Revised 14 June 2003
B-3
The following VSWR vs frequency plot was generated by the NEC-2 model. Actual
measurements of real antennas in the field have typically reproduced the general shape
of this curve. But the measured curves have shown a somewhat wider bandwidth
between the 2:1 VSWR points. This is due to measurements being taken at the
transmitter end of fairly long pieces of coax and to coupling of the antenna to the “stuff”
in its near field region. This curve is shown here only to give some idea of the relative
difference in rate of rise in SWR for frequencies below system resonance as compared
to frequencies above system resonance.
Figure 4-B
2D-40A Modeled VSWR curve
(antenna tuned for 7.1 MHz)
