 | Antennas must be modeled as a group of one or more
straight wires or tubes. Antenna structures with curved wires, such as a
round loop, must be approximated with a group of straight wires.
|
| Wires must be "thin"
compared to a wavelength at the operating frequency. Wire diameters should
be less than 0.020 wavelengths.
|
| Parallel wires should be
several wire diameters or more apart.
|
| ANTENNA MODEL can't model antennas that depend
on surfaces or sheets for their operation, such as discones, bowties, and
parabolic dishes.
|
| ANTENNA MODEL can't solve for near fields
when
the antenna is modeled over
real ground.
|
| Dielectrics other than air can't be modeled. Hence,
the plastic dielectric in a folded dipole made of 300-ohm twin lead can't be
modeled.
|
| Sources and loads don't occupy any space when modeled.
The traps in a trap dipole, for instance, would occupy a certain amount of
space. In
ANTENNA MODEL, they are just points in space with no
dimensions.
|
| Antennas with embedded coaxial transmission lines, such
as "bazooka" dipoles, may be difficult or impossible to model. Parallel-wire
transmission lines are not a problem.
|
| ANTENNA
MODEL's implementation of Sommerfeld-Norton
ground is accurate for wire segments down to about 0.02 wavelengths above
ground. |
