Antenna Theory - Micro Strip

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 applications at frequencies above 100MHz.

Construction & Working of Micro strip Antennas

Micro strip antenna consists of a very thin metallic strip placed on a ground plane with a di-electric material in-between. The radiating element and feed lines 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.

Micro Strip 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.

Board Radiation Pattern

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

Applications

The following are the applications of Micro strip antenna −

  • Used in Space craft applications
  • Used in Air craft applications
  • Used in Low profile antenna applications