Antennas are necessary for many applications, including communication systems. Broadcasts can be transmitted at the microwave level (between 300 MHz and 300 GHz; 1 m to 1 mm wavelengths), and antennas that operate in those frequencies are called microwave antennas.
Different kinds of microwave antennas
Microwave antennas are classified according to certain specifications, including frequency, polarization, and radiation, among others. They are as follows:
- Horn antenna
- Microstrip patch antenna
- MIMO antenna
- Parabolic antenna
- Plasma antenna
As its name suggests, this antenna is shaped like a horn. In particular, its metal waveguides are shaped like a horn and there’s a reason for that: to direct radio waves in a beam. Also called a microwave horn, this is usually used at microwave and ultra-high frequencies.
A horn antenna is usually used for the following applications:
- as a feed antenna for bigger antenna structures like parabolic antennas
- as a standard calibration antenna used to measure the gain of other antennas
- as a directive antenna for devices such as automatic door openers and microwave radiometers
Advantages to using a horn antenna include a simple construction, a broad bandwidth, a moderate directivity, and a low standing wave ratio.
Microstrip Patch Antenna
Just like a horn antenna, this too looks as its name suggests. It is flat, shaped like a patch, made of metal, and will be mounted on a larger piece of metal. The combination of the two metal sheets forms a microstrip transmission line with an operational frequency that ranges between 100 MHz and 100 GHz.
This kind of antenna is advantageous because of its size, weight, and ease of fabrication. Since it doesn’t cost much to make these, they can be produced in large numbers. Given its size, this kind of antenna is mostly used in portable wireless devices.
MIMO stands for multiple inputs and multiple outputs. It is a method used to strengthen a radio link’s capacity by using many antennas to transmit and receive. For this reason, it has become an important to wireless communication standards, including WiFi.
This commonly takes the form of a dish and as such, is known by its other names: dish antenna or parabolic dish. Using a parabolic reflector, which is curved in shape, allows this kind of antenna to direct radio waves.
An advantage that this kind of antenna has is its high directivity. It sends and receives radio waves from a single direction. Since it can produce narrow beam widths, this antenna is used at high frequencies like microwave and UHF.
Instead of using metal like traditional antennas, this one uses plasma. It is capable of operating at the 90GHz frequency range, and it can be used for both transmission and reception. This is usually used in digital communications and radar systems.
Microwave antennas are important for communication, but it’s also equally important to know exactly how and where it will be used so you can pick the right antenna.