Antennas can be classified into many categories depending upon their usage, specification, type of signals they receive, location, etc.
Some major varieties of antennas, based on the design of the antenna, are as follows.
Log amplifier antennas
They are used in scenarios where you require a wide range of frequencies with a variable band. Antenna gain and directivity are slightly compromised.
- Bow-tie antennas – These kinds of antennas derive their name from their shape. They can receive signals from all possible directions. It basically acts as a high pass filter, allowing only high frequencies to enter. Thus, distortion may take place easily because the frequency conformity is not met with. They are also called the Butterfly antenna.
- Log-Periodic Dipole Array – It consists of numerous dipole elements. The leading beam comes from the smaller front end. The array is larger in size at the back. The spacing between the elements moves in decreasing order from the back to the front. It works on wireless technology. When a signal is received, an active region is formed by the smooth flow of the signal between the arrays.
Reflector antennas
- Corner Reflector antenna – In such an antenna, the signal is reflected only by the corners of the structure. Reflectors can increase the directivity of any antenna.
- Parabolic Reflector antenna – The reflector in this type of antenna has the shape of a parabola. Its surface area is much higher than its wavelength. It has the capability of converting a wavefront that seems to be rather diverging. It then converts it into a parallel wavefront, which makes it easier to produce a narrow beam.
Traveling wave antennas
- Helical antennas – These antennas are fed by a coaxial line and are structured into a helix. Surprisingly, their structure is simpler than conventional antennas. The electrical size of the antenna matters the most here. Input impedance is sensitive to the pitch and wire size.
Helical antennas have two operating modes.
An axial mode is used when the antenna has to apply for a wide variety of frequencies. The dimensions of the antenna are the same as the wavelength.
Normal mode antennas have smaller dimensions than the wavelength.
- Yagi-Uda antennas – These kinds of antennas use passive elements. Some of the benefits are that they are affordable as well as effective. The director and reflector elements can be customized according to your need. You can use one or two of both directors and reflectors.
Generally, they are constructed using a driven dipole element along with one reflector. Horizontal polarization principle is applied. The antenna polarizes in the forward direction with the help of directors.
Categorisation of antennas on the basis of some essential factors are listed below.
Type of broadcast
- Satellite – The antennas that catch a satellite broadcast necessarily need to have a parabolic reflector or a dish antenna. They need to be inclined and positioned meticulously, in direction of the satellite. They receive frequencies in the frequency range of 10.95 to 12.75 GHz.
- Terrestrial – These kinds of antennas function in parts of the UHF band. In some countries, the VHF band is still in use. The transmitted signal should basically be a radio wave for a terrestrial antenna to capture it.
Installation area
- Indoor – Antennas installed indoor are usually near your TV. This concept works only when you reside very close to the local station, giving a very strong signal. The walls block the signals and electrical appliances also interfere with the incoming signal. So, indoor antennas should not be preferred if you reside in a weak signal area.
- Outdoor – These antennas are generally installed on the roof of your building or even your balcony. They can capture weak signals as well since they are properly inclined towards the direction of the originating station.