


Terms 
Directivity

This metric is used to describe the ability of the antenna to radiate or receive enery in the direction
of maximum intensity. This description is measured against a isotropic source which radiates or receives
energy equally in all directions.

Far Zone

The far zone region of an antenna is defined at a radial distance away from the antenna such that certain
approximations become valid. If D is defined as the diameter (in wavelengths) of the smallest sphere enclosing
the antenna, then the far zone begins at a radial distance of 2D^{2} away from the antenna.

Input Impedance

The antenna input impedance is a function of the frequency and is determined by the physical configuration.
Maximum power transfer between the antenna and the associated electrical network transmission line
is dependent on a conjugate match between the input impedance and the line impedance.

Power Pattern

The antenna power pattern describes the angular distribution of power. For a transmitting antenna,
the pattern represents the directional flow of power radiated by the antenna. The pattern on
transmit also shows the ability of the antenna to concentrate power within a particular angular
region. For a receiving antenna, the pattern represents the ability of the antenna to capture enery
from a particular direction.

References 
[1] 
W. C. Gibson, "The Method of Moments in Electromagnetics," Chapman & Hall/CRC, 2008.

[2] 
B. D. Popovic and B. M. Kolundzija, "Analysis of Metallic Antennas and Scatterers," IEE, 1994.

[3] 
R. F. Harrington, "Field Computation by Moment Methods," Krieger, 1982.

[4] 
M. R. Hestenes, "Conjugate Direction Methods in Optimization," SpringerVerlag, 1980.

[5] 
T. J. Peters, "A Fast Algorithm for Plotting and Contour Filling Radiation Patterns in Three Dimensions," IEEE Transactions on Antennas and Propagation, April 1992.
