A second problem in the NEC-2 calculation engine is the unreliability of results when wires of unequal diameter join at right or acute angles. Although NEC-4 improves upon this situation, its results are not wholly reliable. The foundation for testing the reliability of NEC-4 outputs when wires of different diameter join at right angles is the single quad loop. When only a single diameter wire is used, all programs perform credibly, so long as models adhere to the antenna geometry criteria of the specific program. All loops were again modeled at 28.5 MHz, with copper wire in free space.
All loops are square.
Dimensions and segmentation are given for one side of the loop. Moreover, and especially significant for this test, there is no significant difference between the values achieved at 31 segments per side and 61 segments per side. Practical convergence of results is achieved at much lower levels of segmentation. Single Quad Loops of a Different Wire Diameters To test the ability of the programs to handle wires of different diameter joining at right angles, I modeled a single square quad loop. This might be a model of a portable quad loop using tubing for the horizontal members and wire for the vertical pieces, thus allowing the assembly to be collapsed for transportation.