Various RFICs integrate differential ports in receiving and sending RF power today. Therefore, the integration of balanced antennas has become a good proposition. The antenna is crucial for ensuring communication between devices. It receives and send signals to indicate some details.
Germans invented the first antenna in 1888. Then, these antennas were integrated to enable wireless communication. These antennas were capable of transmitting both radio and microwave signals. There are various types of antennas and these antennas are classified according to their application like lens, wire, array, log periodic, reflector, aperture, traveling wave, and microchip. Therefore, it is important to understand how each antenna works and the functions they serve in suitable applications.
To this cause, we will be discussing one of the types of antenna known as dipole antenna.
What is a PCB Dipole Antenna?
A PCB dipole antenna is a Radiofrequency antenna with two conductive elements like rods in which the length of metal wire is half of the highest wavelength at the operation of frequency. An insulator known as the antenna section separates the conductive materials at center of the antenna.
A dipole antenna is also referred to as a dipole aerial or doublet. This antenna is the most commonly used antenna. The word ‘dipole’ refers to ‘two poles’. Therefore, the dipole antenna comprises two conductive elements. The middle of the antenna has an RF voltage source and then the current & voltage being supplied all through the conductive elements produce a radio signal which radiates outside the antenna.
At the dipole antenna’s ends, the current is minimum and the voltage is maximum.
PCB Dipole Antenna Design
There are two conductive elements in a dipole antenna. These elements functions like rods and wires or wires in which the radiating sections and the feeder at the center are on either side. The length of the metal wire is ½ of the maximum wavelength. An insulator splits the conductive elements in the middle into two areas.
These areas are linked to a feeder or a coaxial cable at the antenna’s middle. The wavelength describes the distance between two lowest or highest points. There are several characteristics of the antenna that determine the length of the radiating element. Some of these characteristics include feed impedance and center operating frequency. The dipole’s length is a significant property in a dipole antenna.
You can use any antenna option for receiving or sending signals. However, in different wireless applications, you can activate the antenna in between the receiver and the transmitter.
Dipole antenna transmitter
The dipole antenna produces the radio waves at the transmitter area. The antenna is provided with a voltage at the desired frequency. Therefore, there will be electric waves and magnetic waves due to the voltage across this antenna’s conductive elements and the flow of current.
An antenna transmitter is a basic element created with the help of a conductor. In this aspect, where there will be fluctuation of the current and change in RF radiation, the conductor transmits an electric current.
Dipole Antenna Receiver
A little voltage will be triggered due to the flow of electromagnetic wave over the dipole antenna in the receiver area. Therefore, the antenna will be the signal source for the receiver’s input.
A dipole antenna receiver carries out the opposite operation of the transmitter. It gets RF radiation and then transforms it into electric currents within a circuit linked to the antenna.
The Working Principle of the Dipole Antenna
Voltage and current flow all through the conductive elements of the dipole antenna can produce a radio wave or electromagnetic signal radiated outside. This occurs once the source of the RF voltage is integrated to the center of the two sections in the dipole antenna.
At the antenna’s center, the current is maximum while the voltage is minimum. In contrast, the voltage is maximum and the current is minimum at the end of the dipole antenna. The radiation pattern of the dipole antenna describes how it discharges energy into space. This pattern is simply a graphical representation of the radiation properties of the antenna.
Therefore, this antenna transforms electrical signals to radiofrequency electromagnetic signals and then discharges them at the transmitting end. After this, it transforms the RF electromagnetic signals into electrical signals at the receiving side.
Types of Dipole Antenna
There are various types of dipole antennas. Each of these antennas offer different functions and is used in different applications. Examples of dipole antenna types include short dipole, a half-wave, folded dipole, non-resonant dipole, and multiple half-waves.
Half-wave Dipole Antenna
This dipole antenna type has its dipole length half the wavelength. It is sometimes referred to as Hertz antenna. Also, half-wave antenna features a simple resonance structure. Therefore, this is integrated for transmission & receiving purposes in various applications. This antenna has an operating frequency which is between the range of 3 kHz to 300 GHz.
Half-wave dipole antenna has a lot if benefits. This antenna is lightweight and cost-efficient. Also, the input impedance of this antenna is the same as the input impedance transmission line. Despite its benefits, it has its own limitations. One of which is its independency. Therefore, this antenna can be integrated as the basic element for other antenna types that operate at very high frequencies. Half-wave dipole antenna is ideal for use in devices like television and radio receivers.
Short dipole antenna
This type of antenna features a small wavelength, hence, it is named short dipole antenna. In this antenna, an AC source feeds one end while the other end is open-circuited. A short dipole antenna has a frequency range from 3 KHz and 30MHz. Therefore, it suitable for use in low frequency receivers. This antenna’s length is smaller than the wavelength. At one end, there is a voltage source connection.
Folded dipole antenna
This type of dipole antenna is usually folded back, hence, it is called folded dipole antenna. This antenna has two half-wave dipoles in which one is split at the middle while the other one is continuous. The two are then connected and folded at the two ends in parallel. The radiation pattern of the folded dipole is similar to that of a normal dipole.
However, the input impedance is much higher. The folded dipole antenna is an ideal option due to their wide bandwidth and high feed impedance, Therefore, this antenna is independent or can be used as a part of other antennas to offer high bandwidth. Folded dipole antenna comes in three-wire and two-wire types.
FM dipole antenna
This dipole antenna type is simple to design and is cost-efficient. Therefore, this antenna is a perfect option for attic or roof space in an internal FM antenna. Also, it is suitable for use in cases where a temporary antenna is needed. Basically, an FM dipole antenna is mainly integrated in FM broadcasting in which the frequency range is within 88 MHz and 108 MHz.
Properties of PCB Dipole Antenna
Feed Impedance of PCB Dipole Antenna
The feed impedance is one crucial property of a dipole antenna. PCB dipole antenna has neither of the its two sides connected to earth and as such, it is a balance antenna. Therefore, this antenna needs to be fed with a feed system. Also, a balanced feeder could be used. Balanced feeders are integrated at HF and feature low loss levels. However, these feeders can be very difficult to manage when penetrating buildings. This is due to the fact that nearby objects can increase loss or destroy their balance,
Therefore, a coaxial cable is an ideal option. Although, it is unbalanced, it will need a balanced to unbalanced transformer. The feed impedance of the dipole antenna is another crucial factor. 73 Ω is the dipole’s standard feed impedance. However, this value is rare to see as several factors such as wire thickness and height above ground change the impedance. In free space, the impedance is 73 Ω.
Using a feed system to feed the dipole helps to achieve a maximum power transfer. Therefore, it is crucial to understand the feed impedance.
Antenna gain
The antenna gain of a dipole antenna measures how much directivity the antenna’s radiation pattern offers. Any antenna featuring high gain will radiate within a particular direction. Also, the antenna gain is reallocated to offer extra radiated power in a particular direction.
Antenna gain is usually measured in dBd and dBi. While dBd is used in measuring dipole antenna gain, dBi is used in measuring isotropic antenna gain. Make sure you check the application of a dipole antenna when measuring its antenna gain. High gain antennas offer a lot of benefits which include longer range and improved signal quality. Low gain antennas have a shorter range.
Applications of PCB Dipole Antenna
PCB dipole antennas are commonly used in several areas. They can be used independently or part of some complicated antennas. When used as part of a complicated antenna, they can serve as the radiating element. Also, the dipole antenna is used in several radio system forms from broadcasting broadcast reception to a two way radio communication. The frequency of the dipole antenna will determine the dipole construction. Some of the applications of dipole antennas include:
Part of Yagi antenna
A Yagi antenna requires a dipole antenna for proper functioning. Most times, the folded dipole antenna is often integrated since the “parasitic elements” makes the feed impedance of dipole to fall. The integration of a folded dipole improves the impedance match.
Omnidirectional vertical dipole
PCB dipole antennas are commonly integrated as a vertically polarized antenna. The dipole is vertical in such a case. This helps to offer omnidirectional coverage.
Part of a parabolic reflector antenna
A parabolic reflector antenna requires some driven element in order to enable the reflector to direct the antenna in the right direction. In this case, there are different types of radiating antenna that fits into this application. The dipole antenna is a good option.
Other applications of dipole antennas
- Dipole antennas serve as a fundamental part in complicated antennas. Also, they are utilized in several areas where they can enable the radiating element.
- Also, this antenna is ideal for use in radio & telecommunications.
- This antenna is in two-way communication, for reception and transmission.
- A folded dipole antenna can function within a Yagi-uda antenna via the balanced line.
- You can use a half-wave dipole antenna in TV & radio receivers.
- A Dipole antenna can function as a transmitting or receiving antenna since the antenna transmitter transforms electrical signals to electromagnetic and then discharges them. On the other hand the antenna receiver can help in changing electromagnetic signals to electrical signals.
- The FM dipole antenna functions as a broadcasting-receiving antenna, particularly for the FM broadcast band.
- A parabolic reflector type antenna is a type of dipole antenna commonly used in satellite communications, radio astronomy, and other radio communication connections.
- Another type of PCB dipole antenna is the VHF and UHF antennas which are primarily integrated in land mobile communication, industrial, and public communication applications.
Advantages of a Dipole Antenna
A dipole antenna offers a lot of benefits.
- They are omnidirectional during the transmission and reception of signals
- Very efficient when integrated at resonant frequency
- A dipole antenna is very simple
- The performance of this antenna isn’t affected by its gap sizes
- A dipole antenna is very easy to design and install. It allows the installation of various configurations such as drooping, sloping, and inverted V.
- It is easy to receive any signal without the need to worry about the direction.
- A loading coil can be used to minimize and resonate a dipole antenna.
Conclusion
PCB dipole antennas are commonly used in several areas. They can be used independently or part of some complicated antennas. When used as part of a complicated antenna, they can serve as the radiating element. There are various types of dipole antennas. Each of these antennas offer different functions and is used in different applications.
