Wire antennas

An antenna is a metal device used to transmit and receive radio electromagnetic signals, where these signals represent information. Radios are mainly designed for wireless communication to transmit both microwave and radio signals. Generally, antennas are available in different sizes and shapes. There are many reasons to use antennas, but the main reason is to transmit signals or data in an easy way. There are different types of antennas available such as Yagi Uda, Aperture, reflector, wire antenna and many more.

What is a wire antenna?

A wire antenna is a type of radio antenna that contains a long wire that is suspended above the ground. The wire in the antenna receives the signals and radiates them further. In this antenna, the length of the wire antenna has no relation to the wavelength. The wire is simply connected to the transmitter or receiver through the tuner of an antenna to send or receive signals. These antennas are popular because of their easy installation and portability.

The construction of long wire antennas is simple because the length of this wire antenna is a multiple of λ/2 (lambda value). Generally, the antennas having a length of λ/2 or λ/4 are considered as half wave dipole antennas. But an antenna having a length greater than λ/2 is called a long wire antenna. So the length of an antenna with a long wire is con.

How does a wire antenna work?

The long wire antenna is a combination of several half wave dipoles, therefore the working principle is same as that of the half wave dipole antenna. So the length of these antennas is more as compared to half wavelength. When a long conducting wire is simply excited by the input voltage, then the charge carriers will move based on half of the applied signal. If the first half of the signal is applied, then the charge carriers will experience an attraction whereas if a negative half cycle is used, then the charge carriers will experience a repulsion. The cumulative action of these charge carriers in the conductor produces an unstable electric field. Therefore, in this way the signal is radiated at the other end through the long wire antenna.

The long wire antenna is longer than half wavelength, when the length of the long wire antenna increases, the directivity will also improve. It is noteworthy in the case of long wire antenna that, for the lowest frequency of operation, the length is generally regarded as half wavelength and is fed outside at the end.

The different types of wire antennas

Wire antennas are classified into different types and we will discuss each type below;

Short dipole antenna

The simple form of a wire antenna is a short dipole antenna. This is an open circuit where the signal or data is fed within the center. In this antenna, the term “short” does not refer to the antenna length but to the relative wavelength. This antenna has two ends where one end is open and the remaining end is fed by an AC source. The frequency range of this varies from 3 KHz to 30 MHz, so it is mainly used in low frequency receivers.

Dipole antenna

The dipole antenna is one of the most important forms of RF antenna which comprises an electrically conducting wire or rod which is half the length of the maximum desired wavelength. The wire or rod is divided in the middle by an insulator with each end at the middle simply connected to the feed line via a balun to a coaxial cable. These antennas are widely used in various radio communications and is very simple to design and operates in the high frequency, very high frequency and ultra high frequency portions of the RF spectrum.

Loop antenna

A loop antenna is a type of wire antenna that receives radio signals more efficiently than other antennas. These are considered more efficient antennas than other antennas because they consume less electricity and operate at a wide range of frequencies from 300 MHz to 3 GHz. The performance of these loop antennas mainly depends on various factors such as design, placement etc. In loop antennas, wires can be bent into various shapes such as; circular, triangular, rectangular and elliptical. These antennas are very simple, versatile and cheap, so they are used in a wide range of applications such as RFID devices for detecting the transmitter position, as UHF transmitters to receive HF waves in radio receivers and other applications.

Half wave dipole antenna

This is a type of dipole antenna where the dipole length is half of its wavelength at the operating frequency is called a half wave dipole antenna.