You must wonder how antennas work and why we need them to watch television? First of all, an antenna is an electrical device that converts electric power into radio waves and vice versa, creating images on your television.
We use antennas because they provide a simple way to transfer signals or data in cases where other methods are virtually impossible. For example, you cannot attach cables and wires to all the houses that would love to subscribe to your cable company and watch your shows, right? So in times like these, antennas are most feasible.
Novices like us may think there is only one type of antenna or that antennas are all alike but guess what? They are not! There are a LOT of antennas available, and they have their specific uses too! So what are they?
Wire antennas
One of the most commonly used antennas is the wire antenna, which you can find in cars, ships, buildings, and even airplanes. They come in different shapes and sizes, so even wire antennas are sub-categorized!
- Short Dipole Antenna
It is the most common wire antenna available. It is an open circuit wire with the signal being fed at the center. “Short” dipole refers to the size of the wire relative to the wavelength of the signal.
- Dipole Antenna
A dipole antenna, which is evident from its name, is made up of two conductors on the same axis and the length of the wire needs to be small compared to the wavelength.
- Loop Antenna
Obviously, from their name, loop antennas are formed by single or multiple turns of wire forming a loop. The radiation produced by loop antennas is comparable to a short dipole antenna, but the shape is different, hence the name loop antenna.
- Monopole Antenna
Monopole antennas are dipoles that have one conductor instead of two.
Aperture Antennas
Aperture antennas are also another type of antenna, aside from wire antennas. They have openings on the surface. It consists of dipole or loop antennas in a guiding structure with a space to emit radio waves.
- Slot Antenna
The slot antenna is a type of aperture antenna that contains one or more slots cut on the surface of the waveguide. This type of antenna is used in microwave frequencies and has an omnidirectional radiation pattern.
- Horn Antenna
The horn antenna is one of the most commonly used antennas. It helps transition between the transmission line and wave propagation in free space and acts as a natural extension to a waveguide.
By now, we have an idea of an antenna, its types, and how important it is in the wireless communication system. Next, we will be learning the characteristics of an antenna that can affect a typical wireless communication system. These are the characteristics of an antenna:
- Radiation Pattern
An antenna cannot radiate energy in all directions with equal strength. Therefore, radiation from an antenna is maximum in one direction and minimum or almost zero in other directions.
Field strength is the quantity used to represent an antenna’s radiation pattern. Antenna experts measure field strength at a point located at a certain distance from the antenna. You can measure field strength by calculating the voltage at two points on an electric line and dividing the result by the distance between the two points; hence field strength units are volts per meter.
- Input Impedance
The input impedance of the antenna should match the input transmission line; otherwise, the system degrades over time due to the reflected power.
- Effective Length
The length of an imaginary linear antenna with a uniformly distributed current is the effective length of an antenna.
- Bandwidth
The antenna’s bandwidth is the range of frequencies in which the cable companies maintain antennas to the specified value because the gain, impedance, and standing wave ratio may change during operation.
- Effective Aperture
The effective aperture is the ratio of the power received at the load to the average power density produced by the antenna.
- Antenna Polarization
The antenna polarization is the physical orientation of the electromagnetic wave radiated in a given direction. Polarization of an electromagnetic wave is a time-varying direction and relative magnitude of the electric field vector.
If the direction is not specified, then the polarization in the direction of maximum gain is considered.
Other characteristics like antenna temperature, beamwidth, beam efficiency are also considered critical in choosing a suitable antenna. But all these are too complicated to remember. So we leave it all to the experts!
An expert in antennas that you can trust in the Greater Sydney Region is Sydney Cabling! Sydney Cabling assures you of getting the perfect antenna for your cable TV, and you don’t need to know which characteristic of an antenna you would need for your TV! All you need to do is contact them, and they can help you with your antenna needs! No more worrying about getting static on your cable and losing a weekend trying to fix your TV yourself. Sydney Cabling is the one to call!
