Introduction to FM Radio Dipole Antenna | FMUSER BROADCAST

In radio broadcasting, you can see that FM dipole antenna is adopted in many pieces of equipment. It can be used alone or combined with other FM antennas to form an antenna array. It can be said that the FM dipole antenna is one of the most important types of FM antenna. Therefore, it is very important to have a basic understanding of FM dipole antenna. This article will make a basic introduction of FM dipole antenna from the introduction of an FM radio dipole antenna, the working principle of an FM radio dipole antenna, the type of dipole antenna, and how to choose the best FM dipole antenna.


Interesting Facts of FM Dipole Antenna

In the field of radio and telecommunications, the FM radio dipole antenna is the most widely used and simplest type of FM antenna. Most of them look like the word "T", which is composed of two conductors with equal length and connected end-to-end. And they are connected by cables in the middle of the dipole antenna. FM dipole antenna can be used alone or form a more complex antenna array (such as Yagi antenna). 


FM radio dipole antenna can work in HF, VHF, and UHF of the frequency band. Generally speaking, they will be combined with other electronic equipment to form a complete component. For example, an FM radio dipole antenna will be connected with an FM broadcast transmitter to form a complete RF transmitting equipment; At the same time, as a receiver, it can be connected with receivers such as radio to form a complete RF receiving equipment.


How does FM Dipole Antenna work ?

We already know that the name "dipole" means that the antenna has two poles, or consists of two conductors. FM radio dipole antenna can be used as a transmitting antenna or receiving antenna. They work like this:


  • For the transmitting dipole antenna, when the FM dipole antenna receives an electrical signal, the current flows in the two conductors of the FM dipole antenna, and the current and voltage will produce electromagnetic waves, that is, radio signals and radiate outward.

  • For the receiving dipole antenna, when the FM dipole antenna receives these radio signals, the electromagnetic wave in the FM dipole antenna conductor will generate electrical signals, transmit them to the receiving equipment and convert them into sound output.



They work in different ways, their principles are basically similar, but the process of signal conversion is reversed.

4 Types of FM Dipole Antenna

FM dipole antennas can generally be divided into 4 types, they are with different characteristics.


Half-wave dipole antenna

The half-wave dipole antenna is the most widely used one. It is composed of two conductors with a length of one-quarter of the wavelength connected end to end. The length of the antenna is slightly shorter than the electrical half wavelength in free space. Half-wave dipoles are usually center-fed. This provides an easy to manage low impedance feed point.


Multi half-wave dipole antenna

It is also possible if you want to use multiple (often more than 3, and an odd number) half-wave dipole antennas. This antenna array is called Multi half-wave dipole antenna. Although its radiation mode is quite different from that of the half-wave dipole antenna, it still operates effectively. Similarly, this type of antenna is usually center-fed, which again provides low feed impedance.


Folded dipole antenna

As the name suggests, this form of FM dipole antenna is folded back. While still retaining the length between the two ends of the half-wavelength, it uses additional conductors to connect the two ends together. Such a folded dipole antenna can provide higher feed impedance and wider bandwidth.


Short dipole antenna

The short dipole antenna is an antenna whose length is much shorter than that of the half-wave, and the antenna length is required to be less than 1/10 of the wavelength. The short dipole antenna has the advantages of short antenna length and high feed impedance. But at the same time, due to its high resistance, its working efficiency is much lower than that of an ordinary dipole antenna, and most of its energy is dissipated in the form of heat.


According to different broadcasting radio requirements, different FM dipole antennas are optional to meet the various needs of broadcasting.


How to Choose the Best FM Dipole Antenna ?

You need to consider these factors when choosing an FM dipole antenna to build your own radio station.


The Working Frequency

The working frequency of the FM dipole antenna you use should match the working frequency of the FM broadcast transmitter, otherwise, the FM dipole antenna can not transmit the radio signal normally, which will cause damage to the broadcasting equipment.


Sufficient maximum borne power

Each FM radio broadcast transmitter has a maximum borne transmission power. If the FM dipole antenna can not bear the transmission power, the FM antenna can not work normally.



VSWR reflects the efficiency of the antenna. In general, a VSWR below 1.5 is acceptable. A too high standing wave ratio will damage the transmitter and increase the maintenance cost.



FM radio antennas are divided into two types: omnidirectional and directional. It determines the direction of the most concentrated radiation. FM radio dipole antenna belongs to an omnidirectional antenna. If you need a directional antenna, you need to add a reflector.


These are the main factors to be considered in selecting an FM dipole antenna. If you still don't understand, please tell us your needs, and we will customize a professional solution for you. Please feel free to contact us!



How to calculate the length of the FM dipole antenna ?

Some dipole antennas can adjust the working frequency of the dipole antenna by adjusting the length of the conductor. The conductor length can be calculated using this formula: L = 468 / F. L is the length of the antenna, in feet. F is the required frequency, in MHz.


What should I pay attention to when installing FM dipole antenna?

Pay attention to 3 points when installing FM dipole antenna:

1. Install your dipole antenna as high as possible without obstacles;

2. Don't let your antenna touch anything;

3. Fix your antenna and protect it from water and lightning.


What are the different types of FM dipole antennas ?

There are four main types of FM dipole antennas:

  • Half-wave dipole antenna
  • Multi half-wave dipole antenna
  • Folded dipole antenna
  • short dipole 


What kind of feeder is the best for dipole antenna ? Which feeding method is best for dipole antenna ?

The dipole antenna is a balanced antenna, so you should use a balanced feeder, which is true in theory. However, a balanced feeder is rarely used because it is difficult to operate in buildings and is only applicable to the HF band. More coaxial cables with balun are used.



Anyone can buy an FM radio dipole antenna and set up their own radio station. All they need is some suitable equipment and relevant licenses. If you also have the idea of starting up your own radio station, you may need a reliable supplier like FMUSER, a professional radio broadcasting equipment supplier. We can provide you with high-quality and low-cost radio broadcasting equipment packages and solutions, and help you finish all the construction and installation of the equipment until all of the equipment can work normally. If you need to purchase an FM dipole antenna and set up your own radio station, please feel free to contact us. We are all ears !

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