36
| Understanding Antennas
Aruba AP-85 Outdoor Access Point Series
| Installation Guide
Understanding Antenna Pattern Plots and Specifications
Traditional 2-D pattern plots and beamwidth specifications are like mental puzzles waiting to be solved because they only
provide a snapshot of the information in two planes. These two planes are often referred to as the azimuth (H-plane or
horizontal) and elevation (vertical or E-plane) planes. The azimuth view would be considered the view from directly above,
viewing the antenna pattern on the horizontal plane. The elevation view is considered to be a side view, viewing the antenna
pattern on the vertical plane. It is helpful to think of these planes as “cuts” of the real antenna pattern, which is actually 3-D.
Figure 27
illustrates where these “cuts” are located for a typical omni-directional antenna pattern.
Figure 27
Antenna Pattern Conventions (Omni-Directional Pattern Shown)
The antenna illustrated by
Figure 27
is commonly referred to as the dipole pattern because it is the pattern produced by an
ideal dipole antenna. The gain of this antenna is 2.14, which is achieved by compression in the vertical plane (elevation)
compared to the ideal sphere. If referring to the true 3D pattern, this compression is sometimes called the donut shape (see
Figure 28
).
Figure 28
Donut Shape Compression of an Omni-Directional Antenna
Azimuth, H-plane,
or Horizontal
Pattern Diagram
Elevation, E-plane,
or Vertical Pattern
Diagram