The solid line is gain as obtained directly from NEC2, calculated from the absolute value of the far field in the forward direction. The dotted line is the gain as calculated from the far field in the forward direction divided by the average far field. The dotted line includes ohmic losses. . Feed point impedance vs number of segments per element. Original NEC2 for a 10 element yagi with 5mm elements on 144MHz.
Solid line is real part and dotted line is imaginary part.
Note that this design with 5mm elements is much better modelled by NEC2 than the less critical design with 9mm elements. The behaviour of the modified NEC2 for the 10 element design is displayed in the figures below, you may also look at the numerical data Fig 3. Gain vs number of segments per element. Modified NEC2 for a 10 element yagi with 5mm elements on 144MHz. The gain is calculated in two ways.