SWR Calculator

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by Barry A. Brown

Information about software:
SWR Calculator is a handy program to help you calculate the errors in your microwave measurements. It consists of the Directivity Error Calculator, the Mismatch Error Calculator, and the Ratio-to-dB Calculator. This program is absolutely free, but please read the Copyright, License, and Warranty Agreement in this help file.
The Directivity Error Calculator will show you the accuracy of a reflection measurement of an unknown impedance, based upon the directivity of the coupler used for the measurement. It is also a convenient way to convert a reflection coefficient to an equivalent standing wave ratio (SWR), return loss, or mismatch loss.
The Mismatch Error Calculator shows the potential error in a transmission measurement due to imperfect source match and load match. It can also be used in a reflection measurement to determine the error caused by the mismatch between the measurement port and the unknown impedance.
The Ratio-to-dB Calculator simply converts between voltage ratio, power ratio, and dB.
A value can be entered in SWR Calculator either by typing it into a text box, by clicking a scroll bar and dragging it back and forth until the correct value is displayed, or by clicking and dragging a sliding scale with the "grabbing hand" cursor. For quick help, click the ? button in the lower left, and then click on a part of the SWR Calculator window that you are interested in.