Antenna Theory - Micro Strip

Micro strip antennas are low-profile antennas. A metal patch mounted at a ground level with a di-electric material in-between constitutes a Micro strip or Patch Antenna. These are very low size antennas having low radiation.

Frequency Range

The patch antennas are popular for low profile apppcations at frequencies above 100MHz.

Construction & Working of Micro strip Antennas

Micro strip antenna consists of a very thin metalpc strip placed on a ground plane with a di-electric material in-between. The radiating element and feed pnes are placed by the process of photo-etching on the di-electric material. Usually, the patch or micro-strip is choosen to be square, circular or rectangular in shape for the ease of analysis and fabrication. The following image shows a micro-strip or patch antenna.

The length of the metal patch is λ/2. When the antenna is excited, the waves generated within the di-electric undergo reflections and the energyis radiated from the edges of the metal patch,which is very low.

Radiation Pattern

The radiation pattern of microstrip or patch antenna is broad. It has low radiation power and narrow frequency bandwidth.

The radiation pattern of a microstrip or patch antenna is shown above. It has lesser directivity. To have a greater directivity, an array can be formed by using these patch antennas.

Advantages

The following are the advantages of Micro strip antenna −

Lighteweight

Low cost

Ease of installation

Disadvantages

The following are the disadvantages of Micro strip antenna −

Inefficient radiation

Narrow frequency bandwidth

Apppcations

The following are the apppcations of Micro strip antenna −

Used in Space craft apppcations

Used in Air craft apppcations

Used in Low profile antenna apppcations