When you say TDR, if you are referring to an instrument such as a Tektronix 1502, there probably isn't going to be a definitive TDR "image" for you to compare to.
TDR's do an excellent job of determining the length of a transmission line or the distance to an open or short. Because they do this with a fast rise DC pulse, they don't fully characterize your antenna system in the frequency domain. Also, even a partially functional antenna will put enough noise [RF] onto the transmission line that it is difficult to identify issues with a TDR. Most antenna system testing today is done with instruments that use swept frequency techniques. These will produce plots of return loss vs. frequency or distance to fault [computed from the frequency domain sweep by use of an inverse fourier transform] A handheld analyzer such as an Anritsu Sitemaster or a R&S FSH3 is an ideal tool to use for this purpose, however these tests can also be performed using a spectrum analyzer with a tracking generator and a return loss bridge or with a properly equipped HP8920. If that is the type of test you conducted or if you have one of these instruments available to conduct further tests, I have some return loss test sweeps which show what a properly operating DB224 looks like that I could send you for comparison. ------------------------------------------------------------------- --- In [email protected], "Mike Besemer \(WM4B\)" <[EMAIL PROTECTED]> wrote: " ... The next step was to put a TDR on the line. Everything appeared to be okay up to the antenna, but the termination point (antenna) looked pretty ragged. What does a DB-224 (or similar) antenna look like on a TDR? ..."
