Balanis Antenna Theory Explained


Look around outside. There is a good chance that you will see a formal antenna or a tall structure that is acting as an antenna right now. Antennas allow us to maintain communication with one another between devices and equipment so we can maintain a modern lifestyle.

Aircraft controllers speak to pilots via an antenna. You speak to someone over a smartphone because of an antenna. Some homes receive television signals because of an antenna.

The Balanis antenna theory is the classic idea of how antennas should be constructed and arrange to maximize their effectiveness. Constantine Balanis originally developed the theory in 1992 using traditional antenna technologies, but since 2005, has adapted the theory to include fractal and smart antennas. This includes wireless communication applications.

Key Points of the Balanis Antenna Theory

An antenna is more than just a structure that transmits something. It involves questions that must be answered about desired frequencies, polarization, and impedance. Once completed, the antenna creates a radiance that can be evaluated so additional antennas can be constructed to form a complete network.

That’s why these key points of the Balanis antenna theory are so important. It all starts with the frequency of the antenna, which involves the sine and cosine waves, wavelength, and distribution speed.

Each wavelength can transmit specific types of information. These are referred to as “bandwidths.” That is why you can receive television signals and a radio signal at the same time. Each receives a signal from a specific bandwidth where information is being transmitted from the antenna to the receiver.

Once the frequency has been set, the radiation pattern of the antenna must be evaluated. In most instances, an antenna will create a circular pattern of radiation that is more concentrated near the antenna than away from it. Reception is therefore more consistent closer to the antenna than further away from it as well.

Tall antennas are typically symmetrical, but directional antennas are not. A directional antenna points a concentrated wavelength in a specific direction, which creates a single-peak radiation pattern instead.

Additional Thoughts About the Balanis Antenna Theory

Antennas provide information over a specific distance. Directivity is part of the Balanis antenna theory because it must be evaluated when creating a network of coverage. If the primary direction of an antenna is pointed toward the east, then adding another antenna to the east of that antenna wouldn’t make much sense. You’d want to choose one of the other directions to increase the coverage area being provided.

Here are some of the other ideas to think about that are included in this theory.

  • Efficiency. This is a measurement of how much power the antenna is able to radiate, relative to the input power it happens to have.
  • Gain. This is a measurement of power that is radiated in a specific direction. A tall antenna with a generalized broadcast would have a consistent gain in all directions, whereas a directional antenna would have a high gain in one direction and a lower gain in all other directions.
  • Impedance. This measurement is a ratio of the voltage to current that is found at the terminals of the antenna. Their frequency helps to set the type of transmission lines that are used for the antenna. Within the Balanis antenna theory, the impedance must be matched to the transmission for the antenna to properly radiate.
  • Bandwidth. This is the frequency range which the antenna operates within as it offers a radiation pattern.

Antennas are also classified by their polarization. Depending upon the levels of polarization that are available, there can be zero power loss or there can be a massive power loss. An antenna that is vertically polarized, matched with an antenna that is horizontally polarized, will have a 90-degree angle of polarization and no power transfer.

It is the concept of polarization that allows for certain electronic devices to have better reception when they are moved. Many antennas for these devices are polarized linearly, so moving or rotating the device can help it match the polarization of the antenna.
The best reception occurs when polarization matches. When a gap forms between the two, the reception decreases until nothing can be received. At the same time, reception decreases as one moves away from the radiated field of the antenna.

By understanding how antennas work, we can maintain our current levels of communication while exploring new options. That is why the Balanis antenna theory is such an important component of our modern life.