omni antennas

Basic Information on Isotropic and Omni Antennas

Antennas serve as the first receiving point and the last exit point in a satellite transmission system. They can transmit and receive from all directions (these are known as omni antennas) or in a particular direction (like those used in television broadcasting).



Antenna Basics

An isotropic antenna is a hypothetical antenna. It emits the same radiation in all radiation – uniform radiation in short. A directional antenna can radiate or receive electromagnetic waves from certain directions, with some directions better than the others. Omni antennas can radiate or intercept electromagnetic fields fairly well in horizontal directions.



Isotropic Antenna

Although defined as an ideal antenna that can radiate uniformly in all directions, there is no actual physical example of this. It has a three-dimensional radiation pattern, which simply means that it has a 360-degree beam width both in the vertical and horizontal direction. It is also defined as an ideal antenna that can radiate across all directions and has a gain of 1 (0 dB), meaning zero gain and zero loss.


With that, it is used as a reference antenna for antenna gain, one of the characteristics of antennas. The unit used to measure antenna gain is called dBi, which stands for decibels over isotropic. It is calculated by dividing the power in the strongest direction by the power that would be transmitted by the antenna that is emitting the same total power.



Omnidirectional Antenna

An omnidirectional antenna can receive signals of equal quality from all directions, similar to an isotropic antenna. This is in contrast to directional antennas, which are better at receiving signals from a particular direction. Having this kind of quality has its advantages, including the ability to detect signals that are weaker or somewhat distant – something it does better than an omni antenna. However, being able to do so leaves such an antenna unable to pull in signals from other directions.


Although the use of the prefix omni indicates that the antenna can receive signals from any direction, the truth is that such antennas are omnidirectional on just one plane. Put simply, an omni antenna can detect signals from the northern, southern, eastern, and western portions of its location but it can’t do so from above or below.




Given its spherical radiation pattern, omni antennas can be used for a variety of applications. They are widely used for radio broadcasting and in mobile devices that make use of radio. Examples of the latter include cellular phones, cordless phones, FM radios, GPS, walkie-talkies, and wireless computer networks.


Omnidirectional antennas are also used by base stations that need to communicate with mobile radios. Examples of these include dispatchers for the police and taxis, as well as aircraft communications.


Omni antennas are not difficult to install. Since it covers a 360-degree horizontal pattern, this type of antenna can be mounted from a ceiling in an indoor environment in an upside down position.


While omnidirectional antennas certainly have advantages over the directional variety, it’s still best to determine the type to use after a proper site survey.




RF Engineering and Energy Resource have 20 years of experience building products domestically and abroad. We’re located in Portage Michigan and we’re happy to offer our services here and to the surrounding areas: Kalamazoo, Portage, Scotts, Fulton, Vicksburg, Schoolcraft, Mattawan, Delton, and Battle Creek

microwave antenna

Why Are Microwaves Used for Satellite Communication?

What would we do without television or the internet? How can one relax after a stressful day at work without the television? How can one catch up with friends and family or binge-watch that latest series on streaming services without the internet?


All of the activities mentioned above require communications satellites. These satellites make use of different radio and microwave frequencies to transmit and receive data. This article concerns the latter and why it is used for satellite communications.


To be clear, the microwave antenna isn’t the only antenna used for satellite communication.



Microwaves in Satellite Communication

Microwaves are used for their smaller wavelength, which allows antennas to point them directly at a receiving antenna. This feature makes it possible for different microwave equipment to use the same frequency but never interfere with each other.


Another reason for the use of microwaves is their high frequency, which allows them to carry huge amounts of information.


Microwave transmission is carried out with the help of microwave antennas, which are deployed in either of the following radio bands:


  • C band – 4 to 8 GHz
  • X band – 8 to 12 GHz
  • Ku band – 12 to 18 GHz
  • K band – 18 to 26.5 GHz
  • Ka band – 26.5 to 40 GHz
  • Q band – 33 to 50 GHz
  • W band – 75 to 110 GHz


Microwaves are best suited to communicate with geostationary satellites since they have a higher frequency and small wavelength. They are not the best for communication with satellites in low orbit.


Satellites emit microwaves with wavelengths between 1 and 10 cm. The dishes that emit the wavelengths have a larger diameter. This doesn’t produce wide diffraction, therefore, emitting a narrow beam which doesn’t spread out.


Given that, it follows that both transmitting and receiving dishes need to be aligned with one another. You can find a working example of this in a neighborhood with many satellite dish subscribers. If you take a close look at each of the dishes, you’ll find that all of them are pointed in the same direction.




Satellites in geostationary orbit are useful for communications since a microwave antenna can be aimed at them without having to know their exact location. The first geostationary satellite was used to broadcast the 1964 Summer Olympics. Major broadcast television networks have also made use of geostationary satellites to distribute programming to local affiliates. Such satellites are also used by cable TV networks.




Wireless LAN protocols make use of microwaves. If you’ve ever used Bluetooth or the WiFi then you have had experience with one of the uses of microwaves. A lot of tasks of modern living can now be done over the internet, and there’s a microwave to thank for that. Without it, buying groceries, paying bills, and booking movie tickets through smartphones and laptops won’t be possible.


Microwaves are used for satellite communication, but it isn’t the only one. A microwave antenna is used for its high frequency, which allows it to carry lots of information, and its short wavelength, which makes it easier to point directly at a receiving antenna.




RF Engineering and Energy Resource have 20 years of experience building products domestically and abroad. We’re located in Portage Michigan and we’re happy to offer our services here and to the surrounding areas: Kalamazoo, Portage, Scotts, Fulton, Vicksburg, Schoolcraft, Mattawan, Delton, and Battle Creek