All formulas assume lossless transmission lines, but these results are usually within the measurement tolerance achievable by the amateur in normal situations. However, as line loss increases, i.e. with high SWR or long transmission line lengths, these approximations will diverge from the actual values. An excellent program to check the results for lossy lines is TLA, which is included with recent versions of the ARRL Antenna Book. The spreadsheet is divided into convenient functional areas. Each area performs one of the calculations listed below.
All sections share a common layout.
The input data is grouped on the left side of the page, and the output data is grouped to its immediate right. Output values are shown in bold type. On the far right side of each section there are areas that are used for computational purposes, in order to break complex formulas into more manageable chunks. I have learned from experience to keep a backup copy of the spreadsheet for when this eventually happens. This data is entered on the left side.