- October 3, 2016 at 9:29 am #5693
The following short Youtube video provides a good understanding of VSWR, it’s importance in coaxial systems vs open-wire transmission lines.
The video explains why a SWR meter placed close to the transmitter may look better with high loss coax vs low loss cable. Measuring the SWR right at the antenna terminals would give an accurate measurement of the true SWR.
The benefits of a “remote antenna tuner” vs one very close to the transmitter output connector as the high SWR problem only exists on the line or coax between the output of the antenna tuner and the antenna. Keeping that line length as short as practical effectively minimizes the losses associated with the reflected waves.
The line between the transmitter output and the input of the remote antenna tuner will have a very low SWR sucrh that power losses are consistent with the manufacturers cable loss specifications. The cable losses AFTER the antenna tuner will be greater when a high Very high SWR is present. Keeping that cable length as small as possible will help minimize the power loss.October 4, 2016 at 10:18 am #5717
The attached link on “Impedance Matching 101” by Ward Silver N0AX is somewhat long, but will provide some good explanations about various antenna matching solutions. Ward has worked with the ARRL to produce a monthly series of “Hands On Radio” articles for QST magazine.
Ward also provides a chart that explains the boundary limits for various L-Network configurations and shows how reordering the L-C components can find a workable solution (Ying-Yang diagrams). Note: the Ying-Yang image reveals the L-Network boundaries on a Smith Chart.
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