Practical_Antenna_Handbook_0071639586

C h a p t e r 2 5 : A n t e n n a M o d e l i n g S o f t w a r e 547
Figure 25.1 x,y,z coordinate system for NecWin modeling software.
antenna. The wire in Fig. 25.2 has been placed where it is, relative to the three axes, for
user convenience. There is no computational reason it couldn’t have also been placed
along the y axis or at any angle in between the x and y axes. In fact, in free space, it could
be at any angle and offset with respect to all three axes!
In addition to its dimensions and location in model space, the antenna designer
must specify how many segments each wire element is to be divided into and where any
sources of RF current or voltage are to be located. Thus, the wire in Fig. 25.2 can serve
as a center-Âfed dipole or an end-Âfed dipole or long wire, depending on where the feedpoint,
or source, is located and the choice of measurement frequency. With practice, the