Table Of Contents

What Is An Antenna?

Antennas are metal rods used to transmit or receive radio signals. They can be found on both fixed and portable devices. Radio antennas come in different shapes and sizes (they do not need to be circular or spiral) and are used for various purposes.

Antennas are used in a variety of settings, including:

Home use

A TV antenna enables your TV to receive over-the-air programming, portable radios, cellular telephones, landline phones and radios, satellite receivers, and more.

Business use

A wireless access point (WAP) connects a wireless system to the Internet.

Military use

A satellite dish receives transmissions from satellites, which relay military information and images to ground stations on Earth.

Wireless Communication

Antennas have been used for wireless communications for many years, but they have become more sophisticated. New technology such as FM radio has allowed the use of smaller and more efficient antennas.

Wireless communication can be achieved using the following:

  • Radio waves
  • Infrared light signals (used in night vision)
  • Microwave signals (used in cell phones)
  • Laser beams (used in optical communications)
  • Even visible light signals (for television broadcasting)

Antenna Theory

An antenna is an electrically conductive structure that relies on electromagnetic waves to transmit or receive signals. Antenna theory is a branch of physics that studies how electromagnetic (EM) waves propagate through space. A radio wave is an EM wave with electric fields and magnetic fields oscillating at right angles.

Radio waves are used for communication from point to point by various methods. The most common way is sending out an RF signal from a transmitter, which produces a changing magnetic field at the antenna, creating an EM wave in the antenna cable (commonly called feed line).

Antenna theory can be divided into three main categories:

  • Transmitting antenna theory - Explains how to send out signals through an antenna
  • Receiving antenna theory - Describes how to receive signals through an antenna
  • Directional antenna theory - Illustrates how to use an antenna to direct a signal in a particular direction

Antenna Efficiency

Antenna efficiency is the ratio of power delivered to a receiver on an antenna to the power that would have been delivered if no antenna were present. It is expressed as a percentage. Antenna efficiency gets its name because it is the ratio of power reflected or absorbed by an antenna compared with what would have been reflected or absorbed if no antenna was present.

Antennas are designed to maximise their ability to reflect or absorb electromagnetic energy. Antenna efficiency measures how well an antenna radiates or absorbs electromagnetic energy. It also affects how well a given wireless device will perform in terms of range, signal strength, and reliability.

This metric ranges widely across different antennas. Make sure you understand what type of antenna you are using and how that affects its performance before buying one for your wireless devices.

Antenna Types

Wire antennas

Wire antennas are the cheapest and easiest to build but also the most prone to breakage. This can be dangerous because the antenna could be damaged without you noticing.

Tuned antennas

This antenna is constructed from several lengths of wire or metal rods tuned to resonate at different frequencies. Tuned antennas are used in shortwave communication and long-range radio transmission.

Aperture antennas

Aperture antennas are used to facilitate radio communication. They are mainly used in the military and communication industry because they are very effective and efficient. An aperture antenna is a multi-element directional antenna with a large opening in the centre. It works by directing radio waves to a specific location.

Aperture antennas are generally composed of several elements, each having a unique function. The primary purpose of these antennas is to transmit and receive signals from different directions simultaneously.

Fixed versus movable aperture antennas

There are two types of aperture antennas: fixed aperture and movable aperture. Fixed aperture antennas have a permanent structure for mounting on the vehicle or structure. They also perform well in inclement weather conditions like rain, snow, and fog.

These antennas can be installed permanently on any surface, such as roofs or poles, and can be easily removed from these surfaces once they have served their purpose.

Movable aperture antennas don't need any installation process or maintenance requirement. They can be easily moved around according to the needs of users who want to use them. You can use them in places with no visible mounting structure.

Reflector antennas

The reflector antenna is the most common type of antenna and is found in both vertical and horizontal polarisations. It's used for point-to-point transmissions as well as line-of-sight applications.

A typical reflector uses an L-shaped metal frame to support the wire, which may be parabolic or elliptical. The reflector can be made from metal, fibreglass, ceramic, or plastic.

The surface area of its reflector is usually tiny compared to an omnidirectional antenna, but it provides more gain than a simple dipole. This makes them ideal for point-to-point applications such as voice communications over distances of up to about a kilometre (0.62 miles).

Reflector antennas are also used in some handheld radios because they don't require as much space on a vehicle's dash and are less likely to interfere with other devices around you while driving.

Lens antennas

These antennas come in an array of shapes and sizes, but they all have a round lens-shaped element focusing on radio waves. They're also straightforward to manufacture because they can be made from readily available materials.

Parabolic antennas

These antennas have one significant advantage over lens antennas: they can be made very large, which allows them to be installed on tall towers. However, they only work best when receiving signals from long distances away. It takes a bit longer for the signal to get to the antenna.

They are not very useful in close-range situations like domestic communications or military applications where you must communicate within a few miles of your location.

Folded dipole antennas

Folded dipoles are the most common antenna design. They're straightforward to build and tune, so they're often used as a first step in learning how antennas work. The folded dipole consists of two conductive elements that are connected by a transmission line.

The elements are oriented so that their fields cancel each other, resulting in no net power radiating from the antenna. If you imagine a diagram of a folded dipole with all of its fields going into one plane, you'll see that it looks like an upside-down "U" shape.

This antenna has no net radiation pattern and is not sensitive to phase shift. It's ideal for low-powered transmitters where phase noise isn't an issue. It also works well with many feed lines because it doesn't require any tuning.

Microstrip antennas

Microstrip antennas have very small bandwidths and are often used in high-frequency applications, such as satellite communications. The copper strip is covered with a dielectric material such as Mylar in this type of antenna.

The length of the strip is usually not more than one-quarter wavelength long. The microstrip antenna can be made very small, making it ideal for space applications.

The most common application of microstrip antennas is in satellite tracking and navigation systems. These systems use multiple antennas at different frequencies to locate and identify satellites.

You can calculate the exact location of each satellite by correlating the signals received from all antennas. Microstrip antennas are used in cellular phones and radar systems because they have very low loss characteristics, even at high frequencies.

Array antennas

Array antennas are the most common antennas used in television and radio broadcasting. They are also used in satellite communication systems, microwave relay systems, cellular telephone networks, and point-to-point radio communications.

Array antennas consist of several individual antennas arranged in an array to form a single antenna. The number of elements in an array depends on the radio frequency's wavelength.

Higher frequencies require larger arrays, but smaller arrays can be used as the frequency decreases. The number of elements you must use is determined by the number of wavelengths the antenna system must cover.

Loop antennas

Loop antennas are the simplest type of antenna, consisting of a wire loop with a length dependent on the frequency of the radio waves. The antenna can be made from copper or aluminium and can be as simple as a straight wire or as complex as an array of metal rods or loops.

The most common loop antenna type is the half-wave dipole, constructed using two identical wires connected at one end and spaced 180° apart at the other. This configuration has radiation patterns similar to the short section of the half-wavelength monopole but with more gain in the middle part of its range.

Use a high-gain antenna like a half-wave dipole to maximise gain. It requires less power than longer antennas to achieve comparable performance levels.

How Do Antennas Work?

Antennae are used to capture energy from a radio frequency. They are also known as receiving antennas and are commonly used in radio receivers, wireless transmitters, and wireless local area networks (WLANs).

A typical antenna will have a reflector at its base, which helps it catch more radio waves. Antennae work by converting electrical signals into radio waves and then back into electrical signals. This process is called oscillation.

Does Antenna Type Affect Signal Quality?

Your antenna type will depend on the signal strength you need and your home's location. The first thing to consider is whether or not you need a digital TV antenna. Digital TV is being phased out and replaced by over-the-air HDTV broadcasts. You will need an outdoor antenna if you have an older TV set that does not have digital tuners built-in.

An outdoor antenna has two parts: a base unit, which attaches to your roof or deck, and the antenna itself, which extends from the base unit out from your home. The base unit connects to your TV via RF coax cable and then feeds the signal into your house through the coax cable running along your roofline or decking.

An indoor/outdoor hybrid antenna works like an indoor antenna but has features that allow it to function as an outdoor antenna on some frequencies. This design allows you to receive signals from both types of antennas while still taking advantage of the benefits of both designs.

Length Of Antenna

The length of an antenna is the distance between its two terminals. The longer it is, the better its performance will be. Longer antennas are more expensive, but they can also be easier to work with than shorter ones.

Antennas come in many shapes and sizes. Some are short and stubby, while other models are long and thin. The shape of an antenna affects how it works because it determines the length of each conductor that makes up the device, which affects the amount of power that can be transferred from one wire to another.

For example, a half-wave dipole antenna has two wires connecting at right angles to form a V shape. This type of antenna matches up with signals from two different directions and transfers energy from one wire to another using only one circuit.

A quarter-wave vertical rod antenna has four conductors on each side of a vertical rod with no spacing between them; this creates four separate paths for radio waves to travel through before reaching their destination.

Advantages Of Using An Antenna

  • Antennas allow TVs to receive free channels. You will be able to watch your favourite shows and movies for free. If you don't have any cable TV, then this is the best option for you.
  • It reduces the cost of cable TV. You will pay only for the channels you want to watch without any extra charges or hidden fees. This is one of the best means to save money on your monthly bills. You don't need to pay extra monthly just because your cable service provider charges you more than those without cable TV services.
  • There are copious options available on the market when choosing between antennas and cables concerning reception quality. Find an antenna that works best for you.

Disadvantages Of Using An Antenna

  • You need a clear line of sight to the signal generator. Antennas are not the best to have in urban areas where trees and buildings can cause obstruction.
  • If you have any metal objects or metal-clad walls in your living room, the cable will pick up noise from them, causing interference with your TV signals. This can cause picture quality problems.

Contact An Antenna Expert Today

If you want to guarantee that you get the most from your antennae, get in touch with an expert who will survey your location and ensure you get the best reception on all your devices. Some people opt to make their antennas but having someone who is an expert in this field will, in the long run, be cost-efficient, and you will get the best service out of your antennae!

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