ABSTRACT
Conventionally designed directional antennas have considered operation only at the carrier frequency with little regard for bandwidth. This chapter extends the application of Numerical Electromagnetics Code (NEC)-2 to include the total system—antenna-matching networks, phasing networks, and other parts of the system including the transmission lines. The resulting analysis views the bandwidth of the total system plus the bandwidth at some intermediate points along the signal path. The chapter provides a demonstration of modeling towers using the lattice tower model. In creating the lattice tower model, the concrete tower base with four ground straps and the base insulator complete with spider and girth are modeled using normal NEC-2 procedures. The voltages are translated back through each of the system's functional elements until the input to the common point-matching network is reached. At each voltage translation, the field ratios thus generated were calculated to confirm that the translated drive voltages did indeed produce the target field ratios.
