Technology

Understanding Microwave Antennas

An antenna is a device that is made to efficiently radiate and receive radiated electromagnetic waves. An antenna is an electrical conductor or can be a system of conductors. The antenna can collect electromagnetic energy from space and radiate electromagnetic energy back into space. Sometimes the same antenna can be used for both transmission and reception.

 

The polarization of an antenna is the orientation of the electric field in regards to the earth’s surface and is determined by the physical structure of the antenna and how it is oriented. The radio waves from a vertical antenna will be vertically polarized and waves from a horizontal antenna will be horizontally polarized.

 

There are many different types of microwave antennas. Let’s take a look at a few of the different kinds:

 

  1. Horn– Horn antennas have a wide impedance bandwidth. This implies that the input impedance varies slowly over a wide frequency range. There is often a directional radiation pattern with a high antenna gain. They are very popular at UHF (300 MHz-3 GHz) and higher frequencies. The physical size of the horn antenna is fixed.
  2. Parabolic – Parabolic is also known as the satellite dish antenna. They have a very high gain and low cross polarization. The bandwidth is reasonable, and depending on the size of the dish it can be very wide band.
  3. Slot– A slot antenna is a metal surface with a hole cut out of it. They are widely used in radar antennas for the sector antennas used for cell phone base stations.
  4. Dielectric – In the rod of the antenna a surface wave is generated and propagates along the axis of the rod. The lower the phase velocity, the greater the length of the rod will be. Dielectric antennas are used mainly in aircraft radio equipment, which operates on decimeter wavelengths.

 

There are different parts to the antenna, which feed the radio waves to the rest of the structure. Or in receiving antennas collect the radio waves that are coming in and convert them to electric currents and transmit them to the receiver.  If you are having a problem with the efficiency of your antenna it is possible that you may have a sub reflector or supporting structure blockage. You would also want to check the power in your side lobes.

 

If needed there is kit on the market that allows for you to path align your microwave antenna in easily, in mere minutes. The alignment system can help you accurately align point-to-point, short-haul, and long-haul links. With no added software, post processing, or cables – the system is able to calculate exact alignment requirements automatically in real time and helps to provide the user simple targets for giving the link a path.