Wire Antenna : Design, Working, Types & Its Applications

An antenna is a metallic device, used to transmit & receive radio electromagnetic signals, where these signals represent some information. Radios are mainly designed for wireless communication to broadcast both microwave & radio signals. Generally, antennas are available in different sizes & shapes. There are many reasons to use antennas, but the main reason is to provide a simple way to transmit signals or data. There are different types of antennas available like Yagi Uda, Aperture, reflector, wire antenna, and many more. This article discusses one of the types of antenna like wire antenna – working with applications.

Wire Antenna Definition

A wire Antenna is a type of radio antenna that includes a long wire suspended over the ground. The wire in the antenna picks up the signals & radiates them further. In this antenna, the wire antenna length has no relation to its wavelength. The wire is simply connected to the transmitter or the receiver through the tuner of an antenna to transmit or receive the signals. These antennas are well known due to their ease of installation & portability. The wire antenna diagram is shown below.

Wire Antenna Design

The construction of antennas with long wires is simple because the length of this wire antenna is multiple of λ/2. Generally, the antennas which have λ/2 or λ/4 length is known as half-wave dipole antenna. But an antenna that has greater than λ/2 length is known as a long wire antenna. So the length of an antenna with a long wire is considered as multiple of half wavelength. So, the length of the antenna with a long wire is given as (L = n λ/2).

These wires are arranged vertically or horizontally, but the direction is sometimes sloppy relating to the ground. The outside excitation to this antenna is provided throughout feed lines where the feed line is simply provided at the end, center, or anywhere in the middle of the length of the wire.

Here the wire antenna’s polarization is shown by the antenna’s direction with respect to the ground. The feed point’s position represents the lobe’s direction. In this simple wire antenna construction, a simple conducting wire is connected end to end in between transmitting & receiving stations. So, the direct long wire connection between the two ends will allow the signal from the transmitting station & radiate the signal so that it can be obtained at the remaining end.

How Does Wire Antenna Work?

The antenna with a long wire is a combination of several half-wave dipoles; so, its operation principle is the same as the half-wave dipole antenna. So the length of these antennas is greater as compared to the half wavelength. So, when a long conducting wire is simply excited by the input voltage, afterward the charge carriers will drift based on half of the applied signal. If the first half of the signal is applied, then charge carriers will experience attractive force whereas if a negative half cycle is used, then charge carriers will experience repulsion. So this charge carrier’s cumulative action in the conductor produces an unstable electric field. Therefore the signal is radiated in this way at the other end through the long wire antenna.

The antenna with long wire is more as compared to half wavelength long. When the length of the long wire antenna is increased, then directivity will also get better. It is notable in the case of an antenna with a long wire that is; for the lowest frequency of operation, generally, the length is considered as half wavelength & outside feeding is provided at the end.

Wire Antenna Types

These antennas are classified into different types and each type is discussed 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 size but basically, it is the relative wavelength. This antenna has two ends where one end is open-circuited & the remaining end is fed by an AC source. The frequency range of this antenna ranges from 3KHz – 30MHz, so it is used mostly in low-frequency receivers.

Dipole Antenna

The dipole antenna is one of the most significant forms of RF antenna which includes an electrically conducting wire otherwise rod one-half the length of the maximum preferred wavelength. The wire or rod is divided at the center through an insulator where every end at the center is simply connected to the feed line through a balun normally to a coaxial cable.

These antennas are broadly used in different radio communication. This antenna is very simple to design and it operates on the high-frequency, very high-frequency & ultra high-frequency sections of the RF spectrum. Please refer to this link to know more about Dipole Antenna.

Loop Antenna

A loop antenna is one kind of wire antenna that receives radio signals more efficiently as compared to other antennas. These are considered as more efficient antennas than other antennas because they use less electricity & work with a broad range of frequencies (300 MHZ to 3 GHz). The performance of this antenna mainly depends on different factors like design, placement, etc.

In loop antennas, the bending of the wires can form different shapes like circular, triangular, rectangular, and elliptical. These antennas are very simple, versatile & inexpensive, so used in a wide range of applications used in RFID devices for detecting the transmitter position, used as UHF transmitters, used to receive HF waves within radio receivers, etc.

Half-Wave Dipole Antenna

A type of dipole antenna where the dipole length is half of its wavelength at the operating frequency is called half wave dipole antenna. This is a very famous dipole antenna which is also known sometimes as a Hertz antenna.

This antenna has a simple resonance structure for transmission & reception applications. These are basic elements in all the antenna shapes because these antennas help is designing different complex antennas. This antenna’s operating frequency range is between 3 kHz – 300 GHz.

Half-wave dipole antennas are mainly utilized in radio & TV receivers. When these antennas are used with another type of antenna then it shows an outstanding performance.

Folded Dipole Antenna

A folded dipole antenna is one type of antenna which includes two conductors. These conductors are simply connected on two sides & folded to shape a cylindrical closed form. The dipole length is half of the wavelength. thus, it is known as half wave-folded dipole antenna. The frequency range of this folded dipole antenna ranges from 3 KHz to 300 GHz and it is the most frequently utilized by TV receivers.

Monopole Antenna

A monopole antenna is a radio transmission antenna that includes a single conductor that is normally fed at the base of an antenna through a voltage source. This antenna is a very simple and single-wire antenna that is normally mounted vertically & used normally for both transmitting &receiving signals. So these are used for broadcasting or communication purposes. Monopole antennas work at lower RFID bands (2.2 to 2.6 GHz), medium RFID bands (5.3- to 6.8 GHz), and upper RFID bands (8.7 to 9.5 GHz).

Helical Antenna

A helical antenna is one kind of wire antenna which is also known as a helix antenna because the shape of this antenna is a helix. The frequency range of this antenna is approximately 30MHz – 3GHz. So this helical antenna works in the range of VHF & UHF.

A helical antenna is used for transmitting & receiving VHF signals, used for satellite & space probe communications, and for radio astronomy, it establishes communications between the moon & the Earth. Please refer to this link to know more about Helical Antenna.

Broadband Dipoles

The broadband dipole antenna is one type of wire antenna that simply provides outstanding performance for mainly short to medium-range circuits. For short-range communication-based circuits at lower frequencies, the radiation pattern of this antenna has a high take-off angle. Similarly, for medium-range communication-based circuits at higher frequencies, the radiation pattern of this antenna has lower take-off angles.

Cloverleaf Antenna

A cloverleaf antenna is one kind of wire antenna that is polarized circularly and the radiation pattern of this antenna is the same as a dipole antenna. This antenna mainly includes a minimum of 3 or 4 frames which are connected in parallel & also twisted in a particular way to get circular polarization.

Gain of Wire Antenna

The Antenna gain is the capability of the antenna to emit less or more in any direction as compared to a theoretical antenna. This gain simply indicates how strong an antenna can transmit or receive a signal in a particular direction. The gain of the wire antenna is;

For the short dipole it is 1.5 (1.76 dBi) & for

The half-wave dipole, it is rising to 1.64 (2.15 dBi).  Click here to know more on Antenna Gain.

Advantages and Disadvantages

The advantages of wire antennae include the following.

• The construction of this antenna is simple
• These antennas provide satisfactory gain & directivity.
• These antennas have sharp directional patterns.
• These are not expensive.
• At low vertical angles, it simply focuses on radiation
• They radiate on any range of frequency for which their overall length is not below λ/2.

The disadvantages of wire antennae include the following.

• At low frequencies, the dipole antenna exhibits a large size.
• Loop antennas have poor gain, they hard to tune & are extremely narrowband.
• Helical antennas size is bulky & they are very easily de-tuned by near objects.
• Wire antennas need an appropriate matching system to have better results.
• These antennas need a matching system or tuner unit.

Applications

The applications of wire antennae include the following.

• Wire antennas are broadly used as receiving antennas on the short wave, medium wave & long wave bands.
• These antennas are used in point-to-point long-distance communication because of their simple structure.
• These antennas are used in ships, space crafts, buildings, automobiles, satellites, missiles, microwave communication & very high gain applications.

Thus, this is an overview of wire antennae – working with applications. Wire antenna examples are; dipole antenna, helix antenna, monopole antenna & loop antenna. Here is a question for you, what is the function of an antenna?