This article will look at how to build a dipole antenna for the HF, VHF, and UHF bands.
A dipole antenna is an effective and powerful antenna that provides a great performance level when erected or installed as high as possible- where it can’t be affected by obstructions.
Dipoles are not hard to construct. In fact, they are one of the easiest antennas to build and erect for HF radio bands, such as 10, 15, 20, 40, 80, and 160 meters, to achieve top-quality and improved performance levels.
The implementation and construction of a dipole antenna are easy and straightforward. Thanks to the basic calculations involved.
What is a dipole antenna?
A dipole antenna is an important antenna element or component of broadcasting, 2-way radio communications, radio reception, and other radio communication forms.
The name ‘dipole’ means the antenna is made up of two conductive elements.
Since current flows through these elements, the current alongside the associated voltage results in a radio wave formation, commonly known as an electromagnetic wave.
This wave then radiates towards the outside from the antenna.
There are various types of dipole antenna. These are half-wave dipole antennas, multiple half-wave dipole antennas, folded dipole antennas, non-resonant dipole, and short dipole.
Among the 5 dipole antennas listed, the most popular dipole antenna used in radio receivers is the half-wave dipole.
The name “half-wave dipole” was coined from its length. The length of this dipole matches with an electrical half wavelength.
A half-wave dipole antenna can easily function around a frequency range of 3 kHz to 300 GHz.
It can be used as radio and television receivers as it provides better-quality reception of Very High-Frequency FM broadcast.
Cost of a dipole antenna
The half-wave dipole antenna, which is sometimes called the DIY dipole antenna, is easy and affordable to build.
With the use of a few basic items or tools which can be purchased or acquired at pocket-friendly prices, excellent performance is guaranteed.
Most times, the components needed to build a dipole can be extracted or retrieved from old antennas. You can also get them from online and physical stores.
The average minimum cost of building a half-wave dipole antenna is between $12 and $20.
Tool list: How To Make A Dipole Antenna
Below are the basic DIY tools or components you need to build a dipole antenna that can guarantee a top performance level.
- Antenna wire
- Power drill
- Wire stripper
- Soldering iron or gun
- Tape measure
- Hack saw
- Nut driver
Step By Step Guide on How To Build A Dipole Antenna
If you plan to design, build, or construct a dipole antenna yourself, the following are steps you can take to create an antenna that can function on the High Frequency (HF) bands.
- Gather the necessary tools and materials needed for construction.
- Build the two separate sides of the dipole and ensure both sides are extended to the same length. Make use of your tape to measure the length and confirm they are equal.
- Choose the right wire for construction. The antenna wire is one of the most important aspects of dipole antenna construction. Although you can make use of the regular insulated copper wire, they are not the best option. Insulated copper wires are known to stretch easily once a strain is placed on them. This increases the antenna’s length over time.
Instead of using a normal insulated copper wire, go for a hard-drawn copper wire instead.
The hard-drawn copper wire is not as flexible as the insulated copper wire- so it doesn’t stretch too much when strained.
The low level of flexibility the hard-drawn copper wire possesses is not a problem during installation since the wire is not expected to stretch too much.
- Make sure you place an insulator at both ends of the dipole antenna. Make use of high-power transmitters to enhance the potential and effectiveness of your antenna. Make sure the wire is connected firmly to the insulators at both ends of the antenna and, in turn, attach the insulators to a nylon rope.
- Prepare the antenna bracket plate. This component allows easy mounting of the antenna to the pole, mast, tree, or whatever high point you choose for installation.
- Pay attention to the feeder. Choose the perfect cable option for your antenna. The most popular and recognized feeder is coax cable. This cable is durable and not difficult to use. This cable’s durability and sturdiness ensure it is not affected or damaged by nearby objects while extending it into the house.
- Connect the open-wire feeder or coaxial cable to the dipole center. This way, the feeder won’t take the strain that is caused as a result of the tension on the antenna wire. The feeder will be protected from avoidable damage, thereby ensuring it last for an extended period.
A balun can be positioned or attached to the feed point of the dipole.
The balun’s main function is to act as dipole centers, thereby providing strain relief and connect both radiating legs of the dipole antenna to the coaxial feeder.
- Connect a pulley at the end of the dipole antenna. This makes it easier to lift and lower the antenna in case of modifications, tuning, or maintenance.
- Choose a mounting point. A dipole antenna can be installed or mounted on any high point around your house or garden. The popular installation points are pipes and trees. If you want to use a tree as the anchor point, make sure you consider how you keep the antenna wire in place during tree movements, especially when there is a strong wind to avoid damage to the wire.
Maintenance Tips For Dipole Antenna
This section will look at the necessary precautions that you need to follow when building a dipole antenna for radio applications.
- During installation or mounting of the dipole antenna, make sure you keep it away from objects that are made from metal. Metal objects lower the signal levels. Normally, either end of the dipole antenna is very sensitive to metal objects that are close by.
- While trying to attach or connect the antenna wire to the insulator using the mechanical means, make sure the wire is taken through the insulator, have it wrapped, and then have the wire soldered around itself.
- While cutting the wire needed for the antenna, do not forget to add extra to the required length. This allows easy connection to the insulator and dipole centerpiece.
- Make sure the antenna is erected or mounted as high as possible. The higher the antenna, the better the performance. Placing the antenna higher than the surrounding objects eradicates any form of obstructions or competition for signals. In this case, the antenna will receive and transmit the signal better and clearer.
- Make sure you study your environment before the installation. A little planning and foresight will ensure you make the best decision when it comes to installation. For example, look out for items, objects, or equipment that could affect the reception and transmission of signals and find a way to keep the antenna clear of those objects.
- You must understand that a dipole is a balanced antenna. The two sides or parts of the antenna are not connected to the earth. What this means is that the antenna must be fed with the aid of a balanced feeder.
- While feeding the dipole antenna with a feed system or balanced feeder, make sure it has the right impedance. The right impedance allows maximum transfer of power. So, it is important to understand the feed impedance.
- Check for exposed electrical connection. In case you find any, insulate with tape or liquid tape.
- If you are going to make use of coaxial cable, make sure you seal the top end. When the top end is left uncovered, moisture can easily penetrate, leading to decreased performance. In case you don’t know, the cost of purchasing coaxial cables is a bit costly. When the performance is affected or degraded, you will need to replace this component.
Allowing the water in the cable to dry out won’t correct the damage that has already taken place.
This is because the absorption of moisture would have resulted in the braid screen’s oxidation, which increases the loss in performance quite fast.
The advantages-disadvantages of a dipole antenna
- A dipole antenna provides an excellent option for several amateur radio applications
- When installed or erected correctly, a dipole antenna can provide excellent performance at a pocket-friendly price
- A dipole antenna is easy to build and erect for the HF amateur radio bands
- The tools, materials, components, or parts needed to build a dipole antenna are readily available
- When used at the right frequency, dipole antennas are really efficient
- Little directionality
- Can’t withstand obstructions which may lead to signal disruption
- In a situation when the frequency is less than 27 Mhz, a decrease in the antenna length may lead to a fall in the level of efficiency
- Building a folded dipole is stressful and more complicated than a monopole antenna
Related FAQs About How To Build A Dipole Antenna
What determines how a dipole is built?
The construction of a dipole antenna depends mainly on two factors. These factors are the frequency and how you intend to make use of the antenna.
What are the benefits of building a dipole antenna?
When you build and erect a dipole antenna yourself, it gives you a distinct insight into how an antenna works. This way, you can improve the performance of the station over time.
What is the easiest way to install a dipole antenna?
Although there are several ways to mount your dipole antenna after construction, positioning it horizontally is the easiest.
Where can dipoles be erected?
For reliable and adequate support, the most appropriate point for dipole installation includes the house and the garden.
You can fasten the dipole to the chimney or pole in your house or even attach it to a tree.
The good news is that a dipole can be erected in several other places, preferably any high point or areas around you.
What can I do to protect my dipole from being damaged by the wind?
Suppose you live in a windy environment and plan to erect or mount your dipole antennas on a tree.
In that case, it is important to ensure that the antenna wire is not too tight.
In a situation where the antenna wire is extremely tight, the wire could break when the tree moves back and forth in the case of a strong wind.
What are the things to consider when calculating the length of the HF dipole antenna?
There are several things to put into consideration when calculating the length of a dipole antenna.
Most importantly, you need to consider the closeness to other objects to avoid obstructions. You also have to consider the local weather conditions.
This is why it is always advised that the length should be longer than the actual measurement while cutting the antenna.
If needed, it can be eventually trimmed to provide top-quality performance.
Can a dipole antenna function without a balun?
A dipole antenna will function without the use of a balun. This doesn’t take out the importance of a balun in building a dipole antenna.
A balun prevents obstructions or interference by televisions and other forms of radio devices that are near.
What should be the overall length of a dipole antenna?
A dipole antenna should have a total length of about 1.5 meters. That is about 0.75 meters for each leg.
In a situation where the resonant frequency is expected to be higher, you can shorten the antenna a bit.
This article discussed how important the dipole antenna is in the transmission and reception of radio signals.
While the FM dipole antenna is mainly used as a receiving antenna for FM broadcast band between 88 MHz and 108 MHz, the Very High Frequency and Ultra-High Frequency dipole antennas are commonly used in industries, public communication, public safety, and in coastal areas to enhance land mobile communication.
When a dipole antenna is erected rightly- free from obstructions and as high as possible, the performance is efficient for a very low cost.
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