Antenna Theory for Communications #
Someone who needs to communicate a thought, doubt, or idea can be do so by voice communication. Communication is made through sound waves but if people want to communicate from a distance these sound waves need to be turned into electromagnetic waves. The device that does this is called an antenna and antenna theory explains this process from this very wide array of devices.
What is an Antenna? #
An antenna is a device that transfers electrical energy into electromagnetic waves and back. An antenna can function as both a transmitting and receiving antenna. Antenna Theory helps explain how these communicate.
- An antenna that converts electrical impulses into electromagnetic waves and radiates them is known as a transmitting antenna.
- One type of receiving antenna turns electromagnetic waves from a received beam into electrical impulses.
- In two-way communication, the same antenna can be used for both transmission and reception.
Aerial is another term for an antenna. Antennae or antennas is the plural form. Antennas have evolved significantly in terms of size and shape in recent years. Antennas come in a range of shapes and sizes, depending on their intended use.
Need of Antenna #
When it comes to communication systems, an antenna is required whenever there is a need for wireless connection. An antenna is a device that may send or receive electromagnetic waves for the purpose of communication in areas where a wiring system cannot be installed. This is demonstrated in the following situation.
Live Situation #
To reach a remote place, wire must be installed along the entire route, which includes valleys, mountains, winding paths, tunnels, and other obstacles. The advancement of wireless technology has simplified the entire procedure. The antenna is the most important component of this wireless technology.
Radiation Mechanism #
An antenna’s main purpose is to transmit or receive energy. A transmission line connects an antenna (whether it broadcasts, receives, or does both) to the station’s equipment. The radiation mechanism of a transmission line determines how well an antenna works.
A transmission line is a conductor that is designed to transport current over long distances with minimal losses. A wire, for example, that is attached to an antenna. A transmission line that conducts current at a constant velocity and is a straight line with an infinite length radiates no power.
A transmission line must be processed in order to become a waveguide or to radiate power.
- If electricity must be transmitted despite uniform current conduction, the wire or transmission line should be bent, shortened, or terminated.
- Even if the wire is straight, if this transmission line has current that accelerates or decelerates with a timevarying constant, it radiates the power.
- The device or tube, if bent or terminated to radiate energy, then it is called as waveguide. These are especially used for the microwave transmission or reception.
Basic Types of Antennas #
Antennas can be classified into several varieties based on their …
- The antenna’s physical construction.
- The operating frequency ranges.
- The mode of applications etc.
Physical Structure #
The following are the different types of antennas based on their physical construction. These antennas will be discussed in more detail in following chapters.
- Wire antennas
- Reflector antennas
- Micro strip antennas
- Aperture antennas
- Array antennas
- Lens antennas
Frequency of Operation #
The types of antennas are listed below, organized by frequency of operation.
- Very Low Frequency (VLF)
- Low Frequency (LF)
- Medium Frequency (MF)
- High Frequency (HF)
- Very High Frequency (VHF)
- Ultra High Frequency (UHF)
- Super High Frequency (SHF)
- Micro wave
- Radio wave
Mode of Applications #
The varieties of antennas are listed below, organized by application mode …
- Point-to-point communications
- Broadcasting applications
- Radar communications
- Satellite communications