Γ), return loss (RL), and. , thereby assisting engineers to detect system problems and avoid costly, time-consuming system failures. 1 3. A VSWR of 6 or more is pretty high and will generally need to be improved. VSWR Return Loss Calculator. A SWR can be also defined as the ratio of the maximum amplitude to. For support with the MatchCalc tool, contact tool-feedback@qorvo. 4ghz. It measures how much energy is reflected back to the transmitter when a signal is transmitted through an antenna. Linkedin. 3 dB. 98 dB. 005 Γ 0 0, 1 01 VSWR 1 0and RL 40 dB, which is difficult to achieve in reality. Clear. 98 dB is equal to the equaivalent return loss of 1. 15 + 1. Reflections are measured using either VSWR or Return Loss. , if RL = 20dB, then calculate Rho = (10 ^ (20/-20)) = 10 ^ (-1) = 0. Mengapa Nilai RL harus lebih kecil dari -10 dB ? atau Mengapa VSWR harus bernilai di bawah 2 ?VSWR dan RL pada intinya adalah ukuran seberapa banyak energi d. It's assumed that the source impedance is also complex. There are two S-parameters of interest. Next, plug in the calculated return loss value into the formula VSWR = (1 + 10^ (RL/20))/ (1 - 10^ (RL/20)). VSWR and Return Loss RF Calculator VSWR (Voltage Standing Wave Ratio) is a measurement of how well matched a radio transmitter and transmission line is to a load such as an antenna. In this Inside Wireless episode we will look at Voltage Standing Wave Ratio (VSWR), |S11|, and Return Loss. Forward Power vs Return Loss Calculator RF calculators and converters. 211 0. Return Loss (RL) is a measure of all reflections that are caused by the impedance mismatches at all locations along the link and is expressed in decibel (dB). 05 + 1. Voltage standing wave ratio (VSWR), or often given as just standing wave ratio (SWR), is the ratio between the transmitted and reflected voltage standing waves at a signal chain element incident node. VRMSF and VRMSR are measured and the return loss is back calculated. In order to improve the VSWR, this calculator also has an extra input for adding an attenuator to improve or reduce the system VSWR. U. Wavelength Calculator. Just enter the forward and reflected power in watts. vswr-rl変換する計算ツールです。 イノベーションtop; 研究開発の実績; 博士の電波講座; アンテナ作りのこだわりMatchCalc™ RF Design Calculator. This calculator is designed to be an informational and educational tool. Return Loss (dB) 3. . 5 0 0. from Forward and Reflected Power: Transmitter Forward Power : Watts: System Reflected Power : Watts: VSWR = Reflection Coefficient = Follow the discussion. 3 1700–2200 MHz 1. Conversion Formulas. Calculates the absolute load impedance, reflection coefficient, VSWR, return loss and mismatch loss of a load. A low VSWR will minimize reflections from the antenna. These are the standard set of equations for converting between VSWR, return loss, and reflection coefficient (Γ). 8. The VSWR is an important measure of the quality of a radio antenna system. Elite RF. The MAX2016 is a dual logarithmic detector/controller used to monitor the VSWR/return loss of an. Calculation Select input type: Result: VSWR (pronounced "viswar"), or the Voltage Standing Wave Ratio, is the ratio of the maximum standing wave amplitude at one node to the. A table of convenient values are presented at the bottom. Using our 1 foot equals one nanosecond rule of thumb, let's calculate the 0. But the meter at the transmitter will show a VSWR of 1. Calculates the resistor values, attenuation, 'impedance', reflection coefficient, VSWR and return loss of a Pi attenuator. With this calculator, you can calculate the final improved VSWR value when attenuation is inserted between the source and the load impedance that initially do not have a 50 Ohm match. Home Return Loss to VSWR Conversion Chart Due to mismatches in impedance within the connector, some of the signal is reflected. Enter Input Value Output. p65 Author: barbara Created Date:Pi Attenuator Calculator. Voltage standing wave ratio (VSWR) is a way to measure transmission line imperfections. As we have seen, besides of the load impedance, this method measures also the real power delivered to the load.