Examples 1 through 4

##
EXAMPLES 1 THROUGH 4

Examples 1 through 4 are simple cases intended to illustrate the basic formats. Example1 includes a calculation of near-electric-field along the wire. When the field is computed at the center of a segment without an applied field or loading, the Z-component of electric field is small since the solution procedure enforces the boungary condition at these porints. This is a check that the program is operation correctly. The values would be still smaller if the field points were more precisely at the segment centers. The radial, or X, componts of the near-field can also be compared with the charge densities at the segment centers (rho=2*pi*a*epsilon0*Ex). If the fields were computed along the wire axis, the radial field would be set to zero. for a nonplaner structur, however, computation along the axis is the only way to reproduce the conditions of the current solution and obtain small fields at the match points.

In example 2 the wire has an even number of segments so that a charge-discontinuity voltage source can be used at the center. The symble "*" in the table of antenna input parameters is a reminder that this type of source has been used. Three frequencies are run for this case and the EX card option is used to collect and normalize the input impedances. At the end of example 2 the wire is given the conductivity of aluminum. This has a significant effect since the wire is relatively thin.

example 3 is a vertical dipole over ground. Since the wire is thick the extended thin-wire approzimation has been used. Computation of the average power gain is requested on the RP cards. Over a perfectly conductive ground the average power gain should be 2. The computed result differs by about 1.5%, probably due to the 10-degree steps used in integration the radiated power. For a more comples structure, the average gain can provide a check on the accuracy of the computed input impedance over a perfect ground where it should equal 2 or in free space where it should equal 1. example 3 also includes a finitely conducting ground whwere the average gain of 0.72 indicates that only 36% of the power leaving the antenna is going into the space wave. The formats for normalized gain and tht combined space-save and ground-wave fields are illustrated. At the end of example 3, the wire is excited with an incident wave at 10-degree angles and the PT card option is used to print receiving antenna patterns.

example4 includes both patches and wires. Although the structure is over a perfect ground, the average power gain is 1.8. This indicates that the input impedance is inaccurate, probably due to the crude patch model used for the box. Since there is no omic loss, a more accurate input resistance can be obtained as;

Radiated Power=1/2(avg. gain)*(computed input power)
  = 1.016 (10-3)W
Radiated resistance= 2(radiated power)/|Isource|2
  =162.6 ohms

Since the input power used in computing the gains in the radiated pattern table is to large by 0.46 dB, the gains can be corrected by adding this factor.