Saturday, May 7, 2016

Homebrew Portable 2-Meter Antenna: SWR Test Results

The results for the antenna were quite good. I tested it with my Yaesu VX-6R handheld at 5 watts (my usual SOTA rig) on a range of 2-meter FM simplex frequencies from the band plan for my region. The standing wave ratio (SWR) ranged from a low of 1.2:1 at 146.415 MHz to 1.5:1 at 147.585 MHz.

To paraphrase from The ARRL Ham Radio License Manual, SWR is a measure of how well the antenna and feed line impedances are matched. A ratio of 1:1 is a perfect match (and is very difficult to achieve), while SWR greater than 1:1 is called a mismatch. Low SWR indicates the efficient transfer of power from the feed line because less power is reflected by the antenna. It also reduces losses in the feed line resulting from reflected power in the feed line traveling back and forth between the antenna and the transmitter.

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