Quality of antenna

Quality of antennas

The quality of an antenna is determined by various factors, including its shape, transmitting frequencies, and efficiency. Let's explore these in detail:

Shape of the antenna

The shape of an antenna plays a significant role in determining its quality. For example:

1. Parabolic reflector antennas: The best parabolic reflector antennas have a smooth surface with a consistent edge made of materials like iron ore. If made of woven cables or aluminum, it should have small holes to minimize wave loss.
2. Wire antennas: For loop antennas, the quality depends on the loop size. A larger loop circumference results in better performance compared to a smaller one.
3. Array antennas: The quality of array antennas, like the Yagi-Uda antenna, depends on the length of the boom. A longer boom allows for more metal elements, improving the ability to capture weak signals.

Transmitting frequencies

The frequency of the waves that an antenna can handle also influences its quality. The frequency is measured in Hertz (Hz). For example:

1. Horn and Yagi-Uda antennas: These antennas can transmit and receive high-frequency waves (greater than one gigahertz or GHz, which is $10^9$ Hz). Horn antennas are more efficient because they transmit straight waves, covering longer distances compared to Yagi-Uda antennas, which have a more dispersed wave pattern.
2. Yagi-Uda vs. loop antennas: The Yagi-Uda antenna is more efficient at capturing even weak signals and is preferred for transmitting and receiving FM radio waves (88.1 to 108.1 MHz) and long-distance television broadcasts.

Antenna efficiency

Efficiency is another important measure of antenna quality. The ability of an antenna to transmit and receive waves effectively is crucial. For example:

1. Horn antennas: These antennas are efficient for transmitting and receiving waves over long distances. However, they are not ideal for receiving weak signals unless paired with other antennas like parabolic reflector antennas.
2. Parabolic reflector antennas: These antennas are commonly used in satellite communications, weather forecasting, and space observations due to their high efficiency in receiving and transmitting waves over large distances.

Fabrication of antennas

Creating an antenna involves several key steps:

Identify the use of the antenna

Antennas are designed for specific purposes. Some are made for receiving waves (like radios), while others are designed for transmitting waves (like radar antennas). Knowing the intended use helps determine the design and structure of the antenna.

Select the type of antenna

Once the purpose is identified, the appropriate type of antenna should be selected. This choice also depends on factors like efficiency and the location where the antenna will be installed.

Antenna design

The design phase involves creating a sketch of the antenna. For example, a Yagi-Uda antenna consists of several elements: the reflector (behind the antenna), the driven element (where the dipoles are located), and the directors (in front of the driven element). The boom holds the elements in place and directs the antenna toward the signal source.

Selecting materials

The materials used for fabricating antennas should be durable and conductive. Common materials include:

1. Copper: Preferred for its excellent conductivity but is heavier and more expensive.
2. Aluminum: Lightweight, rust-resistant, and commonly used for antenna fabrication.
3. Stainless steel: Provides strength and flexibility, especially useful for antennas like mobile whip antennas, though it is less effective in conducting electricity.

Making the antenna

After completing the design and gathering the materials, the final step is to assemble the antenna. For example, creating a Yagi-Uda antenna requires following the design sketch and assembling the parts such as the reflector, directors, and boom.

Uses of antennas

Antennas have various applications in communication systems. Some of the key uses include:

1. Capturing and transmitting electromagnetic waves: Antennas are crucial for television broadcasting, radio communications, radar, and space communications.
2. Underwater or underground communication: Certain antennas are designed for communication over short-range frequencies, even through water or the ground.
3. Communication systems on ships, airplanes, satellites, and other devices: Antennas are integral to devices such as cell phones, rockets, radios, televisions, and radar systems.
4. Weather forecasting: Antennas capture signals for weather monitoring and forecasting systems.
5. Global Positioning System (GPS): Antennas play a key role in enabling location reporting through GPS devices.