Parabolic Reflector Antenna: Advantages and Disadvantages

This article explores the pros and cons of parabolic reflector antennas, a common type of microwave antenna.

What is a Parabolic Reflector Antenna?

Introduction:

The parabolic reflector antenna is a widely used type of microwave antenna consisting of a parabolic dish and an antenna feed.

Various feed arrangements exist for parabolic reflector antennas, including:

• Center feed with spherical cell
• Center feed with horn antenna
• Cassegrain feed

Parabolic Reflector Antenna working

This antenna type is used for both transmitting and receiving signals. As a transmitter (Figure 1), the feed radiates power onto the parabolic reflecting surface. The reflector then focuses the microwave power along the antenna axis, creating the beam direction. When receiving, waves impacting the dish are concentrated towards the feed, which is positioned at the focal point of the dish.

Benefits or Advantages of Parabolic Reflector Antennas

The following are advantages of using a parabolic reflector antenna:

• Reciprocity: Can be used as both a transmitting and receiving antenna.
• Versatile Feed Options: The feed can be configured in various modes, such as center feed, cassegrain feed, or offset feed, each with its own benefits and applications.
• Smaller Size and Low Cost They are relatively compact and inexpensive.

Drawbacks or Disadvantages of Parabolic Reflector Antennas

The following are disadvantages of using a parabolic reflector antenna:

• Radiation Blockage: The feed antenna and reflector disc can block a small percentage (about 1-2%) of radiation from the main reflector.
• Complex Design: Designing parabolic reflectors is a complex process.
• Side Lobes: Even with the feed horn at the focus and uniform illumination, some power from the feed spills over the edges of the reflector, contributing to side lobes in the radiation pattern.
• Surface Distortions: Very large dishes can experience surface distortions. Using a wide mesh instead of a continuous surface can mitigate this.
• Focal Point Accuracy: Achieving optimal performance requires placing the feed precisely at the focus of the parabolic reflector, which can be difficult in practice.