Amateur Radio Topics and Software Downloads

This page is devoted to Amateur Radio with emphasis on Transmission Lines and Free Software Downloads. The free software was all written by Robert Lay, W9DMK, expressly for the purpose of encouraging a better understanding of the principles of Transmission Lines and Impedance Matching. In addition to the software, there are two articles that are also available – the first is a compilation of Myths and Basic Truths relating to Transmission Lines and Antennas (Transmission Lines for Dummies). The other is An Analysis of the Quarter Wave Matching Transformer.

The available software is listed below, and in some instances there is a screen shot of how it looks when running. Just click on the links to automatically download the relevant file. Note that wherever it is noted that a Visual Basic Run Time module (See note below) is needed, one copy of that Run Time module installed on your system is enough – you do not need a separate copy for each program.

Programs written in “C” or in VB for DOS can run in a DOS environment or in a Windows environment, but they do not require Windows in order to run. Programs written in VB for DOS do not run in a Windows NT or Windows 2000 environment.

"COAX_Z" - A DOS program, written in “C”, that takes you through the measurement of the Characteristic Impedance (Zo) of a piece of coax. Based on the Equations in the ARRL Antenna Book, this program produces the Ro, Xo, Velocity Factor and other useful data about the line. After unzipping the file, the resulting file, Coax_z.exe can be run in a DOS or Windows environment.

"LSECT" - A program that designs L matching sections to transform an antenna impedance to a specified value, such as 50 ohms. This program requires VBDRT10 run time module, also available below. This program was written in Visual Basic for DOS. After unzipping the file, the resulting file, Lsect.exe can be run in a DOS or Windows environment.

"NCS" - A Windows Net Control Program, written in Visual Basic 3.0. Complete with Windows Help file. After unzipping the file, run the setup.exe program to do a Windows installation.

"NEWWAV7" - Similar in functionality to SWAVE, but in a more compact program for DOS. Accepts reactance component of line impedance and allows negative line lengths. It also writes the results to a disk file for future reference or printing out. After unzipping the file, the resulting file, Newwav7.exe can be run in a Windows environment.

Here is a sample of how it looks:

"RFBR1" - A program that computes impedances from measurements made with a General Radio Model 1606 or similar RF Bridge. Dial readings and frequency are input and the impledance is calculated. The special feature of this program is that it performs the necessary calculations to convert from a three -measurement sequence to compute the impedance of a balanced load being measured by an unbalanced bridge. After unzipping the file, the resulting file, RFBR1.exe can be run in a DOS or Windows environment.

This program requires the VBDRT10.EXE run time module.

"SMCHR” - version 8.2 of Windows SMITH CHART PROGRAM. Windows program, written in Visual C++ 1.5. Runs in Windows 3.1 and later. Extensive Windows Help file also included in the zipped up file. After unzipping the file, the resulting file, smchr.exe can be run in a Windows environment. The help file, smchr.hlp, should be in the same folder as smchr.exe.

"SWAVE" - A Windows program for Transmission Lines - written in Visual Basic 3.0 for Windows. Includes the reactive component of characteristic impedance and allows negative values of line length. After unzipping the file, the resulting file, swave.exe can be run in a Windows environment. Requires the VBRUN300.DLL run time module This is how it looks:

"TLE" - Transmission Line Equations for Windows. Written in Visual C++. This program provides the most comprehensive analysis of a transmission line available from this site. In this release, the possibility of non-zero reactance for Zo is introduced. If you are interested in the best of the programs available on this topic from this site - this is it. After unzipping the file, the resulting file, TLE.exe will run in a Windows 9x or Windows Me environment. (Will not run in WinNT/Win2000 – don’t ask!). This is how it looks:

"VBDRT10" - The run time module required for all Visual Basic for DOS programs.

“VBRUN300.ZIP” – The Run Time Module for all programs written in Visual Basic 3.0 for Windows. This zipped up module should be unzipped and installed in the Windows\System folder.

"VECTORS" - A program that does complex arithmetic. If you are challenged by vector arithmetic and want to avoid the cumbersome procedure for adding, subtracting, multiplying or dividing vectors or complex numbers then you will like this program. This program requires the VBDRT10 run time module. After unzipping the file, the resulting file, Vectors.exe, can be run in a DOS or Windows environment.

“XMSL” - Transmission Line Program that calculates the points of maximum current on line. Written in Visual C++, this program will run in any Windows environment. After unzipping the file, the resulting file, Xmsl.exe can be run in a Windows environment.

Run Time Modules

The VBDRT10.EXE run time module that is needed for programs written in VB for DOS can be installed any one of 3 places on your system – in the same folder with the program it supports, anywhere in the path or in the Windows\System folder. The Windows\System folder is recommended as that is where all run time modules and DLL’s normally reside. Similarly, the Visual Basic for Windows programs require VBRUN300.DLL or later and that file should always be installed in the Windows\System folder.