An omni antenna or omnidirectional antenna is one type of antenna that receives and transmits electromagnetic waves with a beam angle of 360 degrees perpendicular to the top.
In contrast to directional antennas, omni antennas transmit and receive electronic waves with a wide coverage area. When described, it looks like a donut. Thus, this type of antenna is more suitable for receiving and transmitting electromagnetic waves in hotspot areas.
Technically this antenna can be used or connected to several directional antennas that are used outdoors in communication systems. This includes broadcasting television and capturing or transmitting cellular telephone waves.
So far this type of antenna is better known as the best wifi antenna. This is because it is in accordance with its distinctive character. This antenna can transmit and receive electromagnetic waves in a wide range with 360 degree coverage and is only strong at the bottom. Thus, this antenna can ignore the signal or electromagnetic waves that are above it.
Under normal circumstances this antenna has a gain of 3-12 dBi. This antenna can be used to connect and transmit electromagnetic waves from one point to many points within the range of the beam area. This is because the shape of the beam is like the donut earlier.
Omni antennas are more often used for the purpose of transmitting and receiving electromagnetic waves in point to multipoint systems. The range of this antenna can receive and transmit signals as far as 1-5 km.
This signal is completely donut shaped so it only receives and radiates waves to the surrounding area within a 360 degree area. Meanwhile, the top does not receive radiation signals at all.
Another peculiarity of this omni antenna is that the antenna beam is more focused. This makes it one of the most popular antennas for transmitting and receiving wifi waves. Omni antennas are also known as wifi antennas.
As mentioned earlier, the antenna can be described as a device that functions to receive and transmit electromagnetic waves. The reception and transmission of electromagnetic waves will run depending on the frequency selection.
Thus not all antennas can receive and transmit all electromagnetic waves. In addition to having directional antennas and omnidirectional antennas, antennas also have various forms but still have the same function. The shape of the antenna can be just a cable, dipole and other shapes.
In some cases the shape of the antenna is also the same as the function of a flashlight reflector. Antenna becomes a tool to focus on a particular signal. The more precise the position of the signal receiver, the correct size and type, the stronger the electromagnetic waves that we want to receive or emit.
When it comes to choosing an antenna, there are several technical things to consider. With the more precisely measuring and adjusting to the purpose of installing the antenna, the better it will be when it will receive electromagnetic waves. These waves are then converted into electric waves, or vice versa just to emit electromagnetic waves.
Some important characteristics to consider when choosing an antenna are gain, polarization, radiation pattern and directivity. The character of the antenna is basically the same when it functions as a transmitter, receiver or when it will be used for both purposes, namely as a receiver and transmitter.
The first character of the antenna that must be considered is the problem of gain. What is gain in antenna? Gain is the ability of an antenna in terms of directing signal transmission or signal reception in a certain direction.
The measure of a gain is the decibel which is a unit of comparison. Then the second is the problem of polarization. Polarization is the direction of propagation of the electric field. The polarization of an antenna is closely related to the maximum signal transmission efficiency.
The more carefully you calculate the polarization of an antenna, the more efficient it will be when receiving electromagnetic waves. Also when sending signals or electromagnetic waves as expected.
Then, what about the radiation pattern? Antenna radiation pattern is a three-dimensional plot on the distribution of signals emitted or received by an antenna. The radiation pattern of an antenna is determined by the plane of the slice and the azimuth direction.
For example, an antenna that has a spherical radiation pattern, then the antenna will transmit signals in all directions. On the other hand, if an antenna has a strong radiation pattern only in certain directions, then such an antenna has directivity.
That way, the more specific the direction, the better the signal will be received and transmitted. That is why antennas for receiving radio waves, televisions, telescopes, waves emitted by submarines and so on, each have a different shape and character.
Omni Antenna Function
As explained briefly at the beginning, the omni antenna function or omnidirectional antenna has a beam angle of 360 degrees perpendicular. Thus the electromagnetic waves emitted by this antenna extend over a short distance.
So the function of this antenna is to serve a wide coverage area but in a short range. Since an omni antenna covers a large area, it is likely that other signals that are completely unwanted will also be collected.
Thus, the omni antenna will cause interference. However, this antenna is suitable when used for hotspot connection or known as a point to multipoint system or one point to many points.
Another function of the omni antenna is to form a direction pattern in a perpendicular plane. Therefore, this antenna will be effective when used for wireless telephone systems or limited television broadcasts.
The gain of this antenna is in the range of 3-12 dBi with a maximum range of five kilometers. With a horizontal radiation pattern, this antenna covers a wide area but only at the bottom. While at the top it is not covered by radiation from this type of antenna.
The vertical polarization of this antenna will cause the transmitted signal to be limited. Because of the unique radiation pattern and polarization pattern of the omni antenna, why can it reach around a large area but only occurs at the bottom.
In addition to receiving and capturing cell phone signals, limited television broadcasts, this antenna is also suitable as a wifi antenna.
Assembling an Omni Antenna
Assembling or making an antenna of this type is not too difficult. By using simple equipment, as long as you can calculate carefully. especially considering the problem of the distinctive character of this antenna which concerns the problems of gain, radiation pattern, directivity and polarization, will produce this antenna perfectly.
The materials needed to make this antenna include:
- 1 inch PVC pipe that matches the antenna elements
- 1 inch PVC pipe cover two pieces of pipe clamps 2 pieces
- Bolts to taste
- Email wire diameter 1 mm
- Plastic foam to taste
How to make this antenna is to first attach the N-connector to the 1-inch pipe cap. This part will be installed at the bottom. Make a circle of plastic foam that is split open. This part of the foam will serve as a support for the enamel wire so it doesn't bend, then install the plastic foam. Insert the enamel wire into the plastic foam stored in the pipe.
The next step is to connect the lower end of the wire to the inner N-Connector by soldering it. Then install the two pipe caps. After that, prepare the clamps.
Use an insulating material that is strong when installed outdoors. Attach the clamp to this antenna and attach it to the mast. Technically the omni antenna is complete and can be used.