Bandwidth is another fundamental antenna parameter. Bandwidth describes the range of frequencies over which the antenna can properly radiate or receive energy. Often, the desired bandwidth is one of t ...
Antenna impedance relates the voltage to the current at the input to the antenna. This is extremely important as we will see.
Let's say an antenna has an impedance of 50 ohms. This means that if ...
In addition to directivity, the radiation patterns of antennas are also characterized by their beamwidths and sidelobe levels (if applicable).
These concepts can be easily illustrated. Consider ...
On this page, we'll introduce two fundamental antenna parameters: antenna efficiency and antenna gain.
Antenna Efficiency
The efficiency of an antenna relates the power delivered to the antenna ...
Directivity is a fundamental antenna parameter. It is a measure of how 'directional' an antenna's radiation pattern is. An antenna that radiates equally in all directions would have effectively zero d ...
The fields surrounding an antenna are divided into 3 principle regions:
Reactive Near Field
Radiating Near Field or Fresnel Region
Far Field or Fraunhofer Region
The far field region is th ...
A radiation pattern defines the variation of the power radiated by an antenna as a function of the direction away from the antenna. This power variation as a function of the arrival angle is observed ...
How can your cell phone and your television work at the same time? Both use antennas to receive information from electromagnetic waves, so why isn't there a problem?
The answer goes back to the funda ...
Why is frequency so fundamental? To really understand that, we must introduce one of the coolest mathematical ideas ever (seriously), and that is 'Fourier Analysis'. I had a class on Fourier Analysis ...
Frequency is one of the most important concepts in the universe and to antenna theory, which we will see. But fortunately, it isn't too complicated.
Beginner Level (or preliminaries):
Antennas fu ...
What is the origin of the antenna? I'm ruling out such early devices as compasses, because while they in some sense receive a magnetic field, it is not an electromagnetic field. Ben Franklin's kite ex ...
In the 1890s, there were only a few antennas in the world. These rudimentary devices were primarly a part of experiments that demonstrated the transmission of electromagnetic waves. By World War II, a ...
