Antenna Gain
An antenna transmits and receives radio waves. Antenna gain is used to indicate the increase in power of one antenna (transmitting or receiving) as compared to another antenna.
Gain is a unit measuring the antenna's performance. It combines the antenna's power and radiation efficiency in the direction of peak transmission. The term "power gain" is also often used. In a transmitting antenna, the gain describes how well the antenna converts input power into radio waves headed in a specified direction. The measurement (either dBi or dbd) is the signal strength of the signal that would be transmitted.
Gain is actually a ratio of power levels and is stated in decibels dBi or dBd. Think of these two types of measurements as you would the metric system vs. imperial system of measurement (feet vs meters, etc). One foot is different from one meter. And so, 3 dBi is very different from 3 dBd.
The dipole or basic antenna concentrates it signals in two directions.
The isotropic antenna doesn't favor any particular direction so its gain equals 0.
- dBd compares the gain of an antenna to the gain of a reference dipole antenna (defined as 2.15 dBi gain).
- dBi on the other hand, compares the gain of an antenna to the gain of a reference isotropic antenna.
- So, a 3 dBi antenna will have a signal strength less than a 3 dBd antenna.
Antenna Types
Two-way radio antennas are essential components of communication systems that enable the transmission and reception of radio signals. There are various types of two-way radio antennas, each designed to suit specific requirements in terms of frequency, coverage area, and transmission power.
Here are some of the most common types of two-way radio antennas for base radios:
- Dipole Antennas: Dipole antennas, also known as half-wave antennas, are the simplest type of two-way radio antennas. They are made of two metal rods and are often used for low-frequency applications. They have an omni-directional radiation pattern, meaning they can transmit and receive signals in all directions.
- Yagi Antennas: Yagi antennas are directional antennas that are commonly used in fixed wireless communications systems. They consist of a driven element and several passive elements, which are used to focus the radio signal in a specific direction. Yagi antennas are ideal for applications where long-range communications are required.
- Ground Plane Antennas: Ground plane antennas are omni-directional antennas that are used in mobile two-way radio systems. They are often mounted on vehicles and consist of a vertical element and a ground plane that helps to reflect the radio signal in all directions. Ground plane antennas are typically compact and easy to install.
- Fiberglass Antennas: Fiberglass antennas are lightweight and durable, making them ideal for mobile communications applications. They are often used in environments where the antenna needs to withstand harsh conditions, such as wind, rain, and extreme temperatures. Fiberglass antennas are usually omnidirectional and provide broad coverage.
- Helical Antennas: Helical antennas are circularly polarized antennas that are used for satellite communications. They consist of a metal wire that is wound in a helical shape around a cylindrical support.Helical antennas provide high-gain and can be directional or omnidirectional, depending on the design.
- Patch Antennas: Patch antennas are flat antennas that are commonly used in wireless local area networks (WLANs) and Wi-Fi systems. They are small, lightweight, and easy to install, making them ideal for applications where space is limited. Patch antennas have a directional radiation pattern and are often used to focus the signal in a specific direction.
In conclusion, the choice of two-way radio antenna depends on the specific requirements of the communication system, including frequency, coverage area, and transmission power. By selecting the right antenna, you can ensure that your communication system performs to its fullest potential and provides reliable and efficient communications.