Wireless communication grows at an incredibly fast pace. In the last decade, the number of smartphone users has nearly quadrupled, per Statista. Almost every industry now implements wireless devices. Smart infrastructure, the Internet of Things, smart vehicles, and the entertainment industry are among the fields where advanced antenna systems are vital to their existence. This article identifies the foundational principles of antenna systems, the different types of antennas, and what the future of advanced antennas may look like.
Four characteristics of modern antenna types
Today’s advanced antenna systems enable the transmission and reception of electromagnetic waves with enhanced efficiency, signal quality, and expanded coverage. To design these systems for optimal performance, engineers consider four fundamental characteristics of antennas for each specific application.
The electromagnetic frequency
Electromagnetic radiation frequency can be adjusted. This measurable level is called RF (radio frequency), which occupies specific frequency bands of the electromagnetic spectrum. Antennas operate by converting electrical signals into electromagnetic waves for transmission and reception. The application determines the frequencies of these waves.
For example, long-distance over-the-horizon radar antennas can transmit and receive lower-frequency electromagnetic waves ranging from 3 to 30MHz, while 5G antennas transmit and receive much higher frequencies ranging from 450MHz to 7GHz and 25GHz to 52GHz.
Antenna bandwidth
While simple antennas process a single frequency, most advanced antenna systems handle a range of electromagnetic frequencies. This range is the antenna’s ‘bandwidth.’ An antenna’s bandwidth defines the spectrum width between the lowest and highest supported frequency bands.
Low-bandwidth antennas are highly efficient, simple, and less prone to interference. However, they are very limited in their ability to adapt to changing communication standards. They fundamentally operate in a limited frequency range.
High-bandwidth antennas offer much greater flexibility across many simultaneous bands and are generally compact. However, these antennas are more prone to interference. They also require meticulous design and signal interpretation systems, making them costly and complex.
The gain of the antenna
The ‘gain’ of the antenna can be adjusted to direct and concentrate the radiated energy in a specific direction. An antenna’s gain, measured in decibels (dB), determines the effectiveness of the signals it is transmitting or receiving. Broadcasting antennas transmit radio signals to various receivers simultaneously at varying distances, resulting in very high gain values ranging from tens to hundreds of decibels. Meanwhile, home Wi-Fi antennas are designed to cover a limited range and rarely have gains higher than 10 decibels. Intuitively, the higher the antenna gain value, the higher the power required to produce the signal.
Signal polarization
Antenna polarization refers to the orientation of the electric field component of the electromagnetic wave created or received by the antenna. Antenna polarization can be utilized to increase point-to-point antenna performance. There are three main types of polarization: vertical (linear), horizontal (linear), and circular.
- Vertical polarization antennas are commonly used in broadcasting systems given that many receiver antennas are vertically oriented, such as automotive antennas.
- Horizontal orientation is often used in long-distance point-to-point communication, as these signals are less vulnerable to atmospheric conditions such as rain, which can scatter the signal and reduce integrity.
- Circular polarization antennas are commonly found in satellite communication systems. They can be used regardless of the orientation or rotation of receiving antennas, which can often change with antenna movement.
Fundamental types of antennas
There are several common antenna types that each offer unique characteristics that make them suitable for specific applications and unsuitable for others.
Dipole antennas
Dipole antennas, such as the Pulse Electronics W5017, are the most recognizable type of antenna and are commonly used in radio and television broadcasting, as well as wireless communications systems like Wi-Fi routers. Dipole antennas typically have a narrow bandwidth optimized for a specific frequency. They have a moderate gain, ranging from 2dB to 6dB. Given their linear nature, they can operate in both vertical and horizontal polarization.
Parabolic reflective antennas
Parabolic reflective antennas, such as 2867885, are stereotypically called ‘satellite dishes,’ given their everyday use in satellite communication systems, but they can also be used for long-range point-to-point communication links. Parabolic reflector antennas can have a moderate to wide bandwidth, thereby supporting more frequencies than a dipole antenna. They are known for their high gain, ranging from 20dB to 100dB, and can support both linear and circular polarization.
Array antennas
Array antennas consist of multiple individual antenna elements arranged in a pattern. By intentionally controlling the phase and amplitude of each antenna element, array antennas can provide beamforming and steer the signal beam to the receiver to improve signal quality. These antenna systems vary depending on the application and can achieve moderate to wide bandwidths. They can provide moderate gain ranging from 10dB to 30dB and can accommodate linear (horizontal or vertical) and circular polarization. However, the polarization of an array antenna is a function of the polarization of the individual antenna elements. Array antennas are often seen atop telecommunication towers and throughout densely populated urban areas. These array antenna systems enable complex communication infrastructures such as 5G antennas, MIMO (multi-input and multi-output) infrastructure, and more.
Patch antennas
As a very low-profile antenna, patch antennas like the Abracon APAGM2704A-C2G are used in portable devices and other wireless communication devices. These antennas consist of a flat metal patch mounted on a dielectric substrate that can be designed to support linear and circular polarization. Patch antennas typically have moderate gain values ranging from 2dB to 9dB and can achieve moderate to wide bandwidth depending on their configuration.
Advanced antenna systems of the future
The fundamental physics that enables wireless antenna types will never change, but the systems that control, optimize, and amplify the effectiveness of antenna communication will only continue to grow in capability. The use of different antenna types is dependent on the frequency, bandwidth, gain, and polarization of the antenna’s function. Modern wireless systems consist of the antenna types listed in this article, as well as purpose-built antennas that draw on the same fundamental types of antennas. The overall capabilities of any wireless system can be drastically affected by the antenna used but can also be manipulated by the signal control system.
Many advanced applications of antenna technology utilize complex control systems, such as MIMO, beamforming, distributed antenna, multiplexing, and spatial diversity systems. These applications use the same core attributes identified in this article but can drastically improve communication performance in current and future wireless communication systems. For more information on this topic, view our other article, Advanced Applications of Antenna Technology.
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