Applying Computational Methods To Test Site And Antenna Design

By Dr. Glen Dash, Ampyx LLC

Antennas commonly used in EMC work include dipole, conical, log periodic, and horn types. These are used on calibrated test sites for precision measurements. In the past, engineers had to rely on electromagnetic theory along with good deal of trial and error to design antennas and test sites. Today, we have computational tools that engineers of 30 years ago could only have dreamed of.

In this article, we will apply the elegant and powerful Method of Moments to the design of a half wave dipole and a biconical antenna. We will also use it to derive a site attenuation model. But first we need to review the physics of an antenna that does not, and cannot, exist, yet is the antenna against which all others are measured. It is called the "isotropic radiator."