Antenna Reflector Types: Plane, Corner, Parabolic

This page covers the basics and different types of reflector antennas, including plane reflectors, corner reflectors, and parabolic reflectors. The fundamental principles behind these antennas are explained below.

Plane Reflector Antenna

Figure 1 illustrates a plane reflector antenna. It comprises a primary antenna and a reflecting surface. This arrangement is useful for radiating electromagnetic (EM) energy in a desired direction. However, it’s not ideal for collimating energy in the forward direction.

The following parameters are influenced by the position of the primary antenna and its polarization:

• Radiation Pattern
• Impedance
• Gain
• Directivity

Corner Reflector Antenna

Figure 2 shows a corner reflector antenna. It consists of two or three mutually intersecting conducting flat surfaces. The feed element can be either a dipole or an array of collinear dipoles.

The dihedral form is the most common type of corner reflector. Trihedral forms with mutually perpendicular surfaces are typically used for radar target applications. Corner reflector antennas excel at collimating EM energy in the forward direction and suppressing radiation in the backward and side directions.

Parabolic Reflector Antenna

Figure 3 depicts a parabolic reflector antenna. This type of antenna is shaped like a paraboloid, giving it the properties of a parabola. Various feed antennas can be used at the focal point; the figure shows a horn antenna as the feed.

Let’s understand how a parabolic reflector antenna works:

Waves generated by the horn antenna are directed toward the reflector. The reflector bounces these waves back, forming a plane wavefront. Radiation is concentrated along the parabola’s axis. Waves in other directions are effectively cancelled due to differences in path length and phase. This is how a parabolic reflector antenna converts a spherical wave into a plane wave.

Parabolic reflectors are further categorized based on the reflector plate design:

• Parabolic cylinder reflector
• Cut or truncated parabolic reflector
• Pill box or cheese antenna reflector
• Torus antenna reflector
• Offset parabolic reflector antenna

Feeding for this type of reflector antenna is typically done using:

• Half-wave Dipole
• Array of collinear dipoles
• Yagi-Uda antenna
• Horn antenna
• Cassegrain feed

Advantages: Small size and low cost.

Disadvantages: The presence of side lobes can create electromagnetic interference (EMI). This effect is more pronounced in low-noise receivers due to imperfections in the reflector.