For maximum coupling calculations, up to five segments may be excited, and for an antenna array pattern calculation, up to ten segments may be excited.
A list of selected segments (specified by their major element tag number, and the segment number5) is shown near the top of the computer screen. Below that, information on all two-node major elements is displayed for one element at a time, while the user is ``paging through'' the list with the left and right arrow keys. In order to select a wire segment, the user ``pages'' to the particular two-node major element, and increments or decrements the segment number with the up and down arrow keys. The insert key is finally used to select a segment for excitation, whereupon WIREGRID will prompt for the excitation voltage, and the segment will be added to the list of excited segments. The delete key is used to remove segments from this list.
We have found from experience that users often have trouble using this particular feature of WIREGRID, partly because their is no visual feedback to confirm the location of the sources. Since it is relatively easy to manually append the necessary source commands to the NEC2 input deck created by WIREGRID, many users elect to do this.